Posted on by Ken Kremer

Dawn Discovers Surprise 2nd Giant South Pole Impact Basin at Strikingly Dichotomous Vesta

Southern Hemisphere of Vesta; Rheasilvia and Older Basin. Colorized shaded-relief map showing identification of older 375-kilometer-wide impact basin beneath and overlapping with the more recent Rheasilvia impact structure at asteroid Vesta’s South Pole. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

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Scientists leading NASA’s Dawn mission have discovered a 2nd giant impact basin at the south pole of the giant asteroid Vesta, which has been unveiled as a surprisingly “dichotomous” and alien world. Furthermore, the cosmic collisions that produced these two basins shuddered through the interior and created vast Vestan troughs, a Dawn scientist told Universe Today.

The newly discovered impact basin, nicknamed ‘Older Basin’, is actually significantly older in age compared to the initially discovered South Pole basin feature named ‘Rheasilvia’ – perhaps by more than a billion years. And that is just one of the many unexplained mysteries yet to be reconciled by the team as they begin to sift through the millions of bits of new data streaming back daily to Earth.

Scientists speculate that ‘Older Basin’ is on the order of 3.8 Billion years old, whereas ‘Rheasilvia’ might be as young as about 2.5 Billion years, but those are just tentative estimates at this time and subject to change. Measurements so far indicate Rheasilvia is composed of basaltic material.

Shaded-relief topographic map of Vesta southern hemisphere showing two large impact basins - Rheasilvia and Older Basin.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

“We found many surprising things at Vesta, which is quite unique and the results have exceeded our expectations”, said Dr. Carol Raymond, Dawn deputy principal investigator, of NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

Researchers presented the latest findings from Dawn’s initial science mapping orbit at a news briefing at the annual meeting of the Geological Society of America in Minneapolis, Minn., on Oct. 13.

The team considers Vesta to be the smallest terrestrial planet.

Since achieving orbit in July, Dawn’s Framing Cameras (FC) have imaged most of Vesta at about 250 meter resolution and the Visible and Infrared mapping spectrometer(VIR) at about 700 meter resolution. The measurements were collected at the survey orbit altitude of 2700 km. Before Dawn, Vesta was just a fuzzy blob in humankind’s most powerful telescopes.

Vesta from Hubble (top) as a fuzzy blob and from Dawn in orbit (bottom) in crystal clear high resolution.
Credit: NASA/JPL-Caltech/ UCLA/MPS/DLR/IDA

“There is a global dichotomy on Vesta and a fundamental difference between the northern and southern hemispheres”, said Raymond. “The northern hemisphere is older and heavily cratered in contrast to the brighter southern hemisphere where the texture is more smooth and there are lots of sets of grooves. There is a massive mountain at the South Pole. One of the more surprising aspects is the set of deep equatorial troughs.”

“There is also a tremendous and surprising diversity of surface color and morphology. The south is consistent with basaltic lithology and the north with impacts. We are trying to make sense of the data and will integrate that with the high resolution observations we are now collecting.”

Indeed Vesta’s completely unique and striking dichotomy can be directly traced back to the basins which were formed by ancient cataclysmic impacts resulting in shockwaves that fundamentally altered the surface and caused the formation of the long troughs that ring Vesta at numerous latitudes.

“The troughs extend across 240 degrees of longitude,” said Debra Buczkowski, Dawn participating scientist, of the Applied Physics Laboratory at Johns Hopkins University, Laurel, Md. “Their formation can be tied back to the two basins at the South Pole.”

Asteroid Vesta and Equatorial Grooves
This full view of the giant asteroid Vesta was taken by NASA’s Dawn spacecraft, as part of a rotation characterization sequence on July 24, 2011, at a distance of 3,200 miles (5,200 kilometers). A rotation characterization sequence helps the scientists and engineers by giving an initial overview of the character of the surface as Vesta rotated underneath the spacecraft. This view of Vesta shows impact craters of various sizes and grooves parallel to the equator. The resolution of this image is about 500 meters per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

In an exclusive follow up interview with Universe Today, Raymond said “We believe that the troughs formed as a direct result of the impacts,” said “The two sets of troughs are associated with the two large basins [Rheasilvia and Older Basin].”

“The key piece of evidence presented was that the set of troughs in the northern hemisphere, that look older (more degraded) are circumferential to the older impact basin,” Raymond told me.

“The equatorial set are circumferential to Rheasilvia. That Rheasilvia’s age appears in places to be much younger is at odds with the age of the equatorial troughs. An explanation for that could be resurfacing by younger mass wasting features (landslides, slumps). We will be working on clarifying all these relationships in the coming months with the higher resolution HAMO (High Altitude Mapping Orbit) data.”

Dawn has gradually spiraled down closer to Vesta using her exotic ion thrusters and began the HAMO mapping campaign on Sept. 29.

Surface features are dated by crater counting methodology.

“Preliminary crater counting age dates for the equatorial trough region yields a very old age (3.8 Billion years). So there is a discrepancy between the apparent younger age for the Rheasilvia basin and the old age for the troughs. These could be reconciled if Rheasilvia is also 3.8 Billion years old but the surface has been modified by slumping or other processes,” Raymond elaborated.

Time will tell as further data is analyzed.

Dawn launch on September 27, 2007 by a Delta II Heavy rocket from Cape Canaveral Air Force Station, Florida. Credit: Ken Kremer

“Vesta is full of surprises, no more so than at the South Pole,” said Paul Schenk at the GSA briefing. Schenk is a Dawn participating scientist of the Lunar and Planetary Institute, Houston, Texas.

The ‘Rheasilvia’ basin was initially discovered in images of Vesta taken a decade ago by the Hubble Space Telescope which revealed it as a gaping hole in the southern hemisphere. But it wasn’t until Dawn entered orbit on July 16, 2011 after a nearly four year interplanetary journey that Earthlings got their first close up look at the mysterious polar feature and can now scrutinize it in detail to elucidate its true nature.

“The South Pole [Rheasilvia] basin is a roughly circular, impact structure and a deep depression dominated by a large central mound,” said Schenk. “It shows sharp scarps, smooth areas, landslide deposits, debris flows. It’s about 475 km in diameter and one of the deepest (ca. 20 -25 km) impact craters in the solar system.”

The central peak is an enormous mountain, about 22 km high and 180 km across- one of the biggest in the solar system. “It’s comparable in some ways to Olympus Mons on Mars,” Schenk stated.

“We were quite surprised to see a second basin in the mapping data outside of Rheasilvia. This was unexpected. It’s called ‘Older Basin’ for now.”

‘Older Basin’ is about 375 km in diameter. They overlap at the place where Rheasilvia has a missing rim.

“These basins are interesting because we believe Vesta is the source of a large number of meteorites, the HED meteorites that have a spread of ages,” Schenk explained.

Images showing key components of Rheasilvia impact basin on Vesta in high resolution ,referred to Shaded-relief topographic map. Credit: NASA/JPL-Caltech/ UCLA/MPS/DLR/IDA

Multiple large impacts over time may explain the source of the HED (Howardite, Eucrite and Diogenite) meteorites.

“We did expect large impacts on Vesta, likely associated with the late heavy bombardment recognized in the lunar impact record,” Raymond told Universe Today. “The surprising element is that the two apparently largest impacts – keeping in mind that other larger impact basins may be lurking under the regolith – are overlapping.”

Dawn’s VIR spectrometer has detected pyroxene bands covering Vesta’s surface, which is indicative of typical basaltic material, said Federico Tosi, a VIR team member of the Italian Space Agency, Rome. “Vesta has diverse rock types on its surface.”

“VIR measured surface temperatures from 220K to 270 K at the 5 micron wavelength. The illuminated areas are warmer.”

So far there is no clear indication of olivine which would be a marker for seeing Vesta’s mantle, Tossi elaborated.

The VIR spectrometer combines images, spectral information and temperature that will allow researchers to evaluate the nature, composition and evolutionary forces that shaped Vesta’s surface.

The team is absolutely thrilled to see a complicated geologic record that’s been preserved for study with lots of apparent surface layering and surprisingly strong and complex structural features with a large range of color and brightness.

Stay tuned for a year of Vestan delights !

Asteroid Vesta from Dawn
South Pole Rheasilvia basin is at lower right. NASA's Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on July 24, 2011 from a distance of about 3,200 miles (5,200 kilometers). Dawn entered orbit around Vesta on July 16, and will spend a year orbiting the body.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Read Ken’s continuing features about Dawn and Vesta starting here:
Amazing New View of the Mt. Everest of Vesta
Dramatic 3 D Imagery Showcases Vesta’s Pockmarked, Mountainous and Groovy Terrain
Rheasilvia – Super Mysterious South Pole Basin at Vesta
Space Spectacular — Rotation Movies of Vesta
3 D Alien Snowman Graces Vesta
NASA Unveils Thrilling First Full Frame Images of Vesta from Dawn
Dawn Spirals Down Closer to Vesta’s South Pole Impact Basin
First Ever Vesta Vistas from Orbit – in 2D and 3D
Dawn Exceeds Wildest Expectations as First Ever Spacecraft to Orbit a Protoplanet – Vesta

Posted on by Tammy Plotner

New Dark Matter Census – The Hubble Survey

This image of galaxy cluster MACS J1206.2-0847 is part of a broad survey with NASA's Hubble Space Telescope. Credit: NASA, ESA, M. Postman (STScI), and the CLASH Team

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Way off in the constellation of Virgo, galaxy cluster MACS J1206.2-0847 -or MACS 1206 for short – is making news as the forerunner of a brand new Hubble Space Telescope survey. What’s new for the aging telescope? Now astronomers are able to assemble a highly detailed dark matter map… one that involves more galaxy clusters than ever before.

These “dark matter” maps are proving their worth by allowing astronomers to test some theories. In this case, it’s some unusual findings which suggest dark matter is more densely packed inside galaxy clusters than some models predict. If this holds true, it may point to evidence that galaxy clusters pulled together sooner than once predicted. The multiwavelength survey, called the Cluster Lensing And Supernova survey with Hubble (CLASH), takes an unprecedented look at the distribution of dark matter in 25 massive clusters of galaxies.

“The era when the first clusters formed is not precisely known, but is estimated to be at least 9 billion years ago and possibly as far back as 12 billion years ago.” says the Hubble team. “If most of the clusters in the CLASH survey are found to have excessively high accumulations of dark matter in their central cores, then it may yield new clues to the early stages in the origin of structure in the universe.”

To date, the CLASH team has finished their observations of six of the 25 clusters. Of these, MACS 1206 has a distance of about 4.5 billion light-years and was photographed with Hubble’s Advanced Camera for Surveys and the Wide Field Camera 3 in April 2011 through July 2011. What are the strange shapes? These “distortions” are where the light is bent by the extreme gravitation of dark matter.

“Lensing effects can also produce multiple images of the same distant object, as evident in this Hubble picture. In particular, the apparent numbers and shapes of distant galaxies far beyond a galaxy cluster become distorted as the light passes through, yielding a visible measurement of how much mass is in the intervening cluster and how it is distributed.” says the team. “The substantial lensing distortions seen are proof that the dominant component of clusters is dark matter. The distortions would be far weaker if the clusters’ gravity came only from the visible galaxies in the clusters.”

Original Story Source: Hubble News Release.

Posted on by Jason Rhian

Book Review: The Space Shuttle: Celebrating Thirty Years of NASA’s First Space Plane

The Space Shuttle: Celebating Thirty Years Of NASA's First Space Plane is chocked full of great imagery and works to cover each of the shuttle's 135 missions. Photo Credit: Zenith Press

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The space shuttle program is over. The orbiters are being decommissioned, stripped of the components that allowed them to travel in space. For those that followed the program, those that wished they did and those with only a passing interest in what the program accomplished a new book has been produced covering the entirety of the thirty years that comprised NASA’s longest human space flight program. The Space Shuttle: Celebrating Thirty Years of NASA’s First Space Plane is written by aerospace author Piers Bizony and weighs in at 300 pages in length.

Bizony is a prolific author who has focused a lot of his work on space flight. Some of the books that he has written include (but definitely are not limited to) include: One Giant Leap: Apollo 11 Remembered, Space 50, The Man Who Ran the Moon: James E. Webb, NASA, and the Secret History of Project Apollo and Island in the Sky: The International Space Station.

Bizony pulls out all the stops in detailing the shuttle era. From thunder and light - to tragedy, the full spectrum of the shuttle program is highlighted here. Photo Credit: NASA

The book contains 900 color images, detailing the entire history of NASA’s fleet of orbiters. From the first launches and the hope that those initial flights were rich in, to the Challenger tragedy and the subsequent realization that the space shuttles would never be what they were intended to be.

The next phase of the book deals with the post-Challenger period and how NASA worked to find a balance with its fleet of orbiters, while at the same time worked to regain the trust of the America public. The path was both hindered and helped by a single payload – the Hubble Space Telescope.

The Space Shuttle: Celebrating Thirty Years of NASA’s First Space Plane - has stunning imagery on every page, allowing the reader to once again view the majesty that the shuttle program provided. Photo Credit: NASA

When the images the orbiting telescope beamed back turned out fuzzy, NASA was a laughing stock. Hubble would become a sensation and NASA redeemed its name after the first servicing mission to Hubble corrected the problem with the telescope’s mirror.

Hubble was not the only telescope or probe that the shuttle placed in the heavens. It would however, be the only one that NASA’s fleet of orbiters would visit during several servicing missions. Besides Hubble the shuttle also sent the Chandra X-Ray telescope, Galileo probe to Jupiter and the Magellan probe to Venus during the course of the program’s history.

It is currently unknown when the U.S. will launch crews into orbit again. Some aerospace experts have even suggested that the shuttles be pulled out of retirement to help fill this gap - but this is highly unlikely to happen. Photo Credit: NASA

NASA was now on course to begin construction of the most ambitious engineering feat in human history – the International Space Station. The Space Shuttle: Celebrating Thirty Years of NASA’s First Space Plane details this period, as well as the tragic loss of the shuttle Columbia in 2003 with great care and attention to detail. Many never-before-seen images are contained within and Bizony uses them to punctuate the history that the space shuttle accomplished with every flight.

With a chance of catastrophic failure estimated by some as being as high as one chance in 53 - the shuttle was a risky endeavor. However, given all of the program's accomplishments - it is not a stretch to say that the shuttle made fact out of last century's science fiction. Photo Credit: NASA

The book also contains a detailed diagram of the orbiter (it is long and therefore was produced as a pull-out section. This element is included near the end and acts as a nice punctuation mark to the stream of imagery contained within.

While it required the combined effort of 16 different nations to make the International Space Station work - the space shuttle made the orbiting laboratory a reality. Photo Credit: NASA

The book is not perfect (but what book is). If one did not know better, upon reading this book one would assume that the Delta Clipper (both DC-X and DC-XA) flew once and upon landing caught fire. DC-X flew eight times – not once. Bizony also describes the lunar element of the Vision for Space Exploration (VSE) as being a repeat of Apollo. Apollo 17 was the longest duration that astronauts roamed the Moon’s surface – they were there for about three days. The VSE called for a permanent crewed presence on the moon.

For those out there that consider themselves “shuttle huggers” this book is simply a must-have. It is perfect to take to autograph shows to be signed by astronauts (as every mission is detailed, it is a simple matter to have crew members sign on the pages that contain their missions). It is also a perfect gift for space aficionados this holiday season. Published by Zenith Press and retailing for $40.00, The Space Shuttle: Celebrating Thirty Years of NASA’s First Space Plane is a welcome addition to your home library.

How will the shuttle be remebered? According to Bizony, given the technological restraints and the numerous accomplishments that the orbiter accomplished - it will be remembered in a positive light. Photo Credit: NASA
Posted on by Tammy Plotner

Welcome To The Heart Of The Milky Way…

The galactic core, observed using infrared light and X-ray light. Credit: NASA, ESA, SSC, CXC, and STScI

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When it comes to my job, I see a lot of astrophotography. I’ve contemplated innumerable nebulae, viewed myriad galaxies and dreamed over abounding star clusters. Each photo is a work of art in its own right – where the palette is a computer program and the canvas is a screen. These creations are stunning, showing us the true nature of what lay just beyond the visible perception of human sight. However, there are very few that when printed seem to have life of their own. This snapshot in time is one of them…

When this image was originally revealed on November 10, 2009, it was meant to commemorate Galileo’s 400th anniversary of turning a telescope towards the heavens. At the time, 150 prints were released to libraries, schools, planetariums, nature centers and observatories across the country. These massive six feet by three feet prints are a composite of a near-infrared view from the Hubble Space Telescope, an infrared view from the Spitzer Space Telescope and an X-ray view from the Chandra X-ray Observatory into one multi-wavelength picture.

What no one could prepare you for is the emotional impact such an image could have on you… If only you let it.

In this revelation of the heart of the Milky Way you’ll witness star birth – and death. You’ll travel along the effects of a supermassive black hole nearly four million times more massive than our Sun. You’ll walk into a complex web weaved from glowing gas clouds, dripping with globules, filaments and dark, dusty cocoons where neophyte stars await their turn to emerge. You’ll be swept away on the glowing blue stellar winds of X-ray light and dropped into the well of infra-red. You’ll feel yourself uplifted… Pulled into the “pillars of creation”. You’ll fly along hundreds of thousands of stars that could never be seen in visible light.

In short, you can’t walk away untouched.

Each telescope's contribution is presented in a different color: Yellow represents the near-infrared observations of Hubble. They outline the energetic regions where stars are being born as well as reveal hundreds of thousands of stars. Red represents the infrared observations of Spitzer. The radiation and winds from stars create glowing dust clouds that exhibit complex structures from compact, spherical globules to long, stringy filaments. Blue and violet represent the X-ray observations of Chandra. X-rays are emitted by gas heated to millions of degrees by stellar explosions and by outflows from the supermassive black hole in the galaxy's center. The bright blue blob on the left side is emission from a double star system containing either a neutron star or a black hole. Credit: NASA, ESA, SSC, CXC, and STScI

To see the full size image here on your screen is one thing, to see it accompanied by the individuals that make up the three by four feet composite is nice… But it’s the difference between looking up an image of the Mona Lisa and looking at the Mona Lisa as it hangs in the art gallery. I strongly urge you to investigate these NASA’s Great Observatories – Galactic Center Image Locations and take the time to visit in person.

You won’t regret the experience.

My many thanks go to Rich Ruggles of Astronomy 1 On 1 for opening my eyes to all the joy, wonder and mystery all over again.

Posted on by Ray Sanders

Buried Treasure: Astronomers Find Exoplanets Hidden in Old Hubble Data

The left image shows the star HR 8799 as seen by Hubble's Near Infrared Camera and Multi-Object Spectrometer (NICMOS) in 1998. The center image shows recent processing of the NICMOS data with newer, sophisticated software. The processing removes most of the scattered starlight to reveal three planets orbiting HR 8799. Based on the reanalysis of NICMOS data and ground-based observations, the illustration on the right shows the positions of the star and the orbits of its four known planets. (Credit: NASA; ESA; STScI, R. Soummer)

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Over the past 21 years, the Hubble Space Telescope has gathered boatloads of data, with the Hubble archive center filling about 18 DVDs for every week of the telescope’s life. Now, with improved data mining techniques, an intense re-analysis of HST images from 1998 has revealed some hidden treasures: previously undetected extrasolar planets.

Scientists say this discovery helps prove a new method for planet hunting by using archived Hubble data. Also, discovering the additional exoplanets in the Hubble data helps them compare earlier orbital motion data to more recent observations.

How did astronomers detect the previously unseen exoplanets, and can the methods used be applied to other HST data sets?

This isn’t the first time hidden exoplanets have been revealed in HST data – In 2009 David Lafreniere of the University of Montreal recovered hidden exoplanet data in Hubble images of HR 8799. The HST images Lafreniere studied were taken in 1998 with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). The outermost planet orbiting HR 8799 was identified and demonstrated the power of a new data-processing technique which could tease out faint planets from the glow of their central star.

Four giant planets are now known to orbit HR 8799, the first three of which were discovered in 2007/2008 in near-infrared images taken with instruments at the W.M. Keck Observatory and the Gemini North telescope by Christian Marois of the National Research Council in Canada. In 2010 Marois and his team uncovered a fourth, innermost, planet. What makes the HR 8799 system so unique is that it is the only multi-exoplanet star system that has been directly imaged.

The new analysis by Remi Soummer of the Space Telescope Science Institute has found all three of the outer planets. Unfortunately, the fourth, innermost planet is close to HR 8799 and cannot be imaged due obscuration by the the NICMOS coronagraph that blocks the central star’s light.

When astronomers study exoplanets by directly imaging them, they study images taken several years apart – not unlike methods used to find Pluto and other dwarf planets in our solar system like Eris. Understanding the orbits in a multi-planet system is critical since massive planets can affect the orbits of their neighboring planets in the system. “From the Hubble images we can determine the shape of their orbits, which brings insight into the system stability, planet masses and eccentricities, and also the inclination of the system,” says Soummer.

Making the study difficult is the extremely long orbits of the three outer planets, which are approximately 100, 200, and 400 years, respectively. The long orbital periods require considerable time to produce enough motion for astronomers to study. In this case however, the added time span from the Hubble data helps considerably. “The archive got us 10 years of science right now,” Soummer says. “Without this data we would have had to wait another decade. It’s 10 years of science for free.”

Given its 400 year orbital period, in the past ten years, the outermost planet has barely changed position. “But if we go to the next inner planet we see a little bit of an orbit, and the third inner planet we actually see a lot of motion,” Soummer added.

When the original HST data was analyzed, the methods used to detect exoplanets such as those orbiting HR 8799 were not available. Techniques to subtract the light from a host star still left residual light that drowned out the faint exoplanets. Soummer and his team improved on the previous methods and used over four hundred images from over 10 years of NICMOS observations.

The improvements on the previous technique included increasing contrast and minimizing residual starlight. Soummer and his team also successfully removed the diffraction spikes, a phenomenon that amateur and professional telescope imaging systems suffer from. With the improved techniques, Soummer and his team were able to see two of HR 8799’s faint inner planets, which are about 1/100,000th the brightness of the host star in infra-red.

Soummer has made plans to next analyze 400 more stars in the NICMOS archive with the same technique, which demonstrates the power of the Hubble Space Telescope data archive. How many more exoplanets are uncovered is anyone’s guess.

Finding these new exoplanets proves that even after the HST is no longer functioning, Hubble’s data will live on, and scientists will rely on Hubble’s revelations for years as they continue in their quest to understand the cosmos.

Source: Hubble Space Telescope Mission Updates

Posted on by Tammy Plotner

Looking Into The Eye Of A Monster – Active Galaxy Markarian 509

Active galaxy Markarian 509 as seen by the Hubble Space Telescope's WFPC2. Credits: NASA, ESA, J. Kriss (STScI) and J. de Plaa (SRON)

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“The world is a vampire, sent to drain… Secret destroyers, hold you up to the flames…” Ah, yes. It’s the biggest vampire of all – the supermassive black hole. In this instance, it’s not any average, garden-variety black hole, but one that’s 300 million times the mass of the Sun and growing. Bullet with butterfly wings? No. This is more a case of butterfly wings with bullets.

An international team of astronomers using five different telescopes set their sites on 460 million light-year distant Markarian 509 to check out the action surrounding its huge black hole. The imaging team included ESA’s XMM-Newton, Integral, NASA/ESA Hubble Space Telescope, NASA’s Chandra and Swift satellites, and the ground-based telescopes WHT and PARITEL. For a hundred days they monitored Markarian 509. Why? Because it is known to have brightness variations which could mean turbulent inflow. In turn, the inner radiation then drives an outflow of gas – faster than a speeding bullet.

“XMM-Newton really led these observations because it has such a wide X-ray coverage, as well as an optical monitoring camera,” says Jelle Kaastra, SRON Netherlands Institute for Space Research, who coordinated an international team of 26 astronomers from 21 institutes on four continents to make these observations.

And the vampire reared its ugly head. Instead of the previously documented 25% changes, it jumped to 60%. The hot corona surrounding the black hole was spattering out cold gas “bullets” at speeds in excess of one million miles per hour. These projectiles are torn away from the dusty torus, but the real surprise is that they are coming from an area just 15 light years away from the center. This is a lot further than most astronomers speculate could happen.

“There has been a debate in astronomy for some time about the origin of the outflowing gas,” says Kaastra.

But there’s more than just bullets here. These new observations at multiple wavelengths are showing the coolest gas in the line of sight toward Markarian 509 has 14 different velocity components – all from different locations at the galaxy’s heart. What’s more, there’s indications the black hole accretion disc may have a shield of gas harboring temperatures ranging in the millions of degrees – the motivating force behind x-rays and gamma rays.

An artist's impression of the central engine of an active galaxy. A black hole is surrounded by matter waiting to fall in. Fearsome radiation from near the black hole drives an outflow of gas. Credits: NASA and M. Weiss (Chandra X-ray Center)

“The only way to explain this is by having gas hotter than that in the disc, a so-called ‘corona’, hovering above the disc,” Jelle Kaastra says. “This corona absorbs and reprocesses the ultraviolet light from the disc, energising it and converting it into X-ray light. It must have a temperature of a few million degrees. Using five space telescopes, which enabled us to observe the area in unprecedented detail, we actually discovered a very hot ‘corona’ of gas hovering above the disc. This discovery allows us to make sense of some of the observations of active galaxies that have been hard to explain so far.”

To make things even more entertaining, the study has also found the signature of interstellar gas which may have been the result of a one-time galaxy collision. Although the evidence may be hundreds of thousands of light years away from Mrk 509, it may have initially triggered this activity.

“The results underline how important long-term observations and monitoring campaigns are to gain a deeper understanding of variable astrophysical objects. XMM-Newton made all the necessary organisational changes to enable such observations, and now the effort is paying off,” says Norbert Schartel, ESA XMM-Newton Project Scientist.

Ah, Markarian 509… “Despite all my rage… I am still just a rat in cage.”

Original Story Source: ESA News. For Further Reading: Multiwavelength Campaign on Mrk 509 VI. HST/COS Observations of the Far-ultraviolet Spectrum.

Posted on by Tammy Plotner

Holmberg II – Forever Blowing Bubbles

Hubble’s famous images of galaxies typically show elegant spirals or soft-edged ellipses. But these neat forms are only representative of large galaxies. Smaller galaxies like the dwarf irregular galaxy Holmberg II come in many shapes and types that are harder to classify. This galaxy’s indistinct shape is punctuated by huge glowing bubbles of gas, captured in this image from the NASA/ESA Hubble Space Telescope.

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“I’m forever blowing bubbles… Pretty bubbles in the air…” Its name is Holmberg II, and it’s a dwarf galaxy that’s only 9.8 million light-years away. It’s part of the M81 Galaxy Group and one of the few that isn’t distracted by gravity from nearby peers. Holmberg II is an active little galaxy and one that’s full of holes – the largest of which spans 5500 light years wide. But what makes this one really fascinating is that it’s expelling huge bubbles of gas…

Here the remnants of mature and dying stars have left thick waves of dust and gas, carved into shape by stellar winds. Some ended their lives as supernovae – sending rippling shockwaves through the thinner material to hang in space like fantasy ribbons. With no dense nucleus to deform it like an elliptical galaxy, nor distorting arms like a spiral, this irregular star-forming factory is the perfect place for astronomers to take a close look stellar formation in a new way.

Keep thinking bubbles, because Holmberg II is the perfect example of the “champagne” model of starbirth – where new stars create even newer ones. How does it work? When a bubble is created by stellar winds, it moves outwards until it reaches the edge of the molecular cloud that spawned it. At the exterior edge, dust and gas have been compressed and form a nodule similar to a blister. Here another new star forms.. and triggers again… and triggers again… similar to the chain reaction which happens when you open a bottle of champagne.

And fill the glass again, because Holmberg II is also known as Arp 268. While Halton Arp certainly knows his stuff when it comes to unusual galaxies, there’s even more. According to the Hubble team, our little dwarf also has an ultraluminous X-ray source in the middle of three gas bubbles which appears in the image’s upper right hand corner. No one is quite sure of what it just might be! Maybe black hole bubbles?

“They fly so high… Nearly reach the sky. Then in my dreams they fade and die…” Perhaps Dean Martin?

Original Story Source: Hubble News.

Posted on by Ken Kremer

Ed Weiler – NASA Science Leader and Hubble Chief Scientist Retires

Dr. Ed Weiler retired on Sept 30, 2011 as the NASA Associate Administrator for the Science Mission Directorate at NASA HQ, Washington, DC after 33 distinguished years at NASA, including 10 years as Chief of all NASA Space Science and nearly 20 years as Chief Scientist for the Hubble Space Telescope. In this photo, Weiler ‘Hugs Hubble' after launch of STS-125 on the final shuttle mission to repair and upgrade the Hubble Space Telescope in May 2009. A happy and relieved Weiler chats post-launch inside the KSC Press Center about Hubble and NASA Space Science. Credit: Ken Kremer

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Ed Weiler, NASA’s Science leader in charge of the robotic missions that continually produce scientific breakthroughs that amaze all humanity and longtime Chief Scientist on the Hubble Space Telescope that has completely revolutionized our understanding of humanities place in the Universe, retired today (Sept. 30) from NASA after a distinguished career spanning almost 33 years.

Weiler is departing NASA during what has been dubbed the “Year of Space Science”- the best year ever for NASA Space Science research. The two most recent successes are the launch of JUNO to Jupiter and the twin GRAIL probes to the Moon. Blastoff of the Curiosity Mars Science Laboratory rover is slated for late November 2011.

Weiler’s official title is associate administrator of NASA’s Science Mission Directorate (SMD) at agency Headquarters in Washington, DC. In that capacity he was responsible for overseeing NASA’s science and research programs in Earth science, heliophysics, planetary science and astrophysics.

Weiler was appointed to lead SMD in 2008. He holds this position now for the second time after serving in between as Director of NASA Goddard Spaceflight Center in Greenbelt, Maryland from 2004 to 2008. His earlier stint as associate administrator lasted from 1998 to 2004 for what was then called the Space Science Enterprise.

Dr. Ed Weiler, NASA Associate Administrator for the Science Mission Directorate. Credit: NASA/Bill Ingalls

Probably the job he loved best was as Chief Scientist of the Hubble Space Telescope from 1979 to 1998, until he was promoted to the top rung of NASA management.

I was very lucky to meet and chat with Ed Weiler while I was covering the final space shuttle flight – STS-125 – to repair and upgrade Hubble. STS 125 blasted off in May 2009 and accomplished every single objective to catapult Hubble to the apex of its capabilities.

At the recent launch of the twin GRAIL lunar mapping probes, I spoke with Weiler about a wide range of NASA missions. Watch for my upcoming interview with Ed.

Weiler is very hopeful that Hubble will continue to operate for several more years at least.

NASA issued this statement from NASA Administrator Charles Bolden, “Ed leaves an enduring legacy of pride and success that forever will remain a part of NASA’s science history. His leadership helped inspire the public with each new scientific discovery, and enabled NASA to move forward with new capabilities to continue to explore our solar system and beyond.”

The successes under Weiler’s leadership include NASA’s great observatory missions, unprecedented advances in Earth science and extensive exploration of Mars and other planets in our solar system. These advances have rewritten science textbooks and earned enormous support for NASA’s science programs from the general public.

The Mars rovers Spirit and Opportunity are just one example of the science missions approved and funded during Weiler’s tenure.

Weiler’s leadership has been instrumental in securing continued support and funding for NASA Space Science from Congress and the White House. He has received numerous prestigious awards including the NASA Distinguished Service Medal and several Presidential Rank Awards for Meritorious Executive and Distinguished Executive.

Ed Weiler remembers Spirit at JPL symposium. Credit: AP
Posted on by Tammy Plotner

Even Small Galaxies Can Have Big Black Holes

Astronomers detected supermassive black holes in 28 distant, low-mass galaxies, including the four shown in these Hubble Space Telescope images. Image credit: A. Koekemoer, Space Telescope Science Institute.

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The Hubble Space Telescope has done it again. By utilizing a slitless grism, the Wide Field Camera 3 has uncovered evidence that supermassive black holes are right at home in some very small galaxies. Apparently these central black holes began their life when their host galaxies were first forming!

“It’s kind of a chicken or egg problem: Which came first, the supermassive black hole or the massive galaxy? This study shows that even low-mass galaxies have supermassive black holes,” said Jonathan Trump, a postdoctoral researcher at the University of California, Santa Cruz. Trump is first author of the study, which has been accepted for publication in the Astrophysical Journal.

It’s another cosmic conundrum. As we’ve learned, large galaxies are host to central supermassive black holes and many of them are the AGN variety. But the real puzzle is why do some smaller galaxies contain them when most do not? By taking a closer look at dwarf galaxies some 10 billion light-years away, astronomers are reaching back in time to when the Universe was about an estimated quarter of its current age.

“When we look 10 billion years ago, we’re looking at the teenage years of the universe. So these are very small, young galaxies,” Trump said.

If your mind is still wondering what a “slitless grism” is, then wonder no more. It’s part of Hubble’s WFC3 infrared camera that provides spectroscopic information. Thanks to highly detailed information on the different wavelengths of light, the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) team could achieve separate spectra from each sector of the candidate galaxies and identify emissions from black hole sources.

“This is the first study that is capable of probing for the existence of small, low-luminosity black holes back in time,” said coauthor Sandra Faber, University Professor of astronomy and astrophysics at UC Santa Cruz and CANDELS principal investigator. “Up to now, observations of distant galaxies have consistently reinforced the local findings–distant black holes actively accreting in big galaxies only. We now have a big puzzle: What happened to these dwarf galaxies?”

It’s possible they are forerunners of the massive galaxies we see today. “Some may remain small, and some may grow into something like the Milky Way,” Trump said. But this theory is a juxtaposition in itself. According to Faber, “To become big galaxies today, the dwarf galaxies would have to grow at a rate much faster than standard models predict. If they remain small, then nearby dwarf galaxies should also have central black holes. There might be a large population of small black holes in dwarf galaxies that no one has noticed before.”

But these distant little dwarfs aren’t quiet – they are actively forming new stars. According to Trump, “Their star formation rate is about ten times that of the Milky Way. There may be a connection between that and the active galactic nuclei. When gas is available to form new stars, it’s also available to feed the black hole.”

But the Hubble wasn’t the only instrument interested in the 28 small galaxy studies. The team also employed x-ray data acquired by NASA’s Chandra X-ray Observatory. To help refine their information on such small, faint objects, the data was combined to improve the signal-to-noise ratio.

“This is a powerful technique that we can use for similar studies in the future on larger samples of objects,” Trump said. “Together the compactness of the stacked OIII spatial profile and the stacked X-ray data suggest that at least some of these low-mass, low-metallicity galaxies harbor weak active galactic nuclei.”

Original Story Source: University of Santa Cruz News. For Further Reading: A CANDELS WFC3 Grism Study of Emission-Line Galaxies at z~2: A Mix of Nuclear Activity and Low-Metallicity Star Formation.

Posted on by Jason Rhian

Book Review: A Dictionary of the Space Age

A Dictionary of the Space Age covers most aspects of space flight but is somewhat lacking in detail. Image Credit: John Hopkins University & Alan Walters/awaltersphoto.com

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Writing a dictionary is not the same as writing a novel. While it might seem difficult to mess up a dictionary, even one with terminology that is as complicated as that used within the space industry – getting it right can be challenging. For those that follow space flight having such a dictionary can be invaluable. While A Dictionary of the Space Age does meet the basic requirements easily it fails somewhat in terms of its comprehensiveness.

When normal folks, even space enthusiasts watch launches and other space-related events (EVAs, dockings, landings and such) there are so many acronyms and jargon thrown about – that it is extremely hard to follow. With A Dictionary of the Space Age on hand, one can simply thumb through and find out exactly what is being said, making it both easier to follow along and making the endeavor being witnessed far more inclusive. That is as long if you are only looking for the most general of terms. The book is far from complete – but given the complex nature of the topic – this might not have been possible.

Crewed, unmanned, military space efforts and satellites – all have key terms addressed within the pages of this book.

The book is published by The Johns Hopkins University Press and was compiled and written by aerospace expert Paul Dickson. One can purchase the book on the secondary market (Amazon.com) for around $12 (new for around $25). The dictionary also has a Kindle edition which is available for $37.76. Dickson’s previous works on space flight is Sputnik: The Shock of the Century.

Weighing in at 288 pages, the book briefly covers the primary terms used within the space community. In short, if you are interested in learning more about space flight – or wish to do so – this is a good book for you.