Posted on by Tammy Plotner

Look Into the Cat’s Eye…

NGC 6543 Parallel - Jukka Metsavainio

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Are you ready for more stereo vision? This haunting Hubble Telescope image has been visualized for dimension by the one and only Jukka Metsavainio and gives us a look at one of the most complex planetary nebulae ever photographed. Inside NGC 6543 – nicknamed the “Cat’s Eye Nebula” – the Hubble has revealed delicate structures including concentric gas shells, jets of high-speed gas, and unusual shock-induced knots of gas… and thanks to Jukka’s “magic vision” we’re able to take a look into the Cat’s Eye as it might appear in dimension. Step inside and let’s learn more…

When Jukka produces an image, it’s more than just a clever Photoshop “trick”. Hours of study must go into each image, because the light is acting differently in each part of the nebula. To make these images work correctly, Jukka must understand which stars are causing the ionization, which stars are nearer and further from our point of perspective and so on. Each type of image is totally unique and what makes dimension work for a reflection nebula won’t work for an emission nebula. Says Jukka; “To be able to make those stereo pairs, one have to learn lots of things about the targets, and beside that, study the actual image more deeply than usual. Star distances must be measured by the size and the color. For example, stars with yellowish hue must be in or behind the nebulosity, white/blue ones are front of it.”

Because dimension will appear reversed by the method you choose to use to view these images, Jukka makes two versions. The first you see at the top of the page is parallel vision – where you relax your eyes and when you are a certain distance from the monitor screen the two images will merge into one to produce a 3D version. The second – which appears below – is crossed vision. This is for those who have better success crossing their eyes to form a third, central image where the dimensional effect occurs. So, now that you understand the images are a visualization and how they are created, let’s take a parallel look…

NGC 6543 Cross - Jukka Metsavainio
NGC 6543 Cross - Jukka Metsavainio

And now it’s my turn to add a little “magic” to what you see.

Estimated to be 1,000 years old, the Cat’s Eye is a portrait of a dying star – and quite possibly an unresolved double-star system. According to research, the dynamical effects of two stars orbiting one could very well be the cause of the complicated and intricate structures revealed here – structures normally not seen in planetary nebulae. When NGC 6543 was first observed spectroscopically, it showed the presence of emission lines, an indicator of multiple stars, but also an indictor of diffuse gas clouds.

As studies progressed, more hypothesis about the NGC 6543’s structure began to emerge. Perhaps a fast stellar wind from the central star created the elongated shell… It could be the companion star is emitting high-speed jets of gas that lie at right angles to the equatorial ring… Maybe the stellar wind has carved out the inner structure of the nebula are there are more than one there? Says L.F. Miranda; “The velocity field of NGC 6543 shows the existence of two concentric ellipsoidal shells in the nebula. The two shells likely represent the inner and outer surface layers of a geometrically ‘Thick Ellipsoid’ (TE) which constitutes the basic structure of NGC 6543.”

Even more research ensued, and with it came the twin jet theory and the ejection of materials spaced over intervals of time – like cosmic smoke rings being puffed off at perfect intervals. According to Bruce Balik; “Hubble archival images of NGC 6543 reveal a series of at least nine regularly spaced concentric circular rings that surround the famous nebular core, known as the Cat’s Eye Nebula. The rings are almost certainly spherical bubbles of periodic isotropic nuclear mass pulsations that preceded the formation of the core. Their ejection period is consistent with a suggestion that quasi-periodic shells are launched every few hundred years in dust-forming asymptotic giant branch (AGB) winds but not consonant with the predictions of extant models of core thermal pulses (~105 yr) and surface pulsations (~10 yr).”

To be sure, there are simply a lot of things that we don’t know or understand about the Cat’s Eye Nebula just yet. It is possible that magnetic activity somewhat similar to our own Sun’s sunspot cycle, could be at work here. Says Dr. Balick; “What do the rings imply? Since they’re larger than the bright cores of the nebulae that they surround, the rings are almost certainly material ejected episodically before the main and bright core of the nebula formed. This means that the start that ejected the nebulae first quivered and shivered and made these concentric rings. Then something big happened, and the density and mechanism for ejecting the mass changed abruptly. This is when the core of the nebula was formed, typically between 1000 and 2000 years ago. The rhythmic ringing of a dying star is expected as the last of its nuclear fuel is suddenly triggered into ignition by the increasing crush of gravity — much like the juice ejected by squeezing an orange with increasing force. Each expulsion of juice temporarily relieves the internal pressure inside the orange. Similarly, each ejection of mass temporarily stops the combustion of the final dregs of the star’s remaining fuel. Why should the pattern of ejection mass change so radically and strongly? We can only conjecture. Its possible that an orbiting star or giant planet falls onto the dying star. It hits the surface with such force that its atoms ignite in a large conflagration. Somehow, the burst of heat drives the remnants of the dying star into space in fantastic patterns.”

And we looked right into its eye…

My many thanks once again to Jukka Metsavainio of Northern Galactic for his artistry and we look forward to the next installment!

Posted on by Tammy Plotner

Weekend SkyWatcher’s Forecast – February 6-8, 2009

Greetings, fellow SkyWatchers! For some parts of the world, baby? It’s cold outside… But those -23C temperatures haven’t kept some of us from chasing Comet C/2007 N3 Lulin and just knowing a few bright stars and having a pair of binoculars is all it takes for you to spot it, too! Or maybe you’d just like to spot the ISS? If skies are clear, why not spot the Moon and where SMART-1 did some imaging? Better yet, how about spotting a bright star to learn about – or a fantastic lunar impact crater? If you’re ready to see some “spots”, then grab your observing equipment and meet me outside…

salyutFriday, February 6, 2009 – This date marks the 1991 fiery return of the Soviet space station Salyut 7. Launched in 1982, electrical and maneuvering problems plagued the mission, but cosmonauts were able to stay on board for as long as 8 months before returning. Abandoned in 1986, equipment and supplies were transferred to the orbiting Mir. If you’d like to spot a space station like the ISS, check Heavens Above on how to get information for your area.

gassendi

Return to the Moon tonight and explore the outstanding ring of crater Gassendi on the north shore of Mare Humorum. It’s over 3.6 billion years old, and about the size of the state of Arkansas! Roughly 110 kilometers in diameter and 2,010 meters deep, this ancient crater contains a central triple mountain peak and forms one of the most ‘‘perfect circles’’ on the Moon. Lava flows have eroded Gassendi’s south wall, and its floor is covered with ridges and rilles. Look for small crater Gassendi A on the northern rim. The northwestern section of the crater wall is slightly higher, saving it from the lava that formed Mare Humorum. Look carefully at the lower southern rim to find the gap where lava spilled over the walls. It’s only 200 meters above the surface, while other areas rise as much as 2,500 meters. The fact that some parts of the rim escaped the lava is what makes this an interesting area for science!

On January 13, 2006, the Advanced Moon Imaging Experiment (AMIE) on board ESA’s SMART-1 spacecraft imaged Gassendi from about 1,220 kilometers above the surface. Previous spectroscopic studies had shown that the central peaks might have experienced their own volcanic period – earlier than the event that filled the lower floors. These ancient highland rocks may one day give us significant insight into the thermal history of the Mare Humorum impact basin and the processes that formed Gassendi. Enjoy this ancient beauty!

hugginsSaturday, February 7, 2009 – On this date in 1889, the Astronomical Society of the Pacific was born. In 1926 celebrated cosmonaut Konstantin Feoktistov, who flew Voskhod 1 and helped design Salyut and Mir, was born. Yet most noteworthy today is the 1824 birth of amateur astronomer William Huggins. By age 30, he’d built his own private observatory and through his studies made important contributions to astronomy. According to scientists Kirchoff and Bunsen, the chemical composition of minerals could be determined from their spectral signatures. The inquisitive Huggins began comparing mineral samples to the spectra of celestial objects. Although his experimental methods were crude by today’s standards, his calculations were perfect. Huggins proved the spectrum of the Orion Nebula was like that of a pure gaseous emission, while the spectrum of the Andromeda Nebula was similar to that of starlight—and this long before confirmation of its galactic nature! Huggins was also the first amateur to measure the radial velocities of stars from their spectral shifts. Although most people assume only professional scientists can make such measurements, many of today’s amateurs (unpaid, but not unskilled!) have measured spectra.

saiphTonight let’s look at a star whose radial velocity has been studied both professionally and personally – Kappa Orionis (RA 05 47 45 Dec -09 40 10). Named Saiph, it’s the often-overlooked eastern ‘‘foot’’ of Orion. According to spectral analysis, this 722 light-year distant blue supergiant is moving away from us at 21 kilometers per second.

Roughly the same type, size, and distance as Rigel, it looks far fainter. But why? Oddly enough, Saiph has an extremely high temperature, burning more than 1,500 K hotter. Near the point where helium fusion replaces hydrogen fusion, the majority of its variable light output is in the ultraviolet band. And as Huggins once said: ‘‘It is remarkable that the elements diffused through the host of stars are some of the most closely connected with the living organisms of our globe.’’

mars_meteoriteSunday, February 8, 2009 – On this date in 2001, the Sayh al Uhaymir 094 Mars Meteorite was discovered. Some space-born debris from Martian impact craters is eventually captured by Earth’s gravity. The surviving meteorites can be identified by their mineral composition, as well as from tiny gas deposits matching Viking lander samples of Mars’s atmosphere.

Tonight, aim your optics toward the Moon and study an impact crater large enough to have blasted lunar material back to Earth. Its name is Tycho… Take one glance at the lunar Southern Hemisphere, and you can’t miss the dazzling display of 85-kilometer-wide Tycho, and its brilliant splash ray pattern. Perhaps 100 million years ago a comet, an asteroid, or a large meteorite impacted the Moon, flinging debris far and wide. One of Tycho’s ejecta paths (rays) crosses the Apollo 17 landing site almost 2,000 kilometers away, where it caused a landslide, revealing deeper materials. Shining like a beacon in Tycho’s center is a mountain peak originating from below the surface crust. The crater floor is lumpy and the rim broken by the force of the impact.

tycho

Could a collision like Tycho’s create Earth-bound meteoroids? Indeed, you may have walked on one unaware! The first confirmed lunar meteorite was found in 1979 in Antarctica, but it was many years before its true identity was known. Confirmation required comparison of its chemical composition to that of Apollo lunar samples. To date, only around 40 confirmed lunar meteorites are known, but as many as one in every thousand may have originated from our nearest neighbor. Noble gas measurements show some of these materials may have left the lunar surface up to 20 million years ago, but most are around 100,000 years old. They might resemble terrestrial rocks, but ones with their chemical composition are found only on the Moon. Have a look at Tycho and imagine the power that sculpted this mighty crater!

C2007 N3 Lulin Imaged on February 5 - Joe Brimacombe
C2007 N3 Lulin Imaged on February 5 - Joe Brimacombe

For those who don’t mind getting up early, be sure to keep your eye on the mighty Comet C/2007 N3 Lulin! If you have trouble reading star charts – don’t worry. It’s a whole lot easier to find in binoculars than you might think. All you need to do is just know how to identify a few bright stars! If you live in the northern hemisphere, about an hour (even two if you have a clear skyline) go out and identify Scorpius rising to the southeast – or Virgo high in the south, if you prefer. (For other locations, simply follow the ecliptic plane.) Between the two constellations you’ll see bright optical double star Alpha Librae – Zubenelgenubi. You’ll know if you have the right star because it will appear as two close stars in your binoculars. As of the morning of February 6th, Comet Lulin appeared in the 2 o’clock position with Zubenelgenubi in the field and it’s slowly headed towards Spica – Alpha Virginis. Remember as each successive day passes to start at Zubenelgenubi (it’s about a hand span east-southeast of Spica) and move the binoculars slowly towards Spica until you spot it. It will appear as a small, faint fuzzy in 5X30 binoculars and elongated in 16X60s. Even with telescopes as small as 114mm in aperture, it’s easy to make out that signature tail! Don’t wait too long to capture it, though… Because it won’t be long until the Moon is going to interfere and make this 7th magnitude comet far more difficult to spot.

Until next week? Ask for the Moon, but keep on reaching for the stars! You could just catch a comet…

This week’s awesome images are: Salyut (historical image-NASA), Gassendi (credit-Wes Higgins), William Huggins (historical image), Kappa Orionis: Saiph (credit-Palomar Observatory, courtesy of Caltech), Mars meteorite (historical image), Tycho (credit-Roger Warner) and Comet Lulin (credit-Joe Brimacombe). Thank you for sharing!

Posted on by Tammy Plotner

Vulpecula

Vulpecula

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The constellation of Vulpecula is unusual, because it did not belong originally to those created by Ptolemy – but to the works of Johannes Hevelius. Vulpecula was included in Firmamentum Sobiescianum, a 56 page atlas created by Hevelius, which outlined seven new constellations which survived time – and many which did not. Positioned north of the ecliptic plane, it spans 268 square degrees of sky, ranking 55th in constellation size. It has 5 main stars in its asterism and 33 Bayer Flamsteed designated stars within its confines. Vulpecula is bordered by the constellations of Cygnus, Lyra, Hercules, Sagitta, Delphinus and Pegasus. It is best seen at culmination during the month of September.

Since Vulpecula is considered a “modern” constellation, there is no mythology associated with it – although the stellar pattern was very visible to the ancient Greeks and Romans. Late in 17th century, astronomer Johannes Hevelius created the constellation of Vulpecula when he was preparing his own set of star charts known as Firmamentum Sobiescianum At the time, he named it “Vulpecula Cum Ansere” which literally translated to the little fox with the goose – and he illustrated it as a fox with a goose caught in its jaws. At the time, Hevelius did not consider it to be two separate constellations – yet it was later divided into two halves – Vulpecula and Anser “The Goose”. When star charts were once again consolidated, the constellations merged again to be known under to modern named assigned to it by the International Astronomical Union as Vulpecula, yet the primary star retains a reminder be being properly named Anser.

Let’s begin our binocular tour of Vulpecula with a look at the Alpha (“a”) star – Anser. Its name literally translates to “goose”, but this class M giant star is anything but flighty. Residing 297 light years from Earth, Anser puts out 390 times more light energy than our Sun from a size about 45 times larger. It may have a dead helium core about to begin hydrogen fusion – and it may have a dead carbon-oxygen core awaiting a second brightening before turning K class. If you’ve notice another nearby star – good for you! Although it’s only a line of sight companion, 8 Vulpeculae makes checking out Anser a real treat!

Now head on to Collinder 399. This wonderful asterism is often called “Brocchi’s Cluster” or the “Coathanger” and it’s a splendid object in binoculars or a rich field telescope. This unique collection of stars was known as far back as 964 AD when astronomer Al Sufi recorded it, and it was independently rediscovered by Giovanni Hodierna in the seventeenth century. In the 1920s, D. F. Brocchi, an amateur astronomer and chart maker for the American Association of Variable Star Observers, created a map of this object for use in calibrating photometers. Thanks to its expansive size of more than 60 arc minutes, it escaped the catalogues of both Messier and Herschel. Only around a half dozen stars share the same proper motion, which may make it a cluster much like the Pleiades, but studies suggest it is merely an asterism…but one with two binary stars at its heart.

Our next target is the magnificent Messier 27 (RA 19 : 59.6 Dec +22 : 43). This incredible planetary nebula appears like a pale green apple core and is unquestionably the brightest study of its kind. Easily located around a finger-width north of Gamma Sagittae, it’s not the largest of all planetaries but is the largest of its kind on the Messier list. M27’s expanse and luminosity suggest that it is quite close to our own system. Some think it difficult to find, but there is a very simple trick. Look for the primary stars of Sagitta just to the west of bright Albireo. Make note of the distance between the two brightest and look exactly that distance north of the “tip of the arrow” and you’ll find M27.

Discovered in 1764 by Messier in a 3.5 foot focal length telescope, I discovered this 48,000 year old planetary nebula for the first time in a 4″ telescope. I was hooked immediately. Here before my eager eyes was a glowing green “apple core” which had a quality about it that I did not understand. It somehow moved… It pulsated. It appeared “living.” For many years I quested to understand the 850 light-year distant M27, but no one could answer my questions. I researched and learned it was made up of doubly ionized oxygen. I had hoped that perhaps there was a spectral reason to what I viewed year after year – but still no answer. Like all amateurs, I became the victim of “aperture fever” and I continued to study M27 with a 12″ telescope, never realizing the answer was right there – I just hadn’t powered up enough.

Several years later while studying at the Observatory, I was viewing through a friend’s identical 12″ telescope and, as chance would have it, he was using about twice the magnification that I normally used on the “Dumbbell.” Imagine my total astonishment as I realized for the very first time that the faint central star had an even fainter companion that made it seem to wink! At smaller apertures or low power, this was not revealed. Still, the eye could “see” a movement within the nebula – the central, radiating star and its companion. Do not sell the Dumbbell short. It can be seen as a small, unresolved area in common binoculars, easily picked out with larger binoculars as an irregular planetary nebula, and turns astounding with even the smallest of telescopes. In the words of Burnham, “The observer who spends a few moments in quiet contemplation of this nebula will be made aware of direct contact with cosmic things; even the radiation reaching us from the celestial depths is of a type unknown on Earth…”

Ready for a galactic star cluster for both binoculars and a small telescope? The return to Alpha and begin about two fingerwidths southeast and right on the galactic equator you’ll find NGC 6823 (RA 19 : 43.1 Dec +23 : 18). The first thing you will note is a fairly large, somewhat concentrated magnitude 7 open cluster. Resolved in larger telescopes, the viewer may note these stars are the hot, blue/white variety. For good reason. NGC 6823 only formed about 2 billion years ago. Although it is some 6000 light-years away and occupies around 50 light-years of space, it’s sharing the field with something more – a very large emission/reflection nebula, NGC 6820. In the outer reaches of the star cluster, new stars are being formed in masses of gas and dust as hot radiation is shed from the brightest of the stellar members of this pair. Fueled by emission, NGC 6820 isn’t always an easy visual object – it is faint and covers almost four times as much area as the cluster. But trace the edges very carefully, since the borders are much more illuminated than the region of the central cluster. Take the time to really observe this one! Its processes are very much like those of the “Trapezium” area in the Orion nebula. Be sure to mark your observing notes. NGC 6823 is Herschel VII.18 and NGC 6820 is also known as Marth 401!

If you’d like to try something new, return to M27 and head 2 degrees west-northwest to find NGC 6830 (RA 19 : 51.0 Dec +23 : 04). This rich 7.9 magnitude, cross-shaped open cluster is a real treat. Continue another 2 degrees in the same direction to pick up 7.1 magnitude cluster NGC 6823. Those with large telescopes should look for a faint sheen of nebulosity associated with this youthful open cluster!

Now let’s work on a pair of open star clusters for both binoculars and small telescopes, starting with NGC 6885 (RA 20 : 12.0 Dec +26 : 29). This little 6th magnitude sparkle of stars includes that bright O class star you can see visually and is also known as Caldwell 37. In binoculars you’ll see another compression nearby listed as NGC 6882 (RA 20 : 11.7 Dec +26 : 33). While it doesn’t contain a bright and splashy star like its neighbor, NGC 6882 is a nice ring shaped collection!

Our last official target in Vulpecula is superb galactic star cluster NGC 6940 (RA 20 : 34.6 Dec +28 : 18). This 6th magnitude, 31 arc minute cloud of stars is sure to please anyone with any size binoculars or telescope. The more aperture you have – the more stars you resolve! Discovered by Sir William Herschel in 1784 and logged as H VIII.23, this intermediate-aged galactic cluster will blow your mind in large aperture. Although visible in binoculars, as aperture increases the field explodes into about 100 stars in a highly compressed, rich cloud. Although not visited often, NGC 6940 is on many observing challenge lists. Use low power to get the full effect of this stunning starfield!

While NGC 6834 (RA 19 : 52.2 Dec +29 : 25) is officially listed as Cygnus, why not visit anyway? You’re in the neighborhood! It’s a very rich and compact small star cluster that’s a worthy challenge to pick out of the Milky Way star field in a telescope!

Sources:
Wikipedia
SEDS
Chart Courtesy of Your Sky.

Posted on by Tammy Plotner

Volans

Volans

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The southern circumpolar constellation of Volans was first introduced in 1589 by Petrus Plancius on a celestial globe which was later added to Johann Bayer’s atlas – Uranometria – in 1603. Volans spans 141 square degrees of sky, ranking 76th in size. It has 6 mains stars in its asterism and 12 Bayer Flamsteed designated stars within its confines. Volans is bordered by the constellation of Carina, Pictor, Dorado, Mensa and Chamaeleon and is best seen at culmination during the month of March.

Since Volans is considered a “new” constellation, it has no mythology associated with it – only what the constellation is meant to represent. The constellation of Volans was originally created by Petrus Plancius from the stellar observations of Dutch sea navigators Pieter Dirkszoon Keyser and Frederick de Houtman when exploring the southern hemisphere. Volans’ stellar patterns became known when it appeared on a celestial globe in 1597 and was considered a constellation when it was added to Johann Bayer’s Uranometria catalog in 1603 and it was then called Piscis Volans – the “Flying Fish”. When it was later adopted as a permanent constellation by the International Astronomical Union, the name was simplified and shortened to just Volans.

Let’s begin our binocular tour of Volans with its Alpha star – the “a” symbol on our chart. Alpha Volantis is located approximately 124 light years from Earth and it is a white class A (A2.5) subgiant star. While it is not anything particularly special, it is about twice the size of our Sun and shines about 30 times brighter. Somehow it got the Alpha designation, even though Beta (the “B” symbol) is physically brighter and 16 light years closer! Want a real trip? Then have a look at Delta – the “8” symbol. Even though it appears almost as bright as the rest of the stars, Delta is an F-type bright giant star that’s 660 light years from our solar system!

Now, get out your telescope for Epsilon Volantis – the backwards “3”. Epsilon is a triple star system! Located approximately 642 light years from Earth, the primary component, Epsilon Volantis A, is a spectroscopic binary star all of its own. It’s a blue-white B-type subgiant star with a companion that orbits so close we can only see it spectroscopically and know that it causes changes about every two weeks. But take a close look and you’ll discover a third, 8th magnitude star there, too. Epsilon Volantis B is 6.05 arcseconds away and an easy capture for a small telescope and large binoculars.

How about Gamma Volantis? It’s the “Y” symbol. This wide double star was just meant for binoculars! The two members are brighter, western Gamma-1 Volantis (magnitude 5.67) and dimmer, eastern Gamma-2 (magnitude 3.78). Set apart by 14.1 seconds of arc, you won’t have any trouble cutting these two stars apart and their color contrast make them a real winner in a telescope. Gamma-2 is a standard orange class K (K0) giant star and Gamma-1 is a a white class F (F2) dwarf star. While you might think this is an optical double star, it isn’t. The pair is physically bound to each other and both stars are about 142 light years away.

For those wishing a challenge, take on about the only deep sky study to be found in Volans – NGC 2442 (RA 7 : 36.4 Dec -69 : 32). At 11th magnitude and 6 arc minutes in size, this low surface brightness barred spiral galaxy is a nice study for a large telescope. Located about 50 million light years away from our Milky Way Galaxy, NGC 2442 was first was discovered by Sir John Herschel and contains a very unusual dark cloud of gas – one devoid of any stars. How did this come to be? Astronomers believe the cloud was torn loose from NGC 2442 by a companion during a galaxy interaction. Why not? After all, NGC is surrounded! If you have large aperture, you’ll see PGC 21457, PGC 21406, NGC 2434, PGC 21212, PGC 21323, PGC 21369 and PGC 21426 are nearby, too. Several of these satellite galaxies are physically related to NGC 2442. Be sure to look for two spiral arms extending from a pronounced central bar, giving the whole galaxy a hook-shaped appearance.

Sources:
Wikipedia
University of Wisconsin
Chart Courtesy of Your Sky.

Posted on by Tammy Plotner

Journey Inside A Bok Globule

NGC281/IC1590 Parallel Vision - Jukka Metsavainio

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You asked for more? You got it. This time our dimensional visualization is going to take us 9500 light years away from where you’re sitting now and deep into the Perseus spiral arm of the Milky Way Galaxy. Buckle your seat belt and relax your eyes, because we’re heading into two versions of a 132 light year expanse known as NGC 281 and the central core called IC 1590…

Just like last time, this dual image requires a little bit of a challenge on your part to create a 3D effect. Thanks to the wizardry of Jukka Metsavainio, we’ve gone even one better. There’s two! The first version you see on this page are for those of you who have success relaxing your eyes and being a certain distance from the screen to get the images to merge. The one below is for those of you who have better luck crossing your eyes and catching dimension in the center image. Are you ready for your journey? Then have a look and let’s learn…

NGC281/IC1590 Hubble Heritage Cross Vision - Jukka Metsavainio
NGC281/IC1590 Hubble Heritage Cross Vision - Jukka Metsavainio

The whole gigantic region of nebulosity is known as NGC 281 and most commonly referred to as the “Pac Man Nebula”. Visible to small telescopes and located in the constellation of Cassiopeia (RA 00:42:59.35 Dec +56:37.18.8), this cloud of high density hydrogen gas is being ionized by an incredible output of ultraviolet radiation from the hot, neophyte stars which coalesced there. Deep in the center of this HII region is a open area called IC 1590 – home to a young galactic star cluster – and several dark patches known as “Bok Globules”.

If that sounds like something you might expel when you have a cold, you’re right. They are cold… Cold pockets of dense dust, molecular hydrogen and gas. Bok globules are the brain child of astronomer Dr. Bart Jan Bok – who, among other things, loved to study the paranormal. When Bok proposed their existence in the 1940’s, he knew what was going on. These dark regions were acting like interstellar cocoons – protecting their inner stars from being stripped by the radioactive stellar winds of nearby companions and blocking visible light. When stellar metamorphosis had occurred, the new star then begins to send out its own winds and radiation to evaporate the globule – but this isn’t always the case. Sometimes the cocoon gets destroyed before the life inside ignites.

In our image you will see bright blue stars, members of the young open cluster IC 1590, near the globules. Meanwhile, the cluster’s partially revealed core in the upper right hand corner is filled with a tight grouping of extremely hot, massive stars emitting visible and ultraviolet light, causing those incredible pink clouds. When these star forming dust clouds were first imaged by Hubble, we thought we knew a lot about them. But what have we learned since?

According to research done by T.H. Henning (et al): “The exciting star HD 5005 of the optical nebulosity is a Trapezium system… and emission shows that the molecular cloud NGC 281 A consists of two cloud fragments. The western fragment is more compact and massive than the eastern fragment and contains an NH3 core. This core is associated with the IRAS source 00494+5617, an H2O maser, and 1.3 millimeter dust continuum radiation. Both cloud fragments contain altogether 22 IRAS point sources which mostly share the properties of young stellar objects. The maxima of the 60 and 100 micrometers HIRES maps correspond to the maxima of the (12)CO (3 to 2) emission. The NGC 281 A region shares many properties with the Orion Trapezium-BN/KL region the main differences being a larger separation between the cluster centroid and the new site of star formation as well as a lower mass and luminosity of the molecular cloud and the infrared cluster.”

Great! It’s confirmed! It’s a star forming region, very much like what we can observe when we see M42. But, maybe… Maybe there’s just a little bit more to it than that? Hubble observations shows the jagged structure of the dust clouds as if they are being stripped apart from the outside. What could have caused that? Only the radiation from the nearby stars? Hmmm…. Not everyone seems to think so.

A 2007 study done by Mayumi Sato (et al) states: “Our new results provide the most direct evidence that the gas in the NGC 281 region was blown out from the Galactic plane, most likely in a superbubble driven by multiple or sequential supernova explosions in the Galactic plane.” Supernova? Yeah, you bet. And someone else thinks so, too…

Says S.T. Megeath (et al): “We suggest that the ring has formed in a superbubble blowout driven by OB stars in the plane of the Galaxy. Within the cloud complex, combined optical, NIR, mm and cm data detailing the interaction of a young O star with neighboring molecular cores, provide evidence of triggered star formation inside the cloud complex on a few parsec scale. These data suggest that two modes of triggered star formation are operating in the NGC 281 complex – the initial supernovae triggered formation of the entire complex and, after the first generation of O stars formed, the subsequent triggering of star formation by photoevaporation-driven molecular core compression.”

You’ve got it. This type of research suggests the cores were created within the molecular cloud. When they were exposed to direct UV radiation, the low density gas was stripped. This increase in pressure then caused a rippling shockwave which triggered star formation – first in the compressed regions and then in the HII areas. Says Megeath, “The total kinetic energy of the ring requires the energy of multiple supernovae. Both the high Galactic latitude and large expansion velocity may be explained if the NGC 281 complex originated in the blowout of an expanding superbubble. The loop of HI seen extending from the Galactic plane may trace the edge of a superbubble powered by supernovae near the Galactic plane. The expansion of a superbubble into the increasingly rarefied Galactic atmosphere can lead to a runaway expansion of the shell and the blowout of the bubble into the Galactic atmosphere. NGC 281 could have formed in the gas swept up and compressed in a blowout. Hence, NGC 281 maybe an example of the supernovae-driven formation of molecular clouds (and consequently, supernovae-triggered star formation).”

What incredible region! Hope you enjoyed your journey… And be sure to tip your hat to Bart Jan Bok who told the IAU (when they named Asteroid Bok for him in 1983) “Thanks for a little plot of land that I can retire to and live on.”

Our many, many thanks to Jukka Metsavainio of Northern Galactic for creating this unique image for Universe Today Readers! We look forward to more…

Posted on by Tammy Plotner

Comet C/2007 N3 Lulin – A Twist In The Tail

Comet C/2007 N3 Lulin - J. Brimacombe

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When Chi-Sheng Lin of Taiwan’s Institute of Astronomy captured three images on July 11, 2007 with something strange in them, it was first believed he’d picked up just another asteroid. But, by July 17 astronomers in Table Mountain Observatory, California were noticing a coma 2-3″ across, with a bright central core. That’s not an asteroid… That’s a comet! And now it’s a comet that’s doing something very strange…

By the end of 2008, Comet C/2007 N3 Lulin had steadily began to brighten and now is within easy reach of binoculars for all observers. How bright is it? At last estimate it is between magnitude 6 and 7. That means just a little too faint to be seen unaided, but bright enough to be spotted easily with just the slightest of visual aids. Our own Nancy A. did an article on this not long ago!

But there’s something going on with N3 Lulin, right now… Something very different. There’s a twist in the tail! Check this out…

Comet C/2007 N3 Lulin (negative luminance) - J. Brimacombe
Comet C/2007 N3 Lulin (negative luminance) - J. Brimacombe

While imaging N3 Lulin for UT Readers, Dr. Joe Brimacombe used a negative luminance frame to take a closer look at what’s going on and discovered something quite out of the ordinary. First off, you’ll notice an anti-tail – quite rare in itself – but if you take a look about halfway down the ion/dust tail, you’ll see a very definite twist in the structure. It it rotating? Exactly what’s causing it? Torsional stress? Is it possible that the kink in the tail is an instability resulting from currents flowing along the tail axis? Right now there’s absolutely no information available about what’s going on in the tail – because what you’re seeing is perhaps one of the most current pictures of the comet that can be found!

Chart Courtesy Heaven's Above
Chart Courtesy Heaven's Above
If you’re interested in viewing Comet C/2007 N3 Lulin for yourself and would like some help locating it, there’s a wonderful resource that’s easy to use. Just go to Chris Peet’s Heaven’s Above website and make use of the tools there. It will give you easy to follow charts and all you need is just a pair of binoculars to spot this comet for yourself. Don’t sit inside… Do it!

My sincere thanks to Dr. Joseph Brimacombe of Northern Galactic for not only his superb imaging – but his sublime sense of curiosity which caught this anomaly!

Posted on by Tammy Plotner

R Coronae Borealis At Faintest

R Coronae Borealis Field - J. Brimacombe

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For those of you who like observing curiosities, it’s time to take a look at R Coronae Borealis. As you may have guessed from the single letter designation, R is a variable star, but it’s not just any old variable – it’s the prototype of its class. What exactly is an R CorBor star, what does it do and why is taking the time to check it out now so important? Then step inside and find out…

R Coronae Borealis stars (RCB) type stars are one of the oldest known classes of variable star. In just a period of a few weeks, they can drop in brightness by factors of thousands and what they do is totally unpredictable. Within months, they recover again to their maximum brightness… But why? While astronomers don’t fully understand the evolutionary origin and the physical mechanism behind what drives R CorBor types, they do know the stars pulsate – generating a sort of sooty dust cloud just above the surface. Like an old-fashioned oil lamp with its wick turned up too high, when R Cororonae Borealis stars burn their fuel, they smoke up their exterior – just like the lamp smokes its glass chimney and dims the light. What remains on the glass? That’s right. Carbon. And the surfaces of RCB stars are unusually poor in hydrogen, and rich in carbon and nitrogen. Chances are very good that R CorBor stars are actually the remnants of more fully evolved stars.

Just a few days ago, M. Templeton of the American Association of Variable Star Observers (AAVSO) released Special Notice #145:

“R Coronae Borealis, the prototype of the R CrB class, is apparently at or near historic minimum; a number of observers have put this star below m(vis)=14.0 since early November 2008, and both visual and instrumental measures are now indicating R CrB is near or below V=14.5. R CrB began its current fading episode around JD 2454288 (2007 July 6 +/- 1 day), and faded from m(vis) ~ 6.0 to below m(vis) ~ 12.0 by JD 2454325 (2007 August 12). The star has continued to fade for the past 17 months. Current visual observations by a number of AAVSO visual observers estimate the star to be around m(vis) 14.3-14.5, and V-band CCD observations suggest the star may be at or near V=15.0. BAAVSS observer J. Toone also visually estimated the star is at m(vis) ~ 14.9 (via baavss-alert). Both visual estimates and instrumental photometry of R CrB are strongly encouraged at this time.

The duration of the current episode and its depth are similar to that observed during the previous extreme fading episode which began circa JD 2438200 (June 1963) and continued with only one brief interruption until circa JD 2439100 (December 1965). During the 1963-1965 event, a few AAVSO observers estimated that R CrB reached m(vis) around 14.9-15.0, although the average visual estimate remained around 14.2-14.3 at minimum. The current episode seems to have reached the same depth; there is no way to tell whether the fade will continue, although the light curve has been flat or trending weakly downward for several months. As J. Toone pointed out, the current magnitude is very close to if not fainter than the historic minimum for this star.”

Of course, nearing magnitude 15 isn’t within the territory of binoculars or small telescopes – but it is within the grasp of many of our amateur astronomer UT readers with larger equipment, clear skies and the willingness to seize the opportunity to record this historic astronomical event. (I dislike the term “amateur” – it only means you don’t get paid for it, folks… Not that you’re any less serious or talented!) One such astronomer is Dr. Joseph Brimacombe, who took up the gauntlet immediately. Although Joe hails from Australia where R Coronae Borealis isn’t visible, today’s astronomy world is far different than it used to be. Thanks to the magic of the Internet, he immediately set about the task of capturing the star on January 30, 2009 via a robotic telescope located in New Mexico and shared his results with us.

R Coronae Borealis True Color - J. Brimacombe
R Coronae Borealis True Color - J. Brimacombe

R CrB Chart - AAVSO
R CrB Chart - AAVSO
For those wishing to also participate in the quest for R Coronae Borealis, you’ll find it located at the following (J2000) coordinates: RA: 15 48 34.40 , Dec: +28 09 24.0 and you may use this field chart provided by the AAVSO to further refine your observations. If R is too faint for your equipment now? Don’t worry. It’s a variable star and within a few months it will return to its easily spotted magnitude 6 self – and a very delightful red star in binoculars. As always, be kind to science and contribute! Please promptly submit all observations to the AAVSO using the name “R CRB” and take part in astronomy history!

My many thanks to Joe Brimacombe of Northern Galactic for his superb talents and to the AAVSO for keeping us on alert!

Posted on by Tammy Plotner

Virgo

Virgo

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As one of the zodiacal signs, Virgo resides directly on the ecliptic plane and was one of the original 48 constellations charted by Ptolemy. It spans 1294 degrees and is the second largest constellation in the sky. Virgo also contains the point where the celestial equator crosses the ecliptic plane – the the autumn equinox. Between 9 and 15 stars make up its asterism and it contains 96 Bayer Flamsteed designated stars within its confines. Virgo is bordered by the constellations of Bootes, Coma Berenices, Leo, Crater, Corvus, Hydra, Libra and Serpens Caput. It is visible to all observers located at latitudes between +80° and ?80° and is best seen at culmination during the month of May.

There are two annual meteor showers associated with constellation Virgo. The Virginids peak on or about April 10th of each year and will appear to come from a point in the sky near Gamma. This is a relatively active and predictable meteor shower and you can expect to see about 10 meteors per hour on the average during a dark night from a dark location. The second is the Mu Virginids, which peak on or about April 25th. This is also a fairly reliable meteor shower and you can expect to see 7 to 10 meteors per hour on the average coming from an area near the Virgo/Leo border.

In mythology, Virgo is meant to represent the “Virgin”, but who exactly this woman is has never been established – only that she plays an important cultural role. Virgo is often portrayed carrying two sheaves of wheat, one of which is marked by the bright star Alpha – Spica – and it is the only astrological sign represented by a female. Perhaps she is Astraea, the virgin daughter of Zeus who was known as the goddess of justice. After all, Libra, the scales of justice is nearby!

Let’s begin our tour of Virgo with its brightest star – Alpha – the “a” symbol on our map. Alpha Viriginis is best known as Spica. Located 262 light-years away from Earth, 1.0 magnitude Spica glows with the combined light of four unresolved stars and has a visual luminosity 2100 times that of the Sun. As a rotating ellipsoidal variable, the four stars cause complex changes in luminosity by distorting the shape of the brightest components. The dominant star – Spica A – has a mass 11 times that of the Sun and fluctuates in physical size as it varies in brightness. The primary star is at maximum when smallest, giving it the highest photospheric surface temperature. Spica B has a mass of 7 suns. As a spectral type B, these two components produce more light in ultraviolet due to exceedingly high surface temperatures. Spica has two distant telescopic companions – magnitude 12 to the north-northeast, and magnitude 10.5 to the east-northeast.

Now head towards Beta – the “B”. Named Zavijava (sounds like something you’d get at Starbuck’s doesn’t it?) and located about 36 light years away from our solar system, this star holds a very special place in history because of its position in the sky. Since it is so near the ecliptic plane, it can frequently be occulted by the Moon, occasionally a planet, and even the Sun. In Zavijava’s case, it had the honor of being the star Einstein used during the solar eclipse of September 21, 1922 to determine the speed of light in space! What’s more, according to studies, Beta Virginis could host two or three Jupiter-sized planets – either brown dwarf stars in wide orbits or true planetary objects.

Ready for Gamma Virginis? That’s the “Y” symbol. Best known as Porrima, this binary star of nearly matched magnitudes was an easy object for amateur astronomers, but now the smaller apparent distance between the stars requires a larger telescope. Because of its relatively quick orbital period of 168.93 years, you’ll sometimes hear Porrima referred to as the “Shrinking Star”. At the time of this writing (early 2009), the pair is only separated by about .04″ and it will be another 11 years before they have moved apart enough again to be easily split with a small telescope!

Because there are massive amounts of deep sky objects in Virgo, annotating a map would be so cluttered it would be difficult to read. Let us begin first with the chart we have above which highlights the brighter objects in Virgo – ones easily seen with binoculars and small telescopes. Ready to dance?

Our first target will be Messier 104 (RA 12 : 40.0 Dec -11 : 37). Now, shake your fist at Spica… Because that’s all it takes to find the awesome M104, eleven degrees due west. (If you still have trouble finding M104, don’t worry. Try this trick! Look for the upper left hand star in the rectangle of Corvus – Delta. Between Spica and Delta is a diamond-shaped pattern of 5th magnitude stars. Aim your scope or binoculars just above the one furthest south.) Also known as the “Sombrero Galaxy” this gorgeous 8th magnitude spiral galaxy was discovered by Pierre Mechain in 1781, added by hand to Messier’s catalog and observed independently by William Herschel as H I.43 – who was probably the first to note its dark inclusion. The Sombrero’s rich central bulge is comprised of several hundred globular clusters and can be hinted at in just large binoculars and small telescopes. Large aperture telescopes will revel in this galaxy’s “see through” qualities and bold, dark dustlane – making it a seasonal favorite!

Now, let’s take a look at one of the brightest members of the Virgo Cluster – Messier 49. Located about eight degrees northwest of Delta Virginis almost directly between a pair of 6th magnitude stars (RA 12 29 46 Dec +07 59 59), the giant elliptical galaxy M49 holds the distinction of being the first galaxy in the Virgo cluster to be discovered – and only the second beyond our local group. At magnitude 8.5, this type E4 galaxy will appear as an evenly illuminated egg shape in almost all scopes, and as a faint patch in binoculars. While a possible supernova event occurred in 1969, don’t confuse the foreground star noted by Herschel with something new! Although most telescopes won’t be able to pick this region apart, there are also many fainter companions near M49, including NGC 4470. But a sharp-eyed observer named Halton Arp noticed them and listed them as Peculiar Galaxy 134 – one with “fragments!”

Next up, Messier 87 (RA 12 : 30.8 Dec +12 : 24). It’s a radio-source galaxy so bright it can be seen in binoculars – 8.6 magnitude M87, about two fingerwidths northwest of Rho Virginis. This giant elliptical galaxy was discovered by Charles Messier in 1781 and cataloged as M87. Spanning 120,000 light-years, it’s an incredibly luminous galaxy containing far more mass and stars than the Milky Way Galaxy – gravitationally distorting its four dwarf satellites galaxies. M87 is known to contain in excess of several thousand globular clusters – up to 150,000 – and far more than our own 200.

In 1918, H. D. Curtis of Lick Observatory discovered something else – M87 has a jet of gaseous material extending from its core and pushing out several thousand light-years into space. This highly perturbed jet exhibits the same polarization as synchrotron radiation – a property of neutron stars. Containing a series of small knots and clouds as observed by Halton Arp at Palomar in 1977, he also discovered a second galaxy jet in 1966 erupting in the opposite direction. Thanks to these two properties, M87 made Arp’s “Catalog of Peculiar Galaxies” as number 152. In 1954 Walter Baade and R. Minkowski identified M87 with radio source Virgo A, discovering a weaker galactic halo in 1956. Its position over an x-ray cloud extending through the Virgo cluster make M87 a source of an incredible amount of x-rays. Because of its many strange properties, M87 remains a target of scientific investigation. The Hubble Space Telescope has shown a violent nucleus surrounded by a fast rotating accretion disc, whose gaseous make-up may be part of a huge system of interstellar matter. As of today, only one supernova event has been recorded – yet M87 remains one of the most active and highly prized study galaxies of all. Capture it tonight!

virgo1

Now we’re heading for our more detailed map and the galaxy fields of Virgo about four fingerwidths east-southeast of Beta Leonis. As part of Markarian’s Chain, this set of galaxies can all be fitted within the same field of view with a 32mm eyepiece and a 12.5″ scope, but not everyone has the same equipment. Set your sights toward M84 and M86 and let’s discover!

Good binoculars and small telescopes reveal this pair with ease as a matched set of elliptical galaxies. Mid-sized telescopes will note the western member of the pair – M84 – is seen as slightly brighter and visibly smaller. To the east and slightly north is larger M86 – whose nucleus is broader, and less intensely brilliant. In a larger scope, we see the galaxies literally “leap” out of the eyepiece at even the most modest magnifications. Strangely though, additional structure fails to be seen. As aperture increases, one of the most fascinating features of this area becomes apparent. While studying the bright galactic forms of M84/86 with direct vision, aversion begins to welcome many other mysterious strangers into view. Forming an easy triangle with the two Messiers and located about 20 arc-minutes south lies NGC 4388. At magnitude 11.0, this edge-on spiral galaxy has a dim star-like core to mid-sized scopes, but a classic edge-on structure in larger ones.

At magnitude 12, NGC 4387 is located in the center of a triangle formed by the two Messiers and NGC 4388. NGC 4387 is a dim galaxy – hinting at a stellar nucleus to smaller telescopes, while the larger ones will see a very small face-on spiral galaxy with a brighter nucleus. Just a breath north of M86 is an even dimmer patch of nebulosity – NGC 4402 – which needs higher magnifications to be detected in smaller scopes. Large apertures at high power reveal a noticeable dust lane. The central structure forms a curved “bar” of light. Luminosity appears evenly distributed end to end, while the dust lane cleanly separates the central bulge of the core. East of M86 are two brighter NGC galaxies – 4435 and 4438. Through average scopes, NGC 4435 is easily picked out at low power with a simple star-like core and wispy round body structure. NGC 4438 is dim, but even large apertures make elliptical galaxies a bit boring. The beauty of NGC 4435 and NGC 4438 is simply their proximity to each other. 4435 shows true elliptical structure, evenly illuminated, with a sense of fading toward the edges… But 4438 is quite a different story! This elliptical galaxy is much more elongated. A highly conspicuous wisp of galactic material can be seen stretching back toward the brighter, nearby galaxy pair M84/86.

Ready for bright galaxy Messier 58 (RA 12 : 37.7 Dec +11 : 49)? It’s a spiral galaxy actually discovered by Messier in 1779! As one of the brightest galaxies in the Virgo cluster, M58 is one of only four that have barred structure. It was cataloged by Lord Rosse as a spiral in 1850. In binoculars, it will look much like our previously studied ellipticals, but a small telescope under good conditions will pick up the bright nucleus and a faint halo of spiral galaxy structure – while larger ones will see the central concentration of the bar across the core. Chalk up another Messier study for both binoculars and telescopes and let’s get on to something really cool!

Around a half degree southwest are NGC 4567 and NGC 4569. L. S. Copeland dubbed them the “Siamese Twins,” but this galaxy pair is also considered part of the Virgo cluster. While seen from our viewpoint as touching galaxies, no evidence exists of tidal filaments or distortions in structure, making them a line of sight phenomenon and not interacting members. While that might take little of the excitement away from the “Twins,” a supernova event has been spotted in NGC 4569 as recently as 2004. While the duo is visible in smaller scopes as two, with soft twin nuclei, intermediate and large telescopes will see an almost V-shaped or heart-shaped pattern where the structures overlap. If you’re doing double galaxy studies, this is a fine, bright one! If you see a faint galaxy in the field as well, be sure to add NGC 4564 to your notes. Moving about a degree north will call up face-on spiral galaxy M89, which will show a nice core region in most telescopes. One half degree northeast is where you will find the delightful 9.5 magnitude M90 – whose dark dust lanes will show to larger telescopes.

Virgo contains many, many more fine objects – so be sure to get a detailed star chart and spend some time with this great constellation!

Sources:
Wikipedia
SEDS
Chandra Observatory
Charts Courtesy of Your Sky.

Posted on by Tammy Plotner

In Depth Observing – M81 and M82

Are you interested in taking a more in-depth look at observing? Then why not wait until the Moon sets this weekend and have a look at two splendid galaxies for any size optics – Messier 81 and Messier 82. If you’ve ever been curious about exactly what can be seen in a particular sized telescope, what else is in the area and what the story is behind these two, then come on in…

Welcome, Traveller. Our celestial journey resumes to the north, in the realms of Ursa Major: the Great Bear. “Let my lamp at midnight hour, Be seen in some high, lonely tower. Where I may oft outwatch the Bear.” Our sojourn will take us to a place of intrigue. A realm where two galaxies hold each other in cosmic grip. A place where a single gem of spiral perfection is mounted against a setting of broken interaction. Here we continue our observing quest in exploration of Bode’s Galaxies – twin jewels of the circumpolar north sky – M81 and M82…

Discovered in December, 1774 by JE Bode at Berlin, these two deep sky favourites hold secrets between themselves. Photographed as early as March, 1899, this pair is central to a group of galaxies encompassing the northern circumpolar constellations of Ursa Major and Camelopardalis. Modern photos (such as at the above taken by Karel Teuwen), show the superb spiral structure of the M81. At some 36,000 light years in diameter, it is one of the densest known galaxies. One third of the mass is concentrated at the core. Its glow is the combined luminosity of twenty billion suns…

Often mistaken in the small telescope for an edge-on spiral, M81’s neighbor – M82 – shows no sign of “swirling”. As a true space “oddity”, the light from M82 journeying back to our eyes is polarized. This galaxy probably contains a super-massive magnetic field. Not only is M82 polarized visually, it is also a powerful radio source. Within its broken structure lay huge masses of dust accompanied by the radiance of stars possessing unusual spectral qualities. These facts lead scientists to believe that a violent outburst may have occurred within the galaxy as recently as 1.5 million years ago… About the time when our own adventurous ancestral species began seeking patterns in the night sky!

It is estimated M82’s defining event released the energy equivalent of several million exploding suns. “Shock waves” emanating from the galaxy greatly resemble synchrotron radiation. This phenomenon was first discovered in association with planetary nebula M1 – but within the M82, on an enormous scale. Can you image a super nova remnant the size of an entire galactic core region?

Roughly every one hundred million years, M81 and M82 make a “pass” at one another. Immensely powerful gravitation arms reach out and intertwine to produce a spectacular embrace. It is theorized that during the last go-round, M82 raised rippling density waves which circulated throughout M81. The result? Possibly the most perfectly formed spiral galaxy in all of space!

M81 is among the nearest and brightest spiral galaxies, visible even with binoculars at dark sites. It is also is one of the nearest to our Local Galaxy Group, being only some 12 million light-years from our own celestial backyard. As with almost all spiral-structured galaxies, star formation is continuing to take place inside this grand galaxy along the arms. When shown in specific wavelengths of light (like the above photo take by Dietmar Hager, F.R.A.S.) it can be evidenced as pink areas of light where the HII regions exist – while the blue areas are home to countless new stars. It is this incredible energy that makes Messier 81 such a breath-taking spectacle…

But M81’s influence left M82 a broken galaxy. Filled with exploded stars and colliding gas, a galaxy so violent it emits X-rays. Reactions induced by colliding dust and gas caused the birth of these numerous brilliant stars. Stars capable of creating extremely dense atoms… Some of which are now excited by the kind of extreme motion that induces immense magnetic fields.

The end may already be envisioned. Scientists speculate within a few billion years, out of the two, there shall be one… Indistinguishable but for the welter of radiation only such an embrace can create. It is known this same fate awaits our own galaxy. Billions of years from now, our own galaxy and its’ largest neighbor – the Great Spiral in Andromeda – will perform this same duet.

Let’s not talk about just this fascinating galactic duet, however. For the M81 and M82 also have some very unusual playmates! Neighboring galaxy NGC3077 displays some of the same “peculiarities” as its larger companion, M82. At 6,000 light years in diameter, NGC3077 is little more than a third the size of its prototype. Southwest of Spiral M81, is yet another “odd ball”. Like NGC3077, NGC2976 is a dwarf. At less than 1/5th the size of M81, NGC2976 is some 7,000 light years across. A value only three times the distance between our own Sun and the nearby, spectacular Great Nebula in Orion!

Three faint, irregular galaxies are also associated with our galactic pair. The NGC2366 jumps the border into Camelopardalis. IC2574 is found just a bit southeast of the M81 and is a real “toughie” for most telescopes. A smaller system known as Ho II was discovered in 1950 by astronomer E. Holmberg. Even farther into Camelopardis is the large spiral NGC2403, also thought to be a member of the M81/82 “family” of galaxies. As one of the two galaxy groups closest to our own Milky Way system (the other lies in Sculptor), this region presents a fascinating opportunity for study by the backyard astronomer. Why, the main pair can even be seen through 6x35mm binoculars!

So, while we have a relatively dark skies left for a few days, let us turn our telescopes toward study. Drawing an imaginary line between Phecda and Dubhe, we extend that just one step further into space… And Galaxy Quest continues!

Some Basic Information:

Like many galaxies seen at right angles to the Milky Way’s galactic plane, M81/M82 Galaxy Group members are best observed during Spring just after skydark. Of course, these galaxies may be observed year-round from the temperate northern hemisphere, but best views are had when found in the middle third of the sky. Despite the brightness and susceptibility of the main pair, amateurs take it as a source of some pride to readily locate the pair in what amounts to a rather nondescript region of sky.

M81 Ursa Majoris, Type: Spiral Galaxy, Magnitude: 7.0, Apparent Size: 26×14′ RA: 09 55.6, Dec:69 04, Optimal Scope Size: 150mm.

M82 Ursa Majoris, Type: Irregular Galaxy, Magnitude: 8.4, Apparent Size: 11×5′ RA: 09 55.8, Dec:69 41, Optimal Scope Size: 150mm.

NGC2976 Ursa Majoris, Type: Irregular Galaxy, Magnitude: 10.2, Apparent Size: 5×2′ RA: 09 47, Dec:67 54, Optimal Scope Size: 250mm.

NGC3077 Ursa Majoris, Type: Elliptical Galaxy, Magnitude: 9.9, Apparent Size: 5×4′ RA: 09 59, Dec:68 58, Optimal Scope Size: 250mm.

IC2574 Ursa Major, Type: Irregular Galaxy, Magnitude: 10.6, Apparent Size: 13×5′ RA: 10 28, Dec:68 25, Optimal Scope Size: 400mm.

NGC2366 Camelopardalis, Type: Irregular Galaxy, Magnitude: 10.9, Apparent Size: 8×3′ RA: 07 29, Dec:69 13, Optimal Scope Size: 325mm.

NGC2403 Camelopardalis, Type: Spiral Galaxy, Magnitude: 8.4, Apparent Size: 18×9′ RA: 07 36.9, Dec:65 36, Optimal Scope Size: 200mm.

Our Telescopes:

80mm Orion ShortTube Refractor mounted on an Orion Skyview Deluxe Equatorial Mount. Eyepieces include 35/25/15/10mm Orion Ultrascopics, 3x Apochromatic and 2x Shorty Barlow Lenses. This scope is capable of revealing stars to magnitude 12.0 with direct vision. It cleanly resolves matched double stars to 1.5 arc seconds of apparent separation. Under optimal seeing conditions, it can reveal all deepsky studies found in the Messier catalogue. (Optimal seeing is defined as unaided and direct perception of stars to magnitude 5.5 overhead and clean resolution of matched double stars at Dawes limit.)

Celestron 114 Newtonian Reflector with CG3 Equatorial Mount. 10 and 25mm, Celestron SMA, 17mm Orion Sirius Plossl, 9 and 26mm Meade Series 4000 eyepieces plus 2X Orion “Shorty” Barlow. This scopes performance is comparable to the 80mm achromat in double star resolution but is able to go half a magnitude deeper in stellar reach.

150mm Orion Argonaut Maksutov-Cassegrain mounted on an Orion Skyview Deluxe Equatorial Mount. Eyepieces include 35/25/15/10mm Orion Ultrascopics, 3x Apochromatic and 2x Shorty Barlow Lenses. This scope is capable of revealing stars to magnitude 13.4 with direct vision. It cleanly resolves matched double stars to .8 arc seconds in apparent separation. Under optimal conditions, almost all studies described by William Herschel may be found in the night sky.

Meade 318mm Starfinder Newtonian Reflector on Altazimuth Dobsonian Mount. 2 inch 32mm Televue plus 17mm Orion Sirius Plossl, 9 and 26mm Meade Series 4000 eyepieces and 2X Orion “Shorty” Barlow. This “lightbucket” actually resolves matched double stars to .5 arc seconds. Stars to magnitude 15.0 may be held direct under good conditions. It is capable of revealing virtually all members of Dreyer’s New General Catalog plus a number of Index catalog (IC) studies as well!

At the Eyepiece:

M81 & M82:

So Traveller, shall we start with the 80mm? Here we find the M81 shows an obvious starlike core, with bright and extended core region blending into the beginnings of faint spiral arms. Although this showpiece galaxy flares to all directions on eye movement (which basically doubles any scope aperture), it appears somewhat “flattened”, showing a better defined frontier to the west. On nights of superb transparency (and at low magnification – 40x), the broad extensions of the galaxy’s spiral arms may be seen clearly with strongly averted vision. And surprisingly, some five arc minutes north of the galaxy’s core, a faint condensation may be detected. But the limits of small aperture leave the observer wanting more…

So, let’s increase to 114mm… At 53X, we find M81 as a lovely, soft “disc” with an intense core. By increasing the power to 90X, its true spiral form begins to show. Meanwhile, the central portion of the galaxy takes on a very concentrated appearance, and the outer frontiers fade gently away. Still, no “definitive” view of this superfine study, however.

Time to check out the view in the 150mm…

At 52x, spiral galaxy M81 sports a very bright, star-like central core. It’s core is large, elongated, and displays a considerable luminosity gradient from core-central to faint spiral arms. At this magnification, extended spiral arms require but the slightest aversion of the sight. As large as M81 is, it’s still helpful to bump up the magnification. At 70x, averted vision reveals a certain subtle “spiral-sweep” about the core region. The core itself orients more or less north-south and extends perhaps 5 by 10 arc-minutes in apparent size. This sweep of the core region is larger than many galaxies. A pair of 12th magnitude stars lie just off axis to the southwest. Careful inspection shows that the galaxy as a whole orients toward the more westerly of these two field stars. Under less than optimal conditions, less than half of M81 is susceptible to direct vision. But under optimal conditions, we are rewarded with fine views of large faint splotches of outlying luminosity. Through a six inch instrument, this grand galaxy needs to be doted over to be truly appreciated. While the core is easy, M81’s spiral arms are quite faint and need a good night of seeing to reveal themselves as something more than vague “mounds of luminosity”.

Increasing the aperture again to 310mm, let’s go to the eyepiece…

At minimum magnification (60X), the M81 does indeed remind one of a miniature “Andromeda” galaxy. The intense core, the sense of spiral arms folding round, all say “Grand Spiral”. But let’s head to a “higher power” (170X) and rock out structure. At this magnification, indications of dark dustlanes begin to exist at the outer edges. The central formation of the galaxy itself is impenetrable. More than two-thirds of its’ structure holds even concentration and makes the core area intense. It is toward the elongated edges that our attention is drawn with direct vision. Here are the classic “spiral arms” we’ve been looking for! At the highest of magnifications (312x), they fold themselves very close to the body of the M81, with each “tip” extending both above and below the central structure evenly. At the outermost fringes of these arms, averted vision reveals the mottling of distant clusters, and a sense of “trailing away” that give this well-endowed spiral real “class”!

Now, let’s go back to the 80mm and examine the M82…

On shifting the field to the more northern M82, we immediately catch the dark vertical break that splits this edge on west of the galaxy’s irregular core. Direct inspection of the galaxy fails to show more than where the break occurs – since little of luminosity can be seen further west of the discontinuity. Both the northern and southern frontiers are well defined and quite linear – even under marginal conditions. Aversion of the sight shows a bit of an extended halo outside the bounds of the flanking frontiers. We also note that the eastern extension shows a well defined “daggerlike” blade and tip.

At 114mm, that first view at low power (36X) screams “edge-on”! But, with patience and practice, delicate detail with averted vision begins to form, and the dark break becomes perceivable. Increasing the magnification to 90X makes this division more apparent, and causes the M82 to appear “spindle-shaped”… much like a child’s dirty kite string wrapped round a stick. Very little in the way of structure is seen, other than the fact than it’s lumpy.

Let’s move to 150mm…

M82 stretches out perhaps 10 arc-minutes east and west like a knife splitting the sky. It’s core is not of the luminous star-like variety… A gradual brightening is seen from one end of the galaxy to the center and back again to the opposite extreme. Unlike M81, the change is very gradual. A curious kneadiness or mottling is apparent – especially to the west. This edge-on irregular galaxy is broken by a dark lane along its southern frontier. The lane is not visible – only the sharpness by which it truncates the galaxy. In addition, a more obvious cleft of darkish matter divides the trailing half of the core. Overall, the visible part of the galaxy covers a region perhaps 2 by 8 arc-minutes in apparent size. A pair of 11th magnitude stars are visible west-southwest. In many ways M82 is more interesting than M81. It’s beauty lies in subtle variations of surface brightness which defy notions of pattern and verbal description.

Shall we seek in the 310mm? Then let’s find some answers…

At moderate magnifications (90X), M82 begins revealing structure to direct vision. The dark “break” one third of the way across its’ breadth is fully apparent, and the thickening portions along the body of the galaxy itself warrant closer investigation. Moving now to higher magnification (170X), we get the structure we were looking for… The galaxy no longer can be called “edge-on”, and clotted appearance of what must be thousands upon thousands of clusters make this one truly fine. The central portion bears no nucleus… pardon the descriptor, but it looks like cottage cheese! Toward one end, the dark division holds the lump of galactic mass in a gravity “lock”, and bleeds away into what almost appears with averted vision to be several open clusters. At the other end of the M82, all thoughts of resolution stop. Here the galactic matter appears to be “smeared”… as if the inner concentration of stars might perhaps be calmer, somehow. A very fine galaxy… It has earned its’ classification as irregular.

NGC2976:

Continuing with our study, we break away from this splendid galactic pair, and move onward toward yet another… This galaxy “lives” within a large house of 10th and 11th magnitude stars south-southwest of M81. The peaked-roof of the house lies to the east. And its’ name? NGC2976…

Starting with our 80mm refractor, this galaxy is difficult, but positively located within the same “house-shape” of stars. The sense of large apparent size remains present. Quite diffuse overall with slight condensation, it requires extreme aversion. Despite a dearth of structure, the galaxy hints at north-south orientation with a possibly better defined frontier to east.

Moving now to the 114mm newtonian reflector, we find it is detectable at 114mm in aperture… but that is all it is. A soft, elongated smudge that requires averted vision just to make out form.

Through 150mm at 52x and under 5.0 ULM conditions, NGC2976 appears large and diffuse. Maybe 3×5 arc minutes of the galaxy is possible with a southeast to northwest orientation. It displays a large, but dim core region. This gives it a sense of structure.

On eye movement, the galaxy flares to all directions, but less so to the southwest. It’s core region appears quite large, football shaped and diffuse. Bumping the magnification to 70x gives the core a somewhat edge-on appearance. At 120x the low surface brightness of this large galaxy causes it to completely dissolve.

At 310mm in aperture, the NGC2976 does not rock out detail in an expected fashion either, Now we are talking about being able to hold this galaxy direct, which means averted should bring out structure… What structure?! A tear drop, grainy-looking patch on the night with a bright star at the edge, tapering off into a chain of stars… That’s it. No sense of a nucleus…. no apparent fading at frontiers.

Time to move on? You bet! Let’s head off to capture another…

NGC3077:

Going to the 80mm, we find this galaxy easily located but lacking structure under direct perception. NGC3077 is small and diffuse, with faint extensions north and south. Sense of vague truncation (flattening) to east along with a soft, but perceptible degree of central condensation. Extreme aversion of the eye is needed to make out any of these details.

Now, moving on to the 114mm we find the NGC3077 is also detectable… as a very dim glow of galactic light with extreme averted vision, and one pinpoint star nearby.

Shifting our view points to 150mm we find at 52x and a 5.0 sky, this vaguely football-shaped galaxy is easily located but lacks obvious structure. There is a subtle sense of east-west orientation. Perceptible flaring appears on eye movement to all directions -except north. This lack of northern flaring hints at a dark lane that direction. A very faint star-like point can occasionally be seen near the center of the nebulosity. A slight amount of central condensation is possible but the lack of a defined core region means a very loose and diffuse appearance.

At 70x, the faint starlike-nucleus occasionally seen at 52x becomes a bit more consistent. The beginnings of a core region also emerges. At 120x a roundish blue core region with a soft, “unstarlike” nucleus can be seen, but the bulk of the galaxy is lost to sight for lack of photons…

Going to the 310mm dobsonian at differing ranges of magnification changes the picture just slightly. The most pleasing view is at 180X. Here we see an egg-shaped elliptical… evenly lighted, but there is a certain amount of degeneration at the edges… a sense that the light is being eroded away. Several field stars are also visible. A chain of three varying magnitudes to one side, and an elongated rectangular structure to the other.

Ready to rock on? Then let’s head toward a particularly difficult study…

IC2574:

IC2574 is next. Welcome only to large aperture telescopes! Once again, a faint, elongated, lumpy bar of light. This one shows “lobes” of concentration at either end of it’s structure. Not only does this one appear as “lumpy”… but there are a great many field stars that accompany it… like very precise open clusters! They are vague… and when the dob presents you with vague light in the presence of pinpoint stars, we would venture to say that this galaxy is accompanied by some nebulosity.

Right? Wrong? It’s a study… and we’re not through yet. So let’s head on back to our galaxy hunt, and see what else we can find. Another faint member of this group stretches across the border into Camelopardis. It is also a rather difficult study… But that’s why we’ve brought along the power of aperture.

NGC2366:

Between apparent size and surface brightness, the NGC2366 is best left to the larger scope. Detectable as low as 48X as a tiny, grainy bar of light, the best view comes at 170X. At this magnification, the NGC2366 takes on structure. Several areas of light concentration are seen, making it appear as though it has three centers. Adding the barlow and increasing to 340X pulls the picture in much closer, losing hard edge clarity, but reveals at one end, a notch occurs in the galaxy… Much like a crescent wrench. Opposite of this “notch” is also what may either be a small open cluster, or perhaps a bit of wayward galactic material. Going back to 170X is much more comfortable, and the lumpy figure of the NGC2366 most definitely has earned its’ classification as an “irregular” galaxy!.

NGC2403:

On to our last study, the NGC2403… This one is definitely a “all scopes” kinda’ galaxy!

In the 80mm there is nothing diffuse about this galaxy. Orienting northwest to southeast, it displays a well-developed northwest spiral extension and surprisingly little to the southeast. (Giving NGC2403 a very “cometlike” appearance.) This baby is definitely overdeveloped. No starlike core, just a general brightening toward the center. Bright stars flanking it complicate the view. It’s not hard to be both baffled and impressed by this bright galaxy way out in the reaches of Camelopardis.

Easily found and recognizable in the 114mm at 17mm as a spiral, the little scope pulls out a stellar core and definately sense of fading toward the frontiers.

Moving up to 150mm, we find that although NGC2403 fails to rival Bode’s Galaxies in terms of brightness and structure, it makes a good run for it. The galaxy is large, conspicuous and possesses a well-defined northern frontier, starlike core and extended core region. It also presents mostly edge-on (cigar-shaped) and shows well even under marginal 5.0 ULM skies.

At 70x, two faint spiral extensions are possible, with the western extension more obvious than the east. This gives the sense of the core region being offset in that direction. At 120x, a tiny blue nucleus can just be held with slight aversion. Complicating the view of this galaxy are a series of bright 7th and 8th magnitude stars flanking it along the southern frontier.

314mm time? Oh, yeah… Now here is some superior structure! Mottling begins even with as little magnification as 60X. Adequately large enough to be studied at lower magnifications, we find the view at 90X the most pleasing. Concentrated, egg-shaped nucleus… one soft “horseshoe” of a dark dust lane, and hints of globular clusters that cry out for more. Comply? Of course. Let’s set 170X on it… We have what appears to be globular structure in a very “open” looking arm. Not only here, but several knots exist throughout the NGC2403. And yet again, we “make out” something that looks like a small, attendant open cluster. No nearby bright stars at magnification as markers, the field is nothing more than some fine chains… But who cares? Cuz’ this is one fine galaxy!!

Parting Thoughts:

And so we have journeyed eight million light-years across the night together. And still I would stay with you, Traveller. For a hundred billion more. “The Bear that sees star setting after star… In the blue brine, descends not to the deep.” The stars, the night, and the far flung universes awaits you …

My many thanks to Karel Teuwen and Deitmar Hager, F.R.A.S. of Northern Galactic for their outstanding images and I would like to gratefully acknowledge Jeff Barbour for being a major contributor to both the studies and writing that went into this article. It’s nice to be able share the view through an 80mm refractor and 150mm SCT from 3,000 miles away!

Posted on by Tammy Plotner

Weekend SkyWatcher’s Forecast: January 30 – February 1, 2009

Greetings, fellow SkyWatchers! The Moon is back again, but what a terrific target for winter studies. Why not get out your binoculars and telescopes as we take a look at strange and unusual places like the Serpent Sea, the Marsh of Sleep and the Lakes of Time, Death and Dreams? If you haven’t wished upon a star lately, then there’s a serious reason to take a look at Sirius this weekend! Step outside in the dark with me where we’ll explore a little history, a little mystery, and just plain have us some fun…

Friday, January 30, 2009 – Tonight’s early evening Moon is high enough to warrant study. During the last lunar cycle, we reviewed maria large enough to be seen unaided, but many more can be revealed telescopically. Magnify the Crisium region and let’s look around. Along the eastern side near the lunar limb is Mare Marginis, whose position between the nearside and farside will never allow us to see more than a thin gray line. Thanks to the lunar orbiters, we know it has an irregular border and shallow lava fill, which lead scientists to believe Marginus wasn’t created from an impact. Located southeast is Mare Undarum , the ‘‘Sea of Waves.’’ This highly elevated part of the Crisium basin is about the size of Massachusetts, and it probably filled with lava around the time of the Imbrium impact. Northeast, and separated by a mountain range, is Mare Anguis, or the ‘‘Serpent Sea.’’ This Vermont-sized area of lunar landscape formed differently and may be home to a vast number of lava tubes.

crisium_region

Now look to Crisium’s northwest for a new feature, Lacus Bonitatis , or the ‘‘Lake of Goodness.’’ With features similar to those of maria, this small, irregularly shaped area has as much ‘‘coastline’’ as the Black Sea! Further south is Palus Somni, the ‘‘Marsh of Sleep.’’ This curious feature is an upland area. Relatively flat—but very uneven—its high albedo (surface reflectivity) makes it a rewarding study. Last on tonight’s tour is Sinus Concordiae , the ‘‘Bay of Harmony.’’ Essentially part of the maria that spawned it, this inlet leads toward higher ground. Concordiae’s small bay is roughly the size of Pedro Bank in Jamaica. Like its earthly counterpart, it may have mountain peaks that are just barely covered – but by lava flow, not seawater. Be sure to list your evening’s observations in your lunar notes. We’ll return in the months ahead here for more!

‘‘Everything has a natural explanation. The moon is not a god, but a great rock.’’ — Anaxagoras (475 BC)

hamSaturday, January 31, 2009 – What a busy date in astronomy history! In 1958 the United States. launched its first satellite – Explorer 1 – which discovered the bands of radiation now referred to as the Van Allen Belts . In 1961 the Mercury-Redstone 2 launched, carrying Ham the chimpanzee to fame. Cabin pressure failed during the suborbital flight, but inside his pressure suit, Ham remained safe and performed his tasks with a reaction time only a half second slower than on the ground, proving primates could function in space! (And a few years later, astronauts started drinking and shooting at each other, proving that humans could function like primates.) Ham lived for another 17 years, and the celebrated chimp gave many performances – even guest starring in movies!

Luna 9 was launched in 1962 and 72 hours after its launch became the first craft to successfully touch down on the Moon and broadcast television from Oceanus Procellarum . Even Apollo 14 was Luna-bound today in 1971! Alvan Graham Clark , Jr, made history at the eyepiece on this date in 1862. While watching Sirius and testing an 18″ refractor his family built, Clark uncovered the intense star’s faint companion – Sirius B. Friedrich Bessel had proposed its existence back in 1844, but this was the first visual confirmation.

sirius_chumack

Try your own hand at the ‘‘Scorching One.’’ Alpha Canis Majoris has an amazing magnitude of -1.42. Next to Alpha Centauri , 8.7 light-year distant Sirius is the closest visual star, but it’s not standing still. Part of the Ursa Major moving stream, Sirius has changed position by one and half times the apparent width of the Moon in just 2,000 years! Telescopically, this main-sequence gem is dazzling white, tinged with blue and diffracts a rainbow of colors. For many of us, beautiful iridescence is all we’ll ever see, but a small telescope (114-150mm) under perfectly steady skies will reveal the secretive companion. In 20 years it will reach maximum separation of 11.500, so keep watching to Sirius’ southeast when you observe – perhaps you’ll spot B!

berknerSunday, February 1, 2009 – On this day we celebrate the 1905 birth of Lloyd Berkner, the first person to measure Earth’s ionosphere. His work with radar led to an understanding of radio wave propagation. He also served as administrator at Green Bank National Radio Astronomy Observatory. For his achievements in space science, NASA awarded Berkner the Distinguished Public Service Medal.

The broad crescent Moon dominates the early evening sky. Tonight we’ll explore new features as we start in the lunar north with Mare Humboldtianum spanning 350 kilometers, this inconspicuous multi-ringed feature depends on libration for best views.

hope

Further south along the limb is Lacus Spei (the Lake of Hope), a diminutive feature so small it could be crossed at walking speed in 10 hours! West of Humboldtianum and Spei is a pair of lighter areas devoid of features— Lacus Temporis (the Lake of Time). These two small overlapping basins were filled by the same lava flow, thus forming this small mare. How long to walk across Temporis? Twice as much ‘‘Time’’ as ‘‘Hope’’!

Relocate Mare Frigoris (the Cold Sea) and look south along the terminator for Lacus Mortis (the Lake of Death) and its counterpart Lacus Somniorum (the Lake of Dreams). Is there a connection here? You betcha! These two basin areas were filled from a basaltic flow, which might have united them, but a small mountain range kept them apart.

‘‘There is something haunting in the light of the Moon; it has all the dispassionateness of a disembodied soul, and something of its inconceivable mystery.’’ –Joseph Conrad

By the way, we believe Werner Heisenberg died on this day in 1976, but no one is certain.

Until next week? Ask for the Moon… But keep on reaching for the stars!

This week’s awesome images are: The Crisium Region (credit—Greg Konkel), Ham
the Chimpanzee (credit—NASA), Sirius (credit—John Chumack), Lloyd Berkner (public image) and Hope, Time, Death, and Dreams (credit—Greg Konkel). We thank you so much for sharing your splendid talents with us!