The Sun and one of physics' biggest unsolved problems

The sun with a coronal hole (the large dark region at the bottom). Credit: NASA

Daniel Wolf Savin and Michael Hahn have been fascinated by the universe since they were boys.

For Savin, a senior research scientist in the Columbia Astrophysics Laboratory, discovering Albert Einstein at age 12 spurred the desire to "learn everything about the universe."

Years later, Hahn, an associate research scientist who grew up 40 miles from Savin's home town in Connecticut, started gazing at the stars as a teenager; he eventually became president of the astronomy club at his alma mater, Carnegie Mellon.

Now the two have made a big leap toward cracking one of the biggest mysteries in astrophysics—why the corona, or plasma surrounding the sun, is so much hotter than the sun's surface.

The coronal heating problem, as it is known, is important because the corona is the source of solar wind, which is responsible for the northern and southern lights and can also disrupt telecommunications and power grids.

"Satellites can be slowly pushed out of their orbits if they're deflected by the solar wind so if we can better understand the cause, we can create better models for space weather," says Savin, referring to conditions beyond the atmosphere.

Scientists have proposed two main theories to explain why the temperature of the gas in the corona, which lies above the solar surface, soars to over 1 million degrees Kelvin even though the surface of the sun is a relatively cool 6,000 degrees. (The center of the sun is 15 million degrees.)

This unexpected phenomenon has puzzled researchers since 1939, when scientists first discovered the temperature difference; it's as if a flame were coming out of an ice cube.

Read the full article here at www.phys.org

HYADES: UCSC new China Huawei astrophysics supercomputer system

The Hyades astrophysics computer system, seen from the front (left) and back (right), is the primary on-campus supercomputer used by astrophysics researchers in the departments of Astronomy and Astrophysics, Earth and Planetary Sciences, and Physics, as well as by computer scientists in the Baskin School of Engineering. 

Photo by P. Madau

State-of-the-art computer systems have been instrumental in making UC Santa Cruz one of the world's leading centers for computational astrophysics and planetary science.

A new supercomputer recently installed on campus provides an order of magnitude improvement in the ability of researchers to address fundamental questions in cosmology and astrophysics.

Its value is further enhanced by a high-capacity data storage system for archiving and sharing the results of astrophysical simulations.

The powerful new "Hyades" supercomputer will be used by UCSC researchers to simulate phenomena such as exploding stars, black holes, magnetic fields, planet formation, the evolution of galaxies, and how structure emerged in the cosmos after the big bang.

The $1.5 million machine was funded by a National Science Foundation (NSF) Major Research Instrumentation grant of $910,000, augmented by campus contributions and favorable deals from vendors such as Dell and Intel.

Paired with the supercomputer is a Huawei Universal Distributed Storage (UDS) system that provides one petabyte of high-performance storage capacity.

The Huawei UDS cloud storage system, on loan to the Center for Research in Storage Systems (CRSS) at the Baskin School of Engineering, is expected to become one of the largest repositories of astrophysical data outside of national facilities.



Shawfeng Dong, scientist and computing cluster administrator for the Department of Astronomy and Astrophysics, oversaw the installation and integration of the Hyades supercomputer and Huawei storage system.

Piero Madau

Piero Madau, professor of astronomy and astrophysics and principal investigator on the NSF grant, said, "Hyades is more than ten times better than our previous machine, and with the Huawei system providing storage for our simulation results, we can maximize the value of those results by making them available to the astrophysics community."

Joel Primack, professor of physics at UCSC and director of the UC High-Performance Astro Computing Center (UC-HiPACC), explained that supercomputer simulations can generate such huge amounts of complex data that it becomes difficult to analyze them on the fly.

An enormous amount of storage capacity is needed for the output of these simulations so that the results can be studied and shared with other researchers.

Joel Primack

"The Huawei system will be used to store our astrophysics results, not only from Hyades but also from simulations that we run at the big national supercomputing facilities, such as at NASA Ames or Oak Ridge National Laboratory," Primack said.

"Those facilities can only store the results for a limited time, and they also restrict access to them. Now, with the Huawei storage system, we can put our results on a local server."

The Theoretical Astrophysics at Santa Cruz (TASC) computational astrophysics group includes about 20 faculty and at least 50 postdoctoral researchers and graduate students in four departments: Applied Math and Statistics, Astronomy and Astrophysics, Earth and Planetary Sciences, and Physics.

In addition, computer scientists at the CRSS will be studying the performance of the new Huawei UDS system. Huawei is among the industry sponsors of CRSS, an Industry/University Cooperative Research Center supported by NSF.

Andy Hospodor

"We're interested in how scientists store and use big data in a system like Hyades," said CRSS executive director Andy Hospodor. "We have studied other operating environments and are very interested in learning about astrophysical data.

Our faculty and students will find ways to improve the performance, reliability, and energy efficiency of such large-scale data systems."

Energetic Space Tornadoes hold the key to Solar Mystery

A team of European scientists has discovered super-hot and super-fast tornados on the Sun, which may help answer a number of outstanding questions in the realm of physics.

Writing in the journal Nature, they report that these `magnetic tornadoes reach speeds of up to 10,000 kilometres per hour, completely dwarfing anything found on Earth.

For images and videos visit www.solartornado.info 

In fact the fastest recorded tornado on Earth only reached speeds of approximately 486 km per hour, and was by no means an example of a common occurrence.

These magnetic tornadoes on the Sun, created by rotating magnetic field structures which force plasma to move in spirals, are not only common but may hold the answer to a long-standing physics conundrum: why the surface of the Sun is cooler than its outermost atmospheric layer.

Think of any fire and it is common knowledge (and sense) that the closer one gets to the fire, the hotter it gets.

The Sun however doesn't quite follow this logic. Its central core is an amazing 15,000,000 degrees Celsius and its surface cools to 5,500 degrees Celsius - following the logic that the further away, the cooler it gets.

The Sun cools to a mere 4,300 degrees Celsius to where a layer of the Sun's atmosphere, the photosphere, meets the chromosphere. In the chromosphere, however, things become topsy-turvy.

When the chromosphere begins to merge with the Sun's outermost atmospheric layer, the corona, the temperature rises to 100,000 degrees Celsius and continues to increase to a scorching 2,000,000 degrees Celsius in the part of the corona that is farthest from the Sun.

This, almost accordion-like sequence of heat, has puzzled many scientists. A puzzle which this recent discovery of magnetic tornadoes may have solved.

Professor Robertus Erdélyi, head of the Solar Physics and Space Plasma Research Centre (SP2RC) of the University of Sheffield's School of Mathematics and Statistics explains: 'One of the major problems in modern astrophysics is why the atmosphere of a star, like our own Sun, is considerably hotter than its surface?

Imagine, that you climb a mountain, e.g. a munro in the Scottish highlands, and it becomes hotter as you go higher and higher.

'It is understood that the energy originates from below the Sun's surface, but how this massive amount of energy travels up to the solar atmosphere surrounding it is a mystery.'

'We believe we have found evidence in the form of rotating magnetic structures - solar tornadoes - that channel the necessary energy in the form of magnetic waves to heat the magnetised solar plasma.'

'We report here the discovery of ubiquitous magnetic solar tornadoes and their signature in the hottest areas of the Sun's atmosphere where the temperature is a few millions of degree kelvin, about thousands of kilometres from the Sun's surface. This is a major step in the field.'

It is estimated that there are as many as 11,000 of these magnetic tornadoes above the Sun's surface at any time, and each one more than 1,600 km wide. Despite their number and size, they have never been seen until now.

Read the full article at EU CORDIS

Read more info on Space Tornadoes here at Institute of Theoretical Physics, University Oslo

Harvard Astronomer Pays Tribute to Van Gogh with Hubble Mosaic

One night, Harvard astronomer Alex Parker was camped out at the telescope for a spot of star-gazing, and found himself facing a long, dry period of waiting for the clouds to clear.

To pass the time, he started playing around with various images from the Hubble Space Telescope, and ended up assembling them into a colorful mosaic.

The resulting image? A recreation of Vincent van Gogh's most famous painting, "Starry Night".

Alex Parker, a postdoctoral fellow at the Harvard-Smithsonian Center for Astrophysics’ Institute for Theory and Computation, has created several astronomical videos on his own time and posted them on the Internet. 

His latest video depicts the 2,299 planet candidates Kepler has found since it began searching for planets around stars in 2009. 

According to sources "Parker used photo-mosaicing software to assemble the digital collage."

He had been thinking about using Hubble images to make a mosaic for awhile, since the telescope's 22nd anniversary was approaching; he just needed the right circumstances to find the time -- a cloudy night.

"Observing can be all over the map," Parker reported about his artistic endeavour. "You will be shut out by clouds on some nights, have to evacuate the mountain because of high winds and ice on other nights, and other times there isn't a moment to pause because you're taking data at such a high rate all night."

NASA Chandra Image: A Surprisingly Bright Superbubble

Credits: X-ray: NASA/CXC/U.Mich./S.Oey, IR: NASA/JPL, Optical: ESO/WFI/2.2-m

This composite image shows a superbubble in the Large Magellanic Cloud (LMC), a small satellite galaxy of the Milky Way located about 160,000 light years from Earth.

Many new stars, some of them very massive, are forming in the star cluster NGC 1929, which is embedded in the nebula N44, so named because it is the 44th nebula in a catalogue of such objects in the Magellanic Clouds.

The massive stars produce intense radiation, expel matter at high speeds, and race through their evolution to explode as supernovas.

The winds and supernova shock waves carve out huge cavities called superbubbles in the surrounding gas. X-rays from NASA's Chandra X-ray Observatory (blue) show hot regions created by these winds and shocks, while infrared data from NASA's Spitzer Space Telescope (red) outline where the dust and cooler gas are found.

The optical light from the 2.2-m Max-Planck-ESO telescope (yellow) in Chile shows where ultraviolet radiation from hot, young stars is causing gas in the nebula to glow.

A long-running problem in high-energy astrophysics has been that some superbubbles in the LMC, including N44, give off a lot more X-rays than expected from models of their structure.

These models assume that hot, X-ray emitting gas has been produced by winds from massive stars and the remains of several supernovas.

A Chandra study published in 2011 showed that there are two extra sources of N44's X-ray emission not included in these models: supernova shock waves striking the walls of the cavities, and hot material evaporating from the cavity walls.

The Chandra observations also show no evidence for an enhancement of elements heavier than hydrogen and helium in the cavities, thus ruling out this possibility as a third explanation for the bright X-ray emission.

Only with long observations making full use of the capabilities of Chandra has it now become possible to distinguish between different sources of the X-rays produced by superbubbles.

Hobby-Eberley Telescope Discovery: First evidence planet's destruction by its star

The first evidence of a planet's destruction by its aging star has been discovered with the Hobby-Eberly Telescope by an international team of astronomers. 

A similar fate may await the inner planets in our solar system, when the sun becomes a red giant and expands all the way out to Earth's orbit some five-billion years from now. 

Credit: Marty Harris/McDonald Obs./UT-Austin 

The first evidence of a planet's destruction by its aging star has been discovered by an international team of astronomers.

The evidence indicates that the missing planet was devoured as the star began expanding into a "red giant" -- the stellar equivalent of advanced age.

"A similar fate may await the inner planets in our solar system, when the Sun becomes a red giant and expands all the way out to Earth's orbit some five-billion years from now," said Alexander Wolszczan, Evan Pugh Professor of Astronomy and Astrophysics at Penn State University, who is one of the members of the research team.

Wolszczan also is the discoverer of the first planet ever found outside our solar system. The astronomers also discovered a massive planet in a surprisingly elliptical orbit around the same red-giant star, named BD+48 740, which is older than the Sun with a radius about eleven times bigger.

Wolszczan and the team's other members detected evidence of the missing planet's destruction while they were using the Hobby-Eberly Telescope to study the aging star and to search for planets around it.

The evidence includes the star's peculiar chemical composition, plus the highly unusual elliptical orbit of its surviving planet.

"Our detailed spectroscopic analysis reveals that this red-giant star, BD+48 740, contains an abnormally high amount of lithium, a rare element created primarily during the Big Bang 14 billion years ago," Adamow said.

Lithium is easily destroyed in stars, which is why its abnormally high abundance in this older star is so unusual.

"Theorists have identified only a few, very specific circumstances, other than the Big Bang, under which lithium can be created in stars," Wolszczan added.

"In the case of BD+48 740, it is probable that the lithium production was triggered by a mass the size of a planet that spiraled into the star and heated it up while the star was digesting it."

The second piece of evidence discovered by the astronomers is the highly elliptical orbit of the star's newly discovered massive planet, which is at least 1.6 times as massive as Jupiter.

"We discovered that this planet revolves around the star in an orbit that is only slightly wider than that of Mars at its narrowest point, but is much more extended at its farthest point," Niedzielski said.

"Such orbits are uncommon in planetary systems around evolved stars and, in fact, the BD+48 740 planet's orbit is the most elliptical one detected so far."

Because gravitational interactions between planets are responsible for such peculiar orbits, the astronomers suspect that the dive of the missing planet toward the star before it became a giant could have given the surviving massive planet a burst of energy, throwing it into an eccentric orbit like a boomerang.

"Catching a planet in the act of being devoured by a star is an almost improbable feat to accomplish because of the comparative swiftness of the process, but the occurrence of such a collision can be deduced from the way it affects the stellar chemistry," Villaver explained.

"The highly elongated orbit of the massive planet we discovered around this lithium-polluted red-giant star is exactly the kind of evidence that would point to the star's recent destruction of its now-missing planet."

The paper describing this discovery is posted in an early online edition of the Astrophysical Journal Letters (Adamow et al. 2012, ApJ, 754, L15).


Read the paper here Astrophysical Journal

NASA Mars HiRISE Image: Gully Monitoring on Crater Slopes in Terra Sirenum

These crater gullies lie on the northern wall of an unnamed 9-kilometer diameter southern hemisphere crater in Terra Sirenum. The image was acquired during early winter in the southern hemisphere, so the crater wall is in shadow.

These gullies were first imaged by HiRISE in 2006. Since that time the possible role of seasonal frost in gully formation along with the association of polygonal terrain with these and other gullies has garnered considerable interest.

As a result, these gullies have become one of several locations being monitored by HiRISE throughout multiple Mars years. Over a dozen images of these gullies have been acquired to date throughout different Mars seasons.

In this image, frost (likely water-ice) is once again forming on these southern hemisphere mid-latitude crater slopes.  

The subimage shows gullies on the shadowed polar-facing slope. The large dynamic range of the HiRISE camera allows one to see into the shadows dimly lit by sunlight scattered by the surface and the atmosphere.

These gullies are thinly veiled with frost and range in width from several meters to tens of meters and in length from a couple kilometers or so. Dark regions within the gullies are warmer areas where frost likely evaporated or melted exposing the darker underlying surface.

Dark matter, scaffolding of universe detected for the first time

A filament of dark matter has been directly detected between the galaxy clusters Abell 222 and Abell 223. 

The blue shading and yellow contour lines represent the density of matter. Image credit: Jorg Dietrich, U-M Department of Physics

Scientists have, for the first time, directly detected part of the invisible dark matter skeleton of the universe, where more than half of all matter is believed to reside.

The discovery, led by a University of Michigan physics researcher, confirms a key prediction in the prevailing theory of how the universe's current web-like structure evolved.

The map of the known universe shows that most galaxies are organized into clusters, but some galaxies are situated along filaments that connect the clusters.

Cosmologists have theorized that dark matter undergirds those filaments, which serve as highways of sorts, guiding galaxies toward the gravitational pull of the massive clusters.

Dark matter's contribution had been predicted with computer simulations, and its shape had been roughed out based on the distribution of the galaxies. But no one had directly detected it until now.

"We found the dark matter filaments. For the first time, we can see them," said Jorg Dietrich, a physics research fellow in the University of Michigan College of Literature, Science and the Arts.

Dietrich is first author of a paper on the findings published online in Nature and to appear in the July 12 print edition.

Dark matter, whose composition is still a mystery, doesn't emit or absorb light, so astronomers can't see it directly with telescopes. They deduce that it exists based on how its gravity affects visible matter.

Scientists estimate that dark matter makes up more than 80 percent of the universe. To "see" the dark matter component of the filament that connects the clusters Abell 222 and 223, Dietrich and his colleagues took advantage of a phenomenon called gravitational lensing.

The gravity of massive objects such as galaxy clusters acts as a lens to bend and distort the light from more distant objects as it passes. Dietrich's team observed tens of thousands of galaxies beyond the supercluster.

They were able to determine the extent to which the supercluster distorted galaxies, and with that information, they could plot the gravitational field and the mass of the Abell 222 and 223 clusters. Seeing this for the first time was "exhilarating," Dietrich said.

"It looks like there's a bridge that shows that there is additional mass beyond what the clusters contain," he said. "The clusters alone cannot explain this additional mass," he said.

Scientists before Dietrich assumed that the gravitational lensing signal would not be strong enough to give away dark matter's configuration. But Dietrich and his colleagues focused on a peculiar cluster system whose axis is oriented toward Earth, so that the lensing effects could be magnified.

"This result is a verification that for many years was thought to be impossible," Dietrich said.

The team also found a spike in X-ray emissions along the filament, due to an excess of hot, ionized ordinary matter being pulled by gravity toward the massive filament, but they estimate that 90 percent or more of the filament's mass is dark matter.

The researchers used data obtained with the Subaru telescope, operated by the National Astronomical Observatory of Japan. They also used the XMM-Newton satellite for X-ray observations.

This work is funded by the National Science Foundation and NASA. Other contributors are from the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University; Ohio University; Max Planck Institut fur extraterrestrische Physik in Germany; The University of Edinburgh and the University of Oxford.

Images from NASA's Wide-field Infrared Survey Explorer (WISE) reveal an old star in the throes of a fiery outburst, spraying the cosmos with dust.

The findings offer a rare, real-time look at the process by which stars like our sun seed the universe with building blocks for other stars, planets and even life.

 The star, catalogued as WISE J180956.27-330500.2, was discovered in images taken during the WISE survey in 2010, the most detailed infrared survey to date of the entire celestial sky.

It stood out from other objects because it glowed brightly with infrared light. When compared to images taken more than 20 years ago, astronomers found the star was 100 times brighter.

"We were not searching specifically for this phenomenon, but because WISE scanned the whole sky, we can find such unique objects," said Poshak Gandhi of the Japan Aerospace Exploration Agency (JAXA), lead author of a new paper to be published in the Astrophysical Journal Letters.

Results indicate the star recently exploded with copious amounts of fresh dust, equivalent in mass to our planet Earth. The star is heating the dust and causing it to glow with infrared light.

"Observing this period of explosive change while it is actually ongoing is very rare," said co-author Issei Yamamura of JAXA.

"These dust eruptions probably occur only once every 10,000 years in the lives of old stars, and they are thought to last less than a few hundred years each time. It's the blink of an eye in cosmological terms."

The aging star is in the "red giant" phase of its life. Our own sun will expand into a red giant in about 5 billion years.

When a star begins to run out of fuel, it cools and expands. As the star puffs up, it sheds layers of gas that cool and congeal into tiny dust particles.

This is one of the main ways dust is recycled in our universe, making its way from older stars to newborn solar systems.

The other way, in which the heaviest of elements are made, is through the deathly explosions, or supernovae, of the most massive stars.

"It's an intriguing glimpse into the cosmic recycling program," said Bill Danchi, WISE program scientist at NASA Headquarters in Washington. "Evolved stars, which this one appears to be, contribute about 50 percent of the particles that make up humans."

The Trouble With Neutrinos That Outpaced Einstein’s Theory

The British astrophysicist Arthur S. Eddington once wrote, “No experiment should be believed until it has been confirmed by theory.”

So when a group of physicists going by the acronym Opera announced in September that a batch of the strange subatomic particles known as neutrinos had traveled faster than the speed of light in a 457-mile trip through the earth, the first response among many physicists was to wonder what had gone wrong with the experiment. 

After all, Albert Einstein’s theory of relativity, which proclaimed the speed of light as the cosmic speed limit, is the foundation of modern science and has been shown to work to exquisite precision zillions of times. 

Knock it down and you potentially open the door to all kinds of things, like the ability to go back in time and kill your grandfather.

That, of course, did not stop the rest of us in the physics bleachers from dragging the old guru of space-time by his frizzy coronal hair into the media version of the public square and crowing that, perhaps this time at last, Einstein was finally going to be proved wrong. 

Neutrino jokes proliferated on the Internet, as well as this rousing song by the Corrigan Brothers and Pete Creighton: 

Tooraloo, tooraloo, tooraloo, tooralino,

Is light now slower than a neutrino?

Now it seems that Einstein’s six-month nightmare may be over.

Last week another team of physicists whose apparatus lives right next door to the Opera group — under Gran Sasso mountain in Italy — reported that they had clocked neutrinos, produced in an accelerator at CERN, outside Geneva, racing over the same path to Gran Sasso at the speed of light and not a whit faster. 

Which is exactly how fast scientists had always thought the enigmatic particles, with barely zilch for mass, should go.

The second group, which goes by the acronym Icarus, was led by Carlo Rubbia, a former director of CERN and a Nobel-winning physicist, who called the results “very convincing.”

Physicists swung into line with great sighs of relief.

“The evidence is beginning to point toward the Opera result being an artifact of the measurement,” said CERN’s research director, Sergio Bertolucci.

Cue the famous picture of Einstein sticking out his tongue. As it happened, the Icarus result was announced on March 16, two days after his 133rd birthday — almost in time for the cake.

Adding to the sense of finality was the simple fact — as Eddington might have pointed out — that faster-than-light neutrinos had never been confirmed by theory. Or as John G. Learned, a neutrino physicist at the University of Hawaii, put it in an e-mail, “An interesting result of all this fracas is that no new model I have seen (or heard of from my friends) really is credible to explain the faster-than-light neutrinos.”

During a panel discussion recently at the American Museum of Natural History, Sheldon L. Glashow, a physics professor and Nobel laureate from Boston University, said the best theory he had heard was that the neutrinos had behaved lawfully in Switzerland and speeded up when they crossed the border into Italy.

Eddington’s dictum is not as radical as it might sound. He made it after early measurements of the rate of expansion of the universe made it appear that our planet was older than the cosmos in which it resides — an untenable notion.

“It means that science is not just a book of facts, it is understanding as well,” explained Michael S. Turner, a cosmologist at the University of Chicago, who says the Eddington saying is one of his favourites. 

If a “fact” cannot be understood, fitted into a conceptual framework that we have reason to believe in, or confirmed independently some other way, it risks becoming what journalists like to call a “permanent exclusive” wrong. 

Read more of this article: The Trouble With Neutrinos - NYTimes.com

Astronomers put forward new theory on size of black holes

Astronomers have put forward a new theory about why black holes become so hugely massive – claiming some of them have no 'table manners', and tip their 'food' directly into their mouths, eating more than one course simultaneously.

Researchers from the UK and Australia investigated how some black holes grow so fast that they are billions of times heavier than the sun.

The team from the University of Leicester (UK) and Monash University in Australia sought to establish how black holes got so big so fast.

Their research is due to published in the Monthly Notices of the Royal Astronomical Society.

The research was funded by the UK Science and Technology Facilities Council.

Professor Andrew King from the Department of Physics and Astronomy, University of Leicester, said: "Almost every galaxy has an enormously massive black hole in its centre. Our own galaxy, the Milky Way, has one about four million times heavier than the sun. But some galaxies have black holes a thousand times heavier still. We know they grew very quickly after the Big Bang."

"These hugely massive black holes were already full--grown when the universe was very young, less than a tenth of its present age."

Black holes grow by sucking in gas. This forms a disc around the hole and spirals in, but usually so slowly that the holes could not have grown to these huge masses in the entire age of the universe. `We needed a faster mechanism,' says Chris Nixon, also at Leicester, "so we wondered what would happen if gas came in from different directions."

Nixon, King and their colleague Daniel Price in Australia made a computer simulation of two gas discs orbiting a black hole at different angles.

After a short time the discs spread and collide, and large amounts of gas fall into the hole. According to their calculations black holes can grow 1,000 times faster when this happens.

"If two guys ride motorbikes on a Wall of Death and they collide, they lose the centrifugal force holding them to the walls and fall," says King. The same thing happens to the gas in these discs, and it falls in towards the hole.

This may explain how these black holes got so big so fast. "We don't know exactly how gas flows inside galaxies in the early universe," said King, "but I think it is very promising that if the flows are chaotic it is very easy for the black hole to feed."

The two biggest black holes ever discovered are each about ten billion times bigger than the Sun.

The Most Astounding Fact - Astrophysicist Dr Neil De Grasse

Astrophysicist Dr. Neil DeGrasse Tyson was asked in an interview with TIME magazine, “What is the most astounding fact you can share with us about the Universe?”

ESA: Astrophysicist Anthony Marston one of the minds behind ESA Science

Excellence and perseverance - astrophysicist Anthony Marston is one of the brilliant minds behind ESA Science

Fermi telescope: Gamma-ray bursts' highest power side unveiled

Detectable for only a few seconds but possessing enormous energy, gamma-ray bursts are difficult to capture because their energy does not penetrate the Earth's atmosphere.

Now, thanks to an orbiting telescope, astrophysicists are filling in the unknowns surrounding these bursts and uncovering new questions.

The Fermi Gamma-Ray Space Telescope, formerly called the Gamma-Ray Large Area Space Telescope, launched on June 11, 2008. As part of its mission, the telescope records any gamma-ray bursts within its viewing area.

"Fermi is lucky to measure the highest energy portion of the gamma-ray burst emission, which last for hundreds to thousands of seconds -- maybe 20 minutes," said Péter Mészáros, Eberly Chair Professor of Astronomy and Astrophysics and Physics, Penn State.

Most gamma-ray bursts occur when stars that are more than 25 times larger than our sun come to the end of their lives. When the internal nuclear reaction in these stars ends, the star collapses in on itself and forms a black hole. The outer envelope of the star is ejected forming a supernova.

"The black hole is rotating rapidly and as it is swallowing the matter from the star, the rotation ejects a jet of material through the supernova envelope," said Mészáros.

This jet causes the gamma-ray burst, which briefly becomes the brightest thing in the sky. However, unlike supernovas that radiate in all directions, gamma-ray bursts radiate in a very narrow area, and Fermi sees only jets ejecting in its direction.

This, however, is the direction in which they send their highest energy photons. Any gamma-ray bursts on the other side of the black hole or even off at an angle are invisible to the telescope.

"We actually miss about 500 gamma-ray bursts for every one we detect," Mészáros told attendees today at the annual meeting of the American Association for the Advancement of Science in Vancouver, British Columbia.

The gamma-ray bursts that Fermi has seen have allowed astrophysicists to clarify previous theories about gamma-ray bursts.

"We have been able to rule out the simplest version of theories which combine quantum mechanics with gravity, although others remain to be tested," said Mészáros.

Mészáros notes that Fermi and other programs like the SWIFT telescope have shown that gamma-ray bursts last longer than we thought they did and that there are long and short gamma-ray bursts.

Read more about the SWIFT Telescope discovery here

Eta Carinae: Echoes of the Ancient 'Great Eruption' Reach Astronomers

When the binary star system Eta Carinae experienced a spectacular outburst in 1837, dubbed the "Great Eruption," there were no cameras or other sophisticated scientific instruments around to record the event for posterity.

But now, 170 years later, remnants of light from the Great Eruption are finally reaching Earth, providing new insight into how massive stars behave when they are on the brink of exploding.

Astrophysicists at the University of California, Santa Barbara and the Las Cumbres Observatory Global Telescope Network, announced the detection of this "light echo" in a Feb. 16 letter to the journal Nature.

UCSB Postdoc Federica Bianco, who compared the light echo to eyewitness reports from the 1800s, phrased the phenomenon best: "You are at the stadium, watching the game, and your team scores. But you do not have modern instruments, detectors and spectrographs to study it," she said in a press release.

"Now we are getting a replay -- an up-close detailed view of our cosmic eruption," she continued. "And just like with the replay, we get to see the outburst from a different point of view, as the light that we see now was originally traveling in a different direction than the light seen in the 1840s."

Eta Carinae is a rare, massive binary star, and the dominant partner in this cosmic coupling belongs to the class of luminous blue variable stars. When it erupted 170 years ago, it became one of the brightest stars in the sky for a time. So why are we suddenly seeing light from that event again?

The astrophysicists explain that originally, the light traveled away from Earth, and then bounced off dust clouds, which rerouted it to Earth -- just like an echo. The longer path means we are only now seeing that echo.


There might not be photographs, but there are a few historical eyewitness accounts on record to help astrophysicists determine that what they are seeing really is a "light echo" from Eta Carinae's 19th century outburst.

Some young Milky Way stars may be much older

The new analysis shows that stars over a wide range of masses in Upper Scorpius - from slightly more massive than our Sun, up to the mass of the bright star Antares (17 times the mass of our Sun) are giving ages consistent with a mean age of 11 million years.

Low in the south in the summer sky shines the constellation Scorpius and the bright, red supergiant star Antares. Many of the brightest stars in Scorpius, and hundreds of its fainter stars, are among the youngest stars found near the earth, and a new analysis of them may result in a rethinking of both their ages and the ages of other groups of stars.

New research by astrophysicists from the University of Rochester focused on stars in the north part of the constellation, known as Upper Scorpius, which is a part of the Scorpius-Centaurus OB association, one of our best studied groups of young stars and a benchmark sample for investigating the early lives of stars and the evolution of their planet-spawning disks.

The Upper Scorpius stellar group lies roughly 470 light years from Earth.

While those stars have been thought to be just five million years old, the team concludes that those stars are actually more than twice as old, at 11 million years of age. The findings are surprising given Upper Scorpius's status as one of the best-studied samples of young stars in the sky.

The findings by graduate student Mark Pecaut and Assistant Professor Eric Mamajek of Rochester, and Assistant Professor Eric Bubar of Marymount University, were accepted for publication in the Astrophysical Journal.

The scientists came to their conclusions after analyzing hundreds of optical spectra measured with the SMARTS 1.5-meter telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile, as well as reanalyzing previously published data on the stars.

"We combined our new estimates for the temperatures of the stars based on our spectra, with data on the brightnesses and distances to estimate accurate luminosities," said Pecaut. "Then we used state-of-the-art stellar evolution models to determine the ages."

The Scorpius OB association is a loose group of stars. This group contains many hot, extremely luminous OB-type stars. It is the site of recent star formation.

The stars in such groups are mostly not gravitationally bound but are expanding away from some common center, which presumably marks their birthplace. 

A recent study indicates that the Scorpius association has had 20 supernova explosions over the past 11 million years.

While similar methods were used in the past to calculate ages for some of the Upper Scorpius stars, Pecaut says no previous study has determined independent age estimates for members of the group over such a wide range of stellar masses.

The new analysis shows that stars over a wide range of masses in Upper Scorpius - from slightly more massive than our Sun, up to the mass of the bright star Antares (17 times the mass of our Sun) are giving ages consistent with a mean age of 11 million years.

"For one thing, the distances to the stars are now much more accurately known," said Pecaut. "Also, the newer computer models take into account the rotation of the stars and its effect on the mixing on the star's hydrogen - its nuclear fuel source."

"The first criticism that we heard of the work was that our age estimates for the stars more massive than the Sun in Upper Scorpius disagreed drastically with previously published ages for the smaller stars in the group," said Mamajek.

"However, we think the stellar parameters and models are on much firmer footing for the higher mass stars than for the lowest mass stars.

"The computer models of stars have trouble predicting the correct masses of low-mass stars when they are dynamically measureable, as well as the rate at which the low-mass stars consume their lithium through nuclear reactions.

Astromers Discovery: Some Ancient Stars Have Huge Heavy Metal Deposits

A new study revealed that some ancient stars in the outer reaches of the Milky Way were found to have an unusually large amounts of heavy metals like gold, platinum and uranium.

This discovery has puzzled astronomers as it is the younger generations of stars that typically have an abundance of heavy metals, scientists said.

Researchers tried to unravel the mystery by observing these ancient stars for several years using the European Southern Observatory's fleet of telescopes in Chile, training the telescopes on 17 "abnormal" stars in the Milky Way that were found to be rich in the heaviest chemical elements.

"In the outer parts of the Milky Way there are old 'stellar fossils' from our own galaxy's childhood," the study's lead author Terese Hansen, an astrophysicist at the Niels Bohr Institute at the University of Copenhagen.

"These old stars lie in a halo above and below the galaxy's flat disc. In a small percentage - approximately 1-to-2 percent of these primitive stars - you find abnormal quantities of the heaviest elements relative to iron and other 'normal' heavy elements."

According to the researchers, there are two possible theories to explain these discoveries about ancient stars and both are about supernova explosions.

One theory focuses on the formation of the first stars shortly after the universe was created. The universe then was dominated by light elements like hydrogen and helium and the first stars were formed as clouds of these gasses gathered and collapsed under their own gravity.

The hydrogen and helium in the stars then merged together and formed the first heavy elements like carbon, nitrogen and oxygen.

Supernova explosions cause these stars to die, and the newly formed elements are spread as gas clouds into space, which eventually formed into new stars containing heavier elements.

This process have made the newer generations of stars more abundant with heavy elements.

A second theory is that early supernovas disperse these elements in different directions, which eventually formed some of the stars in the Milky Way. This explains how many of the old stars became abnormally rich in heavy elements, the researchers said.

"In the supernova explosion the heavy elements like gold, platinum and uranium are formed and when the jets hit the surrounding gas clouds, they will be enriched with the elements and form stars that are incredibly rich in heavy elements," Hansen said.

The study was published in the Astrophysical Journal Letters.

Stephen Colbert Talks Science with Astrophysicist Neil deGrasse Tyson - YouTube

With a fast-moving mixture of comedy and seriousness, an interview on The Colbert Report is something of an improvisational flying trapeze act.

“Stephen Colbert is an amazingly good interviewer,” writes physicist Sean Carroll, “managing to mix topical jokes and his usual schtick with some really good questions, and more than a bit of real background knowledge.”

Beneath the humor there is a sense that Colbert understands and respects science. The sad thing, writes Carroll, “is that more people are exposed to real scientists doing cutting-edge research by watching Comedy Central than by watching, shall we say, certain channels you might have thought more appropriate venues for such conversations.” But the exposure is all too brief. An interview on The Colbert Report typically lasts only a few minutes.

So it was interesting when Colbert stepped away from his comedic character for a more in-depth conversation with one of his frequent guests, astrophysicist Neil deGrasse Tyson. The interview took place last year at Montclair Kimberley Academy in Montclair, New Jersey.

Earlier this week Tyson uploaded the video to the website of the Hayden Planetarium, where he is director, but the server was overwhelmed by the resulting surge in traffic.

So someone placed the version above on YouTube. It’s an interesting, and witty, one-hour-and-19-minute conversation. For more of Tyson with Colbert, you can watch his appearances on The Colbert Report at the Hayden Planetarium site.

NASA Sky Survey - Cygnus X-1: A Stellar Mass Black Hole

On the left, an optical image from the Digitized Sky Survey shows Cygnus X-1, outlined in a red box.

Cygnus X-1 is located near large active regions of star formation in the Milky Way, as seen in this image that spans some 700 light years across.

An artist's illustration on the right depicts what astronomers think is happening within the Cygnus X-1 system. Cygnus X-1 is a so-called stellar-mass black hole, a class of black holes that comes from the collapse of a massive star.

The black hole pulls material from a massive, blue companion star toward it. This material forms a disk (shown in red and orange) that rotates around the black hole before falling into it or being redirected away from the black hole in the form of powerful jets.

A trio of papers with data from radio, optical and X-ray telescopes, including NASA's Chandra X-ray Observatory, has revealed new details about the birth of this famous black hole that took place millions of years ago.

Using X-ray data from Chandra, the Rossi X-ray Timing Explorer, and the Advanced Satellite for Cosmology and Astrophysics, scientists were able to determine the spin of Cygnus X-1 with unprecedented accuracy, showing that the black hole is spinning at very close to its maximum rate.

Its event horizon -- the point of no return for material falling towards a black hole -- is spinning around more than 800 times a second.

Using optical observations of the companion star and its motion around its unseen companion, the team also made the most precise determination ever for the mass of Cygnus X-1, of 14.8 times the mass of the Sun.

It was likely to have been almost this massive at birth, because of lack of time for it to grow appreciably.

The researchers also announced that they have made the most accurate distance estimate yet of Cygnus X-1 using the National Radio Observatory's Very Long Baseline Array (VLBA).

The new distance is about 6,070 light years from Earth. This accurate distance was a crucial ingredient for making the precise mass and spin determinations.

Credits: X-ray: NASA/CXC; Optical: Digitized Sky Survey

> Read more/access all images

Hobby-Eberly Telescope Finds Three planets - each orbiting its own giant, dying star

Three planets - each orbiting its own giant, dying star - have been discovered by an international research team led by Alex Wolszczan, an Evan Pugh Professor of Astronomy and Astrophysics at Penn State, using the Hobby-Eberly Telescope.

Penn State is a major partner in the design, construciton, and operation of this telescope, which is one of the largest in the world. In 1992, Wolszczan became the first astronomer ever to discover planets outside our solar system. 

Credit: Marty Harris/McDonald Obs./UT-Austin

One of the massive, dying stars has an additional mystery object orbiting it, according to team leader Alex Wolszczan, an Evan Pugh Professor of Astronomy and Astrophysics at Penn State, who, in 1992, became the first astronomer ever to discover planets outside our solar system. 

The new research is expected to shed light on the evolution of planetary systems around dying stars. It also will help astronomers to understand how metal content influences the behavior of dying stars.

 

The research will be published in December in the Astrophysical Journal. The first author of the paper is Sara Gettel, a graduate student from Penn State's Department of Astronomy and Astrophysics, and the paper is co-authored by three graduate students from Poland.

The three newly-discovered planetary systems are more evolved than our own solar system. "Each of the three stars is swelling and has already become a red giant - a dying star that soon will gobble up any planet that happens to be orbiting too close to it," Wolszczan said.

"While we certainly can expect a similar fate for our own Sun, which eventually will become a red giant and possibly will consume our Earth we won't have to worry about it happening for another five-billion years." 

Wolszczan also said that one of the massive, dying stars - BD +48 738 - is accompanied not only by an enormous, Jupiter-like planet, but also by a second, mystery object.

According to the team, this object could be another planet, a low-mass star, or - most interestingly - a brown dwarf, which is a star-like body that is intermediate in mass between the coolest stars and giant planets.

"We will continue to watch this strange object and, in a few more years, we hope to be able to reveal its identity," Wolszczan said.