Posted on by Tammy Plotner

Gemini Adaptive Optics System Revolutionizes Astrophotography

Gemini South laser guide star system propagating as the Milky Way rises.

[/caption]When it comes to astrophotography, most of us would think that space-based telescopes like the Hubble are the epitome of imagining. However, there’s something new to be said about being “grounded”. On December 16, 2011, the Gemini South telescope in Chile revealed its first wide-field, ultra-sharp image… the product of a decade of hard work. By employing a new generation of adaptive optics (AO), the scope produced an incredible look into the densely concentrated globular cluster, NGC 288, and captured stars at close to the theoretical resolution limit of Gemini’s massive 8-meter mirror.

The Gemini Multi-conjugate adaptive optics System (GeMS for short), produced an incredible vision… one of incredible resolution. This new system will allow astronomers to study galactic centers and their black holes – as well as the life patterns of singular stars – with incredible clarity. It’s the largest amount of area ever captured in a single observation – one that’s ten times larger than any adaptive optics systems has ever been able to capture before. It has cause quite a stir in the astronomical community. When Space Telescope Science Institute director Matt Mountain saw the first light image, he praised the GeMS instrument team: “Incredible! You have truly revolutionized ground-based astronomy!”

As the director of the Gemini Observatory, Dr. Mountain was around when the project first began 10 years ago. He was responsible for assembling the team, including Francois Rigaut as the lead scientist to develop the GeMS instrument. And, Rigaut was there for first light… “We couldn’t believe our eyes!” Rigaut recalls. “The image of NGC 288 revealed thousands of pinpoint stars. Its resolution is Hubble-quality – and from the ground this is phenomenal.” Of course, one of the most amazing aspects of the image was how widely spaced the stars appeared, to which Rigaut comments: “This is somewhat uncharted territory: no one has ever made images so large with such a high angular resolution.”

Gemini South’s “first light” image from GeMS/GSAOI shows extreme detail in the central part of the globular star cluster NGC 288. The image, taken at 1.65 microns (H band) on December 16, 2011, has a field-of-view 87 x 87 arcseconds. The average full-width at half-maximum is slightly below 0.080 arcsecond, with a variation of 0.002 arcsecond across the entire field of the image. Exposure time was 13 minutes. Insets on the right show a detail of the image (top), a comparison of the same region with classical AO (middle; this assumes using the star at the upper right corner as the guide star), and seeing-limited observations (bottom). The pixel size in the latter was chosen to optimize the signal-to-noise ratio while not degrading the intrinsic angular resolution of the image. North is up, East is right.

Even though this is an incredible insight, some members of the scientific team which use the Gemini telescope are a bit more reserved in their comments. According to University of Toronto astronomer Roberto Abraham, one of a community of hundreds of astronomers worldwide who uses the 8-meter Gemini telescopes for cutting-edge research: “This is fan-freaking-tastic!!!!!!!” Exuberant? Of course! Even the environmental conditions remained as perfect as they could be for the first run of the GeMS equipment. “We were lucky to have clear weather and stable atmospheric conditions that night,” said Gemini AO scientist Benoit Neichel. “Even despite interruptions of the laser propagation due to satellites and planes passing by, we obtained our first image with the system. It was surprisingly crisp and large, with an exquisitely uniform image quality.”

How is it accomplished? GeMS employs five laser guide stars, three deformable mirrors and a full arsenal of computers to provide a near diffraction limited image to the Gemini South Adaptive Optics Imager (GSAOI, built by the Australian National University) and the infrared-sensitive imager attached to it. This means the smallest detail that can be resolved measures about 0.04 to 0.06 arcsecond over a field of 85 arcseconds squared. Compared to 0.5 arcsecond “seeing limited” at a good viewing location, that’s phenomenal! Once resolution was solved, the next problem was extending the field of view through a technique called Multi-Conjugate Adaptive Optics (MCAO) – an endeavor which borrowed technology from other scientific fields, such as medical imaging.

“MCAO is game-changing,” Abraham said. “It’s going to propel Gemini to the next echelon of discovery space as well as lay a foundation for the next generation of extremely large telescopes. Gemini is going to be delivering amazing science while paving the way for the future.”

Original Story Source: Gemini Observatory News. For Further Reading: Gemini News Release.

Posted on by Tammy Plotner

Tranquillityite – Moon Mineral Found In Western Australia

A mineral brought back to Earth by the first men on the Moon and long thought to be unique to the lunar surface has been found in Australian rocks more than one billion years old, scientists say. Image Credit: Birger Rasmussen

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When it comes to our natural human curiosity, we want to know if there’s something new out there… something we haven’t discovered yet. That’s why when lunar rock samples were returned, geologists were thrilled to find very specific minerals – armalcolite, pyroxferroite and tranquillityite – which belonged only to our Moon. However, over the years the first two were found here on Earth and tranquillityite was disclosed in specific meteorites. Named for Tranquility Base, site of the first Moon landing, tranquillityite was supposed to be the final hold-out… the last lunar unique mineral… until now.

Birger Rasmussen, paleontologist with Curtin University in Perth, and colleagues report in their Geology paper that they’ve uncovered tranquillityite in several remote locations in Western Australia. While the samples are incredibly small, about the width of a human hair and merely microns in length, their composition is undeniable. What’s more, tranquillityite may be a lot more common here on Earth than previously thought.

Rasmussen told the Sydney Morning Herald, “This was essentially the last mineral which was sort of uniquely lunar that had been found in the 70s from these samples returned from the Apollo mission.The mineral has since been found exclusively in returned lunar samples and lunar meteorites, with no terrestrial counterpart. We have now identified tranquillityite in six sites from Western Australia.”

Why has this remote mineral stayed hidden for so long? One major reason is its delicate structure. Composed of iron, silicon, oxygen, zirconium, titanium and a tiny bit of yttrium, a rare earth element, tranquillityite erodes at a rapid pace when exposed to natural environmental conditions. Another explanation is that tranquillityite can only form through a unique set of circumstance – through uranium decay. Rasmussen explains it’s evidence these minerals were ‘always’ located here on Earth and we share the same chemical processes as our satellite.

“This means that basically we have the same chemical phenomena on the Moon and on Earth.” says Rasmussen. And one of the reasons it has taken so long to be found is, “No one was looking hard enough.”

Image Credit: Birger Rasmussen
And exactly what does it take to locate it? More than a billion years old, the only sure way to identify tranquillityite is to subject it to a series of electron blasts. By exposing it to a high-energy accelerating electron beam, it produces spectra. From there “an elemental composition in combination with back-scattered electron (BSE) brightness and x-ray count rate information is converted into mineral phases.” According to Rasmussen’s paper, “Terrestrial tranquillityite commonly occurs as clusters of fox-red laths closely associated with baddeleyite and zirconolite in quartz and K-feldspar intergrowths in late-stage interstices between plagioclase and pyroxene.”

While it has no real economic value, terrestrial tranquillityite is another good reason mankind should try to preserve pristine regions such as the northeast Pilbara Region and the Eel Creek formation. Who knows what else we might find?

Original Story Source: PhysOrg.com.

Posted on by Tammy Plotner

Suburu Telescope Captures Hidden Planets In Stellar Dust Ring

Near-infrared (1.6 micron) image of the debris ring around the star HR 4796 A. An astronomical unit (AU) is a unit of length that corresponds to the average distance between the Earth and Sun, almost 92 million miles (over 149 million km). The ring consists of dust grains in a wide orbit (roughly twice the size of Pluto's orbit) around the central star. Its edge is so precisely revealed that the researchers could confirm a previously suspected offset between the ring's center and the star's location. This "wobble" in the dust's orbit is most likely caused by the unbalancing action of – so far undetected – massive planets likely to be orbiting within the ring. Furthermore, the image of the ring appears to be smudged out at its tips and reveals the presence of finer dust extending out beyond the main body of the ring. Credit: Suburu

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No. It’s not a new atomic image – it’s a very unusual look at a star which could help further our understanding of stellar disk structure and planetary formation. As part of the SEEDS (Strategic Exploration of Exoplanets and Disks with Subaru Telescope/HiCIAO) project, this image of star HR 4796 was taken with Subaru’s planet-finder camera, HiCIAO (High Contrast Instrument for the Subaru Next Generation Adaptive Optics). At only about 8-10 million years old, the feature of this stellar image is only about 240 light years away from Earth, yet fully displays its ring of dust grains which reach out about twice the distance as Pluto’s orbit from the central star. This image produced by an international group led by Motohide Tamura of NAOJ (National Astronomical Observatory of Japan) is so wonderfully detailed that an offset between its center and the star’s position can be measured. While the offset was predicted by data from the Hubble and another research group, this new photographic evidence not only confirms its presence – but shows it to be larger than expected.

With new data to work from, researchers began to wonder exactly what could have caused the dust torus to run off its axis. The easiest explanation would be gravitational force – where one or more planets located inside the gap within the ring could possibly be affecting the disk. This type of action could account for an “unbalancing” which could act in a predictable manner. Current computer modeling has shown these types of “gravitational tides” can mold a dust torus in unusual ways and they cite similar data gathered from observations of bright star, Formalhaut. Since no planet candidates have yet been directly observed around HR 4796, chances are any planets present are simply too small and dim to be spotted. However, thanks to the new Suburu image, researchers feel confident their presence could be the source of the circumstellar dust ring wobble.

With image accuracy as pinpoint as the Hubble Space Telescope, the Suburu near-infrared depiction allows for extremely accurate measurements by employing its adaptive optics system. This type of advanced astrophotography also allows for angular differential imaging – by-passing the glare of the central star and enhancing the faint signature of the dust ring. Such techniques are able to establish heightened information about the relationship of the circumstellar disk and gelling planets… a process which may begin from the “left-overs” of initial star formation. As surmised, this material could either be picked up by newly formed planets or be pushed out the system via stellar winds. Either way, it is a process which eliminates the majority of the dust within a few tens of millions of years. However, there are a few stars which continue to hold on to a “secondary disk” – a collection of dust which could be attributed to the collision of planetesimals. In the case of HR 4796, this is a likely scenario and studying it may provide a better understanding of how planets could form in this alternate debris disk.

Original Story Source: Suburu Telescope News Release. For Further Reading: Direct Images of Disks Unravel Mystery of Planet Formation.

Posted on by Tammy Plotner

Storms And Lakes On Titan Revealed By Computer Modeling

An artist's imagination of hydrocarbon pools, icy and rocky terrain on the surface of Saturn's largest moon Titan. Image credit: Steven Hobbs (Brisbane, Queensland, Australia).

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Thanks to the Cassini mission and the Huygens probe, we’ve glimpsed a wet world when science took a look at Saturn’s moon, Titan. Its atmosphere is rich in methane and its average temperature is about -300 degrees Fahrenheit (about 90 kelvins). Although the chemical composition is different than ours, Titan still has similar features such as clouds, fog, rain and even lakes. However, the origin of these features haven’t really been well explained until now.

Researchers at the California Institute of Technology (Caltech) have been hard at work creating a computer program based on observations made by Cassini imaging and radar that could help explain Titan’s weather patterns and liquid surface deposits. One major oddity was discovered in 2009 when Oded Aharonson, Caltech professor of planetary science, and his team confirmed Titan’s lakes appeared to be gathered around its poles – more predominately in the northern hemisphere than compared to the south – yet that’s not the only curiosity. The areas around the equator were suspected to be dry, but the Huygens probe revealed areas of run-off and four years later researchers observed a storm system delivering moisture. Need more? Then check out the clouds observed by ground-based telescopes… They gather around southern middle and high latitudes during Titan’s southern hemisphere summer season.

“We can watch for years and see almost nothing happen. This is bad news for people trying to understand Titan’s meteorological cycle, as not only do things happen infrequently, but we tend to miss them when they DO happen, because nobody wants to waste time on big telescopes—which you need to study where the clouds are and what is happening to them—looking at things that don’t happen,” explains Mike Brown of the California Institute of Technology (Caltech).

Sure. The researchers have worked hard at creating models that could explain these exotic weather features, but such explanations involve way out theories, such as cryogenic volcanoes that blast out methane vapor to cause clouds. However, the latest computer renderings are much more basic – the principles of atmospheric circulation. “We have a unified explanation for many of the observed features,” says Tapio Schneider, the Frank J. Gilloon Professor of Environmental Science and Engineering. “It doesn’t require cryovolcanoes or anything esoteric.” Schneider, along with Caltech graduate student Sonja Graves, former Caltech graduate student Emily Schaller (PhD ’08), and Mike Brown, the Richard and Barbara Rosenberg Professor and professor of planetary astronomy, have published their findings in the January 5 issue of the journal Nature.

Why is this data set different than its predecessors? According the Schneider, these new simulations were able to reproduce cloud patterns which match factual observations – right down to the distribution of lakes. “Methane tends to collect in lakes around the poles because the sunlight there is weaker on average,” he explains. “Energy from the sun normally evaporates liquid methane on the surface, but since there’s generally less sunlight at the poles, it’s easier for liquid methane there to accumulate into lakes.” Because Titan has an elongated orbit, it’s a bit further away during the northern hemisphere summer allowing for a longer rainy season and thus a stronger accumulation of lakes.

So what about storms? Near the equator, Titan isn’t very exciting – or is it? Originally it was theorized the area was almost desert-like. That’s why when the Huygens probe discovered evidence of run-off, it became apparent that existing models could be wrong. Imagine the surprise when Schaller, Brown, Schneider, and then-postdoctoral scholar Henry Roe discovered storms in this supposedly arid region in 2009! No one could figure it out and the programs did little more than predict a drizzle. With the new model, heavy rains became a possibility. “It rains very rarely at low latitudes,” Schneider says. “But when it rains, it pours.”

So what else makes the new Titan weather computer model even more unique? This time it runs for 135 Titan years and links the methane lakes – and how methane is distributed – to its atmosphere. According to the research, this matches current Titan weather observations and will help to predict what could be seen in coming years. Making testable predictions is “a rare and beautiful opportunity in the planetary sciences,” Schneider says. “In a few years, we’ll know how right or wrong they are.”

“This is just the beginning,” he adds. “We now have a tool to do new science with, and there’s a lot we can do and will do.”

Original Story Source: California Institute of Technology News Release. For Further Reading: Caltech Scientists Discover Storms in the Tropics of Titan.

Posted on by Tammy Plotner

Dusty Plasma From Enceladus Might Affect Saturn’s Magnetosphere

Saturn. NASA/JPL/Caltech
Saturn. NASA/JPL/Caltech

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Discovered by the Cassini mission, Saturn Kilometric Radiation (SKR) has been something of an enigma to astronomers. According to the radio and plasma wave instruments, variations occur in sync with the planet’s rotation. However, there are periodic “bursts” of radiation which are in line with Saturn’s magnetosphere. What makes this odd? The rate isn’t quite the same.

Thanks to investigations of Enceladus by Cassini in 2008, new information about the plasma environment surrounding Saturn’s satellite could show a marked impact on the magnetosphere. This image and video show a changing pattern of radio waves from Saturn known as Saturn Kilometric Radiation, as detected by NASA’s Cassini spacecraft. The colors indicate the emitted power of the radio waves, with red as the strongest.

How is it being affected? Thanks to Enceladus’ “spraying” nature, the huge plume of water vapor and ice from its southern pole provides a hefty source of plasma to feed Saturn’s magnetosphere and E-Ring. These negatively charged particles are again impacting the motion of the localized plasma.

“These signatures result from half or more of the electrons being attached to dust grains and by the interaction between the surrounding cold plasma and the predominantly negatively charged submicrometer-sized dust grains.” says M. W. Morooka (et al). “The dust and plasma properties estimated from the observations clearly show that the dust-plasma interaction is collective.”

According to the AGU Journal, this dust-plasma interaction impacts the dynamics of Saturn’s magnetosphere, possibly influencing the rate of SKR emissions.

Original Story Source: American Geophysical Union.

Posted on by Tammy Plotner

New Year – New Calendar… But Johns Hopkins Scholars Say We Need A Permanent Edition

Hanke-Henry Permanent Calendar - Credit: Richard Conn Henry/Johns Hopkins University

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It’s another new year and time to remember to write new dates again. While it might take a few weeks to remember to do it right first time, Johns Hopkins Scholars say our traditional calendar needs a major overhaul. By utilizing computer programs and mathematical formulas, Richard Conn Henry, an astrophysicist in the Krieger School of Arts and Sciences, and Steve H. Hanke, an applied economist in the Whiting School of Engineering, have devised a new calendar where each year is identical to the year before it… and the year after.

Dubbed the Hanke-Henry Permanent Calendar, there would be no problem remembering dates. For example, if your birthday was Thursday, May 10, it would remain Thursday, May 10 throughout eternity. Can you fathom holidays always being on the same day of the week? Or a weekend date always remaining the same? All the same… Always.

“Our plan offers a stable calendar that is absolutely identical from year to year and which allows the permanent, rational planning of annual activities, from school to work holidays,” says Henry, who is also director of the Maryland Space Grant Consortium. “Think about how much time and effort are expended each year in redesigning the calendar of every single organization in the world and it becomes obvious that our calendar would make life much simpler and would have noteworthy benefits.”

Of course, it would seem rational to have certain dated functions, such as work holidays, religious holidays and even birthdays fall on the same date each year. However, according to Hanke, an expert in international economics, the monetary benefits would be the real motivation behind such a change… ones that should motivate the consumer.

“Our calendar would simplify financial calculations and eliminate what we call the ‘rip off’ factor,” explains Hanke. “Determining how much interest accrues on mortgages, bonds, forward rate agreements, swaps and others, day counts are required. Our current calendar is full of anomalies that have led to the establishment of a wide range of conventions that attempt to simplify interest calculations. Our proposed permanent calendar has a predictable 91-day quarterly pattern of two months of 30 days and a third month of 31 days, which does away with the need for artificial day count conventions.”

But is the Hanke-Henry Permanent Calendar a true progression over various forms of permanent calendars that have been proposed before? “Attempts at reform have failed in the past because all of the major ones have involved breaking the seven-day cycle of the week, which is not acceptable to many people because it violates the Fourth Commandment about keeping the Sabbath Day,” Henry explains. “Our version never breaks that cycle.”

Sure, the current Gregorian calendar has been working for 430 years now. What’s the point in change? It, too, was an alteration to a calendar put forth in 46 BC by Julius Caesar to stay in sync with the changing seasons. The real problem is we humans just have to deal with a celestial calendar in which a true year is 365.2422 days long. The new calendar simply proposes we add an extra week every so often to make up for the fragmented days. But personally, I can’t see where this is any different than the concept we are already working under! If we’re adding an extra week every five or six years at the end of December, is that really any different than the few months that sport an extra day…. or leap year for that matter?

Yeah. Well, they don’t want to stop there, either. They are also in favor of doing away with world time zones by fully adopting GMT. “One time throughout the world, one date throughout the world,” they write, in a January 2012 Global Asia article about their proposals. “Business meetings, sports schedules and school calendars would be identical every year. Today’s cacophony of time zones, daylight savings times and calendar fluctuations, year after year, would be over. The economy – that’s all of us – would receive a permanent ‘harmonization’ dividend.”

Is it really harmony or just another way of putting us in neat, little boxes? Maybe we humans like our confusion. Maybe if it’s not broke, we don’t need to fix it. For those of us who practice astronomy, we already use both GMT and (in some circumstances) a Julian calendar as well. Do we really need to standardize everything? We’ve tried with money and we’ve tried with measurements. What’s next? We should all be born the same sex with exactly the same features so we can standardize the human population, too? Think of all the money that could be saved from the fashion industry alone! Then we’d need to have exactly the same tastes. That would make it ever so much easier to standardize food. No need to be wasting perfectly good dishes because one liked it and one didn’t. Maybe we all need the same sense of humor, that way we could just tell standard jokes. Perhaps we could all find exactly the same set of tones agreeable, so one song would do us all. Of course, it’s just my opinion, but…

Move over, Mr. Roboto.

Original Story Source: John Hopkins University Press Release. For further opinions and reading: Wired Science.

Posted on by Tammy Plotner

Little Galaxies Are Big on Dark Matter

The stellar stream in the halo of the nearby dwarf starburst galaxy NGC 4449 is resolved into its individual starry constituents in this exquisite image taken with the 8.2-meter Subaru Telescope and Suprime-Cam. Image credit: R. Jay GaBany and Aaron J. Romanowsky (UCSC) in collaboration with David Martinez-Delgado (MPIA) and NAOJ. Image processed by R. Jay GaBany

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Dark matter… It came into existence at the moment of the Big Bang. Within its confines, galaxies formed and evolved. If you add up all the parts contained within any given galaxy you derive its mass, yet its gravitational effects can only be explained by the presence of this mysterious subatomic particle. It would be easy to believe that the larger the galaxy, the larger the amount of dark matter should be present, but new research shows that isn’t so. Dwarf galaxies have even higher proportions of dark matter than their larger counterparts. Although the dwarfs are the most common of all, we know very little about them – even when they consume each other. Enter the star stream…

“Several of my previous images feature the fossil remnants of these ancient mergers as faint stellar rivers called tidal streams. These stellar streams are the table crumbs from small dwarf galaxies that were gravitationally dismembered as they were devoured by the larger galaxy they orbited.” says astrophotographer, R. Jay Gabany. “The theory implies dwarf galaxies also merged and are still merging with each other. But, there has never been clear photographic evidence or a close investigation of dwarf galactic mergers until now.”

The target is NGC 4449, a small, irregular dwarf galaxy much like the Milky Way’s Large Magellanic Cloud. What makes it interesting to astronomers is the presence of thousands of hot blue stars and massive red regions interspaced with thick dust clouds. It isn’t just forming new stars… it’s experiencing an explosion of star birth! According to current theory, dwarf galaxies such as this one could be undergoing a merger event, but there hasn’t been photographic proof until now.

“The picture I am sharing is of a small, dwarf galaxy known as NGC 4449 that’s located about 12.5 million light years from Earth towards the northern constellation of Canes Venatici, the Hunting Dogs. This galaxy is about the size of our Milky Way’s largest satellite galaxy, the Magellanic Cloud. But, NGC 4449 is much farther away and it is experiencing a major star burst event- an episode characterized by the production of new stars at a furious rate.” says Gabany. “This image is unique because it captures the first dwarf galaxy known to have its own tidal stream of stars. Therefore, it represents the first closely studied example of a dwarf galaxy merging with an even smaller dwarf star system! The professional astronomers with whom I work also suspect the merger may have contributed to the ferocious production rate of new stars inside NGC 4449.”

The research done by the team led by Dr. David Martinez-Delgado has some very interesting ramifications and their paper has been accepted for publication in the Astrophysical Journal Letters.. As so well put in Jay’s photographic explanation in his webpage; “Although the cold dark matter theory predicts mergers and interactions between dwarf galaxies, there is scant observational evidence that these types of mergers are still happening in the nearby local Universe. Interactions between dwarf galaxies invoke the possibility of exploring a very different merger regime. For example, research has shown that multiple dwarf galaxies with different stellar masses may exist in similar sized dark matter halos, hence what appears as a minor merger of stars could be a major dark matter merger. Studying interactions on a small scale, such as NGC 4449, provides unique insights on the role of stars versus dark matter in galactic merger events.”

Where once amateur astrophotographers painted beautiful portraits of what lay just beyond human perception in deep space, they are now crafting images capable of true science. The eyes of their telescopes are being combined with professional instruments and producing amazing results.

“We live in an age where science has become unfettered from examining the Universe with only our physical six senses.” concludes Gabany. “This has unlocked a profound new level of understanding, resolved ancient mysteries and unlatched a Pandora’s chest filled with new questions begging for answers. We still have much to learn.”

For Further Reading: Dwarfs Gobbling Dwarfs: A Stellar Tidal Stream Around NGC 4449 and Hierarchical Galaxy Formation On Small Scales and The Big Deal About Dwarf Galaxies.

Posted on by Tammy Plotner

In The Still Of The Night… Listening To The “Heartbeat” Of A Tiny Black Hole

Artist's rendering showing the jet fully established. Credit: NASA/Goddard Space Flight Center/CI Lab

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Is everything quiet in deep space?  Not hardly.  It’s a place jammed with noises of all kinds.  So much noise, in fact, that it could be quite difficult to pick up a faint signature of something small…  something like the smallest black hole known.  Thanks to  NASA’s Rossi X-ray Timing Explorer (RXTE) , an international team of astronomers have found the pulse they were looking for and it’s a pattern that’s only been seen in one other black hole system.

Its name is IGR J17091-3624 and it’s a binary system which consists of a normal star and a black hole with a mass that measures only about three times solar.  In theoretical terms, that’s right at the edge where possibility of being a black hole begins.

Here’s the picture…  In this binary system, escaping gas from the “normal” star flows across space in the direction of the black hole.  This action creates a disk where friction heats it to millions of degrees – releasing X-rays.  Periodic changes in the strength of the X-ray emissions point towards the actions taking place within the gas disk.  Scientists theorize that fast changes occur at the event horizon… the point of no return.

IGR J17091-3624 was discovered when it went into outburst in 2003. Current observations have it becoming active every few years and its most recent flare began in February of this year and has been kicking up cosmic dust ever since. Observations place it in the general direction of Scorpius, but astronomers aren’t sure of an exact distance – somewhere between 16,000 light years to more than 65,000. However, IGR J17091-3624 isn’t absolutely alone in its unique changes. Black hole binary, GRS 1915+105, also displays a number of well-ordered rhythms, too.

This animation compares the X-ray ‘heartbeats’ of GRS 1915 and IGR J17091, two black holes that ingest gas from companion stars. GRS 1915 has nearly five times the mass of IGR J17091, which at three solar masses may be the smallest black hole known. A fly-through relates the heartbeats to hypothesized changes in the black hole’s jet and disk. Credit: NASA/Goddard Space Flight Center/CI Lab

“We think that most of these patterns represent cycles of accumulation and ejection in an unstable disk, and we now see seven of them in IGR J17091,” said Tomaso Belloni at Brera Observatory in Merate, Italy. “Identifying these signatures in a second black hole system is very exciting.”

Binary GRS 1915 has some very cool characteristics.  Right now astronomers have observed jets blasting out in opposite directions cruising along at 98% the speed of light.  These originate at the event horizon where strong magnetic fields fuel them and each pulsation matches the occurrence of the jets. By observing the X-ray spectrum with RXTE, researchers have discovered the interior of the disk creates enough radiation to halt the gas flow – an outward wind which negates the inward flow – and shuts down activity.  As a result, the inner disk glows hot and bright, eliminating itself as it flows toward the black hole and kick starts the jet activity again.  It’s a process that happens in as little as 40 seconds!

Right now astronomers aren’t able to prove that IGR J17091 has a particle jet, but the regular pulsations indicate it. Records show this “heartbeat” occurs about every five seconds – about 8 times faster than its counterpart and some 20 times more faint. Numbers like this would make it a very tiny black hole.

“Just as the heart rate of a mouse is faster than an elephant’s, the heartbeat signals from these black holes scale according to their masses,” said Diego Altamirano, an astrophysicist at the University of Amsterdam in The Netherlands and lead author of a paper describing the findings in the November 4 issue of The Astrophysical Journal Letters. It’s just the beginning of a full scale program involving RXTE to compare information from both black holes.  Even more detailed data will be added from NASA’s Swift satellite and XMM-Newton, too.

“Until this study, GRS 1915 was essentially a one-off, and there’s only so much we can understand from a single example,” said Tod Strohmayer, the project scientist for RXTE at NASA’s Goddard Space Flight Center in Greenbelt, Md. “Now, with a second system exhibiting similar types of variability, we really can begin to test how well we understand what happens at the brink of a black hole.”

Original Story Source: NASA Mission News

Posted on by Tammy Plotner

New NASA Probe – The Comet Harpoon

This is an artist's concept of a comet harpoon embedded in a comet. The harpoon tip has been rendered semi-transparent so the sample collection chamber inside can be seen. Credit: NASA/Chris Meaney/Walt Feimer

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It’s not easy to sample a comet. These outer solar system travelers speed around the inner solar system at 241,000 km/h (150,000 mph) – twisting and turning while spewing chunks of ice, dust and debris. To consider landing on one becomes a logistical nightmare, but how about shooting at it? Why not send a mission to rendezvous with these frozen, inhospitable rocks and insert a probe? A method like this could even mean a sample could be taken where a landing would be impossible!

Thanks to the work of scientists at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, a new comet “harpoon” is being designed to make comet sample returns not only more efficient, but more detailed.


Roughly the size of a clothes closet, this syringe-like probe stands roughly two meters tall and will be inserted with a cross-bow like arrangement that will contact the surface of the comet. Positioned to fire vertically downward, this bow arrangement consists of a pair of truck leaf springs and 1/2 inch steel cable.. an arrangement which could fire up to a mile if pointed in the wrong direction! When it impacts, an electric winch will draw the bow back into position and eject the harpoon with 1,000 pounds of force at 100 feet per second.

So what would it be like to witness the harpooning of the cosmic whale? An explosive adventure, to be sure. Donald Wegel of NASA Goddard, lead engineer on the project, has been experimenting with the ballista and the core sample box in various impact environments. According to the press release, the resultant impact is something of a combination of rifle report and cannon blast.

This is a photo of the ballista testbed preparing to fire a prototype harpoon into a bucket of material that simulates a comet. Credit: NASA/Rob Andreoli

“We had to bolt it to the floor, because the recoil made the whole testbed jump after every shot,” said Wegel. “We’re not sure what we’ll encounter on the comet – the surface could be soft and fluffy, mostly made up of dust, or it could be ice mixed with pebbles, or even solid rock. Most likely, there will be areas with different compositions, so we need to design a harpoon that’s capable of penetrating a reasonable range of materials. The immediate goal though, is to correlate how much energy is required to penetrate different depths in different materials. What harpoon tip geometries penetrate specific materials best? How does the harpoon mass and cross section affect penetration? The ballista allows us to safely collect this data and use it to size the cannon that will be used on the actual mission.”

Studying comet core samples will provide researchers with important information on the original solar nebula and help us to further understand how life may have originated. “One of the most inspiring reasons to go through the trouble and expense of collecting a comet sample is to get a look at the ‘primordial ooze’ – biomolecules in comets that may have assisted the origin of life,” says Wegel. Comet sample return missions – such as the one from Wild 2 – have shown us that that amino acids exist in these inhospitable places, yet may have helped stimulate life here on Earth.

However, there’s more to the story than just searching out reasons for life… the biggest being the preservation of life itself. As we know, there’s always a possibility that a comet could impact Earth and create an extinction level event. By understanding comet composition, we can get a better grip on what we might need to do should a cataclysmic scenario rear its ugly head. For example, we’d know if a certain type of comet might tend to fragment – or another explode. “So the second major reason to sample comets is to characterize the impact threat,” according to Wegel. “We need to understand how they’re made so we can come up with the best way to deflect them should any have their sights on us.”

“Bringing back a comet sample will also let us analyze it with advanced instruments that won’t fit on a spacecraft or haven’t been invented yet,” adds Dr. Joseph Nuth, a comet expert at NASA Goddard and lead scientist on the project.

If we were to be in a movie, perhaps we might consider getting a comet sample through a method like drilling – but lack of gravity on these small, moving worlds isn’t going to allow that to happen. “A spacecraft wouldn’t actually land on a comet; it would have to attach itself somehow, probably with some kind of harpoon. So we figured if you have to use a harpoon anyway, you might as well get it to collect your sample,” says Nuth.

This is a demonstration of the sample collection chamber. Credit: NASA/Rob Andreoli

At the present, the design team is currently hard at work studying the harpoon’s reactions to different mediums – and what needs to be done to sample and collect what they might encounter. This isn’t easy considering they are working with a basic unknown.

“You can’t do this by crunching numbers in a computer, because nobody has done it before — the data doesn’t exist yet,” says Nuth. “We need to get data from experiments like this before we can build a computer model. We’re working on answers to the most basic questions, like how much powder charge do you need so your harpoon doesn’t bounce off or go all the way through the comet. We want to prove the harpoon can penetrate deep enough, collect a sample, decouple from the tip, and retract the sample collection device.”

Nothing will be left to chance, however. By creating multiple tips, collection devices and planning for different firing techniques and needs, the team is sure to make the most of their research dollars and the spacecraft that will be available to them. To further assist in their planning, they will also be able to use data from the current Rosetta mission and its lander, Philae, which will hook up with “67P/Churyumov-Gerasimenko” in 2014.

“The Rosetta harpoon is an ingenious design, but it does not collect a sample,” says Wegel. “We will piggyback on their work and take it a step further to include a sample-collecting cartridge. It’s important to understand the complex internal friction encountered by a hollow, core-sampling harpoon.” Even more information will be added from recent NASA mission, OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security — Regolith Explorer), which is an asteroid sample return mission. It will all add up to some very unique findings and one thing we do know is…

“Admiral? Thar’ be whales here…”

Posted on by Tammy Plotner

Incoming! Meteorite Shockwaves Could Set Off Martian Dust Avalanches

Artist's conception of an asteroid impact on Mars. (Image painted by William K. Hartmann, co-founder of the Planetary Science Institute, Tucson, Ariz.)

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They are headed toward the surface like a speeding freight train… and running ahead of them is a shockwave. Just like a loud sound can trigger a snow avalanche here on Earth, the shockwave of a meteorite crashing through the Martian atmosphere could trigger dust avalanches on the surface before an actual impact.

According to a study led by University of Arizona undergraduate student, Kaylan Burleigh, there is sufficient photographic evidence to prove that incoming meteorites are producing enough energy to impact the surface environment just as much as the strike. Mars’ thin atmosphere also contributes, since the lesser density means most meteorites survive the trip to the surface. “We expected that some of the streaks of dust that we see on slopes are caused by seismic shaking during impact,” said Burleigh. “We were surprised to find that it rather looks like shockwaves in the air trigger the avalanches even before the impact.”

HiRISE image of the study area showing the central crater with two dagger-like features extending at an angle (red and blue arrows). Called scimitars, these features most likely resulted from shockwave interference just before impact. (Image: NASA/JPL-Caltech/The University of Arizona)
Spotting new craters happens frequently. Thanks to the HiRISE camera on board NASA’s Mars Reconnaissance Orbiter, researchers find up to twenty newly formed craters that measure between 1 and 50 meters (3 to 165 feet) each year. To perform their study, the team focused their attention on a grouping of five craters which formed at the same time. This quintuplet is located near the Martian equator, about 825 kilometers (512 miles) south of the boundary scarp of Olympus Mons. Earlier investigations of the area had revealed dark streaks which were surmised at the time to be landslides, but no one thought to credit them to an impact theory. The largest crater in the cluster measures 22 meters, or 72 feet across and the multiple formation is thought to have occurred due to a shattering of the meteor just ahead of final impact.

“The dark streaks represent the material exposed by the avalanches, as induced by the airblast from the impact,” Burleigh said. “I counted more than 100,000 avalanches and, after repeated counts and deleting duplicates, arrived at 64,948.”

As Burleigh took a closer look at the distribution of avalanches around the impact site, he noticed a lot of relative things, but the most important was a curved formation described as scimitars. This was a major clue as to how they were formed. “Those scimitars tipped us off that something other than seismic shaking must be causing the dust avalanches,” Burleigh said.

Just as a freight train sends a rumble before it arrives, so does the incoming meteor. By using computer modeling, the team was able to simulate how a shockwave could form and match the scimatar patterns to the HiRISE images. “We think the interference among different pressure waves lifts up the dust and sets avalanches in motion. These interference regions, and the avalanches, occur in a reproducible pattern,” Burleigh said. “We checked other impact sites and realized that when we see avalanches, we usually see two scimitars, not just one, and they both tend to be at a certain angle to each other. This pattern would be difficult to explain by seismic shaking.”

Because there are no plate tectonics, nor water erosion issues, these types of findings are very important to understanding how many Martian surface features are formed. “This is one part of a larger story about current surface activity on Mars, which we are realizing is very different than previously believed,” said Alfred McEwen, principal investigator of the HiRISE project and one of the co-authors of the study. “We must understand how Mars works today before we can correctly interpret what may have happened when the climate was different, and before we can draw comparisons to Earth.”

Original Story Source: University of Arizona News.