galaxies Archives

November 20, 2012December 23, 2015 by Jason Major

Hot Gas Bridge Discovered Connecting Galaxy Clusters

An “bridge” of hot gas stretches between galaxy clusters Abell 401 and Abell 399

It may not be good practice to burn bridges but this is one super-heated bridge that astronomers were happy to find: an enormous swath of hot gas connecting two galaxy clusters 10 million light-years apart, and nearly a billion light-years away.

Using ESA’s Planck space telescope, astronomers have identified leftover light from the Big Bang interacting with a filament of hot gas stretching between Abell 401 and Abell 399, two galactic clusters each containing hundreds of individual galaxies.

Launched in May 2009, Planck is designed to study the Cosmic Microwave Background (CMB) — the leftover light from the Big Bang. When this radiation interacts with large-scale cosmic structures, like the hot gas bridging clusters of galaxies, its energy is modified in a specific way. This is referred to as the Sunyaev–Zel’dovich Effect (SZE), and Planck is specifically attuned to finding it.

This, however, is Planck’s first discovery of inter-cluster gas found using the SZ technique.

The temperature of the gas is estimated to be around 80 million degrees C, similar to the temperature of the gas found within the clusters themselves. It’s thought that the gas may be a combination of cosmic web filaments left over from the early Universe mixed with gas from the clusters.

The image above shows the clusters Abell 401 and Abell 399 as seen at optical wavelengths with ground-based telescopes overlaid with the SZE from Planck. The entire bridge spans a distance about the size of two full Moons in the sky.

Now Even Further: Ancient Galaxy is Latest Candidate for Most Distant

It seems that every few months or so comes a new discovery of a new “most distant galaxy ever found.” It’s not really a surprise that new benchmarks are reached with such an amazing frequency as our telescopes get better and astronomers refine their techniques for observing faraway and ancient objects. This latest “most distant” is pretty interesting in that it was found by combining observations from two space telescopes – Hubble and Spitzer – as well as using massive galaxy clusters as gravitational lenses to magnify the distant galaxy behind them. It’s also extremely small and may not even be a fully developed galaxy at the time we are seeing it.

While this galaxy, named MACS0647-JD, appears as a diminutive blob in the new images, astronomers say it offers a peek back into a time when the universe was just 3 percent of its present age of 13.7 billion years. This newly discovered galaxy was observed 420 million years after the Big Bang, and its light has traveled 13.3 billion years to reach Earth.

“This object may be one of many building blocks of a galaxy,” said Dan Coe of the Space Telescope Science Institute, lead author of a new paper on the observations. “Over the next 13 billion years, it may have dozens, hundreds, or even thousands of merging events with other galaxies and galaxy fragments.”

The discovery comes from the Cluster Lensing And Supernova Survey with Hubble (CLASH), a program that combines the power of space telescopes with the natural zoom of gravitational lensing to reveal distant galaxies in the early Universe. Observations with Spitzer’s infrared eyes allowed for confirmation of this object.

The light from MACS0647-JD was magnified by a massive galaxy cluster named MACS J0647+7015, and without the cluster’s magnification powers, astronomers would not have seen the remote galaxy. Because of gravitational lensing, the CLASH research team was able to observe three magnified images of MACS0647-JD with the Hubble telescope. The cluster’s gravity boosted the light from the faraway galaxy, making the images appear about eight, seven, and two times brighter than they otherwise would that enabled astronomers to detect the galaxy more efficiently and with greater confidence.

“This cluster does what no manmade telescope can do,” said Marc Postman, also from STScI. “Without the magnification, it would require a Herculean effort to observe this galaxy.”

MACS0647-JD is just a fraction of the size of our Milky Way galaxy, and is so small it may not even be a fully formed galaxy. Data show the galaxy is less than 600 light-years wide. Based on observations of somewhat closer galaxies, astronomers estimate that a typical galaxy of a similar age should be about 2,000 light-years wide. For comparison, the Large Magellanic Cloud, a dwarf galaxy companion to the Milky Way, is 14,000 light-years wide. Our Milky Way is 150,000 light-years across.

Loading player…

The galaxy was observed with 17 filters, spanning near-ultraviolet to near-infrared wavelengths, using Hubble’s Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys (ACS). Coe discovered the galaxy in February while poring over a catalogue of thousands of gravitationally lensed objects found in Hubble observations of 17 clusters in the CLASH survey. But the galaxy appeared only in the two reddest filters.

“So either MACS0647-JD is a very red object, only shining at red wavelengths, or it is extremely distant and its light has been ‘redshifted’ to these wavelengths, or some combination of the two,” Coe said. “We considered this full range of possibilities.”

The CLASH team identified multiple images of eight galaxies lensed by the galaxy cluster. Their positions allowed the team to produce a map of the cluster’s mass, which is primarily composed of dark matter. Dark matter is an invisible form of matter that makes up the bulk of the universe’s mass. “It’s like a big puzzle,” said Coe. “We have to arrange the mass in the cluster so that it deflects the light of each galaxy to the positions observed.” The team’s analysis revealed that the cluster’s mass distribution produced three lensed images of MACS0647-JD at the positions and relative brightness observed in the Hubble image.

Coe and his collaborators spent months systematically ruling out these other alternative explanations for the object’s identity, including red stars, brown dwarfs, and red (old or dusty) galaxies at intermediate distances from Earth. They concluded that a very distant galaxy was the correct explanation.

Redshift is a consequence of the expansion of space over cosmic time. Astronomers study the distant universe in near-infrared light because the expansion of space stretches ultraviolet and visible light from galaxies into infrared wavelengths. Coe estimates MACS0647-JD has a redshift of 11, the highest yet observed.

Images of the galaxy at longer wavelengths obtained with the Spitzer Space Telescope played a key role in the analysis. If the object were intrinsically red, it would appear bright in the Spitzer images. Instead, the galaxy barely was detected, if at all, indicating its great distance. The research team plans to use Spitzer to obtain deeper observations of the galaxy, which should yield confident detections as well as estimates of the object’s age and dust content.

MACS0647-JD galaxy, however, may be too far away for any current telescope to confirm the distance based on spectroscopy, which spreads out an object’s light into thousands of colors. Nevertheless, Coe is confident the fledgling galaxy is the new distance champion based on its unique colors and the research team’s extensive analysis. “All three of the lensed galaxy images match fairly well and are in positions you would expect for a galaxy at that remote distance when you look at the predictions from our best lens models for this cluster,” Coe said.

The new distance champion is the second remote galaxy uncovered in the CLASH survey, a multi-wavelength census of 25 hefty galaxy clusters with Hubble’s ACS and WFC3. Earlier this year, the CLASH team announced the discovery of a galaxy that existed when the universe was 490 million years old, 70 million years later than the new record-breaking galaxy. So far, the survey has completed observations for 20 of the 25 clusters.

The team hopes to use Hubble to search for more dwarf galaxies at these early epochs. If these infant galaxies are numerous, then they could have provided the energy to burn off the fog of hydrogen that blanketed the universe, a process called re-ionization. Re-ionization ultimately made the universe transparent to light.

Read the team’s paper (pdf).

Sources: HubbleSite, ESA Hubble

October 29, 2012December 23, 2015 by Nancy Atkinson

Astronomers Uncover a Crime of Galactic Proportions

As the Milky Way rises over the horizon at the European Southern Observatory, its companion galaxies also come into view. Credit: ESO/Y. Beletsky

A previously undetected heist of stars was uncovered by astronomers who were actually looking for why an unexpected amount of microlensing events were being seen around the outskirts of the Milky Way. Instead, they found the Large Magellanic Cloud (LMC) had been stealing stars from its neighbor, the Small Magellanic Cloud (SMC), leaving behind a trail of stars. Although the crime was likely committed hundreds of milllions of years ago during a collision between the two galaxies, the new information is helping astronomers to understand the history of these two galaxies that are in our neighborhood.

“You could say we discovered a crime of galactic proportions,” said Avi Loeb of the Harvard-Smithsonian Center for Astrophysics.

The Large Magellanic Cloud almost got away with it, if it wasn’t for those meddling astronomers….

Astronomers were originally monitoring the LMC to hunt for the reason for the unexpected microlensing events. Their initial hypothesis was that massive compact halo objects, or MACHOs were causing the effect, where a nearby object passes in front of a more distant star. The gravity of the closer object bends light from the star like a lens, magnifying it and causing it to brighten. The MACHOs were thought to be faint objects, roughly the mass of a star, but not much is known about them. Several surveys looked for MACHOs in order to find out if they could be a major component of dark matter – the unseen stuff that holds galaxies together.

In order for MACHOs to make up dark matter, they must be so faint that they can’t be directly detected. So, the team of astronomers hoped to see MACHOs within the Milky Way by lensing distant LMC stars.

“We originally set out to understand the evolution of the interacting LMC and SMC galaxies,” said lead author of a new paper on the results, Gurtina Besla of Columbia University. “We were surprised that, in addition, we could rule out the idea that dark matter is contained in MACHOs.”

“Instead of MACHOs, a trail of stars removed from the SMC is responsible for the microlensing events,” said Loeb.

Only a fast-moving population of stars could yield the observed rate and durations of the microlensing events. The best way to get such a stellar population is a galactic collision, which appears to have occurred in the LMC-SMC system.

“By reconstructing the scene, we found that the LMC and SMC collided violently hundreds of millions of years ago. That’s when the LMC stripped out the lensed stars,” said Loeb.

Their research also supports recent findings suggesting that both Magellanic Clouds are on their first pass by the Milky Way.

However, this isn’t a closed case. The evidence for the trail of lensed stars is persuasive, but they haven’t been directly observed yet. A number of teams are searching for the signatures of these stars within a bridge of gas that connects the Magellanic Clouds.

The simulation results will be published in the Monthly Notices of the Royal Astronomical Society.

Read the team’s paper: The Origin of the Microlensing Events Observed Towards the LMC and the Stellar Counterpart of the Magellanic Stream

Source: CfA

October 26, 2012December 23, 2015 by John Williams

Stirred, Not Shaken. Black Hole Antics Puff Up Whopper of a Galaxy

Its massive gravitational field warping space, the huge elliptical galaxy A2261-BCG, seems to have a diffuse halo of stars instead of a bright central galactic core. Image credit: NASA/ESA Hubble

Bloated far beyond the size of normal galaxies, one or more black holes may have puffed up an elliptical galaxy to a whopping size, according to astronomers. To their surprise, however, the black holes are missing.

Normally, scientists measure a concentrated peak of light surrounding the central black hole surrounded by a fuzzy halo of stars. Instead, astronomers, using NASA’s Hubble Space Telescope, find that the galaxy, known as A2261-BCG, is just a diffuse, bloated foggy patch of light. The intensity of starlight remains even across the entire galaxy. Past Hubble observations show supermassive black holes, each weighing billions of times more than our Sun, reside at the cores of nearly all galaxies.

“Expecting to find a black hole in every galaxy is sort of like expecting to find a pit inside a peach,” explained astronomer and co-author Tod Lauer in a press release. Lauer is with the National Optical Astronomy Observatory in Tucson, Ariz. “With this Hubble observation, we cut into the biggest peach and we can’t find the pit. We don’t know for sure that the black hole is not there, but Hubble shows that there’s no concentration of stars in the core.”

So where are the black holes?

Astronomers, in a paper that appeared in the September 10 issue of The Astrophysical Journal, have two ideas, both involving galactic billiards, for the galaxy’s puffy appearance. In one scenario, a pair of merging black holes gravitationally stir up then scatter the galaxy’s stars. In another, the merging black holes are ejected leaving the swarm of stars with no gravitational anchor allowing them to wander outward.

Galaxy cores tend to be sized proportionally to the wheeling expanse of the host galaxy. In the case of A2261-BCG, which spans about a million light-years (10 times that of our Milky Way Galaxy), the central region is three times larger than other very luminous galaxies, according to the paper. The monster galaxy is the most massive and brightest galaxy in the Abell 2261 galaxy cluster.

Team leader Marc Postman of the Space Telescope Science Institute in Baltimore, Md., said in the press release that the galaxy stood out in the Hubble image. “When I first saw the image of this galaxy, I knew right away it was unusual,” Postman explained. “The core was very diffuse and very large. The challenge was then to make sense of all the data, given what we knew from previous Hubble observations, and come up with a plausible explanation for the intriguing nature of this particular galaxy.”

The team admits the ejected black-hole ideas sound far-fetched, “but that’s what makes observing the universe so intriguing — sometimes you find the unexpected,” said Postman.

As a follow-up, the team is searching for the sound of material falling into the black hole using the Very Large Array (VLA) radio telescope in New Mexico. Comparing the VLA data with Hubble images will allow the researchers to confirm the existence of a black hole and map its location.

Source: Hubblesite

October 24, 2012December 23, 2015 by Nancy Atkinson

Astronomers Find Ultimate Oxymoron: A Small Supermassive Black Hole

There’s jumbo shrimp and accurate rumors; now there’s even a mini supermassive black hole. Astronomers have identified the smallest supermassive black hole ever observed, and while it’s considered a shrimp as far as supermassive black holes go, this guy is still pretty big: the mass of the black hole in galaxy NGC 4178 is estimated to be about 200,000 times the mass of our Sun. But it was a surprise that this galaxy had a black hole at all.

Astronomers using the Chandra X-Ray Observatory in conjunction with other observatories took a look at NGC 4178, a late-type spiral galaxy located about 55 million light years from Earth. It does not contain a bright central concentration, or bulge, of stars in its center, and so it was thought that perhaps this galaxy was one of the few that didn’t harbor a black hole.

With using Chandra’s X-Ray vision, as well as infrared data the NASA’s Spitzer Space Telescope and radio data from the Very Large Array, Nathan Secrest, from George Mason University and his team identified a weak X-ray source at the center of the galaxy, and also saw varying brightness at infrared wavelengths, suggesting that a black hole was actually in the center of NGC 4178 and was pulling in material from its surroundings. The same data also suggested that light generated by this infalling material is heavily absorbed by gas and dust and was therefore surrounding a black hole.

They were able to estimate the size of the black hole by using the known relationship between the mass of a black hole and the amount of X-rays and radio waves it generates.

While this is the lowest mass supermassive black holes ever observed, astronomers admit this is probably near the extreme low-mass end of being in the “supermassive” range. And as the team pointed out in their paper, there is increasing evidence that several late-type galaxies do host supermassive black holes, and that a classical bulge is not a requirement for a supermassive black hole to form and grow.

Read the team’s paper.

Source: NASA

October 19, 2012December 23, 2015 by John Williams

Surprise! Galaxies Still Evolving in Present Universe

A giant spiral of gas dust and stars, Messier 101 spans 170,000 light-years and contains more than a trillion stars. Astronomers have uncovered a surprising trend in galaxy evolution where galaxies like M101 and the Milky Way Galaxy continued to develop into settled disk galaxies long after previously thought. Credit: NASA/ESA Hubble

Graceful in their turnings, spiral galaxies were thought to have reached their current state billions of years ago. A study of hundreds of galaxies, however, upsets that notion revealing that spiral galaxies, like the Andromeda Galaxy and our own Milky Way, have continued to change.

“Astronomers thought disk galaxies in the nearby universe had settled into their present form by about 8 billion years ago, with little additional development since,” said Susan Kassin, an astronomer at NASA’s Goddard Space Flight Center in Greenbelt, Md., and the study’s lead researcher in a press release. “The trend we’ve observed instead shows the opposite, that galaxies were steadily changing over this time period.”

A study of 544 star-forming galaxies observed by the Earth-based Keck and Hubble Space Telescope shows that disk galaxies like our Milky Way Galaxy unexpectedly reached their current state long after much of the universe’s star formation had ceased. Credit: NASA’s Goddard Space Flight Center

Astronomers used the twin 10-meter earth-bound W.M. Keck Observatory atop Hawaii’s Mauna Kea volcano and NASA’s Hubble Space Telescope to study 544 star-forming galaxies. Farther back in time, galaxies tend to be very different, say astronomers, with random and disorganized motions. Nearer to the present, star-forming galaxies look like well-ordered disk-shaped systems. Rotation in these galaxies trumps other internal, random motions. These galaxies are gradually settling into well-behaved disks with the most massive galaxies always showing higher organization.

This plot shows the fractions of settled disk galaxies in four time spans, each about 3 billion years long. There is a steady shift toward higher percentages of settled galaxies closer to the present time. At any given time, the most massive galaxies are the most settled. More distant and less massive galaxies on average exhibit more disorganized internal motions, with gas moving in multiple directions, and slower rotation speeds. Credit: NASA’s Goddard Space Flight Center

The sampling of galaxies studied, from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Redshift Survey, ranged between 2 billion and 8 billion light-years from Earth with masses between 0.3 percent to 100 percent that of our own Milky Way Galaxy. Researchers looked at all galaxies in this time range with emission lines bright enough to determine internal motions. Researchers focused on emission lines characteristically emitted by gas within the galaxy. The emission lines not only tell scientists about the elements that make up the galaxies but also red shifting of emission lines contains information on the internal motions and distance.

“Previous studies removed galaxies that did not look like the well-ordered rotating disks now common in the universe today,” said co-author Benjamin Weiner, an astronomer at the University of Arizona in Tucson. “By neglecting them, these studies examined only those rare galaxies in the distant universe that are well-behaved and concluded that galaxies didn’t change.”

In the past 8 billion years, mergers between galaxies, both large and small, has decreased. So has the overall rate of star formation and associated disruptions due to supernovae explosions. Both factors may play a role in the newly found trend, say scientists.

The Milky Way Galaxy may have gone through the same chaotic growing and changing as the galaxies in the DEEP2 sample before settling into its present state at just about the same time the Sun and Earth were forming, say team scientists. By observing the pattern, astronomers can now adjust computer simulations of galaxy evolution until they replicate the observations. Then the hunt will be on to determine the physical processes responsible for the trend.

This cosmological simulation follows the development of a single disk galaxy throughout the life of the Universe; about 13.5 billion years. Red colors show old stars, young stars show as white and bright blue while the distribution of gas shows as a pale blue. The computer-generated view spans about 300,000 light-years. The simulation, running on the Pleiades supercomputer at NASA’s Ames Research Center in Moffett Field, California, took about 1 million CPU hours to complete. Credit: F. Governato and T. Quinn (Univ. of Washington), A. Brooks (Univ. of Wisconsin, Madison), and J. Wadsley (McMaster Univ.).

A paper detailing the findings will be published in the October 20, 2012 The Astrophysical Journal.

Source: NASA

October 8, 2012December 23, 2015 by Tammy Plotner

Weekly SkyWatcher’s Forecast: October 8-14, 2012

Messier 73 - Credit: Palomar Observatory, courtesy of Caltech

Greetings, fellow SkyWatchers! With early evening dark skies, this is a perfect opportunity to take on some more serious studies. We’ll start off BIG… and work down to the really small. (Think Hickson Compact Groups.) There’s even a meteor shower this week! Now, get out your telescopes and get ready, cuz’ I’m waitin’ in the backyard and lookin’ for the “Double Dark”…

Monday, October 8 – Today marks the birthday of Ejnar Hertzsprung. Born 1873, Hertzsprung was a Danish astronomer who first proved the existence of giant and dwarf stars in the early 1900s. His discoveries included the relationship between color and luminosity, which wasn’t truly recognized until it was recovered by Henry Russell. Now it is a familiar part of all our studies as the Hertzsprung-Russell diagram. His use of absolute magnitudes will come into play tonight as we have a look at the age-old mystery of M73.

Located about three fingerwidths north-northwest of Theta Capricorni (RA 58.9 Dec -12 38), this 9th magnitude open cluster consisting of four stars was discovered by Charles Messier on October 4, 1780. He described it as a “Cluster of three or four small stars, which resembles a nebula at first glance…” Hotly debated as to whether or not the grouping is a genuine cluster or simply an asterism, it was also included in J. Herschel’s catalog (GC 4617) and given the NGC 6994 designation by Dreyer. In 1931 Collinder cataloged M73 as Cr 426, with an estimated distance of 12,000 light-years. Still, the debate about its authenticity as a physically related group continued.

At least two stars show the same proper motion, leading scientists to believe M73 may be the remnant of a much older and now dispersed cluster – or simply two related stars. Of the 140 stars investigated in the region, 24 may be real members, including those in Messier’s original observation. Thanks to the work of Hertzsprung and Russell, these candidates fall within the color-magnitude diagram of a 2 to 3 billion year old cluster with Messier’s suspect four being evolved giants. The most recent data indicates M73 may simply be an asterism – sharing no common proper motion, but until more studies are undertaken you can enjoy this unusual Messier in even a small telescope!

Tuesday, October 9 – Tonight is the peak of the Draconid meteor shower whose radiant is near the westering constellation of Hercules. This particular shower can be quite impressive when comet Giacobini-Zinner passes near Earth. When this happens, the fall rate jumps to 200 per hour and has even been known to reach 1000. So what am I going to tell you about this year? Comet Giacobini-Zinner reached perihelion on July 2nd of 2005, passing with 8 million kilometers of Earth, but has now greatly distanced itself from our solar system. Chances are the Draconids will only produce around 3 to 5 per hour, but no one knows for sure!

While we’re out, let’s take the time to have a peek at M72, just about a degree and a half west (RA 20 53.5 Dec -12 32) of last night’s target M73.

Originally found by Mechain on the night of August 29-30, 1780, this class IX globular cluster is one of the faintest and most remote of the Messiers, and Charles didn’t catalog it until over a month after its discovery. At around magnitude 9, this 53,000 light-year distant globular will be not much more than a faint round smudge in smaller aperture, but will take on a modicum of resolution in larger telescopes. Well beyond the galactic center and heading toward us at 255 kilometers per second, M72 is home to 42 variables and the average magnitude of its members is around 15. While mid-sized scopes will pick up a graininess in the texture of this globular, notice how evenly the light is distributed, with little evidence of a core region. Be sure to write down your observations!

Wednesday, October 10 – Today in 1846, William Lassell was busy at his scope as he made a new discovery – Neptune’s moon Triton! Although our everyday equipment can’t “see” Triton, we can still have a look at Neptune which is also hanging out in tonight’s study constellation of Capricornus. Try checking astronomy periodicals or many great on-line sites for accurate locator charts.

Tonight let’s head to the eastern portion of Capricornus and start by identifying Zeta about a fistwidth southwest of the eastern corner star – Delta. Now look southeast about 2 fingerwidths and identify 5th magnitude star 41. About one half degree west is our target we’ll be revisiting this evening, M30 (Right Ascension: 21 : 40.4 – Declination: -23 : 11).

At near magnitude 8, this class V globular cluster is well suited to even binoculars and becomes spectacular in a telescope. Originally discovered by Messier in August 1764 and resolved by William Herschel in 1783, some of M30?s most attractive features are the branches of stars which seem to radiate from its concentrated core region. Estimated to be around 26,000 light-years away, you’ll find it fairly well resolved in large aperture, but take time to really look. The dense central region may have already undergone core collapse – yet as close as these stars are, very few have collided to form x-ray binaries. For the smaller scope, notice how well M30?s red giants resolve and be sure to mark your notes!

Thursday, October 11 – Tonight is time for a telescopic challenge – a compact galaxy group. You’ll find it less than half a degree southeast of stellar pair 4 and 5 Aquarii (RA 20 52 26.00 Dec -05 46 19.1).

Known as Hickson 88, this grouping of four faint spiral galaxies is estimated to be around 240 million light-years away and is by no means an easy object – yet the galactic cores can just be glimpsed with mid-sized scopes from a very dark site. Requiring around 12.5? to study, you’ll find the brightest of these to be northernmost NGC 6978 and NGC 6977. While little detail can be seen in the average large backyard scope, NGC 6978 shows some evidence of being a barred spiral, while NGC 6977 shows the even appearance of a face-on. Further south, NGC 6976 is much smaller and considerably fainter. It is usually caught while averting and studying the neighborhood. The southernmost galaxy is NGC 6975, whose slender, edge-on appearance makes it much harder to catch.

Although these four galaxies seem to be in close proximity to one another, no current data suggests any interaction between them. While such a faint galaxy grouping is not for everyone, it’s a challenge worthy of seasoned astronomer with a large scope! Enjoy…

Friday, October 12 – Today in 1891, the Astronomical Society of France was established. Exactly one year later in 1892, astronomy great E. E. Barnard was hard at work using the new tool of photography and became the first to discover a comet – 1892 V – in this way!

Not only did Barnard use photography for comets, but his main interest of study was details within the Milky Way. Tonight let us take out binoculars or a telescope at the widest possible field of view and have a look at two such regions in the westering Aquila – The “Double Dark Nebula.”

Just northeast of Altair is bright star Gamma Aquilae, and about a fingerwidth west is a pair of Barnard discoveries: B142 and B143 – two glorious absences of stars known as interstellar dust clouds. B143 is no more than a half degree in size and will simply look like a blank area shaped like a horseshoe, with its extensions point toward the west. Just south is B142, an elongated comma shape, which seems to underline its companion.

Located anywhere from 1000 to 3000 light-years away, these non-luminous clouds of gas and dust are a very fine example of Barnard’s passion. Do not be upset if you don’t see them on your first attempt – for the chances are if you are seeing “nothing,” you are looking in the right place!

Saturday, October 13 – Today marks the founding of the British Interplanetary Society in 1933. “From imagination to reality,” the BIS is the world’s oldest established organization devoted solely to supporting and promoting the exploration of space and astronautics.

Tonight we’ll do them proud as we go back for another look at the mighty M2. You’ll find it located about three fingerwidths north-northeast of Beta Aquarii (RA 33.5 Dec 00 49).

At slightly dimmer than 6th magnitude, this outstanding globular cluster is just inside that region where it can’t quite be viewed unaided, but even the smallest of binoculars will pick it out of a relatively starless field with ease. Holding a Class II designation, it was first discovered by Maraldi on September 11, 1746 and rediscovered independently by Messier exactly 14 years later. At a distance of roughly 37,500 light-years, it is estimated to contain in the neighborhood of 150,000 stars.

Even a small telescope will reveal M2’s rich and concentrated core region and slight ellipticity. Not bad for a 13 billion year old group of stars! As aperture increases, some of the brightest stars will begin to resolve, and in larger telescopes it will approach total resolution. You might well note a dark area in the northeastern section, and several more located throughout the splendid field. Feast your eyes on one of the finest in the skies!

Sunday, October 14 – Before we leave Cygnus for the year, try your luck with IC 5070 (Right Ascension: 20 : 50.8 – Declination: +44 : 21), also known as the “Pelican Nebula.” You’ll find it just about a degree southeast of Deneb and surrounding the binary star 56 Cygni.

Located around 2000 light-years away, the Pelican is an extension of the elusive North American Nebula, NGC 7000. Given its great expanse and faintness, catching the Pelican does require clean skies, but it can be spotted best with large binoculars. As part of this huge star forming region, look for the obscuring dark dust cloud Lynds 935 to help you distinguish the nebula’s edges. Although it is every bit as close as the Orion Nebula, this star hatchery isn’t quite as easy!

Now let’s give deep sky a rest as we travel to the northwest corner of Capricornus and have a look just south of Alpha at beautiful Beta.

Named Dabih, this lovely white 3rd magnitude star has a very easily to split 6th magnitude companion which will appear slightly blue. Over 100 times brighter than our own Sun, the primary star is also a spectroscopic triple – one whose unseen companions orbit in a little over 8 days and 1374 days. Oddly enough the B star is also a very tight binary as well – yet the two major stars of this system are separated by about a trillion miles! If you have a large aperture telescope – power up. According to T. W. Webb, a 13th magnitude unrelated double is also found in between the two brighter stars. No matter if you chose binoculars or a telescope, I’m sure you’ll find the 150 light-year trip worth your time to add to your doubles list!

Until next week? Wishing you clear skies!

September 20, 2012December 23, 2015 by Nancy Atkinson

Early Galaxy Found from the Cosmic ‘Dark Ages’

In the big image at left, the many galaxies of a massive cluster called MACS J1149+2223 dominate the scene. Gravitational lensing by the giant cluster brightened the light from the newfound galaxy, known as MACS 1149-JD, some 15 times. At upper right, a partial zoom-in shows MACS 1149-JD in more detail, and a deeper zoom appears to the lower right. Image credit: NASA/ESA/STScI/JHU

Take a close look at the pixelated red spot on the lower right portion of the image above, as it might be the oldest thing humanity has ever seen. This is a galaxy from the very early days of the Universe, and the light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching the Spitzer and Hubble space telescopes. The telescopes — and the astronomers using them — had a little help from a gravitational lens effect to be able to see such a faint and distant object, which was shining way back when our Universe was just 500 million years old.

“This galaxy is the most distant object we have ever observed with high confidence,” said Wei Zheng, a principal research scientist in the department of physics and astronomy at Johns Hopkins University in Baltimore who is lead author of a new paper appearing in Nature. “Future work involving this galaxy, as well as others like it that we hope to find, will allow us to study the universe’s earliest objects and how the dark ages ended.”

This ancient and distant galaxy comes from an important time in the Universe’s history — one which astronomers know little about – the early part of the epoch of reionization, when the Universe began to move from the so-called cosmic dark ages. During this period, the Universe went from a dark, starless expanse to a recognizable cosmos full of galaxies. The discovery of the faint, small galaxy opens a window onto the deepest, most remote epochs of cosmic history.

“In essence, during the epoch of reionization, the lights came on in the universe,” said paper co-author Leonidas Moustakas, from JPL.

Because both the Hubble and Spitzer telescopes were used in this observation, this newfound galaxy, named MACS 1149-JD, was imaged in five different wavebands. As part of the Cluster Lensing And Supernova Survey with Hubble Program, the Hubble Space Telescope registered the newly described, far-flung galaxy in four visible and infrared wavelength bands. Spitzer measured it in a fifth, longer-wavelength infrared band, placing the discovery on firmer ground.

Objects at these extreme distances are mostly beyond the detection sensitivity of today’s largest telescopes. To catch sight of these early, distant galaxies, astronomers rely on gravitational lensing, where the gravity of foreground objects warps and magnifies the light from background objects. A massive galaxy cluster situated between our galaxy and MACS 1149-JD magnified the newfound galaxy’s light, brightening the remote object some 15 times and bringing it into view.

Astronomers use redshift to describe cosmic distances, and the ancient but newly-found galaxy has a redshift, of 9.6. The term redshift refers to how much an object’s light has shifted into longer wavelengths as a result of the expansion of the universe.

Based on the Hubble and Spitzer observations, astronomers think the distant galaxy was less than 200 million years old when it was viewed. It also is small and compact, containing only about 1 percent of the Milky Way’s mass. According to leading cosmological theories, the first galaxies indeed should have started out tiny. They then progressively merged, eventually accumulating into the sizable galaxies of the more modern universe.

The epoch of reionization refers to the period in the history of the Universe during which the predominantly neutral intergalactic medium was ionized by the emergence of the first luminous sources, and these first galaxies likely played the dominant role in lighting up the Universe. By studying reionization, astronomers can learn about the process of structure formation in the Universe, and find the evolutionary links between the smooth matter distribution at early times revealed by cosmic microwave background studies, and the highly structured Universe of galaxies and clusters of galaxies at redshifts of 6 and below.

This epoch began about 400,000 years after the Big Bang when neutral hydrogen gas formed from cooling particles. The first luminous stars and their host galaxies emerged a few hundred million years later. The energy released by these earliest galaxies is thought to have caused the neutral hydrogen strewn throughout the Universe to ionize, or lose an electron, a state that the gas has remained in since that time.

The paper is available here (pdf document).

Source: JPL

September 17, 2012April 26, 2016 by Tammy Plotner

Weekly SkyWatcher’s Forecast – September 17-23, 2012

Globular Cluster M15 from Hubble Space Telescope. There are likely one or more intermediate-mass black holes at its heart. Courtesy: ESA, Hubble, NASA

Greetings, fellow SkyWatchers! This looks like a great week to take in some galactic star clusters and enjoy the Andromeda Galaxy! Some lucky viewers are in for a Mars occultation event and everyone wins with a meteor shower. What’s that, you say? Darn right. This week is also the time of the Autumnal Equinox! When ever you’re ready to learn more, just meet me in the back yard…

Monday, September 17 – Today in 1789, William Herschel discovered Saturn’s moon Mimas.

Tonight we’ll hunt with the “Fox” as we head to Vulpecula to try two more open star cluster studies. The first can be done easily with large binoculars or a low power scope. It’s a rich beauty that lies in the constellation of Vulpecula, but is more easily found by moving around 3 degrees southeast of Beta Cygni.

Known as Stock 1, this stellar swarm contains around 50 or so members of varying magnitudes that you will return to often. With a visual magnitude of near 5, loose associations of stars – like Stock clusters – are the subject of recent research. The latest information indicates that the members of this cluster are truly associated with one another.

A little more than a degree to the northeast is NGC 6815 (Right Ascension:19 : 40.9 – Declination: +26 : 51). While this slightly more compressed open cluster has no real status amongst deep sky objects, it is another one to add to your collection of things to do and see!

Tuesday, September 18 – Tonight we’ll start with an asterism known as the “Coat Hanger,” but it is also known as Brocchi’s Cluster, or Collinder 399. Let the colorful double star Beta Cygni – Albireo – be your guide as you move about 4 degrees to its south-southwest. You will know this cluster when you see it, because it really does look like a coat hanger! Enjoy its red stars.

First discovered by Al Sufi in 964 AD, this 3.5 magnitude collection of stars was again recorded by Hodierna. 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.
And for larger scopes? Fade east to the last prominent star in the cluster and power up. NGC 6802 (Right Ascension: 19 : 30.6 – Declination: +20 : 16) awaits you! At near magnitude 9, Herschel VI.14 is a well compressed open cluster of faint members. The subject of ongoing research in stellar evolution, this 100,000 year old cluster is on many observing challenge lists!

Wednesday, September 19 – On this day in 1848, William Boyd was watching Saturn – and discovered its moon Hyperion. On this date a moon will be on everyone’s mind as our Moon occults Mars (Pacific, South America, SW Atlantic). Be sure to check information such as the International Occultation Timing Assoication (IOTA) for specific details in your area. Even if you aren’t in a position to catch the occultation, it will still make a splendid scene! Also today in 1988, Israel launched its first satellite. How long has it been since you’ve watched an ISS pass or an iridium flare? Both are terrific events that don’t require any special equipment to be seen. Be sure to check with Heavens Above for accurate times and passes in your location and enjoy!

Tonight we again visit the M15 (Right Ascension: 21 : 30.0 – Declination: +12 : 10) globular and learn more about the scale of the Universe – circa 1900. On a decent night, a modest telescope will resolve about a dozen 13th magnitude stars outside M15?s core region. Most of these stars are red giants with absolute magnitudes of -2. Such stars appear 15 magnitudes fainter than they would be if they were at an astronomically standardized distance. Based on this 15 magnitude loss in intensity, we should be able to figure out how far away M15 is, but this is circular reasoning. In the early 1900s, astronomers didn’t know that the brightest stars in M15 were absolute magnitude -2. They first needed to know how far away the globular was to make sense of that.

Here’s where the H-R diagram helps out.

The most massive and swollen red giants (those nearing the end of their lives such as Betelgeuse and Antares) can be as luminous as absolute magnitude -6, but you can’t assume that the brightest red giants in a globular cluster are as bright as Antares and Betelgeuse. Why? Because we later discovered that all stars in a globular cluster entered the main sequence about the same time – some 12 billion years ago. Meanwhile, the very brightest ones – the Denebs – are no longer around. They exited the main sequence, became red giants and exploded a long, time ago, and possibly in a dwarf galaxy far, far away!

Now let’s take a a stellar tour of Lyra! First we’ll look at a double which has a close separation – Epsilon Lyrae. Known to most of us as the “Double Double,” look about a finger width northeast of Vega. Even the slightest optical aid will reveal this tiny star as a pair, but the real treat is with a telescope – for each component is a double star! Both sets of stars appear as primarily white and both are very close to each other in magnitude. What is the lowest power that you can use to split them?

Now let’s head for the northeast corner of the little parallelogram that is part of Lyra for easy unaided eye and binocular double Delta 1 and 2 Lyrae.

The westernmost Delta 1 is about 1100 light-years away and is a class B dwarf, but take a closer look at brighter Delta 2. This M-class giant is only 900 light-years away. Perhaps 75 million years ago, it, too, was a B class star, but it now has a dead helium core and it keeps on growing. While it is now a slight variable, it may in the future become a Mira-type. A closer look will show that it also has a true binary system nearby – a tightly matched 11th magnitude system. Oddly enough they are the same distance away as Delta-2 and are believed to be physically related.

Thursday, September 20 – Now let the Moon head west, because on this night in 1948, the 48? Schmidt telescope at Mt. Palomar was busy taking pictures. The first photographic plate was being exposed on a galaxy by the same man who ground and polished the corrector plate for this scope – Hendricks. His object of choice was reproduced as panel 18 in the Hubble Atlas of Galaxies and tonight we’ll join his vision as we take a look at the fantastic M31 – the Andromeda Galaxy.

Seasoned amateur astronomers can literally point to the sky and show you the location of M31 (Right Ascension: 0 : 42.7 – Declination: +41 : 16), but perhaps you have never tried. Believe it or not, this is an easy galaxy to spot even under the moonlight. Simply identify the large diamond-shaped pattern of stars that is the “Great Square of Pegasus.” The northernmost star is Alpha, and it is here we will begin our hop. Stay with the north chain of stars and look four finger-widths away for an easily seen star. The next along the chain is about three finger-widths away… And we’re almost there. Two more finger-widths to the north and you will see a dimmer star that looks like it has something smudgy nearby. Point your binoculars there, because that’s no cloud – it’s the Andromeda Galaxy!

Friday, September 21 – And what was Sir William Herschel doing on this date a couple of centuries ago? You can bet he was out telescoping; and his discoveries on this night were many. How about if we take a look at two logged on September 21 which made the Herschel “400? list?

Our first stop is northern Cygnus for NGC 7086 (RA 21 30 30 Dec +51 35 00). Located on the galactic equator about five degrees west of Beta Cephei, our target is an open cluster. At magnitude 8.4, this loose collection will be difficult for the smaller scope, and show as not much more than an arrow-like asterism. However, larger scopes will be able to resolve many more stars, arrayed in long loops and chains around the brighter members. Although it’s sparse, NGC 7086 has been studied for metal abundance, galactic distance, membership richness, and its luminosity function. Be sure to mark your notes for H VI.32, logged by Herschel in 1788.

Now hop on over to Andromeda for NGC 752 (RA 01 57 41 Dec +37 47 06). You’ll find it just a few degrees south of Gamma and in the field north of star 56. Located 1300 light-years away, there’s a strong possibility this cluster was noted first by Hodierna before being cataloged by Herschel on this night (1786). At near magnitude 5, this “400? object is both large and bright enough to be seen in binoculars or small telescopes, and people have often wondered why Messier did not discover it. The star-studded field containing about 70 members of various magnitudes belong to H VII.32 – a very old cluster which has more recently been studied for its metallicity and the variations in the magnetic fields of its members. Enjoy them both tonight! Sir William did…

Saturday, September 22 – Today marks the universal date of Autumnal Equinox. Enjoy this “equal” period of day and night!

Tonight we’ll return again to Vulpecula – but with a different goal in mind. What we’re after requires dark skies – but can be seen in both binoculars and a small telescope. Once you’ve found Alpha, begin about two fingerwidths southeast and right on the galactic equator you’ll find NGC 6823 (Right Ascension: 19 : 43.1 – Declination: +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 (Right Ascension: 19 : 43.1 – Declination: +23 : 17).

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!

Now we’re off to a spectacular open cluster – NGC 6940. At close to magnitude 6, you’ll find this unsung symphony of stars around three fingerwidths southwest of Epsilon Cygni (RA 20 34 24.00 Dec +28 17 -0.0).

Discovered by Sir William Herschel on Oct 15, 1784, and logged as H VIII.23, this intermediate aged galactic cluster will blow your mind in larger aperture. Visible in binoculars, as size increases the field explodes into about 100 stars in a highly compressed, rich cloud. Although it is not an often visited cluster, it is part of many observing challenge lists. Use low power to get the full effect of this stunning starfield!

Sunday, September 23 – On this day in 1846, Johann Galle of the Berlin Observatory makes a visual discovery. While at the telescope, Galle sees and identifies the planet Neptune for the first time in history. On this day in 1962, the prime time cartoon “The Jetsons” premiered. Think of all the technology this inspired!

Rather than doing lunar work tonight, why not wait until the Moon has westered and have an “Autumn Planetary Marathon”? Start easy with M57 between Gamma and Beta Lyrae. Head north-northwest to the “Cat’s Eye” (NGC 6543) roughly between Delta and Zeta Draconis – you’ll need your charts for this one! Now southwest to the “Blinking Planetary” (NGC 6543) – found less than three degrees east-southeast of Iota Cygni. Continue east-southeast a little less than 6 degrees past Deneb to the “Box Planetary” – NGC 7027. Now on to the brightest of the ten – M27. The “Dumbbell Nebula” is located a little more than 3 degrees north of Gamma Sagittae. Now drop two hand spans south to the “Little Gem” (NGC 6818) – around 7 degrees northeast of Rho Sagittarii.

One hand span east of the “Little Gem” leads you toward the “Saturn Nebula” in Aquarius – a little more than a degree west of Nu. Now it’s a huge jump of more than two hand spans west-northwest to tiny NGC 6572 – located around two finger-widths south-southeast of 72 Ophiuchi. Continue on to compact NGC 6790 a finger-width south of Delta Aquilae. Did you find them all? Well, if the “Cat’s Eye” is the toughest to locate, then NGC 6790 is the hardest to identify. Good going! But don’t stop now… Two hand spans west-northwest leads to NGC 6210 – best located using pointer stars Gamma and Beta Herculis. Excellent work!

Ready for the finale? Now, kick back… relax… and watch the Alpha Aurigid meteor shower. Face northeast and look for the radiant near Capella. The fall rate is around 12 per hour, and they are fast and leave trails!

Until next week? Wishing you clear skies…

September 10, 2012December 23, 2015 by John Williams

Holy Galaxify Batman! Galaxy Zoo Allows Users to Put Their Name in Big Lights

If you’re going to put your name in lights, you might as well go big; REALLY big. And with millions of galaxies forming all sorts of shapes including letters, numbers and punctuation, GalaxyZoo has created a way for you to do just that.

More than 250,000 people, sorting through about a million images, have taken part in the Galaxy Zoo project since its launch in 2007. “Their findings have ranged from the scientifically exciting to the weird and wonderful,” says the Galaxy Zoo team. And among the weird, the Zooites – that’s what project volunteers call themselves – have found an alphabet of galaxies.

The new “font,” available for anyone to use, is a way to thank all the Zooites for their hard work. But now a new challenge awaits.

Starting today, the Galaxy Zoo now has more than 250,000 new images of galaxies, most of which have never been seen by humans…. and the GZ team really wants them to be seen by humans!

But first, the reward:

Galaxy Zoo team member Dr. Steven Bamford, of the University of Nottingham, created the website at http://www.mygalaxies.co.uk allowing users to create a message in stars.

“We’d like to thank all those that have taken part in Galaxy Zoo in the past five years. Humans are better than computers at pattern recognition tasks like this, and we couldn’t have got so far without everyone’s help,” says Galaxy Zoo principal investigator Dr. Chris Lintott from the University of Oxford, in a press release. “Now we’ve got a new challenge, and we’d like to encourage volunteers old and new to get involved. You don’t have to be an expert — in fact we’ve found not being an expert tends to make you better at this task. There are too many images for us to inspect ourselves, but by asking hundreds of thousands of people to help us we can find out what’s lurking in the data.”

New images available at the Galaxy Zoo website come from large surveys with NASA‘s Hubble Space Telescope as well as ground-based imagery from the Sloan Digital Sky Survey.

“The two sources of data work together perfectly: the new images from Sloan give us our most detailed view of the local universe, while the CANDELS survey from the Hubble telescope allows us to look deeper into the universe’s past than ever before,” says Astronomer and Galaxy Zoo team member Kevin Schawinski from ETH Zurich in Switzerland.

Team members are quick to point out, however, that the quirky nature of the galactic alphabet is not the focus of Galaxy Zoo. Finding unusual galaxies that resemble animals and letters help scientists learn about galaxy interactions as well as the formation and evolution of the biggest structures in the Universe.

Image Credit: Sloan Digital Sky Survey, NASA Hubble Space Telescope and Galaxy Zoo

About the author:John Williams is owner of TerraZoom, a Colorado-based web development shop specializing in web mapping and online image zooms. He also writes the award-winning blog, StarryCritters, an interactive site devoted to looking at images from NASA’s Great Observatories and other sources in a different way. A former contributing editor for Final Frontier, his work has appeared in the Planetary Society Blog, Air & Space Smithsonian, Astronomy, Earth, MX Developer’s Journal, The Kansas City Star and many other newspapers and magazines.