Astronomers thrilled by extreme storms on Uranus

These are infrared images of Uranus (1.6 and 2.2 microns) obtained on Aug. 6, 2014, with adaptive optics on the 10-meter Keck telescope. 

The white spot is an extremely large storm that was brighter than any feature ever recorded on the planet in the 2.2 micron band. 

The cloud rotating into view at the lower-right limb grew into the large storm that was seen by amateur astronomers at visible wavelengths. 

Credit: Imke de Pater (UC Berkeley) & Keck Observatory images.

The normally bland face of Uranus has become increasingly stormy, with enormous cloud systems so bright that for the first time ever, amateur astronomers are able to see details in the planet's hazy blue-green atmosphere.

Imke de Pater

"The weather on Uranus is incredibly active," said Imke de Pater, professor and chair of astronomy at the University of California, Berkeley, and leader of the team that first noticed the activity when observing the planet with adaptive optics on the W. M. Keck II Telescope in Hawaii.

"This type of activity would have been expected in 2007, when Uranus's once every 42-year equinox occurred and the sun shined directly on the equator," noted co-investigator Heidi Hammel of the Association of Universities for Research in Astronomy.

"But we predicted that such activity would have died down by now. Why we see these incredible storms now is beyond anybody's guess."

Heidi Hammel

In all, de Pater, Hammel and their team detected eight large storms on Uranus's northern hemisphere when observing the planet with the Keck Telescope on August 5 and 6.

One was the brightest storm ever seen on Uranus at 2.2 microns, a wavelength that senses clouds just below the tropopause, where the pressure ranges from about 300 to 500 mbar, or half the pressure at Earth's surface.

The storm accounted for 30 percent of all light reflected by the rest of the planet at this wavelength.

When amateur astronomers heard about the activity, they turned their telescopes on the planet and were amazed to see a bright blotch on the surface of a normally boring blue dot.

'I got it!'

French amateur astronomer Marc Delcroix processed the amateur images and confirmed the discovery of a bright spot on an image by French amateur Régis De-Bénedictis, then in others taken by fellow amateurs in September and October.

He had his own chance on Oct. 3 and 4 to photograph it with the Pic du Midi one-meter telescope, where on the second night, "I caught the feature when it was transiting, and I thought, 'Yes, I got it!'" said Delcroix.

"I was thrilled to see such activity on Uranus. Getting details on Mars, Jupiter or Saturn is now routine, but seeing details on Uranus and Neptune are the new frontiers for us amateurs and I did not want to miss that," said Delcroix, who works for an auto parts supplier in Toulouse and has been observing the skies, Jupiter in particular, with his backyard telescope since 2006 and, since 2012, occasionally with the Pic du Midi telescope.

"I was so happy to confirm myself these first amateur images on this bright storm on Uranus, feeling I was living a very special moment for planetary amateur astronomy."

These are optical images of Uranus on Sept. 19 and Oct. 2, showing the dramatic appearance of a bright storm on a planet that normally displays only a diffuse bright polar region. 

Credit: Photo by Anthony Wesley, Murrumbateman, Australia.

Interestingly, the extremely bright storm seen by Keck in the near infrared is not the one seen by the amateurs, which is much deeper in the atmosphere than the one that initially caused all the excitement. De Pater's colleague Larry Sromovsky, a planetary scientist at the University of Wisconsin, Madison, identified the amateur spot as one of the few features on the Keck images from August 5 that was only seen at 1.6 microns, and not at 2.2 microns.

The 1.6 micron light is emitted from deeper in the atmosphere, which means that this feature is below the uppermost cloud layer of methane-ice in Uranus's atmosphere.

"The colours and morphology of this cloud complex suggests that the storm may be tied to a vortex in the deeper atmosphere similar to two large cloud complexes seen during the equinox," Sromovsky said.

Such vortices could be anchored much deeper in the atmosphere and extend over large vertical distances, as inferred from similar vortices on Jupiter, including its Great Red Spot.

An expanded team of astronomers led by Kunio M. Sayanagi, an Assistant Professor at Hampton University in Virginia, leveraged the amateur observations to activate a "Target of Opportunity" proposal on the Hubble Space Telescope, which imaged the entire planet on Oct. 14.

Observing at a variety of wavelengths, HST revealed multiple storm components extending over a distance of more than 9,000 kilometers (5,760 miles) and clouds at a variety of altitudes.

De Pater, Sromovsky, Hammel and Pat Fry of the University of Wisconsin will report the details of their observations on Nov. 12 at a meeting of the American Astronomical Society's Division of Planetary Sciences in Tucson, Ariz.

Ice giant

This is an animation showing the movement of the bright spot as Uranus rotated over a two hour period on Oct. 4, 2014. 

The infrared images were taken at the Pic du Midi telescope in the French Pyrénées. 

Credit: Marc Delcroix and F. Colas (S2P).

Uranus is an ice giant, about four times the diameter of Earth, with an atmosphere of hydrogen and helium, with just a bit of methane to give it a blue tint.

Because it is so distant, 30 times farther from the sun than Earth, astronomers were able to see little detail on its surface until adaptive optics on the Keck telescopes revealed features much like those on Jupiter.

De Pater and her colleagues have been following Uranus for more than a decade, charting the weather on the planet, including bands of circulating clouds, massive swirling storms and convective features at its north pole.

Bright clouds are probably caused by gases such as methane rising in the atmosphere and condensing into highly reflective clouds of methane ice.

Because Uranus has no internal source of heat, its atmospheric activity was thought to be driven solely by sunlight, which is now weak in the northern hemisphere. Hence astronomers were surprised when these observations showed such intense activity.

Observations taken with the Keck telescope by Christoph Baranec, an Assistant Professor at the University of Hawaii on Manoa, revealed that the storm was still active, but had a different morphology and possibly reduced intensity.

"If indeed these features are high-altitude clouds generated by flow perturbations associated with a deeper vortex system, such drastic fluctuations in intensity would indeed be possible," Sromovsky added.

"These unexpected observations remind us keenly of how little we understand about atmospheric dynamics in outer planet atmospheres," the authors wrote in their paper.

ALMA and ATCA Astronomers dissect the remnants of a supernova

Simulated still showing components of Supernova Remnant 1987A. 

Credit: The International Centre for Radio Astronomy Research (ICRAR)

In research published today in the Astrophysical Journal, an Australian led team of astronomers has used radio telescopes in Australia and Chile to see inside the remains of a supernova.

The supernova, known as SN1987A, was first seen by observers in the Southern Hemisphere in 1987 when a giant star suddenly exploded at the edge of a nearby dwarf galaxy called the Large Magellanic Cloud.

In the two and a half decades since then the remnant of Supernova 1987A has continued to be a focus for researchers the world over, providing a wealth of information about one of the Universe's most extreme events.

PhD Candidate Giovanna Zanardo at The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR) led the team that used the Atacama Large Millimetre/submillimeter Array (ALMA) in Chile's Atacama Desert and the Australia Telescope Compact Array (ATCA) in New South Wales to observe the remnant at wavelengths spanning the radio to the far infrared.

"By combining observations from the two telescopes we've been able to distinguish radiation being emitted by the supernova's expanding shock wave from the radiation caused by dust forming in the inner regions of the remnant," said Zanardo.

A panel of images showing different views of Supernova 1987A. 

Left Panel: SNR1987A as seen by the Hubble Space Telescope in 2010. 

Middle Panel: SNR1987A as seen by the ATCA in New South Wales and the ALMA in Chile. 

Right Panel: A computer generated visualisation of the remnant showing the possible location of a Pulsar. 

Credit: ATCA & ALMA Observations & data - G. Zanardo et al. / HST Image: NASA, ESA, K. France (University of Colorado, Boulder), P. Challis and R. Kirshner (Harvard-Smithsonian Center for Astrophysics)

"This is important because it means we're able to separate out the different types of emission we're seeing and look for signs of a new object which may have formed when the star's core collapsed. It's like doing a forensic investigation into the death of a star."

"Our observations with the ATCA and ALMA radio telescopes have shown signs of something never seen before, located at the centre or the remnant. It could be a pulsar wind nebula, driven by the spinning neutron star, or pulsar, which astronomers have been searching for since 1987."

"It's amazing that only now, with large telescopes like ALMA and the upgraded ATCA, we can peek through the bulk of debris ejected when the star exploded and see what's hiding underneath."

More research published recently in the Astrophysical Journal also attempts to shine a light on another long-standing mystery surrounding the supernova remnant.

Since 1992 the radio emission from one side of the remnant has appeared 'brighter' than the other.

More information: 'Spectral and Morphological Analysis of the Remnant of Supernova 1987a with ALMA & ATCA' G. Zanardo, L. Staveley-Smith, R. Indebetouw et al. Astrophysical Journal November 10th, 2014: arxiv.org/abs/1409.7811 and iopscience.iop.org/0004-637X/796/2/82

'Multi-dimensional simulations of the expanding supernova remnant SN 1987a' T.M Potter, L Staveley-Smith, B. Reville et al. Astrophysical Journal October 20th, 20144: arxiv.org/abs/1409.4068 and iopscience.iop.org/0004-637X/794/2/174

Astronomers solve puzzle about bizarre object at the center of our galaxy

Telescopes from Hawaii's W.M. Keck Observatory use a powerful technology called adaptive optics, which enabled UCLA astronomers to discover that G2 is a pair of binary stars that merged together, cloaked in gas and dust. 

Credit: Ethan Tweedie

For years, astronomers have been puzzled by a bizarre object in the center of the Milky Way that was believed to be a hydrogen gas cloud headed toward our galaxy's enormous black hole.

Having studied it during its closest approach to the black hole this summer, UCLA astronomers believe that they have solved the riddle of the object widely known as G2.

A team led by Andrea Ghez, professor of physics and astronomy in the UCLA College, determined that G2 is most likely a pair of binary stars that had been orbiting the black hole in tandem and merged together into an extremely large star, cloaked in gas and dust, its movements choreographed by the black hole's powerful gravitational field.

The research is published today in the journal Astrophysical Journal Letters.

Astronomers had figured that if G2 had been a hydrogen cloud, it could have been torn apart by the black hole, and that the resulting celestial fireworks would have dramatically changed the state of the black hole.

"G2 survived and continued happily on its orbit; a simple gas cloud would not have done that," said Ghez, who holds the Lauren B. Leichtman and Arthur E. Levine Chair in Astrophysics. "G2 was basically unaffected by the black hole. There were no fireworks."

Black holes, which form out of the collapse of matter, have such high density that nothing can escape their gravitational pull, not even light.

They cannot be seen directly, but their influence on nearby stars is visible and provides a signature, said Ghez, a 2008 MacArthur Fellow.

Ghez, who studies thousands of stars in the neighborhood of the supermassive black hole, said G2 appears to be just one of an emerging class of stars near the black hole that are created because the black hole's powerful gravity drives binary stars to merge into one.

She also noted that, in our galaxy, massive stars primarily come in pairs. She says the star suffered an abrasion to its outer layer but otherwise will be fine.

Ghez and her colleagues, who include lead author Gunther Witzel, a UCLA postdoctoral scholar, and Mark Morris and Eric Becklin, both UCLA professors of physics and astronomy, conducted the research at Hawaii's W.M. Keck Observatory, which houses the world's two largest optical and infrared telescopes.

When two stars near the black hole merge into one, the star expands for more than 1 million years before it settles back down, said Ghez, who directs the UCLA Galactic Center Group. "This may be happening more than we thought.

The stars at the center of the galaxy are massive and mostly binaries. It's possible that many of the stars we've been watching and not understanding may be the end product of mergers that are calm now."

Ghez and her colleagues also determined that G2 appears to be in that inflated stage now. The body has fascinated many astronomers in recent years, particularly during the year leading up to its approach to the black hole.

"It was one of the most watched events in astronomy in my career," Ghez said.

Ghez said G2 now is undergoing what she calls a "spaghetti-fication", a common phenomenon near black holes in which large objects become elongated.

At the same time, the gas at G2's surface is being heated by stars around it, creating an enormous cloud of gas and dust that has shrouded most of the massive star.

Witzel said the researchers wouldn't have been able to arrive at their conclusions without the Keck's advanced technology.

"It is a result that in its precision was possible only with these incredible tools, the Keck Observatory's 10-meter telescopes," Witzel said.

The telescopes use adaptive optics, a powerful technology pioneered in part by Ghez that corrects the distorting effects of the Earth's atmosphere in real time to more clearly reveal the space around the supermassive black hole.

The technique has helped Ghez and her colleagues elucidate many previously unexplained facets of the environments surrounding supermassive black holes.

"We are seeing phenomena about black holes that you can't watch anywhere else in the universe," Ghez added.

"We are starting to understand the physics of black holes in a way that has never been possible before."

More information: Astrophysical Journal Letters, iopscience.iop.org/2041-8205/796/1/L8/article

Astronomers find stream of gas, 2.6 million light years long

The bridge of gas (shown in green) stretches from the large galaxy at the bottom left to the group of galaxies at the top. 

A third nearby galaxy to the right also has a shorter stream of gas attached to it. 

The three insets show expanded views of the different galaxies and the green circle indicates the Arecibo telescope beam.

Credit: Rhys Taylor /Arecibo Galaxy Environment Survey /The Sloan Digital Sky Survey Collaboration

Atronomers and students have found a bridge of atomic hydrogen gas 2.6 million light years long between galaxies 500 million light years away.

They detected the gas using the William E. Gordon Telescope at the Arecibo Observatory, a radio astronomy facility of the US National Science Foundation sited in Puerto Rico.

The results are published today in a paper in Monthly Notices of the Royal Astronomical Society.

The stream of atomic hydrogen gas is the largest known, a million light years longer than a gas tail found in the Virgo Cluster by another Arecibo project a few years ago.

Dr Rhys Taylor, a researcher at the Czech Academy of Sciences and lead author of the paper, said "This was totally unexpected.

We frequently see gas streams in galaxy clusters, where there are lots of galaxies close together, but to find something this long and not in a cluster is unprecedented."

It is not just the length of the stream that is surprising but also the amount of gas found in it. Roberto Rodriguez, a 2014 graduate from the University of Puerto Rico in Humacao who worked on the project as an undergraduate, explained "We normally find gas inside galaxies, but here half of the gas, 15 billion times the mass of the Sun, is in the bridge. That's far more than in the Milky Way and Andromeda galaxies combined!"

The team is still investigating the origin of the stream. One notion surmises that the large galaxy at one end of the stream passed close to the group of smaller galaxies at the other end in the past, and that the gas bridge was drawn out as they moved apart, while a second notion presumes that the large galaxy plowed straight through the middle of the group, pushing gas out of it.

The team plan to use computer simulations to find out which of these ideas can best match the shape of the bridge that is seen with the Arecibo Telescope.

The project involved three undergraduate researchers: Roberto Rodriguez and Clarissa Vazquez from UPR Humacao, and Hanna Herbst, now a graduate student at the University of Florida. Dr Robert Minchin, a staff astronomer at Arecibo Observatory and the principal investigator on the project, said "Student involvement is very important to us."

"We are proud to be inspiring the next generation of astronomers, and particularly proud of the involvement of Puerto Rican students."

The bridge was found in data taken between 2008 and 2011 for the Arecibo Galaxy Environment Survey (AGES), which is using the power of the Arecibo Telescope to survey a large area of sky with a high level of sensitivity.

Journal Reference: R. Taylor, R. F. Minchin, H. Herbst, J. I. Davies, R. Rodriguez And C. Vazquez. The Arecibo Galaxy Environment Survey – VII. A dense filament with extremely long H i streams. Monthly Notices of the Royal Astronomical Society, 2014 DOI: 10.1093/mnras/stu1305

Astronomers bring the third dimension to a doomed star's outburst

A new shape model of the Homunculus Nebula reveals protrusions, trenches, holes and irregularities in its molecular hydrogen emission. 

The protrusions appear near a dust skirt seen at the nebula's center in visible light (inset) but not found in this study, so they constitute different structures. 

Credit: NASA Goddard (inset: NASA, ESA, Hubble SM4 ERO Team)

In the middle of the 19th century, the massive binary system Eta Carinae underwent an eruption that ejected at least 10 times the sun's mass and made it the second-brightest star in the sky.

Now, a team of astronomers has used extensive new observations to create the first high-resolution 3-D model of the expanding cloud produced by this outburst.

"Our model indicates that this vast shell of gas and dust has a more complex origin than is generally assumed," said Thomas Madura, a NASA Postdoctoral Program fellow at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and a member of the study team.

"For the first time, we see evidence suggesting that intense interactions between the stars in the central binary played a significant role in sculpting the nebula we see today."

Eta Carinae lies about 7,500 light-years away in the southern constellation of Carina and is one of the most massive binary systems astronomers can study in detail.

The smaller star is about 30 times the mass of the sun and may be as much as a million times more luminous.

The primary star contains about 90 solar masses and emits 5 million times the sun's energy output.

Both stars are fated to end their lives in spectacular supernova explosions.

Between 1838 and 1845, Eta Carinae underwent a period of unusual variability during which it briefly outshone Canopus, normally the second-brightest star.

As a part of this event, which astronomers call the Great Eruption, a gaseous shell containing at least 10 and perhaps as much as 40 times the sun's mass was shot into space.

This material forms a twin-lobed dust-filled cloud known as the Homunculus Nebula, which is now about a light-year long and continues to expand at more than 1.3 million mph (2.1 million km/h).


NASA Goddard astrophysicists Ted Gull and Tom Madura discuss Eta Carinae and their new model of the Homunculus Nebula, a shell of gas and dust ejected during the star's mid-19th century eruption. Credit: NASA's Goddard Space Flight Center

Using the European Southern Observatory's Very Large Telescope (VLT) and its X-Shooter spectrograph over two nights in March 2012, the team imaged near-infrared, visible and ultraviolet wavelengths along 92 separate swaths across the nebula, making the most complete spectral map to date.

The researchers have used the spatial and velocity information provided by this data to create the first high-resolution, fully 3-D model of the Homunculus Nebula.

The new model contains none of the assumptions about the cloud's symmetry found in previous studies.

The shape model, which is now published by the journal Monthly Notices of the Royal Astronomical Society, was developed using only a single emission line of near-infrared light emitted by molecular hydrogen gas.

The characteristic 2.12-micron light shifts in wavelength slightly depending on the speed and direction of the expanding gas, allowing the team to probe even dust-obscured portions of the Homunculus that face away from Earth.

"Our next step was to process all of this using 3-D modeling software I developed in collaboration with Nico Koning from the University of Calgary in Canada.

The program is simply called 'Shape,' and it analyzes and models the three-dimensional motions and structure of nebulae in a way that can be compared directly with observations," said lead researcher Wolfgang Steffen, an astrophysicist at the Ensenada campus of the National Autonomous University of Mexico.

The new shape model confirms several features identified by previous studies, including pronounced holes located at the ends of each lobe and the absence of any extended molecular hydrogen emission from a dust skirt apparent in visible light near the center of the nebula.

New features include curious arm-like protrusions emanating from each lobe near the dust skirt; vast, deep trenches curving along each lobe; and irregular divots on the side facing away from Earth.

"One of the questions we set out to answer with this study is whether the Homunculus contains any imprint of the star's binary nature, since previous efforts to explain its shape have assumed that both lobes were more or less identical and symmetric around their long axis," explained team member Jose Groh, an astronomer at Geneva University in Switzerland.

"The new features strongly suggest that interactions between Eta Carinae's stars helped mold the Homunculus."

Animation of 3-D Homunculus Nebula model. 

Credit: NASA Goddard's Conceptual Image Lab

Every 5.5 years, when their orbits carry them to their closest approach, called periastron, the immense and brilliant stars of Eta Carinae are only as far apart as the average distance between Mars and the sun.

Both stars possess powerful gaseous outflows called stellar winds, which constantly interact but do so most dramatically during periastron, when the faster wind from the smaller star carves a tunnel through the denser wind of its companion.

The opening angle of this cavity closely matches the length of the trenches (130 degrees) and the angle between the arm-like protrusions (110 degrees), indicating that the Homunculus likely continues to carry an impression from a periastron interaction around the time of the Great Eruption.

A 3-D-printed model of the Homunculus Nebula is compared to a Hubble image of the object. Credit: NASA's Goddard Space Flight Center/Ed Campion

Once the researchers had developed their Homunculus model, they took things one step further.

They converted it to a format that can be used by 3-D printers and made the file available along with the published paper.

"Now anyone with access to a 3-D printer can produce their own version of this incredible object," said Goddard astrophysicist Theodore Gull, who is also a co-author of the paper.

"While 3-D-printed models will make a terrific visualization tool for anyone interested in astronomy, I see them as particularly valuable for the blind, who now will be able to compare embossed astronomical images with a scientifically accurate representation of the real thing."

More information: This research has been published in Steffen W. el al., 2014, "The three-dimensional structure of the Eta Carinae Homunculus", Monthly Notices of the Royal Astronomical Society, vol. 442, p. 3316-3328, published by Oxford University Press. mnras.oxfordjournals.org/content/442/4/3316

Mysterious X-ray signal intrigues astronomers

Credit: X-ray: NASA/CXC/SAO/E.Bulbul, et al.

A mysterious X-ray signal has been found in a detailed study of galaxy clusters using NASA's Chandra X-ray Observatory and ESA's XMM-Newton.

One intriguing possibility is that the X-rays are produced by the decay of sterile neutrinos, a type of particle that has been proposed as a candidate for dark matter.

While holding exciting potential, these results must be confirmed with additional data to rule out other explanations and determine whether it is plausible that dark matter has been observed.

Astronomers think dark matter constitutes 85% of the matter in the Universe, but does not emit or absorb light like "normal" matter such as protons, neutrons and electrons that make up the familiar elements observed in planets, stars, and galaxies. Because of this, scientists must use indirect methods to search for clues about dark matter.

The latest results from Chandra and XMM-Newton consist of an unidentified X-ray emission line, that is, a spike of intensity at a very specific wavelength of X-ray light.

Astronomers detected this emission line in the Perseus galaxy cluster using both Chandra and XMM-Newton.

They also found the line in a combined study of 73 other galaxy clusters with XMM-Newton.

"We know that the dark matter explanation is a long shot, but the pay-off would be huge if we're right," said Esra Bulbul of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass. who led the study. "So we're going to keep testing this interpretation and see where it takes us."

The authors suggest this emission line could be a signature from the decay of a "sterile neutrino." Sterile neutrinos are a hypothetical type of neutrino that is predicted to interact with normal matter only via gravity. Some scientists have proposed that sterile neutrinos may at least partially explain dark matter.

"We have a lot of work to do before we can claim, with any confidence, that we've found sterile neutrinos," said Maxim Markevitch, a co-author from NASA's Goddard Space Flight Center in Greenbelt, Maryland. "But just the possibility of finding them has us very excited."

One source of uncertainty is that the detection of this emission line is pushing the capabilities of the two observatories in terms of sensitivity. Also, there may be explanations other than sterile neutrinos if this X-ray emission line is deemed to be real.

There are ways that normal matter in the cluster could have produced the line, although the team's analysis suggested that all of these would involve unlikely changes to our understanding of physical conditions in the galaxy cluster or the details of the atomic physics of extremely hot gases.

The authors note that even if the sterile neutrino interpretation is correct, their detection does not necessarily imply that all of dark matter is composed of these particles.

More information: The paper describing the new Chandra and XMM-Newton observations appears in the June 20, 2014, issue of The Astrophysical Journal: dx.doi.org/10.1088/0004-637X/789/1/13

Astronomers pierce galactic clouds to shine light on black hole development - video

This is an illustration of the physical, spatial and temporal picture for the outflows emanating from the vicinity of the super massive black hole in the galaxy NGC 5548. 

The behaviour of the emission source in five epochs is shown along the time axis. 

The obscurer is situated at roughly 0.03 light years (0.01 parsecs) from the emission source and is only seen in 2011 and 2013 (it is much stronger in 2013). 

Outflow component 1 shows the most dramatic changes in its absorption troughs. Different observed ionic species are represented as colored zones within the absorbers. 

Credit: Ann Feild/Space Telescope Science Institute 

Jelle Kaastra

An international team of scientists including a Virginia Tech physicist have discovered that winds blowing from a supermassive black hole in a nearby galaxy work to obscure observations and x-rays.

The discovery in today's (June 19, 2004) issue of Science Express sheds light on the unexpected behavior of black holes, which emit large amounts of matter through powerful, galactic winds.

Using a large array of satellites and space observatories, the team spent more than a year training their instruments on the brightest and most studied of the "local" black holes—the one situated at the core of Type I Seyfert Galaxy NGC 5548.

What they found was a bit of a surprise.

The researchers discovered much colder gas than expected based on past observations, showing that the wind had cooled and that a stream of gas moved quickly outward and blocked 90 percent of x-rays.

The observation was the first direct evidence of an obscuration process that—in more luminous galaxies—has been shown to regulate growth of black holes.

By looking at data from different sources, scientists found that a thick layer of gas lay between the galactic nucleus and the Earth blocked the lower energy x-rays often used to study the system, but allowed more energetic x-rays to get through.


An animated journey through the active galaxy NGC 5548. For a more in-depth explanation of the video, please see the Supporting Online Material. Credit: Kaastra et al., Science/

Data from Hubble Space Telescope also showed ultraviolet emissions being partially absorbed by a stream of gas.

A multi-wavelength observational campaign simultaneously looking at an object to decipher its secrets is rare, the researchers said.

In this illustration, the position of a dark, absorbing cloud of material is located high above the supermassive black hole and accretion disk in the center of the active galaxy NGC 5548. 

Numerous other filaments twist around the black hole as they are swept away by a torrent of radiation "winds." 

Credit: NASA, ESA, and A. Feild (STScI)

"I don't think anyone has trained so many scopes and put in so much time on a single object like this," said Nahum Arav, an associate professor of physics with Virginia Tech's College of Science.

"The result is quite spectacular. We saw something that was never studied well before and we also deciphered the outflow in the object."

"We know far more about this outflow than any studied previously as to where it is and how it behaves in time. We have a physical model that explains all the data we've taken of the outflow over 16 years."

This image depicts the galaxy NGC 5548 taken at the MDM Observatory 1.3m telescope. 

Credit: Dr. Misty Bentz

The discovery was made by an international team led by SRON Netherlands Institute for Space Research scientist Jelle Kaastra using the major space observatories of the European Space Agency, NASA, the Hubble Space Telescope, Swift, NuSTAR, Chandra, INTREGRAL, and other satellites and observation platforms.

"These outflows are thought to be a major player in the structure formation of the universe," Arav said.

"This particular outflow is comparatively small but because it's so close we can study it very well and then create a better understanding of how the phenomenon will work in very large objects that do affect the structure formation in the universe."

More information: "A fast and long-lived outflow from the supermassive black hole in NGC 5548," by J.S. Kaastra et al. Science Express, 2014. www.sciencemag.org/lookup/doi/… 1126/science.1253787

Astronomers detect Light from Gamma Ray Burst from huge explosion 12 billion years ago

Light from the explosion 12 billion years ago of a massive star at the end of its life reached Earth recently. 

An image of its peak afterglow, circled with blue and yellow, was captured by Southern Methodist University's ROTSE-IIIb telescope at McDonald Observatory, Fort Davis, Texas. 

A bright star sits alongside the afterglow from GRB 140419A. 

Credit: ROTSE-IIIb, SMU

Known as a gamma-ray burst, the intense light captured in the night sky resulted from one of the biggest and hottest explosions in the universe, occurring shortly after the Big Bang.

Intense light from the enormous explosion of a star more than 12 billion years ago, shortly after the Big Bang, recently reached Earth and was visible in the sky.

Known as a gamma-ray burst, light from the rare, high-energy explosion traveled for 12.1 billion years before it was detected and observed by a telescope owned by Southern Methodist University, Dallas.


Gamma-ray bursts (GRBs) are believed to be the catastrophic collapse of a star at the end of its life. SMU physicists report that their telescope was the first on the ground to observe the burst and to capture an image, said Farley Ferrante, a graduate student in SMU's Department of Physics, who monitored the observations along with two astronomers in Turkey and Hawaii.

Recorded as GRB 140419A by NASA's Gamma-ray Coordinates Network, the burst was spotted at 11 p.m. April 19 by SMU's robotic telescope, ROTSE-IIIb, at the McDonald Observatory in the Davis Mountains of West Texas.

Gamma-ray bursts (GRBs) are not well understood by astronomers, but they are considered important, Ferrante said.

"As NASA points out, gamma-ray bursts are the most powerful explosions in the universe since the Big Bang," he said. "These bursts release more energy in 10 seconds than our Earth's sun during its entire expected lifespan of 10 billion years."

Some of these gamma-ray bursts appear to be related to supernovae, and correspond to the end-of-life of a massive star, said Robert Kehoe, physics professor and leader of the SMU astronomy team.

"Gamma-ray bursts (GRBs) may be particularly massive cousins to supernovae, or may correspond to cases in which the explosion ejecta are more beamed in our direction. By studying them, we learn about supernovae," Kehoe said.

Scientists weren't able to detect optical light from gamma-ray bursts until the late 1990s, when telescope technology improved.

Among all lights in the electromagnetic spectrum, gamma rays have the shortest wavelengths and are visible only using special detectors.

SMU's ROTSE-IIIb at the McDonald Observatory, Fort Davis, Texas had the earliest and brightest observation from the ground of a gamma-ray burst that occurred more than 12 billion years ago. 

The telescope is part of the Robotic Optical Transient Search Experiment, which has telescopes in four locations on Earth to cover the entire sky in search of gamma-ray bursts. 

Credit: ROTSE Collaboration.

Gamma-ray bursts (GRBs) result from hot stars that measure as enormous as 50 solar masses. The explosion occurs when the stars run out of fuel and collapse in on themselves, forming black holes.

Outer layers detonate, shooting out material along the rotation axis in powerful, high-energy jets that include gamma radiation.

As the gamma radiation declines, the explosion produces an afterglow of visible optical light. The light, in turn, fades very quickly, said Kehoe.

Physicists calculate the distance of the explosion based on the shifting wavelength of the light, or redshift.

"The optical light is visible for anywhere from a few seconds to a few hours," Kehoe said. "Sometimes optical telescopes can capture the spectra."

"This allows us to calculate the redshift of the light, which tells us how fast the light is moving away from us. This is an indirect indication of the distance from us."

CFA Astronomers find a new type of planet: The 'mega-Earth'

The newly discovered 'mega-Earth' Kepler-10c dominates the foreground in this artist's conception. 

Its sibling, the lava world Kepler-10b, is in the background. 

Both orbit a sunlike star. Kepler-10c has a diameter of about 18,000 miles, 2.3 times as large as Earth, and weighs 17 times as much. 

Therefore it is all solids, although it may possess a thin atmosphere shown here as wispy clouds. 

Credit: David A. Aguilar (CfA)

Astronomers announced today that they have discovered a new type of planet - a rocky world weighing 17 times as much as Earth.

Theorists believed such a world couldn't form because anything so hefty would grab hydrogen gas as it grew and become a Jupiter-like gas giant.

This planet, though, is all solids and much bigger than previously discovered "super-Earths," making it a "mega-Earth."

"We were very surprised when we realized what we had found," says astronomer Xavier Dumusque of the Harvard-Smithsonian Center for Astrophysics (CfA), who led the data analysis and made the discovery.

"This is the Godzilla of Earths!" adds CfA researcher Dimitar Sasselov, director of the Harvard Origins of Life Initiative. "But unlike the movie monster, Kepler-10c has positive implications for life."

The team's finding was presented today in a press conference at a meeting of the American Astronomical Society (AAS).

The newfound mega-Earth, Kepler-10c, circles a sunlike star once every 45 days. It is located about 560 light-years from Earth in the constellation Draco. The system also hosts a 3-Earth-mass "lava world," Kepler-10b, in a remarkably fast, 20-hour orbit.

Kepler-10c was originally spotted by NASA's Kepler spacecraft. Kepler finds planets using the transit method, looking for a star that dims when a planet passes in front of it.

By measuring the amount of dimming, astronomers can calculate the planet's physical size or diameter. However, Kepler can't tell whether a planet is rocky or gassy.

Kepler-10c was known to have a diameter of about 18,000 miles, 2.3 times as large as Earth. This suggested it fell into a category of planets known as mini-Neptunes, which have thick, gaseous envelopes.

The team used the HARPS-North instrument on the Telescopio Nazionale Galileo (TNG) in the Canary Islands to measure the mass of Kepler-10c.

They found that it weighed 17 times as much as Earth - far more than expected. This showed that Kepler-10c must have a dense composition of rocks and other solids.

"Kepler-10c didn't lose its atmosphere over time. It's massive enough to have held onto one if it ever had it," explains Dumusque. "It must have formed the way we see it now."

Planet formation theories have a difficult time explaining how such a large, rocky world could develop. However, a new observational study suggests that it is not alone.

Also presenting at AAS, CfA astronomer Lars A. Buchhave found a correlation between the period of a planet (how long it takes to orbit its star) and the size at which a planet transitions from rocky to gaseous.

This suggests that more mega-Earths will be found as planet hunters extend their data to longer-period orbits.

The discovery that Kepler-10c is a mega-Earth also has profound implications for the history of the universe and the possibility of life.

The Kepler-10 system is about 11 billion years old, which means it formed less than 3 billion years after the Big Bang.

"Finding Kepler-10c tells us that rocky planets could form much earlier than we thought. And if you can make rocks, you can make life," says Sasselov.

Astronomers identify signature of Earth-eating stars

What if we could determine if a given star is likely to host a planetary system like our own by breaking down its light into a single high-resolution spectrum and analyzing it? 

A spectrum taken of the Sun is shown above. 

The dark bands result from specific chemical elements in the star’s outer layer, like hydrogen or iron, absorbing specific frequencies of light. 

By carefully measuring the width of each dark band, astronomers can determine just how much hydrogen, iron, calcium and other elements are present in a distant star. 

The new model suggests that a G-class star with levels of refractory elements like aluminum, silicon and iron significantly higher than those in the Sun may not have any Earth-like planets because it has swallowed them. 

Credit: N.A.Sharp, NOAO /NSO /Kitt Peak FTS /AURA /NSF

Some Sun-like stars are 'Earth-eaters.' During their development they ingest large amounts of the rocky material from which 'terrestrial' planets like Earth, Mars and Venus are made.

Trey Mack, a graduate student in astronomy at Vanderbilt University, has developed a model that estimates the effect that such a diet has on a star's chemical composition and has used it to analyze a pair of twin stars that both have their own planets.

The results of the study were published online May 7 in the Astrophysical Journal.

"Trey has shown that we can actually model the chemical signature of a star in detail, element by element, and determine how that signature is changed by the ingestion of Earth-like planets," said Vanderbilt Professor of Astronomy Keivan Stassun, who supervised the study.

"We can actually see the signature predicted by our model, in detail, element by element."

This ability will add substantially to astronomers' understanding of the process of planet formation as well as assist in the ongoing search for Earth-like exoplanets, according to the astronomers.

First, some background: Stars consist of more than 98 percent hydrogen and helium. All the other elements make up less than 2 percent of their mass.

Astronomers have arbitrarily defined all the elements heavier than hydrogen and helium as metals and have coined the term "metallicity" to refer to the ratio of the relative abundance of iron to hydrogen in a star's chemical makeup.


Since the mid-1990's, when astronomers developed the capability to detect extrasolar planets in large numbers, there have been several studies that attempt to link star metallicity with planet formation.

In one such study, researchers at Los Alamos National Laboratory argued that stars with high metallicity are more likely to develop planetary systems than those with low metallicity.

Another study concluded that hot Jupiter-sized planets are found predominantly circling stars with high metallicity while smaller planets are found circling stars with a wide range of metal content.

Building on the work of coauthor Simon Schuler of the University of Tampa, Mack took this type of analysis a step further by looking at the abundance of 15 specific elements relative to that of the Sun.

He was particularly interested in elements like aluminum, silicon, calcium and iron that have melting points higher than 1,200 degrees Fahrenheit (600 degrees Celsius) because these are the refractory materials that serve as building blocks for Earth-like planets.

More information: Paper: iopscience.iop.org/0004-637X/787/2/98/ On Arxiv: arxiv.org/abs/1404.1967

ILLUSTRIS: Astronomers create first realistic virtual universe

Move over, Matrix - astronomers have done you one better. They have created the first realistic virtual universe using a computer simulation called "Illustris."

Illustris can recreate 13 billion years of cosmic evolution in a cube 350 million light-years on a side with unprecedented resolution.

Mark Vogelsberger

"Until now, no single simulation was able to reproduce the universe on both large and small scales simultaneously," says lead author Mark Vogelsberger (MIT/Harvard-Smithsonian Center for Astrophysics), who conducted the work in collaboration with researchers at several institutions, including the Heidelberg Institute for Theoretical Studies in Germany.

These results are being reported in the May 8th issue of the journal Nature.

Previous attempts to simulate the universe were hampered by lack of computing power and the complexities of the underlying physics.

As a result those programs either were limited in resolution, or forced to focus on a small portion of the universe.

Earlier simulations also had trouble modeling complex feedback from star formation, supernova explosions, and supermassive black holes.

Illustris employs a sophisticated computer program to recreate the evolution of the universe in high fidelity. It includes both normal matter and dark matter using 12 billion 3-D "pixels," or resolution elements.

Large scale projection through the Illustris volume at z=0, centered on the most massive cluster, 15 Mpc/h deep. 

Shows dark matter density (left) transitioning to gas density (right). 

Credit: Illustris Collaboration

The team dedicated five years to developing the Illustris program.

The actual calculations took 3 months of "run time," using a total of 8,000 CPUs running in parallel.

If they had used an average desktop computer, the calculations would have taken more than 2,000 years to complete.

The computer simulation began a mere 12 million years after the Big Bang. When it reached the present day, astronomers counted more than 41,000 galaxies in the cube of simulated space.

Importantly, Illustris yielded a realistic mix of spiral galaxies like the Milky Way and football-shaped elliptical galaxies.

It also recreated large-scale structures like galaxy clusters and the bubbles and voids of the cosmic web. On the small scale, it accurately recreated the chemistries of individual galaxies.

Large scale projection through the Illustris volume at z=0, centered on the most massive cluster, 15 Mpc/h deep. 

Shows dark matter density overlaid with the gas velocity field. 

Credit: Illustris Collaboration

Since light travels at a fixed speed, the farther away astronomers look, the farther back in time they can see.

A galaxy one billion light-years away is seen as it was a billion years ago.

Telescopes like Hubble can give us views of the early universe by looking to greater distances.

However, astronomers can't use Hubble to follow the evolution of a single galaxy over time.

"Illustris is like a time machine. We can go forward and backward in time. We can pause the simulation and zoom into a single galaxy or galaxy cluster to see what's really going on," says co-author Shy Genel of the CfA.

The team is releasing a high-definition video, which morphs between different components of the simulation to highlight various layers (e.g. dark matter density, gas temperature, or chemistry).

They also are releasing several smaller videos and associated imagery online

More information: Paper: dx.doi.org/10.1038/nature13316

CAASTRO Astronomers Make precise measurement of neutron star

The densely packed matter of a pulsar spins at incredible speeds, and emits radio waves that can be observed from Earth, but how neutron stars emit these waves is still a mystery. 

Credit: Swinburne Astronomy Productions /CAASTRO.

An international team of astronomers has made a measurement of a distant neutron star that is one million times more precise than the previous world's best.

The researchers were able to use the interstellar medium (ISM), the 'empty' space between stars and galaxies that is made up of sparsely spread charged particles, as a giant lens to magnify and look closely at the radio wave emission from a small rotating neutron star.

This technique yielded the highest resolution measurement ever achieved, equivalent to being able to see the double-helix structure of our genes from the Moon!

"Compared to other objects in space, neutron stars are tiny – only tens of kilometres in diameter – so we need extremely high resolution to observe them and understand their physics," Dr Jean-Pierre Macquart from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) in Perth, Australia, said.

Dr Macquart, a member of the ARC Centre of Excellence for All-sky Astrophysics (CAASTRO), said neutron stars were particularly interesting objects to study, as some of them – called pulsars – gave off pulsed radio waves whose beams swept across telescopes at regular intervals.

"More than 45 years since astronomers discovered pulsars, we still don't understand the mechanism by which they emit radio wave pulses," he said.



A spinning neutron star emitting a stream of radio waves that appear as regular pulses when observed from Earth. Simulation credit to Swinburne Astronomy Productions /CAASTRO.

The researchers found they could use the distortions of these pulse signals as they passed through the turbulent interstellar medium (ISM) to reconstruct a close in view of the pulsar from thousands of individual sub-images of the pulsar.

"The best we could previously do was pointing a large number of radio telescopes across the world at the same pulsar, using the distance between the telescopes on Earth to get good resolution," Dr Macquart said.

The previous record using combined views from many telescopes was an angular resolution of 50 microarcseconds, but the team - led by Professor Ue-Li Pen of the Canadian Institute of Theoretical Astrophysics and a CAASTRO Partner Investigator, has now proven their 'interstellar lens' can get down to 50 picoarcseconds, or a million times more detail, resolving areas of less than 5km in the emission region.

"Our new method can take this technology to the next level and finally get to the bottom of some hotly debated theories about pulsar emission," Professor Pen said.

This new technique also opens up the possibilities for precise distance measurements to pulsars that orbit a companion star and 'image' their extremely small orbits, which is ultimately a new and highly sensitive test of Einstein's theory of General Relativity," Professor Pen said.

More information: Ue-Li Pen, Jean-Pierre Macquart, Adam T. Deller, and Walter Brisken. "50 picoarcsec astrometry of pulsar emission." MNRAS (May 01, 2014) Vol. 440 L36-L40 first published online February 14, 2014. DOI: 10.1093/mnrasl/slu010 . 

Also available on arXiv: http://adsabs.harvard.edu/abs/2014MNRAS.440L..36P

Exoplanet Astronomers: 'Tilt-a-worlds' could harbour life

Tilted orbits such as those shown might make some planets wobble like a top that’s almost done spinning, an effect that could maintain liquid water on the surface, thus giving life a chance. 

Credit: NASA

A fluctuating tilt in a planet's orbit does not preclude the possibility of life, according to new research by astronomers at the University of Washington, Utah's Weber State University and NASA. In fact, sometimes it helps.

That's because such "tilt-a-worlds," as astronomers sometimes call them, turned from their orbital plane by the influence of companion planets, are less likely than fixed-spin planets to freeze over, as heat from their host star is more evenly distributed.

This happens only at the outer edge of a star's habitable zone, the swath of space around it where rocky worlds could maintain liquid water at their surface, a necessary condition for life.

Further out, a "snowball state" of global ice becomes inevitable, and life impossible.

The findings, which are published online and will appear in the April issue of Astrobiology, have the effect of expanding that perceived habitable zone by 10 to 20 percent.

And that in turn dramatically increases the number of worlds considered potentially right for life.

Such a tilt-a-world becomes potentially habitable because its spin would cause poles to occasionally point toward the host star, causing ice caps to quickly melt.

Rory Barnes

"Without this sort of 'home base' for ice, global glaciation is more difficult," said UW astronomer Rory Barnes.

"So the rapid tilting of an exoplanet actually increases the likelihood that there might be liquid water on a planet's surface."

John Armstrong

Barnes is second author on the paper. First author is John Armstrong of Weber State, who earned his doctorate at the UW.

Earth and its neighbour planets occupy roughly the same plane in space. But there is evidence, Barnes said, of systems whose planets ride along at angles to each other.

As such, "they can tug on each other from above or below, changing their poles' direction compared to the host star."

The team used computer simulations to reproduce such off-kilter planetary alignments, wondering, he said, "what an Earthlike planet might do if it had similar neighbours."

Their findings also argue against the long-held view among astronomers and astrobiologists that a planet needs the stabilizing influence of a large moon, as Earth has, to have a chance at hosting life.

"We're finding that planets don't have to have a stable tilt to be habitable," Barnes said. Minus the moon, he said, Earth's tilt, now at a fairly stable 23.5 degrees, might increase by 10 degrees or so. Climates might fluctuate, but life would still be possible.

"This study suggests the presence of a large moon might inhibit life, at least at the edge of the habitable zone."

The work was done through the UW's Virtual Planetary Laboratory, an interdisciplinary research group that studies how to determine if exoplanets—those outside the solar system—might have the potential for life.

"The research involved orbital dynamics, planetary dynamics and climate studies. It's bigger than any of those disciplines on their own," Barnes said.

Armstrong said that expanding the habitable zone might almost double the number of potentially habitable planets in the galaxy.

Applying the research and its expanded habitable zone to our own celestial neighborhood for context, he said, "It would give the ability to put Earth, say, past the orbit of Mars and still be habitable at least some of the time, and that's a lot of real estate."

More information: Paper: online.liebertpub.com/doi/abs/10.1089/ast.2013.1129