Astronomy Archives

January 7, 2009December 24, 2015 by Ian O'Neill

Could Quark Stars Explain Magnetars Strong Magnetic Field?

The magnetic field surrounding the mysterious magnetar (NASA)

[/caption]Magnetars are the violent, exotic cousins of the well known neutron star. They emit excessive amounts of gamma-rays, X-rays and possess a powerful magnetic field. Neutron stars also have very strong magnetic fields (although weak when compared with magnetars), conserving the magnetic field of the parent star before it exploded as a supernova. However, the huge magnetic field strength predicted from observations of magnetars is a mystery. Where do magnetars get their strong magnetic fields? According to new research, the answer could lie in the even more mysterious quark star…

It is well known that neutron stars have very strong magnetic fields. Neutron stars, born from supernovae, preserve the angular momentum and magnetism of the parent star. Therefore, neutron stars are extremely magnetic, often rapidly spinning bodies, ejecting powerful streams of radiation from their poles (seen from Earth as a pulsar should the collimated radiation sweep through our field of view). Sometimes, neutron stars don’t behave as they should, ejecting copious amounts of X-rays and gamma-rays, exhibiting a very powerful magnetic field. These strange, violent entities are known as magnetars. As they are a fairly recent discovery, scientists are working hard to understand what magnetars are and how they acquired their strong magnetic field.

Denis Leahy, from the University of Calgary, Canada, presented a study on magnetars at a January 6th session at this week’s AAS meeting in Long Beach, revealing the hypothetical “quark star” could explain what we are seeing. Quark stars are thought to be the next stage up from neutron stars; as gravitational forces overwhelm the structure of the neutron degenerate matter, quark matter (or strange matter) is the result. However, the formation of a quark star may have an important side effect. Colour ferromagnetism in color-flavour locking quark matter (the most dense form of quark matter) could be a viable mechanism for generating immensely powerful magnetic flux as observed in magnetars. Therefore, magnetars may be the consequence of very compressed quark matter.

These results were arrived at by computer simulation, how can we observe the effect of a quark star — or the “quark star phase” of a magnetar — in a supernova remnant? According to Leahy, the transition from neutron star to quark star could occur from days to thousands of years after the supernova event, depending on the conditions of the neutron star. And what would we see when this transition occurs? There should be a secondary flash of radiation from the neutron star after the supernova due to liberation of energy as the neutron structure collapses, possibly providing astronomers with an opportunity to “see” a magnetar being “switched on”. Leahy also calculates that 1-in-10 supernovae should produce a magnetar remnant, so we have a pretty good chance at spotting the mechanism in action.

January 7, 2009December 24, 2015 by Tammy Plotner

Sagitta

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Sagitta belongs to the original 48 constellations charted by Ptolemy and it remains one of the 88 modern constellations defined by the International Astronomical Union. Located north of the ecliptic plane, it spans 80 square degrees of sky, ranking 86th in constellation size. Sagitta contains 4 main stars in its asterism and has 19 Bayer Flamsteed designated stars within its confines. It is bordered by the constellations of Vulpecula, Hercules, Aquila and Delphinus. Sagitta is visible to all observers located at latitudes between +90° and ?70° and is best seen at culmination during the month of August.

In ancient history, the constellation of Sagitta was once known as Sham – a name applied today to its Alpha star. It was the Romans who named it Sagitta, the “Arrow”. In ancient Greek myth, it depicted the weapon which Hercules used to kill the eagle Aquila – or perhaps the Stymphalian birds. Perhaps it is Cupid’s Arrow, or the one which the Centaur shot at Chiron… No matter which tale you choose, it’s unmistakeable arrow shape was clear to all cultures, including the Persians, Hebrews, Greeks and Romans. Only Johann Bayer seemed to have trouble with it… For it is one of those constellation in which he named the bright stars out of order!

Let’s begin our binocular tour of Sagitta with Alpha – the “a” symbol on our chart. While Sham isn’t the brightest star in the constellation, this yellow bright giant star’s name really does mean “arrow”. Located about about 475 light years from Earth, it has a stellar luminosity 340 times that of the Sun and is about 20 times larger. Sham falls inside the “Hertzsprung Gap,” a perimeter of stellar temperature and luminosity that few stars fit inside. From its point in stellar evolution, it should have stopped fusing hydrogen to helium and began to brighten. However, that’s not the case. For some reason, Sham’s surface shows an abundance of nitrogen – a state which could only occur from interior helium fusion. A Cepheid variable star in the making? Perhaps!

Take a look at Beta in binoculars – the “B” symbol on our map. It’s G-type yellow star like our own Sun. Beta Sagittae is a giant star and, like Sham, is only about 467 light years away from our solar system. Delta, in the center of the arrow, is a spectroscopic binary star. It consists of a class M giant star and a quiet little hydrogen fusing dwarf star. Both are happy at a distance of about 448 light years from here and both happily separated from each other by a little less than 9 AU. Don’t forget red giant star, Gamma, either! The “Y” star on our chart might be 275 light years away, but it shines 640 times brighter than our Sun! It, too, is highly evolved…. Surrounded by a shell and well on its way to becoming a Mira-type variable star and eventually a white dwarf star about the size of the Earth.

For large binoculars and small telescopes, set your sights towards Messier 71 (RA 19 : 53.8 Dec +18 : 47). At around 8th magnitude, this loosely structured globular cluster is a challenge for smaller optics, but a wonderful study. It was originally discovered by Philippe Loys de Chéseaux in 1746 and included by Charles Messier in his Messier catalog of comet-like objects in 1780. Residing about 12,000 light years away and spanning about 27 light years across, there has long been a debate about this star cluster’s proper designation… globular cluster or concentrated galactic star cluster? Thanks to modern photometry, astronomers have detected a short “horizontal branch” in the H-R diagram of M71, which is characteristic of a globular cluster. Its low metallicity content has now been recognized as that of a “youthful” globular cluster and its lack of RR Lyrae variables places it at an age of between 9 and 10 billion years old.

For two challenging large telescope studies, let’s try your hand with planetary nebulae. The first is NGC 6879 (RA 20 : 10.5 Dec +16 : 55). At an apparent magnitude of 13, this challenging study will require high magnification and careful alignment to pick out from the stellar field. However, don’t be discouraged, because the nebula itself is rather bright and conspicuous as a “hairy star”. Just as challenging is NGC 6886 (RA 20 : 12.7 Dec +19 : 59). While the central star is a magnitude brighter at 12, you’re going to need at least an 8″ telescope to detect this one. It has an unusual chemical composition which an OIII filter helps to reveal.

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

January 7, 2009December 24, 2015 by Tammy Plotner

Reticulum

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Located south of the ecliptic plane, the small, faint constellation of Reticulum was first named Rhombus by astronomical clock creator – Isaac Habrecht. It was later renamed Reticulum by Nicolas Louis de Lacaille in 1763. It spans 114 square degrees of sky, ranking 82nd in constellation size, has 4 main stars in its primary asterism and contains 11 Bayer Flamsteed designated stars within its confines. Reticulum is bordered by the constellations of Horologium, Dorado and Hydrus. It is visible to all observers located at latitudes between +23° and ?90° and is best seen at culmination during the month of January.

Since Reticulum is a “new” constellation, there is no mythology associated with it – only the story of how its name came to be. Originally named Rhombus by Isaac Habrecht, it was a name the fit the star pattern, considering a rhombus is a basic diamond pattern. Habrecht and his brother were talented Germany clock makers and one of their specialities was in fashioning astronomical clocks. As a matter of fact, they built the second astronomical clock in Strasbourg between 1571 and 1574. It was designed by mathematician Christian Herlin, and as well as the Habrecht brothers, had astronomer and musician David Wolckenstein to assist. This fantasy clock had a staircase, huge amounts of artwork, musical embellishments, but was best known for its complexity as an astronomical device. It had a calendar dial, the astrolabe, the indicators for planets and eclipses… and a celestial globe. When Lacaille made his sojourn to the Cape of Good Hope, his intent wasn’t to usurp Habrecht’s place in astronomical history – but to unify astronomical catalogs. In an attempt to honor instruments of science and his telescope for which he used to chart the southern skies, Lacaille named this trapezoidal collection of stars Reticulum, the Latin derivative for the reticule crosshairs on his spyglass which enabled him to accurately pinpoint star positions. The name Reticulum stuck and was later adopted as one of the 88 modern constellations by the International Astronomical Union.

Let’s begin our binocular tour of Reticulum with its brightest star – Alpha – the “a” symbol on our chart. Alpha Reticuli is a yellow G class giant star which is about 163 light years away from Earth. It shines about 237 times brighter than our Sun and is about 21 times larger. It will eventually end its life quietly as a white dwarf star. But, take out your telescope and have a closer look! You’ll find out that Alpha is also a binary star with a very disparate 12th magnitude companion star nearby. While the star hasn’t moved in the last 150 years, the pair does display the same proper motion.

Keep binoculars handy and hop west for Zeti Reticuli. This binary star system located about 39 light years away from our own solar system. The pair of twin suns are very much like our own in temperature and mass – yellow dwarf stars – but it’s there the similarities end. At one time, astronomers believed the Zeta pairing to be old galactic halo Population II subdwarf stars, but recent research indicates the may belong to the younger galactic disk population. This makes the twin Zetas far older than our Sun – in the neighborhood of 8 billion years old. And they aren’t moving along alone! The pair belongs to the Zeta Herculis Moving Star Group. Both stars share similar proper motions and distances – and despite being so widely spaced, they are a true binary star with an orbital period of an estimated million years!

While viewing Zeta, keep in mind all the legends behind this particular pair. In 1961, alien abductees – Barney and Betty Hill – were “taken” by citizens who imparted information to Betty that their home star was the Zeta system. After a map was constructed by an amateur astronomer and eventually debunked by Carl Sagan, then later sensationalized by Bob Lazar, the Zeta “planet” theory eventually went into hibernation for fear of media attention. On September 20, 1996 a tentative discovery of a “hot Jupiter” in the Zeta system was discovered and quickly retracted as being “pulsations” from the star… and while conditions are possible for Earth-like planets to exists around these twins suns, low solar metallicity makes their presence unlikely.

Before you give up planetary hopes, hop to Epsilon Reticuli – the backwards “3” symbol on our map. Now here’s a binary system located approximately 59 light-years away that really does have a confirmed planet! The primary star is an orange subgiant star, while the secondary star is a white dwarf star. As of 2000, an extrasolar planet has been confirmed to be orbiting the primary star in the system! It is roughly the size of Jupiter and it orbits around the star every 418 days. What’s more, there could possibly be an Earth-like trojan accompanying it!

For binoculars, keep a watch on R Reticuli – a Mira-type variable star. While it takes 278.3 days for it to go through it’s changes, they are very dramatic. You’ll find this incredible star begins by shining at respectable magnitude of 6.5 only to virtually turn telescopic at magnitude 14 during its minima. Now that’s variable!

For a small telescope and big binocular challenge, try your hand at NGC 1313 (RA 3 : 18.3 Dec -66 : 30). At magnitude 9 and more than 8 arc minutes in size, this starburst galaxy is often referred to as the “Topsy Turvy” because of its unusual supershell spiral galaxy structure. Located about 15 million light years away, large telescopes will pick out strange features, like spiral arms which are lopsided and its rotational axis is not at the center of the nuclear bar.

Now, have a go at NGC 1559 (RA 4 : 17.6 Dec -62 : 47). Although this barred spiral galaxy is over a magnitude fainter and about half the size of the last, you’ll still find it quite bright and rich in the telescope. Although it was originally thought to be a member of the Dorado Galaxy Group, this Seyfert Galaxy is all alone in space. NGC 1559 has massive spiral arms and strong star formation. It contains a small bar which is oriented nearly east-west and spans 40?. Its bar and galactic disc are the source of very strong radio emissions!

Our last galaxy is NGC 1543 (RA 4 : 12.8 Dec -57 : 44). Also about magnitude 10.5 and about 4 arc minutes in size, Dunlop 100 really is considered part of the Dorado Galaxy Group. Look for a very bright nucleus in this spiral galaxy, with a faint east to west extension!

Chart Courtesy of Your Sky.

January 6, 2009December 24, 2015 by Fraser Cain

If Brown Isn’t a Color, What Color are Brown Dwarfs?

Artist's impression of a brown dwarf. Image credit: NASA/JPL

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We’ve talked about brown dwarfs here on Universe Today for years and years. These are the “failed stars”; objects with too little mass to fully ignite nuclear fusion in their cores. Instead of blazing with red, yellow or the white light of our own stars, they’re heated by the gravitational collapse of material. They’re called brown dwarfs, but you might be surprised to know that they aren’t actually brown. In fact, it’s impossible to have brown light. So what color are they?

The term “brown dwarf” was originally coined by Jill Tarter in 1975 to describe these objects, and there were other suggestions for names, like planetar and substar. But the name “brown dwarf” stuck. And here’s the problem, as described by Jill Tarter, “it was obvious that we needed a color to describe these dwarfs that was between red and black. I proposed brown and Joe (Silk) objected that brown was not a color.”

Brown isn’t a color?!

Not for astronomers. When they consider the color of a star, astronomers are talking about the wavelength of the light being emitted. Stars emit light at various wavelengths, and whatever photons are mostly being emitted are what we see. Yellow stars emit primarily yellow photons, red stars emit mostly red photons, etc. But you can’t have a star emit brown photons because the “color” brown is a de-saturated yellow. Brown dwarfs can’t be brown because it’s impossible to emit brown light. So what color are they?

Dr. Kenneth Brecher is a professor at Boston University and the primary investigator for Project LITE. This is a research project that uses a variety of experiments to understand how people see color. I highly recommend you check out the Project LITE website and take a look at the Flash experiments they have available. You’ve probably seen some of these optical illusions in the past, where spinning wheels of black-and-white can actually create different colors in our brains. Brecher demonstrated one of these color wheels for me – it’s a CD that can spin like a top. At rest, you see black-and-white, and then spin up the disk and you can see red, green and blue. Very cool stuff (totally unconnected from the color of brown dwarfs).

Brecher did a presentation at the American Astronomical Society Meeting about the actual color of brown dwarfs. He even had a flashlight that shines a light the color of brown dwarfs. Unfortunately, I didn’t catch a photo of it, but check out Nature’s blog, they got one. It’s sort of a dull orange color. But here’s the cool part. There’s no way to actually see the color of a brown dwarf unless you’re having the photons strike your eyeballs.

All you color theory folks might want to know the hexidecimal code: EB4B25. And here are the RGB values: R-235, G-75, B-37

So what color would an isolated brown dwarf look like? Dr. Brecher had a slide in his presentation that shows the color – we’ve extracted it and made it bigger. I think it looks kind of reddish orange, but then color is in the eye of the beholder.

January 6, 2009December 24, 2015 by Nancy Atkinson

“Lighthouse” Analogy No Longer Works for Pulsars

NASA's Fermi Gamma-ray Space Telescope has found 12 previously unknown pulsars (orange). Fermi also detected gamma-ray emissions from known radio pulsars (magenta, cyan) and from known or suspected gamma-ray pulsars identified by NASA's now-defunct Compton Gamma-Ray Observatory (green). Credit: NASA/Fermi/LAT Collaboration

NASA’s Fermi Gamma-ray Space Telescope has found 12 previously unknown gamma-ray only pulsars, as well as identifying gamma-ray emissions from 18 known or suspected radio pulsars. And what the telescope is finding is changing the way we think of these stellar cinders. The old analogy for pulsars was a lighthouse: gamma-rays were thought to pulse out in a narrow beam from the neutron star’s magnetic poles. But this new research shows that cannot be the case. A new class of gamma-ray-only pulsars shows that the gamma rays must form in a broader region than the lighthouse-like radio beam. “We used to think the gamma rays emerged near the neutron star’s surface from the polar cap, where the radio beams form,” says Alice Harding of NASA’s Goddard Space Flight Center. “The new gamma-ray-only pulsars put that idea to rest.” She and Roger Romani from Stanford University in California spoke today at the American Astronomical Society meeting.

A pulsar is a rapidly spinning and highly magnetized neutron star, the crushed core left behind when a massive sun explodes. Most were found through their pulses at radio wavelengths, and were thought to be caused by narrow, lighthouse-like beams emanating from the star’s magnetic poles.

If the magnetic poles and the star’s spin axis don’t align exactly, the spinning pulsar sweeps the beams across the sky. Radio telescopes on Earth detect a signal if one of those beams happens to swing our way. Unfortunately, any census of pulsars is automatically biased because we only see those whose beams sweep past Earth.

“That has colored our understanding of neutron stars for 40 years,” Romani says. The radio beams are easy to detect, but they represent only a few parts per million of a pulsar’s total power. Its gamma rays, on the other hand, account for 10 percent or more. “For the first time, Fermi is giving us an independent look at what heavy stars do,” he adds.

Watch an animation of the new look at these pulsars.

Pulsars are phenomenal cosmic dynamos. Through processes not fully understood, a pulsar’s intense electric and magnetic fields and rapid spin accelerate particles to speeds near that of light. Gamma rays let astronomers glimpse the particle accelerator’s heart.

Astronomers now believe the pulsed gamma rays arise far above the neutron star. Particles produce gamma rays as they accelerate along arcs of open magnetic field. For the Vela pulsar, the brightest persistent gamma-ray source in the sky, the emission region is thought to lie about 300 miles from the star, which is only 20 miles across.

Existing models place the gamma-ray emission along the boundary between open and closed magnetic field lines. One version starts at high altitudes; the other implies emission from the star’s surface all the way out. “So far, Fermi observations to date cannot distinguish which of these models is correct,” Harding says.

Because rotation powers their emissions, isolated pulsars slow as they age. The 10,000-year-old CTA 1 pulsar, which the Fermi team announced in October, slows by about a second every 87,000 years.

Fermi also picked up pulsed gamma rays from seven millisecond pulsars, so called because they spin between 100 and 1,000 times a second. Far older than pulsars like Vela and CTA 1, these seemingly paradoxical objects get to break the rules by residing in binary systems containing a normal star. Stellar matter accreted from the companion can spin up the pulsar until its surface moves at an appreciable fraction of light speed.

“We know of 1,800 pulsars, but until Fermi we saw only little wisps of energy from all but a handful of them,” said Romani. “Now, for dozens of pulsars, we’re seeing the actual power of these machines.”

Source: NASA

January 6, 2009December 24, 2015 by Nancy Atkinson

Molecules in Gamma-Ray Burst Detected

This image merges Swift optical (blue, green) and X-ray views of GRB 080607. The white spot at center is the burst’s optical afterglow. Credit: NASA/Swift/Stefan Immler

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Gamma-ray bursts are the universe’s most brilliant events, and now astronomers have been able to shed light on the composition of these spectacular phenomena, providing insight into star formation when the universe was about one-sixth its present age. Combining data from NASA’s Swift satellite, the W. M. Keck Observatory in Hawaii, and other facilities astronomers have, for the first time, identified gas molecules in the host galaxy of a gamma-ray burst. “We clearly see absorption from two molecular gases: hydrogen and carbon monoxide. Those are gases we associate with star-forming regions in our own galaxy,” said Xavier Prochaska, from the University of California Santa Cruz. He and his team believe that the burst exploded behind a thick molecular cloud similar to those that spawn stars in our galaxy today.

The explosion, designated GRB 080607, occurred in June, 2008. “This burst gave us the opportunity to ‘taste’ the star-forming gas in a young galaxy more than 11 billion light-years away,” said Prochaska.

Gamma rays from GRB 080607 triggered Swift’s Burst Alert Telescope shortly after 2:07 a.m. EDT on June 7, 2008. Swift calculated the burst’s position, beamed the location to a network of observatories, and turned to study the afterglow.

That night, University of California, Berkeley, professor Joshua Bloom and graduate students Daniel Perley and Adam Miller were using the Low Resolution Imaging Spectrometer on the 10m Keck I Telescope in Hawaii. “Because afterglows fade rapidly, we really had to scramble when we received the alert,” Perley says. “But in less than 15 minutes, we were on target and collecting data.”

The Peters Automated Infrared Imaging Telescope (PAIRITEL) in Arizona caught GRB 080607’s afterglow (circled) about three minutes after the explosion. The afterglow’s light has been greatly dimmed and reddened by interstellar dust in its host galaxy, 11.5 billion light years away. Credit: Adam Miller and Daniel Perley/UC Berkeley

A pair of robotic observatories also responded quickly. The NASA-supported Peters Automated Infrared Imaging Telescope (PAIRITEL) on Mount Hopkins, Ariz., and the Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory on Mount Hamilton, Calif., observed the burst’s afterglow within three minutes of Swift’s alert.

The spectrum from Keck established that the explosion took place 11.5 billion light-years away. GRB 080607 blew up when the universe was just 2.2 billion years old.

The molecular cloud in the burst’s host galaxy was so dense, less than 1 percent of the afterglow’s light was able to penetrate it. “Intrinsically, this afterglow is the second brightest ever seen. That’s the only reason we were able to observe it at all,” Prochaska says.

Screening from thick molecular clouds provides a natural explanation for so-called “dark bursts,” which lack associated afterglows. “We suspect that previous events like GRB 080607 were just too faint to be observed,” says team member Yaron Sheffer of the University of Toledo, Ohio.
Nearly half of the absorption lines found in the Keck spectrum are unidentified. The team expects that understanding them will provide new data on the simplest space molecules.

Prochaska and Sheffer presented the findings today at the 213th meeting of the American Astronomical Society in Long Beach, Calif. A paper describing the results will appear in a future issue of Astrophysical Journal Letters.

Most gamma-ray bursts occur when massive stars run out of nuclear fuel. As the star’s core collapses into a black hole or neutron star, gas jets punch through the star and into space. Bright afterglows occur as the jets heat gas that was previously shed by the star. Because a massive star lives only a few tens of millions of years, it never drifts far from its natal cloud.

Source: NASA

January 6, 2009December 24, 2015 by Tammy Plotner

Pyxis

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The constellation of Pyxis is located south of the ecliptic plane. At one time its stars were considered part of the ancient constellation of Argo Navis as the “mast” of the great ship. In later years, Argo Navis was split into three seperate constellations – Puppis, Vela and Carina – by Nicolas Louis de Lacaille. At the time he named the Pyxis group of stars Pyxis Nautica – the “Mariner’s Compass”. It was suggested by John Herschel the group of stars be named Malus, the “Mast”, but the suggestion was not followed. When the constellation was officially recognized and placed permanently by the IAU, the name was shortened to just Pyxis. It covers 221 square degrees of sky and ranks 65th in size. Pyxis contains 3 main stars in its asterism and has 10 Bayer Flamsteed designated stars within its confines. It is bordered by the constellations of Hydra, Puppis, Vela and Antlia. Pyxis is visible to all observers located at latitudes between +50° and ?90° and is best seen at culmination during the month of March.

As a section of the great ship Argo Navis, the mythology of Pyxis is the legend of the great sea and the adventures of Jason and the Argonauts. The great galley was built under the orders of the goddess Athene, where she then fitted a beam into the prow from the oracle of Zeus. On board was a crew of Greek heroes, including such notable mythological figures such as Hercules, Castor and Pollux. Of course, their journeys were legendary, and after having acquired the golden fleece they dedicated the ship to the sea god Poseidon, who immortalized it in the stars and the first of the ocean-going vessels. Due to it’s enormous size, early cartographers often had difficulty portraying it on star charts and its magical prow had disappeared. The mariner’s compass, the constellation of Pyxis, was also once considered a part of Argo Navis, too… But has also been divided away with time. Small wonder since the magnetic compass was virtually unknown to the ancient Greeks! However, we cannot default Lacaille for his love of scientific instruments and his wish to immortalize them in the stars. Where charts did not depict the mast, Lacaille figured it was anchored in a reef and called his new constellation “la Boussole” to represent a marine compass.

Let’s begin our binocular tour of Pyxis with its brightest star – Alpha – the “a” symbol on our map. Alpha Pyxidis is 850 light years away from Earth and appears quite dim because of interstellar dust. In reality, this hot, blue-white giant star is about 18,000 times brighter than our own Sun and about 8 times larger. Hiding inside a circumstellar shell, Alpha might very well be a Beta Cephi variable star!

For large binoculars and small telescopes, try your hand at open cluster and planetary nebula combination, NGC 2818 (RA 9 : 16.0 Dec -36 : 37). At magnitude 8 and 9 arc minutes in size, it will be a challenge for smaller optics, but a fun one! The planetary nebula is very unique due to its association with a Population I open star cluster. This means the cluster itself is overabundant in HII regions and studies have shown that it is associated with the cluster and not just a chance alignment. Large telescopes will pick up lobes in the planetary nebula structure and a faint green coloration, while the cluster structure is very open and scattered.

Another challenging galactic star cluster for binoculars and small telescopes is NGC 2627 (RA 8 : 37.3 Dec -29 : 57). At magnitude 8 and 11 arc minutes in size, it makes a slightly better presentation with more compression and stars. While it will only be a hazy patch in binoculars, larger telescopes can expect to resolve out around 40 or so stars in the rich field and pick out some color in this intermediate aged open wonderland!

How about a telescope challenge? Then try your hand at NGC 2613 (RA 8 : 33.4 Dec -22 : 58). This 10th magnitude spiral galaxy is surprisingly large, bright, and overlooked! Located about 60 million light years away from our solar system, this under-rated jewel is a case study in radial velocity dispersions and stellar kinematics. According to research, massive edge-on spiral galaxy NGC 2613 shows evidence of supershells which, if confirmed, would be among the largest known!

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

January 6, 2009December 24, 2015 by Tammy Plotner

Puppis

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The constellation of Puppis once belonged to a much larger constellation known as Argo Navis – the mythological ship used by Jason and the Argonauts. Argo Navis was recognized as one of the original 48 constellations charted by Ptolemy, but was later subdivided in 1752 by Nicolas Louis de Lacaille into three sections and renamed into Carina (the keel of the ship), Puppis (the poop deck), and Vela (the sails). Because Bayer Flamsteed designations were already in use at the time, the designations were also split, with each constellation taking the Argo Navis designation with it – such as Alpha and Beta belonging to Carina – while Vela has Gamma and Delta. After officially being listed as one of the 88 modern constellation by the International Astronomical Union, Puppis now occupies 673 square degrees of sky and ranks 20th in constellation size from its position just south of the ecliptic plane. Puppis is bordered by the constellations of Monoceros, Pyxis, Vela, Carina, Pictor, Columba, Canis Major and Hydra It contains 76 Bayer Flamsteed stars within its confines and its primary asterism is composed of 9 main stars. Puppis is visible to all observers located at latitudes between +40° and ?90° and is best seen at culmination during the month of February.

There are three minor annual meteor showers associated with the constellation of Puppis. Beginning each year on about April 15 through April 28, you can watch for activity from the Pi Puppids, with the peak date of maximum activity on or about April 23. The meteoroid stream is very irregular and the fall rate is variable. The Zeta Puppids begin activity around November 2 and end around December 20th with a peak date of on or about November 13th. This is also a very weak meteoroid stream which produces no more than about 3 meteors per hour at maximum. The Puppid-Velid meteor shower begins around December 2 and lasts through December 16th with a peak date on or about December 12. While this is also an understudied meteor shower, it does have a slightly more productive rate at a maximum of 4 meteors per hour during peak activity. The radiant for this shower is very complex, so keep an eye out in the whole general area. It contains several substreams and may have several different times of maxima.

As a section of the great ship Argo Navis, the mythology of Puppis is the legend of the great sea and the adventures of Jason and the Argonauts. The great galley was built under the orders of the goddess Athene, where she then fitted a beam into the prow from the oracle of Zeus. On board was a crew of Greek heros, including such notable mythological figures such as Hercules, Castor and Pollux. Of course, their journeys were legendary, and after having acquired the golden fleece they dedicated the ship to the sea god Poseidon, who immortalized it in the stars and the first of the ocean-going vessels. Due to it’s enormous size, early cartographers often had difficulty portraying it on star charts and its magical prow had disappeared. The mariner’s compass, the constellation of Pyxis, was also once considered a part of Argo Navis, too… But has also been divided away with time. As for Puppis the Poop Deck? Actually, being on the roof of the stern cabin is a mighty fine place to be if you’re sailing amongst the stars….

Let’s begin our binocular tour of Puppis with a look at the bright star right in the middle – Zeta. Named Naos, which means “ship”, this grand spectral class is O5Ia star is one of the hottest known that is visible to the unaided eye. Punching in with a surface temperature of 42,400 K, what you are looking at is an extreme blue supergiant star – one of the brightest stars in the Milky Way Galaxy! At a distance of about 1400 light years from Earth, it doesn’t appear to be that impressive, but if it were as close as Sirius, it would light up our nights bright enough to cause shadows! Putting of 21,000 times more visible light and 790,000 times more light across the spectrum than our own Sun, this incredible star would absolutely vaporize our Earth if it were anywhere near our solar system. In several hundred thousand years, Naos will begin to cool and eventually become a red supergiant star. When it ends its life in a couple of million years, chances are it will go hypernova – forming a black hole and eventually a new nebula for starbirth in the never-ending cycle of cosmic wonder. What causes it to be so unusual? There’s evidence that Noas is a “runaway star”… once formed in the Vela region and now 400 light years away from the womb.

Now, let’s begin in the north with binoculars for a look at open cluster Melotte 71 (RA 07:37:30 Dec -12:03:06). This outer disc cluster is also known as Tombaugh 2 and will show as a compression of stars in binoculars and reveal about 80 or so members to mid-sized telescopes at low magnification. It is fairly rich and contains several reddish stars.

Keep your binoculars handy, or stick with the scope for Messier 46 (RA 07: 41.8 Dec ?14:49). This grand galactic star cluster was discovered by Charles Messier in 1771. Located about 5500 light years away from Earth, you’ll find about 150 stars spread over a 30 light year wide area… But one will stand out from the rest. Good reason – it’s a planetary nebula! Planetary nebula NGC 2438 will appear at the cluster’s northern edge and is probably just in the line of sight since it does not share the same velocity as M46.

Do you see other open cluster nearby? That’s Messier 47 (RA 07:36.6 Dec -14:30). It was discovered by Giovanni Batista Hodierna before 1654 and independently discovered by Charles Messier on February 19, 1771 and added to the Messier Catalog. While it contains only about 50 or so stars, it’s much brighter and more well resolved in smaller optics. Not bad for being 78 million years old!!

Stick to the telescope to discover NGC 2440 (RA 07:41: 54.91 Dec -18:12:29.7). This planetary nebula has a central star with an exceptionally high surface temperature of 200,000 kelvins. Studied by the Hubble Space Telescope for its strange bow shape, NGC 2440 has a complex structure with dense ridges of material swept back from the nebula’s central star.

Take your telescopes or binoculars out and look just north of Xi Puppis (RA 07 44 36 Dec -23 52 00) for a “mass concentration” of starlight known as Messier 93. Discovered in March of 1781 by Charles Messier, this bright open cluster is a rich concentration of various magnitudes which will simply explode in sprays of stellar fireworks in the eyepiece of a large telescope. Spanning 18 to 22 light-years of space and residing more than 3400 light-years away, it contains not only blue giants, but lovely golds as well. Jewels in the dark sky! As you view this open star cluster, seize the moment to remember Messier, because this is one of the last objects he discovered personally. He described it as “A cluster of small stars without nebulosity” – but did he realize the light he was viewing at the time left the cluster during the reign of Ramses III? Ah, yes…sweet time. Did Charles have a clue this cluster of stars was 100 million years old? Or realize it was forming about the time Earth’s land masses were breaking up, dinosaurs ruled, and the first mammals and birds were evolving? Although H. G. Wells “Time Machine” is a work of fiction, each time we view through a telescope we take a journey back across time itself. Enjoy the mystery!

Now, head off for NGC 2669 (RA 8 : 44.9 Dec -52 : 58). At magnitude 6, this 12 arc minute open cluster is a dazzling little gem that is on many southern sky observing lists… one that’s a study for proper motions! More? Then try Collinder 135. It is also a bright and dazzling open cluster that contains Pi Puppis and may have once been part of an OB cluster. Pick Pi out of the group… with a mass of between 13 and 14 solar masses, it will most likely explode in it’s future taking its binary star companion with it! Oddly enough, Collinder 135 wasn’t even recognized as an open star cluster until the Hipparchos satellite revealed that all the stars there were at a similar distance!

Are you ready for a globular cluster? Then try NGC 2298 (RA 6 : 49.0 Dec -36 : 00). At around magnitude 9 and 7 arc minutes in size this one will be a challenge for smaller optics. NGC 2298 was discovered by James Dunlop on May 30, 1826 and cataloged as Dunlop 578. It contains a lot of variable stars and it is on its way to disruption. According to Hubble Space Telescope studies, it’s losing mass.

For the big telescope, try your luck with NGC 2427 (RA 7 : 36.5 Dec -47 : 38). At around 11th magnitude and about 7 arc minutes in size, this super low surface brightness spiral galaxy won’t take to any kind of magnification, so use a low power eyepiece. Studies have shown it displays peculiar velocities in it’s HII regions and may display gravitation instability.

Don’t forget, Puppis is located right in the Milky Way, so there’s plenty more deep sky objects to go! Get yourself a good star map and explore…

Sources:
SEDS
Wikipedia
Chart courtesy of Your Sky.

January 6, 2009December 24, 2015 by Tammy Plotner

Piscis Austrinus

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Located just south of the ecliptic plane, Piscis Austrinus was one of the original 48 constellations charted by Ptolemy, and it remains one of the 88 modern constellations adopted by the IAU. Spanning 245 square degrees of sky, it ranks 60th in size. Piscis Austrinus contains 7 mains stars in its asterism and has 21 Bayer Flamsteed designated stars within its confines. It is bordered by the constellations of Capricornus, Microscopium, Grus, Sculptor and Aquarius. Piscis Austrinus can be seen by all observers located at latitudes between +55° and ?90° and is best seen at culmination during the month of October.

Piscis Austrinus is also known as Piscis Australis – Latin for the “Southern Fish”. Prior to the 20th century, it was also known as Piscis Notius. In mythology it is said to represent the parent of Pisces. Perhaps the legend came from the Syrians who did not eat fish, but worshipped them as gods. The Greeks also kept fish ponds at their temples and one legend tells of woman who was turned into a mermaid when she threw herself into a pond in a suicide attempt. There are those who believe Pisces Austrinus is associated with the Assyrian fish god Dagon and the Babylonian god Oannes, but at least all accounts give a rather “fishy” tale!

Let’s begin our binocular tour of Piscis Austrinus with its brightest star – Alpha – the “a” symbol on our map. Alpha Piscis Austrini is best known as Formalhaut – the “Mouth of the Whale”. This class-A main sequence star is about 25 light years from Earth, and like Vega, has an excess of infra-red radiation which indicated a circumstellar disk. Not only does it have a disk, but it has an extrasolar planet, too… One that was photographed by the Hubble Space Telescope between 2004 and 2006 and confirmed in 2008! The Jupiter-sized planet orbits about 11 billion miles away from the parent star and takes about 872 years to make the full trip – and may very well have a ring system which dwarf’s that of Saturn’s.

As stars go, Formalhaut is quite interesting enough on its own. In ancient times it was considered one of the four “royal” stars that marked the cardinal directions and Ptolemy gave it astrological significance as well. It is a young star, maybe around 100 to 300 million years old and part of the Castor Group of Moving Stars. The stellar association in the Castor group include stars of similar age, origin and similar velocity and include Castor, Fomalhaut, Vega, Alpha Cephei and Alphae Librae. All of these stars may have originated from the same location at some point in time which may have made them part of star cluster. In binoculars you will also notice another nearby star – TW Piscis Austrini – it is also a member of this group and may actually be a physical companion of Formalhaut. Keep a watch on TW, though! Because as its two letter designation indicates, it is a variable star… But not just any variable. TW Piscis Austrini is a flare star! While flares can erupt periodically within a matter of hours or days with no predictable timetable, TW is also a prime candidate for harboring an Earth-like habitable zone, too!

Are you ready to take out your telescope and conquer a few nice binary stars? Then have a look at Beta, Delta, Gamma and Eta! Both Beta, Delta and Gamma are widely separated, but disparate… While Eta is a more difficult split and more closely matched in magnitude. For a visual double star in binoculars, have a look at Upsilon… While the two aren’t physically related, they still make a pretty appearance in small optics!

For a big telescope challenge, let’s take on NGC 7314 (RA 22 : 35.8 Dec -26 : 03). At close to magnitude 11, this larger than 4 arc second barred spiral galaxy will really capture your attention. Why? Because it’s a Seyfert Galaxy! Containing an active galactic nucleus and home to starburst activity, NGC 7314 will present a bright, star-like core region surrounded by wispy arms in the eyepiece.

Or, try your luck with NGC 7221 (RA 22 : 11.3 Dec -30 : 37). At magnitude 12, this very faint and small spiral galaxy is going to be a challenge even for a large telescope. Stick with low magnification, because low surface brightness makes this particular galaxy more difficult to see.

Are you ready for a galaxy grouping? Then start with NGC 7172 (RA 22 : 02.0 Dec -31 : 52). At magnitude 12, this very small irregular galaxy is the brightest of the group, but details will be difficult to distinguish. Just south you will notice smaller and fainter elliptical galaxies NGC7176 and NGC 7174, too. While this Hickson Compact Group is a difficult visual study, it makes for a great astrophotography target! NGC 7172 is also a Seyfert Galaxy which is riddled from galaxy interaction with its neighbors and was extensively studied by Chandra in 2007 for its “hidden” properties!

Sources:
Chandra Observatory
Wikipedia
Chart courtesy of Your Sky.

January 5, 2009December 24, 2015 by Nancy Atkinson

Watch More Events Live from AAS on Tuesday Jan. 6

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Once again our sister site Astronomy Cast LIVE will be providing live video coverage of press events at the 213th AAS meeting being held in Long Beach CA. The video streams can be found at Astronomy Cast’s UStream Channel. You can join the chat to suggestion questions to ask at the news conference or report any issues with the feed.

If for some reason this link does not work try searching for Astronomy Cast on at www.ustream.tv

Here is the tentative schedule for tomorrow, Tuesday January 6. We’ll try to keep you updated if there are any changes, or check back with Astronomy Cast Live for updates. All times are Pacific Standard Time so please adjust accordingly. These recordings may or may not be available for viewing later.

9:00 AM – Cassiopeia A

10:30 AM – Star News

11:30 AM – Bright Flashes in the Universe

1:00 PM – News from Fermi and SWIFT

3:00 PM – History Mysteries

More might be added to the list tomorrow morning. Remember to join the chat room to suggest questions, and report issues. We will do our best to accommodate. Scott Miller from Astronomy Cast is manning the camera and the UStream Chat (and wowing the UStream and AAS world, I might add!)