Posted on by Tammy Plotner

Hubble Eyes Hanny’s Voorwerp

This diagram explains the formation of the strange green object known as Hanny’s Voorwerp. Astronomers believe that it is part of the long streamer of gas that extends from galaxy IC 2497, lit up brightly by the searchlight beam of a recently extinguished quasar.

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Almost four years ago a group of astronomers known as the Galaxy Zoo made a very exciting discovery – one they named “Hanny’s Voorwerp”. Although the action occurred a hundred thousand years ago and somewhere in the neighborhood of 700 million light years away, a once upon a time quasar burned brighter than its neighboring galaxy. While the tidal pull of massive spiral IC 2497 shredded a gas rich dwarf galaxy, the incredible outpouring of ultraviolet and X-ray radiation combined with the quasar ignited the gases to light… but what exactly is it? The Hubble Space Telescope turned its eye in the direction of Leo Minor to find out…

According to the American Astronomical Society press release: “One of the strangest space objects ever seen is being scrutinized by the penetrating vision of the NASA/ESA Hubble Space Telescope. A mysterious, glowing green blob of gas is floating in space near a spiral galaxy. Hubble uncovered delicate filaments of gas and a pocket of young star clusters in the giant object, which is the size of the Milky Way. The Hubble revelations are the latest finds in an ongoing probe of Hannyrquote s Voorwerp (Hanny’s Object in Dutch). It is named after Hanny van Arkel, the Dutch schoolteacher who discovered the ghostly structure in 2007 while participating in the online Galaxy Zoo project. Galaxy Zoo enlists the public to help classify more than a million galaxies catalogued in the Sloan Digital Sky Survey. The project has expanded to include Galaxy Zoo: Hubble, in which the public is asked to assess tens of thousands of galaxies in deep imagery from the Hubble Space Telescope.” In the sharpest view yet of Hanny’s Voorwerp, Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys have uncovered star birth in a region of the green object that faces the spiral galaxy IC 2497 — a bright, energetic object that is powered by a black hole.

In this image by the NASA/ESA Hubble Space Telescope, an unusual, ghostly green blob of gas appears to float near a normal-looking spiral galaxy.

This Hubble view reveals new details in colorful clarity – such as a area of star clusters whose members are only a couple of million years old… and the chemically charged yellowish-orange area at the tip of Milky Way sized Hanny’s Voorwerp. The image was made by combining data from the Advanced Camera for Surveys (ACS) and the Wide Field Camera 3 (WFC3) onboard Hubble, with data from the WIYN telescope at Kitt Peak, Arizona, USA. The ACS exposures were taken 12 April 2010; the WFC3 data, 4 April 2010.

“The star clusters are localized, confined to an area that is over a few thousand light-years wide,” explains astronomer William Keel of the University of Alabama in Tuscaloosa, leader of the Hubble study. “The region may have been churning out stars for several million years. They are so dim that they have previously been lost in the brilliant light of the surrounding gas.”

The press release goes on to state that recent X-ray observations have revealed why Hanny’s Voorwerp caught the proverbial eye of astronomers. The galaxy’s rambunctious core produced a quasar, a powerful light beacon powered by a black hole. The quasar shot a broad beam of light in Hanny’s Voorwerp’s direction, illuminating the gas cloud and making it a space oddity. Its bright green color is from glowing oxygen. “We just missed catching the quasar, because it turned off no more than 200,000 years ago, so what we’re seeing is the afterglow from the quasar,” Keel says. “This implies that it might flicker on and off, which is typical of quasars, but we’ve never seen such a dramatic change happen so rapidly.”

The quasar’s outburst also may have cast a shadow on the blob. This feature gives the illusion of a gaping hole about 20,000 light-years wide in Hanny’s Voorwerp. Hubble reveals sharp edges around the apparent opening, suggesting that an object close to the quasar may have blocked some of the light and projected a shadow on Hanny’s Voorwerp. This phenomenon is similar to a fly on a movie projector lens casting a shadow on a movie screen. (Or your little brother Tom making a duck face with his hand while your Mom isn’t looking.) Radio studies have revealed that Hanny’s Voorwerp is not just an island gas cloud floating in space awaiting a three-hour tour. The glowing blob is part of a long, twisting rope of gas, or tidal tail, about 300,000 light-years long that wraps around the galaxy. The only optically visible part of the rope is Hanny’s Voorwerp. The illuminated object is so huge that it stretches from 44,000 light-years to 136,000 light-years from the galaxy’s core. The quasar, the outflow of gas that instigated the star birth, and the long, gaseous tidal tail point to a rough life for IC 2497.

“The evidence suggests that IC 2497 may have merged with another galaxy about a billion years ago,” Keel explains. “The Hubble images show in exquisite detail that the spiral arms are twisted, so the galaxy hasn’t completely settled down.” In Keel’s scenario, the merger expelled the long streamer of gas from the galaxy and funneled gas and stars into the center, which fed the black hole. The engorged black hole then powered the quasar, which launched two cones of light. One light beam illuminated part of the tidal tail, now called Hanny’s Voorwerp.” says Keel. “About a million years ago, shock waves produced glowing gas near the galaxy’s core and blasted it outward. The glowing gas is seen only in Hubble images and spectra. The outburst may have triggered star formation in Hanny’s Voorwerp. Less than 200,000 years ago, the quasar dropped in brightness by 100 times or more, leaving an ordinary-looking core.

New images of the galaxy’s dusty core from Hubble’s Space Telescope Imaging Spectrograph show an expanding bubble of gas blown out of one side of the core, perhaps evidence of the sputtering quasar’s final gasps. The expanding ring of gas is still too small for ground-based telescopes to detect. “This quasar may have been active for a few million years, which perhaps indicates that quasars blink on and off on timescales of millions of years, not the 100 million years that theory had suggested,” Keel says. He added that the quasar could light up again if more material is dumped around the black hole.

Fascinating evidence which confirms the team’s original explanation… Go Zoo!

Credits: NASA, ESA, William Keel -University of Alabama, Tuscaloosa, the Galaxy Zoo team and STScI Press releases.

Posted on by Nancy Atkinson

Hubble Takes a Spectacular Look Inside the Eagle Nebula

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A new look at the Eagle Nebula by Hubble. Credit: ESA/Hubble & NASA

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There are some stellar powerhouses inside the Eagle Nebula, and Hubble has captured a collection of these hot, blue stars. These dazzling stars are an open star cluster called NGC 6611, whose fierce ultraviolet glow make the surrounding Eagle Nebula glow brightly. But there are also areas in this image that look dark and empty. Are those areas just empty? No, they are actually very dense regions of gas and dust, which obstruct light from passing through.

Hubble astronomers say that many of these dark areas may be hiding the sites of the early stages of star formation, before the fledgling stars clear away their surroundings and burst into view. Dark nebulae, large and small, are dotted throughout the Universe. If you look up to the Milky Way with the naked eye from a dark, remote site, you can easily spot some huge dark nebulae blocking the background starlight.

This region in the Eagle Nebula formed about 5.5 million years ago and is found approximately 6,500 light-years from the Earth. The cluster and the associated nebula together are also known as Messier 16.

Astronomers refer to areas like the Eagle Nebula as HII regions. This is the scientific notation for ionised hydrogen from which the region is largely made. Extrapolating far into the future, this HII region will eventually disperse, helped along by shockwaves from supernova explosions as the more massive young stars end their brief but brilliant lives.

This picture was created from images from Hubble’s Wide Field Channel of the Advanced Camera for Surveys through the unusual combination of two near-infrared filters (F775W, colored blue, and F850LP, colored red). The image has also been subtly colorized using a ground-based image taken through more conventional filters. The Hubble exposure times were 2000 s in both cases and the field of view is about 3.2 arcminutes across.

Source: ESA/Space Telescope

Posted on by Nancy Atkinson

‘Ring’ in the Holidays with New Hubble Bubble Image

SNR 0509 is the visible remnant of a powerful stellar explosion in the Large Magellanic Cloud. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA). Acknowledgement: J. Hughes (Rutgers University)

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From a Hubble/ESA press release:

A festive, delicate ring –photographed by the Hubble Space Telescope — appears to float serenely in the depths of space, but this apparent calm hides an inner turmoil. The gaseous envelope formed as the expanding blast wave and ejected material from a supernova tore through the nearby interstellar medium. Called SNR B0509-67.5 (or SNR 0509 for short), the bubble is the visible remnant of a powerful stellar explosion in the Large Magellanic Cloud (LMC), a small galaxy about 160,000 light-years from Earth.

Ripples seen in the shell’s surface may be caused either by subtle variations in the density of the ambient interstellar gas, or possibly be driven from the interior by fragments from the initial explosion. The bubble-shaped shroud of gas is 23 light-years across and is expanding at more than 18 million km/h.

Astronomers have concluded that the explosion was an example of an especially energetic and bright variety of supernova. Known as Type Ia, such supernova events are thought to result when a white dwarf star in a binary system robs its partner of material, taking on more mass than it is able to handle, so that it eventually explodes.

Hubble’s Advanced Camera for Surveys observed the supernova remnant on 28 October 2006 with a filter that isolates light from the glowing hydrogen seen in the expanding shell. These observations were then combined with visible-light images of the surrounding star field that were imaged with Hubble’s Wide Field Camera 3 on 4 November 2010.

With an age of about 400 years, the supernova might have been visible to southern hemisphere observers around the year 1600, although there are no known records of a “new star” in the direction of the LMC near that time. A much more recent supernova in the LMC, SN 1987A, did catch the eye of Earth viewers and continues to be studied with ground- and space-based telescopes, including Hubble.

Posted on by Nancy Atkinson

Hollywood-like Galactic Encounter Results in Baby Stars

Images of the core of NGC 4150, taken in near-ultraviolet light with the sharp-eyed Wide Field Camera 3 (WFC3). Credit: NASA, ESA, R.M. Crockett (University of Oxford, U.K.), S. Kaviraj (Imperial College London and University of Oxford, U.K.), J. Silk (University of Oxford), M. Mutchler (Space Telescope Science Institute, Baltimore), R. O'Connell (University of Virginia, Charlottesville), and the WFC3 Scientific Oversight Committee

Like news ripped from a Hollywood tabloid, this saga includes an encounter between two individuals; one aging, and thought to be past its prime, the other youthful and vigorous. And for good measure, thrown in on this story are cannibalism and even zombies. The result of the meet-up? Babies. Baby stars, that is, and the individual galaxies in this tale ended up, seemingly, living together happily-ever-after. The Hubble Space Telescope’s Wide Field Camera 3 (WFC3) captured images of NGC 4150, an aging elliptical galaxy, and at the core of the galaxy was some vigorous star birth. The star-making days of this galaxy should have ended long ago, but here was active star birth taking place. This isn’t the first time astronomers have seen something like this, so they took a closer look.
Continue reading “Hollywood-like Galactic Encounter Results in Baby Stars”

Posted on by Nancy Atkinson

Hubble Provides Most Detailed Dark Matter Map Yet

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This NASA Hubble Space Telescope image shows the distribution of dark matter in the center of the giant galaxy cluster Abell 1689, containing about 1,000 galaxies and trillions of stars. Credit: NASA, ESA, D. Coe (NASA Jet Propulsion Laboratory/California Institute of Technology, and Space Telescope Science Institute), N. Benitez (Institute of Astrophysics of Andalusia, Spain), T. Broadhurst (University of the Basque Country, Spain), and H. Ford (Johns Hopkins University)

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Using Hubble’s Advanced Camera for Surveys, astronomers have been able to chart invisible dark matter in a distant galaxy, which enabled them to create one of the sharpest and most detailed maps of dark matter in the universe. Looking for invisible and indeterminate matter is a difficult job, but one that astronomers have been trying to do for over a decade. This new map also might provide clues on that other mysterious stuff in the universe — dark energy – and what role it played in the universe’s early formative years.

A team led by Dan Coe at JPL used Hubble to look at Abell 1689, located 2.2 billion light-years away. The cluster’s gravity, which mostly comes from dark matter, acts like a cosmic magnifying glass, bending and amplifying the light from distant galaxies behind it. This effect, called gravitational lensing, produces multiple, warped, and greatly magnified images of those galaxies, making the galaxies look distorted and fuzzy. By studying the distorted images, astronomers estimated the amount of dark matter within the cluster. If the cluster’s gravity only came from the visible galaxies, the lensing distortions would be much weaker.

What they found suggests that galaxy clusters may have formed earlier than expected, before the push of dark energy inhibited their growth.

Dark energy pushes galaxies apart from one another by stretching the space between them, thereby suppressing the formation of giant structures called galaxy clusters. One way astronomers can probe this primeval tug-of-war is through mapping the distribution of dark matter in clusters.

“The lensed images are like a big puzzle,” Coe said. “Here we have figured out, for the first time, a way to arrange the mass of Abell 1689 such that it lenses all of these background galaxies to their observed positions.” Coe used this information to produce a higher-resolution map of the cluster’s dark matter distribution than was possible before.

Based on their higher-resolution mass map, Coe and his collaborators confirm previous results showing that the core of Abell 1689 is much denser in dark matter than expected for a cluster of its size, based on computer simulations of structure growth. Abell 1689 joins a handful of other well-studied clusters found to have similarly dense cores. The finding is surprising, because the push of dark energy early in the universe’s history would have stunted the growth of all galaxy clusters.

“Galaxy clusters, therefore, would had to have started forming billions of years earlier in order to build up to the numbers we see today,” Coe said. “At earlier times, the universe was smaller and more densely packed with dark matter. Abell 1689 appears to have been well fed at birth by the dense matter surrounding it in the early universe. The cluster has carried this bulk with it through its adult life to appear as we observe it today.”

Astronomers are planning to study more clusters to confirm the possible influence of dark energy. A major Hubble program that will analyze dark matter in gigantic galaxy clusters is the Cluster Lensing and Supernova survey with Hubble (CLASH). In this survey, the telescope will study 25 clusters for a total of one month over the next three years. The CLASH clusters were selected because of their strong X-ray emission, indicating they contain large quantities of hot gas. This abundance means the clusters are extremely massive. By observing these clusters, astronomers will map the dark matter distributions and look for more conclusive evidence of early cluster formation, and possibly early dark energy.

For more information see the HubbleSite.

Posted on by Nancy Atkinson

Hubble Predicts the Future of Omega Centauri

The current and future positions of stars in Omega Centauri. Credit: NASA, ESA, and J. Anderson and R. van der Marel (STScI)

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Using four years of data from the Hubble Space Telescope’s Advanced Camera for Surveys, astronomers have made the most accurate measurements of the movement of stars in the globular cluster Omega Centauri, and now can predict their movements for the next 10,000 years. This “beehive” of stars is tightly crammed together, so resolving the individual stars was a job that perhaps only Hubble could do. “It takes high-speed, sophisticated computer programs to measure the tiny shifts in the positions of the stars that occur in only four years’ time,” says astronomer Jay Anderson of the Space Telescope Science Institute in Baltimore, Md., who conducted the study with fellow Institute astronomer Roeland van der Marel. “Ultimately, though, it is Hubble’s razor-sharp vision that is the key to our ability to measure stellar motions in this cluster.”

Astronomers say that the precise measurement of star motions in giant clusters can yield insights into how stellar groupings formed in the early universe, and whether an “intermediate mass” black hole, one roughly 10,000 times as massive as our Sun, might be lurking among the stars.

Analyzing archived images taken over a four-year period by Hubble’s astronomers have made the most accurate measurements yet of the motions of more than 100,000 cluster inhabitants, the largest survey to date to study the movement of stars in any cluster.

The astronomers used the Hubble images, which were taken in 2002 and 2006, to make a movie simulation of the frenzied motion of the cluster’s stars. The movie shows the stars’ projected migration over the next 10,000 years.

Omega Centauri is the biggest and brightest globular cluster in the Milky Way, and one of the few that can be seen by the unaided eye. It is located in the constellation Centaurus, Omega Centauri, so is viewable in the southern skies, and is one of about 150 such clusters in our Milky Way Galaxy.

In this video below, astronomers Jay Anderson and Roeland van der Marel discuss their in-depth study of the giant cluster Omega Centauri.

Source: HubbleSite

Posted on by Nancy Atkinson

VLT, Hubble Smash Record for Eyeing Most Distant Galaxy

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The Universe. So far, no duplicates found@

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Using the Hubble Space Telescope and the Very Large Telescope (VLT), astronomers have looked back to find the most distant galaxy so far. “We are observing a galaxy that existed essentially when the Universe was only about 600 million years old, and we are looking at this galaxy – and the Universe – 13.1 billion years ago,” said Dr. Matt Lehnert from the Observatoire de Paris, who is the lead author of a new paper in Nature. “Conditions were quite different back then. The basic picture in which this discovery is embedded is that this is the epoch in which the Universe went from largely neutral to basically ionized.”

Lehnert and an international team used the VLT to make follow-up observations of the galaxy — called UDFy-38135539 – which Hubble observations in 2009 had revealed. The astronomers analyzed the very faint glow of the galaxy to measure its distance — and age. This is the first confirmed observations of a galaxy whose light is emerging from the reionization of the Universe.

The reionization period is about the farthest back in time that astronomers can observe. The Big Bang, 13.7 billion years ago, created a hot, murky universe. Some 400,000 years later, temperatures cooled, electrons and protons joined to form neutral hydrogen, and the murk cleared. Some time before 1 billion years after the Big Bang, neutral hydrogen began to form stars in the first galaxies, which radiated energy and changed the hydrogen back to being ionized. Although not the thick plasma soup of the earlier period just after the Big Bang, this galaxy formation started the reionization epoch, clearing the opaque hydrogen fog that filled the cosmos at this early time.

A simulation of galaxies during the era of deionization in the early Universe. Credit: M. Alvarez, R. Kaehler, and T. Abel

“The whole history of the Universe is from the reionization,” Lehnert said during an online press briefing. “The dark matter that pervades the Universe began to drag the gas along and formed the first galaxies. When the galaxies began to form, it reionized the Universe.”

UDFy-38135539 is about 100 million light-years farther than the previous most distant object, a gamma-ray burst.

Studying these first galaxies is extremely difficult, Lehnert said, as the dim light falls mostly in the infrared part of the spectrum because its wavelength has been stretched by the expansion of the Universe — an effect known as redshift. During the time of less than a billion years after the Big Bang, the hydrogen fog that pervaded the Universe absorbed the fierce ultraviolet light from young galaxies.

The new Wide Field Camera 3 on the NASA/ESA Hubble Space Telescope discovered several candidate objects in 2009, and with 16 hours of observations using the VLT, the team was able to was used to detect the very faint glow from hydrogen at a redshift of 8.6.

The team used the SINFONI infrared spectroscopic instrument on the VLT and a very long exposure time.

“Measuring the redshift of the most distant galaxy so far is very exciting in itself,” said co-author Nicole Nesvadba (Institut d’Astrophysique Spatiale), “but the astrophysical implications of this detection are even more important. This is the first time we know for sure that we are looking at one of the galaxies that cleared out the fog which had filled the very early Universe.”

One of the surprising things about this discovery is that the glow from UDFy-38135539 seems not to be strong enough on its own to clear out the hydrogen fog. “There must be other galaxies, probably fainter and less massive nearby companions of UDFy-38135539,” said co-author Mark Swinbank from Durham University, “which also helped make the space around the galaxy transparent. Without this additional help the light from the galaxy, no matter how brilliant, would have been trapped in the surrounding hydrogen fog and we would not have been able to detect it.”

Sources: ESO, press briefing

Posted on by Nancy Atkinson

Hubble Spins the Wheel on Star Birth

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Spiral galaxy NGC 3982. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

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Galaxies are like snowflakes, with no two looking exactly the same. The latest image released from the Hubble Space Telescope shows a striking face-on spiral galaxy named NGC 3982, which is a swirl of activity and star birth along with its winding arms. The arms are lined with pink star-forming regions of glowing hydrogen, newborn blue star clusters, and obscuring dust lanes that provide the raw material for future generations of stars. The bright nucleus is home to an older population of stars, which grow ever more densely packed toward the center.

NGC 3982 is located about 68 million light-years away in the constellation Ursa Major. The galaxy spans about 30,000 light-years, one-third of the size of our Milky Way galaxy. This color image is composed of exposures taken by three different instruments, taken over a substantial portion of the space telescope’s life, from March 2000 and August 2009: The Wide Field Planetary Camera 2 (WFPC2), the Advanced Camera for Surveys (ACS), and the Wide Field Camera 3 (WFC3). The observations were taken between The rich color range comes from the fact that the galaxy was photographed in visible and near-infrared light. Also used was a filter that isolates hydrogen emission that emanates from bright star-forming regions dotting the spiral arms.

Source: HubbleSite

Posted on by Jon Voisey

Missing Molecules in Exoplanet Atmospheres

Artist's View of Extrasolar Planet HD 189733b

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Every day, I wake up and flip through the titles and abstracts of recent articles posted to arXiv. With increasing regularity, papers pop up announcing the discovery of a new extra-solar planet. At this point, I keep scrolling. How many more hot Jupiters do you really want to hear about? If it’s a record setter in some way, I’ll read it. Another way I’ll pay attention is if there’s reports of detections of spectroscopic detection of components of the atmosphere. While a fistful of transiting planets have had spectral lines discovered, they’re still pretty rare and new discoveries will help constrain our understanding of how planets form.

The holy grail in this field would be to discover elemental signatures of molecules that don’t form naturally and are characteristic of life (as we know it). In 2008, a paper announced the first detection of CO2 in an exoplanet atmosphere (that of HD 189733b), which, although not exclusively, is one of the tracer molecules for life. While HD 189733b isn’t a candidate for searches for ET, it was still a notable first.

Then again, perhaps not. A new study casts doubt on the discovery as well as the report of various molecules in the atmospheres of another exoplanet.

Thus far there have been two methods by which astronomers have attempted to identify molecular species in the atmosphere of exoplanets. The first is by using starlight, filtered by the planet’s atmosphere to search for spectral lines that are only present during transit. The difficulty with this method is that, spreading the light out to detect the spectra weakens the signal, sometimes down to the very point that it’s lost in systematic noise from the telescope itself. The alternative is to use photometric observations, which look at the change in light in different color ranges, to characterize the molecules. Since the ranges are all lumped together, this can improve the signal, but this is a relatively new technique and statistical methodology for this technique is still shaky. Additionally, since only one filter can be used at a time, the observations must generally be taken on different transits, which allow the characteristics of the star to change due to star spots.

The 2008 study by Swain et al. that announced the presence of CO2 used the first of these methods. Their trouble started the following year when a followup study by Sing et al. failed to reproduce the results. In their paper, Sing’s team stated,”Either the planet’s transmission spectrum is variable, or residual systematic errors still plague the edges of the Swain et al. spectrum.”

The new study, by Gibson, Pont, and Aigrain (working from the Universities of Oxford and Exeter) suggests that the claims of Swain’s team were a result of the latter. They suggest that the signal is swamped with more noise than Swain et al. accounted for. This noise comes from the telescope itself (in this case Hubble since these observations would need to be made out of Earth’s atmosphere which would add its own spectral signature). Specifically, they report that since there’s changes in the state of the detector itself that are often hard to identify and correct for, Swain’s team underestimated the error, leading to a false positive. Gibson’s team was able to reproduce the results using Swain’s method, but when they applied a more complete method which didn’t assume that the detector could be calibrated so easily by using observations of the star outside the transit and on different Hubble orbits, the estimation of the errors increased significantly, swamping the signal Swain claimed to have observed.

Gibson’s team also reviewed the case of detections of molecules in the atmosphere of an extra solar planet around XO-1 (on which Tinetti et al. reported to have found methane, water, and CO2). In both cases, they again find that detections of were overstated and the ability to tease signal from the data was dependent on questionable methods.

This week seems to be a bad week for those hoping to find life on extra-solar planets. With this article casting doubt on our ability to detect molecules in distant atmospheres and the recent caution on the detection of Gliese 581g, one might worry about our ability to explore these new frontiers, but what this really underscores is the need to refine our techniques and keep taking deeper looks. This has been a frank reassessment of the current state of knowledge, but does not in any way claim to limit our future discoveries. Additionally, this is how science works; scientists review each others data and conclusions. So, looking on the bright side, science works, even if it’s not exactly telling us what we’d like to hear.

Posted on by Nicholos Wethington

Hubble Sees Asteroid Collision in Slow-Motion

The collision between two asteroids in early 2009 produced a strange, X-shaped aftermath. Image Credit: NASA, ESA and D. Jewitt (UCLA)

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Alas, the image above is not marking alien pirate treasure in space – for the first time, the aftermath of a collision between two asteroids has been imaged. Last January, an international team of astronomers saw the strange X-shaped object with the Hubble Space Telescope after ground-based observatories spotted evidence of an asteroid collision in the asteroid belt. The team has now used Hubble to do follow-up observations and uncovered a few surprises about the collision.

The collision produced an X shape, followed by a long comet-like tail. The astronomers, led by David Jewitt of the University of California in Los Angeles, were surprised to find that the collision did not happen as recently as they’d thought, but had actually occurred almost a year previous to the detection. It’s likely that the two asteroids smashed together sometime in February or March of 2009.

“When I saw the Hubbble image I knew it was something special,” said ESA astronomer Jessica Agarwal in a press release.

Named P/2010 A2, the object is located in the asteroid belt between Mars and Jupiter. Asteroid collisions are thought to be a commonplace occurrence, and are responsible for kicking up dust in our Solar System and other planetary systems. Just how much dust is produced, and how frequent the collisions happen is still a hazy topic, and the recent observation of P/2010 A2 should help astronomers to better model this phenomenon.

By figuring out how much dust is produced by the process of ‘collisional grinding’, astronomers could better model the dusty debris disks of other planetary systems, as well as our own.

The team monitored the slow-motion expansion of the leftovers of the colliding asteroids with the Hubble Space Telescope between January and May of 2010. They’ve determined that P/2010 A2 is about 120 meters (393 feet) wide, and the particles of dust that make up the tail following it are between 1 millimeter (0.04 inches) to 2.5 centimeters (1 inch) in diameter.

The collision producing the object P/2010 A2, as observed over the course of a few months by Hubble. Image Credit: NASA, ESA and D. Jewitt (UCLA)

The remnants of the collision suggest that a smaller asteroid – 3 to 5 meters (10-16 feet) wide – collided into a larger one at about 18,000 km per hour (11,000 miles per hour). This vaporized the smaller asteroid, and ejected material from the larger one.

Why is the object X-shaped? That mystery has yet to be determined. It is likely, according to the team, that the filaments produced by the collision suggest asymmetries in the colliding objects. Further observations of P/2010 A2 with the Hubble in 2011 will show just how the collision continues to change, allowing for a more precise model of how it started out.

The observed tail is caused by the same mechanism that produces cometary tails – radiation pressure from the Sun pushes the dust away from the nucleus of the object.

As to why we don’t have thousands of Hubble images to produce a whole alphabet of asteroid collisions shapes – “Catching colliding asteroids on camera is difficult because large impacts are rare, while small ones, such as the one that produced P/2010 A2, are exceedingly faint,” Jewitt said. The results of their observations will be published in the October 14th issue of the journal Nature.

Source: ESA Press Release