Universe Today

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 Fraser Cain

American Astronomical Society Meeting, Long Beach – Day 2

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After a day of crazy traveling through a Vancouver blizzard I’m now having my first full day down at the American Astronomical Society Meeting in Long Beach, California. As you’ve probably read, Ian’s here with me and Nancy’s supporting us back at Atkinson HQ.

My last AAS meeting was a year ago. It was fun but a really frustrating experience. I spent the whole conference sitting in the press room, pounding out stories based on press releases released at the conference. I was writing 10-12 stories a day, but there was a terrible irony. I was doing work I could have done from home, without even attending the convention. In fact, I got so busy working on articles that I didn’t even bother going to the press conferences at all. And the whole point of attending a convention like this is to meet with people, to find the news that you just can’t find anywhere else.

I think we’ve learned our lesson this time around. Nancy’s running the news release side of things back at Atkinson HQ, and Ian and I will be searching for original, unreported news. We’re attending the oral sessions, sitting in on the town hall meetings, and walking the isles to see all the poster sessions. We’re playing with Microsoft’s World Wide Telescope, learning more about Google Sky, and reporting on the launch of the 2009 International Year of Astronomy.

We’re going to be gathering news and contacts, and we’ll be reporting as much as we can. Of course, gathering (sitting and listening to speakers) and reporting (getting the info out to you) are mutually exclusive – you can’t report while you’re gathering, and vice versa. So it might be that the news trickles out after the conference.

A big thanks to Pamela Gay for coordinating our visit and finding hotel space for us – we couldn’t be here without that. Thanks to Scott Miller at Astronomy Cast for doing the live video feeds of the press conferences. Make sure you check them out.

January 6, 2009December 24, 2015 by Nancy Atkinson

Could Mystery Outburst be a New Stellar Phenomenon?

Hubble's mystery object. Credit: NASA, ESA, and K. Barbary (University of California, Berkeley/Lawrence Berkeley National Lab, Supernova Cosmology Project)

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The Hubble Space Telescope serendipitously captured a mysterious burst of light on February 21, 2006. Over the next 100 days, the object, cataloged as SCP 06F6, brightened and then slowly faded. Astronomers do not know the object’s distance, so it can either be in our Milky Way galaxy or at a great astronomical distance, and the light-signature of this event does not match the behavior of a supernova or any previously observed astronomical transient phenomenon in the universe. It might represent an entirely new class of stellar phenomena that has previously gone undetected in the universe, said Kyle Barbary of the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, Calif.y researchers. “No one has been able to come up with a good explanation for this object” he said at a press conference at today’s American Astronomical Society meeting in Long Beach, California. (Read on for an outlandish explanation one scientist proposed!)

Astronomers commonly observe intense flashes of light from a variety of stellar explosions and outbursts, such as novae and supernovae. But the rise and fall in brightness has a signature that simply has never been recorded for any other type of celestial event. Supernovae peak after no more than 70 days, and gravitational lensing events are much shorter. Therefore, this observation defies a simple explanation, said Barbary. “We have never seen anything like it.”

Hubble was aimed at a cluster of galaxies 8 billion light-years away in the spring constellation Bootes. But the mystery object could be anywhere in between, even in the halo of our own Milky Way galaxy.

Papers published by other researchers since the event was reported in June 2006, have suggested a bizarre zoo of possibilities: the core collapse and explosion of a carbon rich star, a collision between a white dwarf and an asteroid, or the collision of a white dwarf with a black hole. At the press conference Barbary was asked what the most bizarre explanation of the object was: “Jokingly, someone said it was another civilization turning on their Large Hadron Collider and exploding,” — which got laughs from the audience. “Don’t quote me on that!,” he added.

But Barbary does not believe that any model offered so far fully explains the observations. “I don’t think we really know what the discovery means until we can observe similar objects in the future.”

All-sky surveys for variable phenomena, such as those to be conducted with the planned Large Synoptic Survey Telescope, may ultimately find similar transient events in the universe.

Source: HubbleSite

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 Nancy Atkinson

Cassiopeia A Comes Alive in 3-D Movies

Cassiopeia A from Chandra. Credit: NASA/CXC/D.Berry

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Want to know what it’s like to fly through a supernova remnant? Then, THIS, you have to see. You’ll be able to experience SNR Cassiopeia A (Cas A) as never before, and see it across both time and space. Another time lapse animation shows the remnant’s expansion and changes over time, and still another provides a 3-D model of Cas A. Almost ten years ago, Chandra’s “First Light” image of Cas A revealed previously unseen structures and detail, and now, after eight years of observation, scientists have been able to construct these incredible animations which were presented at today’s American Astronomical Society meeting in Long Beach, California.

The fly-through movie is based on data from Chandra, NASA’s Spitzer Space Telescope, and ground-based optical telescopes. “We have always wanted to know how the pieces we see in two dimensions fit together with each other in real life,” said Tracey Delaney of the Massachusetts Institute of Technology. “Now we can see for ourselves with this ‘hologram’ of supernova debris.”

Delaney said there are two components to the explosion, a spherical component from the outer layers of the star and a flattened component from the inner layers of the star. Most intriguing, said Delaney is that the jets of the explosion are not all over the place but came out of the same plane in the supernova. Plumes, or jets, of silicon appear in the northeast and southwest, while plumes of iron are seen in the southeast and north. Astronomers had known about the plumes and jets before, but did not know that they all came out in a broad, disk-like structure.

Cas A expansion. Credit: NASA/CXC/SAO/D.Patnaude et al.

The time-lapse animation tracks the remnant’s expansion and changes over time, measuring the expansion velocity of features in Cas A. “With Chandra, we have watched Cas A over a relatively small amount of its life, but so far the show has been amazing,” said Daniel Patnaude of the Smithsonian Astrophysical Observatory in Cambridge, Mass. “And, we can use this to learn more about the aftermath of the star’s explosion.”

Using estimates of the properties of the supernova explosion, including its energy and dynamics, Patnaude’s group show that about 30% of the energy in this supernova has gone into accelerating cosmic rays, energetic particles that are generated, in part, by supernova remnants and constantly bombard the Earth’s atmosphere. The flickering in the movie provides valuable new information about where the acceleration of these particles occurs.

The researchers found the expansion is slower than expected based on current theoretical models. Patnaude thinks the explanation for this mysterious loss of energy is cosmic ray acceleration.

Cas A in 3-D. Credit: NASA/CXC/MIT/T.Delaney et al.

The 3-D model of Cas A was made possible through a collaboration with the Astronomical Medicine project based at Harvard. The goal of this project is to bring together the best techniques from two very different fields, astronomy and medical imaging.

“Right now, we are focusing on improving three-dimensional visualization in both astronomy and medicine,”said Harvard’s Alyssa Goodman who heads the Astronomical Medicine project. “This project with Cas A is exactly what we have hoped would come out of it.”

3-D visualization and the 3-D expansion model provide researchers with a unique ability to study this remnant. The implication of this work is that astronomers who build models of supernova explosions must now consider that the outer layers of the star come off spherically, but the inner layers come out more disk like with high-velocity jets in multiple directions.

Cassiopeia A is the remains of a star thought to have exploded about 330 years ago, and is one of the youngest remnants in the Milky Way galaxy. The study of Cas A and remnants like it help astronomers better understand how the explosions that generate them seed interstellar gas with heavy elements, heat it with the energy of their radiation, and trigger blast waves from which new stars form.

Source: Chandra site

January 6, 2009December 24, 2015 by Nancy Atkinson

New Ares Construction “Towers” Over 39B

On Launch Pad 39B at NASA's Kennedy Space Center, a crane completes construction of one of the towers in the new lightning protection system for the Constellation Program. Credit: NASA

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Things are a-changing over at the Kennedy Space Center launch complex. The first lightning tower for the Ares rockets has been completed, dwarfing all the other structures on pad 39B. The tower is for the new lightning protection system for the Constellation Program. Other towers are being constructed at left and behind the service structures on the pad. Each of the three new lightning towers will be 152 meters (500 feet) tall with an additional 30 meter (100-foot) fiberglass mast atop supporting a catenary, or overhead wire system. This compares to the height of the shuttle Fixed Service Structure at 105.7 meters (347ft) to the top of the lightning mast. The new and improved lightning protection system allows for the taller height of the Ares I rocket compared to the space shuttle. Pad 39B will be the site of the first Ares vehicle launch, including the Ares I-X test flight that is targeted for July 2009. See image below for what the completed system will look like.

This is an artist’s rendition of what the new lightning protection system being built at Launch Pad 39B will look like when fully completed. The launch pad will also be modified to support future launches of Ares and Orion spacecraft.

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!)

January 5, 2009December 24, 2015 by Nancy Atkinson

Triple Whammy: Milky Way More Massive, Spinning Faster and More Likely to Collide

Artist's Conception of our Milky Way Galaxy: Blue, green dots indicate distance measurements. CREDIT: Robert Hurt, IPAC; Mark Reid, CfA, NRAO/AUI/NSF

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For many of us, looking closely in the mirror and stepping on the bathroom scale just after the holidays can reveal a substantial surprise. Likewise, astronomers looking closely at the Milky Way have found our galaxy is more massive than previously thought. High-precision measurements of the Milky Way disclose our galaxy is rotating about 100,000 miles per hour faster than previously understood. That increase in speed, said Mark Reid of the Harvard-Smithsonian Center for Astrophysics, increases the Milky Way’s mass by 50 percent. The larger mass, in turn, means a greater gravitational pull that increases the likelihood of collisions with the Andromeda galaxy or smaller nearby galaxies. So even though we’re faster, we’re also heavier and more likely to be annihilated. Bummer!

The scientists are using the National Science Foundation’s Very Long Baseline Array (VLBA) radio telescope to remake the map of the Milky Way. Taking advantage of the VLBA’s unparalleled ability to make extremely detailed images, the team is conducting a long-term program to measure distances and motions in our Galaxy. At the American Astronomical Society’s meeting in Long Beach, California, Reid said they are using trigonometric parallax to make the measurements. “This is exactly what surveyors use on Earth to measure distances,” he said. “And this is gold standard of measurement in astronomy.”

Trigonometric parallax was first used in 1838 to measure the first stellar distance. However, with better technology, the accuracy is now about 10,000 times greater.

Our solar system is about 28,000 light-years from the Milky Way’s center. At that distance, the new observations indicate, we’re moving at about 600,000 miles per hour in our Galactic orbit, up from the previous estimate of 500,000 miles per hour.

The scientists observed 19 regions of prolific star formation across the Galaxy. In areas within these regions, gas molecules are strengthening naturally-occurring radio emission in the same way that lasers strengthen light beams. These areas, called cosmic masers, serve as bright landmarks for the sharp radio vision of the VLBA. By observing these regions repeatedly at times when the Earth is at opposite sides of its orbit around the Sun, the astronomers can measure the slight apparent shift of the object’s position against the background of more distant objects.

The astronomers found that their direct distance measurements differed from earlier, indirect measurements, sometimes by as much as a factor of two. The star-forming regions harboring the cosmic masers “define the spiral arms of the Galaxy,” Reid explained. Measuring the distances to these regions thus provides a yardstick for mapping the Galaxy’s spiral structure.

The star forming regions are shown in the green and blue dots on the image above. Our sun (and us!) are where the red circle is located.

The VLBA can fix positions in the sky so accurately that the actual motion of the objects can be detected as they orbit the Milky Way’s center. Adding in measurements of motion along the line of sight, determined from shifts in the frequency of the masers’ radio emission, the astronomers are able to determine the full 3-dimensional motions of the star-forming regions. Using this information, Reid reported that “most star-forming regions do not follow a circular path as they orbit the Galaxy; instead we find them moving more slowly than other regions and on elliptical, not circular, orbits.”

The researchers attribute this to what they call spiral density-wave shocks, which can take gas in a circular orbit, compress it to form stars, and cause it to go into a new, elliptical orbit. This, they explained, helps to reinforce the spiral structure.

Reid and his colleagues found other surprises, too. Measuring the distances to multiple regions in a single spiral arm allowed them to calculate the angle of the arm. “These measurements,” Reid said, “indicate that our Galaxy probably has four, not two, spiral arms of gas and dust that are forming stars.” Recent surveys by NASA’s Spitzer Space Telescope suggest that older stars reside mostly in two spiral arms, raising a question of why the older stars don’t appear in all the arms. Answering that question, the astronomers say, will require more measurements and a deeper understanding of how the Galaxy works.

So, now that we know we’re more massive, how do we compare with other galaxies in our neighborhood? “In our local group of galaxies, Andromeda was thought to be the dominant big sister,” said Reid at the conference, “but we’re basically equal in size and mass. We’re not identical twins, but more like fraternal twins. And its likely the two galaxies will collide sooner than we thought, but it depends on a measurement of the sideways motion, which hasn’t been done yet.”

The VLBA is a system of 10 radio-telescope antennas stretching from Hawaii to New England and the Caribbean. It has the best resolving power, of any astronomical tool in the world. The VLBA can routinely produce images hundreds of times more detailed than those produced by the Hubble Space Telescope. The VLBA’s tremendous resolving power, equal to being able to read a newspaper in Los Angeles from the distance of New York, is what permits the astronomers to make precise distance determinations.

Source: AAS, Harvard-Smithsonian Center for Astrophysics