Saturday, June 18, 2011

Black Hole Devours Star and Hurls Energy Across 3.8 Billion Light Years

Written by Tammy Plotner

What University of Warwick researchers think the star may have looked like at the start of its disruption by a black hole at the center of a galaxy 3.8 billion light years distant resulting in the outburst known as Sw 1644+57. Credit: University of Warwick / Mark A. Garlick

Engaging the Hubble Space Telescope, Swift satellite and the Chandra X-ray Observatory, astronomers at the University of Warwick were quick to pick up a signal from Swift's Burst Alert Telescope on March 28, 2011. In a classic line from Easy Rider, Jack Nicholson says: "It's a UFO beaming back at you." But this time it isn't a UFO, but the death scream of a star being consumed by a black hole. It was just the beginning of a series of x-ray blasts that turned out to be the largest and most luminous event so far recorded in a distant galaxy.

Originating 3.8 billion light years from Earth in the direction of the constellation of Draco, the beam consisting of high energy X-rays and gamma-rays remained brilliant for a period of weeks after the initial event. As more and more material from the doomed star crossed over the event horizon, bright flares erupted signaling its demise. Dr Andrew Levan, lead researcher on the paper from the University of Warwick "Despite the power of this the cataclysmic event we still only happen to see this event because our solar system happened to be looking right down the barrel of this jet of energy".

Dr Levan's findings were published in the Journal Science in a paper entitled "An Extremely Luminous Panchromatic Outburst from the Nucleus of a Distant Galaxy". His findings leave no doubt as to the origin of the event and it has been cataloged as Sw 1644+57. "The only explanation that so far fits the size, intensity, time scale, and level of fluctuation of the observed event, is that a massive black at the very centre of that galaxy has pulled in a large star and ripped it apart by tidal disruption." says Levan. "The spinning black hole then created the two jets one of which pointed straight to Earth."

And straight into our eager eyes...

Original Story Source: Eurekalert.

EPOXI Encounters Energetic Comet Hartley 2

Written by Tammy Plotner

No, EPOXI isn't the name of a new super glue, but an abbreviation for the continuation of Deep Impact. While the original mission to study Comet 9P/Tempel was a huge success, the spacecraft continues to explore objects of opportunity. Its name is derived from Extrasolar Planet Observations and Characterization (EPOCh) and the Deep Impact Extended Investigation (DIXI)... and it's now fulfilling another goal as it swings by Comet Hartley 2. It approached, encounter and departed, sending back 117,000 images and spectral findings - along with some surprising observations.

"From all the imaging we took during approach, we knew the comet was a little skittish even before flyby," said EPOXI Project Manager Tim Larson of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It was moving around the sky like a knuckleball and gave my navigators fits, and these new results show this little comet is downright hyperactive."

What EPOXI found was a "hyperactive comet" - one that didn't react in anticipated ways. From a distance of 431 miles (694 kilometers), the spacecraft watched as water and carbon-dioxide jets erupted from the flying space rock's surface. While this in itself isn't unusual, the fact that it didn't happen uniformly caused scientists to sit up and take notice. Jets occurred at both ends of the comet with the strongest activity centered on the small end. Water vapor ejected from the central portion showed a notable lack of carbon-dioxide and ice, leading investigators to speculate the material was re-deposited from the ends of Hartley 2.

"Hartley 2 is a hyperactive little comet, spewing out more water than most other comets its size,” said Mike A'Hearn, principal investigator of EPOXI from the University of Maryland, College Park. "When warmed by the sun, dry ice -- frozen carbon dioxide -- deep in the comet's body turns to gas jetting off the comet and dragging water ice with it."

Is Hartley 2 unique? No. Scientists are aware of at least a dozen comets that behave similarly, but this is the first we've been able to examine closely via a spacecraft. These odd comets are extremely active for their size and may be driven by carbon dioxide or carbon monoxide. "These could represent a separate class of hyperactive comets," said A'Hearn. "Or they could be a continuum in comet activity extending from Hartley 2-like comets all the way to the much less active, "normal" comets that we are more used to seeing."

What makes this new class of comets so unusual? Just three ingredients: deposits around the inactive center which may have originated at the ends, a tumbling state of rotation and a large end containing ubiquitous inclusions which can span`approximately 165 feet (50 meters) high and 260 feet (80 meters) wide. EXPOXI also picked up another surprise at Hartley 2's smaller end - shiny cublicals reaching 16 stories tall and two to three times more reflective than other average surface materials. But that's not all. For nine days in September, the energetic comet expelled 10 million times more CN gas in its coma - a dramatic and unexpected change called the "CN anomaly". It was analyzed by McFadden and Dennis Bodewits, a former postdoctoral fellow at NASA Goddard who is now at the University of Maryland, and their colleagues. This comet exhaust normally includes a a similar amount of dust, but not in this case.

"We aren't sure why this dramatic change happened," says McFadden. "We know that Hartley 2 gives off considerably more CN gas than comet Tempel 1, which was studied earlier by a probe released by the Deep Impact spacecraft. But we don't know why Hartley 2 has more CN, and we don't know why the amount coming off the comet changed so drastically for a short period of time. We’ve never seen anything like this before."

Until now...

Images and Original Story Source: NASA Mission News.

Sunday, June 12, 2011

Coming Up... June 15th Total Lunar Eclipse LIVE

Written by Tammy Plotner

Don't say we didn't warn you ahead of time! The upcoming total lunar eclipse will happen on June 15, 2011... and it's a rare one. This time the Moon will pass directly through the center of the Earth's shadow cone - an event that hasn't happened in 11 years and won't happen again until 2018. The eclipse visibility path will be over Africa, and Central Asia, visible rising over South America, western Africa, and Europe, and setting over eastern Asia. In western Asia, Australia and the Philippines - visible just before sunrise. But before you just read on to another article because you can't see it from where you live, remember I've got a few tricks up my sleeve...

Thanks to this fantastic magic we call the Internet, all you need to do is tune into our friends around the world! The first of our live eclipse broadcasters will be Coordinating the eclipse project and different activities for this year is Mohan Sanjeevan, a science and science fiction writer from India. Since May 2011, Mohan is the Event & Broadcast Organizer of AstronomyLive covering his country. But Mohan is more than just a coordination, he's also involved in other venues like writing poetry - including science poems (freelance science writing for more than twenty years; writer of nano science and tech articles for Nano Digest a monthly magazine from India), popularization of science and creating awareness on global warming, alternative sources of energy and making the planet a more livable place. Space and astronomy are his natural areas of interest. To top it off, Sanjeevan is also a researcher full of implementable ideas for space and future technologies.

AstronomyLive is the center for LIVE astronomy and you can participate, too! Host your broadcasts of various types here on AstronomyLive. Amateur astronomers, professional astronomers, observatories, astronomy associations and more are all very welcome. The current team consists of Sander Klieverik, Voskuh and Dennis from the Netherlands, LesD from the United States, Mohan Sanjeevan, Aakanksha, Prof. M. Jothi Rajan, Jhon Kennedy, Bhaskar, Abhilasha and Sanyam Kumar Shrivastava from India. All of these great people came together to share the view with you!

And there's more...

A free, live webcast from Bareket Observatory in Israel will feature the total lunar eclipse on June 15, 2011. How do you get there? Simply click on this link for the Bareket Observatory Live Eclipse Broadcast! The hardworking group in Israel invite you to discover the Moon during the eclipse using hands-on eclipse activities. Conduct your own science projects using the live lunar eclipse feed! What a great opportunity for your students, family and friends!

The great folks at Bareket Observatory have expanded tremendously over the years and now they're pleased to announce the launch of the Astro-Edu Network, a free state-of-the-art astronomy education database for teachers, students and the general public. Among the goals of AStro-Edu is increased communication and understanding within the population of the Middle East using astronomy as the catalyst. Astro-Edu net can be translated to more than 60 different languages using the integrated translation module (move your cursor over the flag in the upper left to translate the materials).

So don't sit out the total lunar eclipse on July 15, 2011 - 17.00 - 23.00 UTC (GMT). Be sure to enjoy the event with our friends around the world!

Image - Total lunar eclipse captured January 20-21, 2000. (Courtesy of Mr. Eclipse/Fred Espenak / NASA). Visibility Chart: Public Domain.

Sunday, June 5, 2011

Supernova Discovered in M51 The Whirlpool Galaxy

Written by Tammy Plotner

A new supernova has been discovered in the famous Whirlpool Galaxy, M51. Found in the constellation of Canes Venatici, close to Alkaid. The discovery was made on June 2nd by French astronomers and the supernova is reported to be around magnitude 14. The supernova will be evasive to identify visually and it will require a larger aperture telescope. However, this makes a great target for all you astrophotographers out there!

Image by BBC Sky at Night Presenter Pete Lawrence.

Revealing A Hybrid Star Cluster

Written by Tammy Plotner

Almost a century ago, astronomers Shapley and Melotte began classifying star clusters. This rough, initial go-around took in the apparent number of stars and the compactness of the field - along with color. By 1927, these "classes" were again divided to include both open and globular clusters. But there are some that simply defy definition.

According to Johns Hopkins astronomer Imants Platais, there is one case which has puzzled astronomers for decades: a well-known, seemingly open star cluster in the constellation of Lyra, named NGC 6791.

“This cluster is about twice the age of the sun and is unusually metal rich (at least twice the Sun’s metallicity),” said Platais, of the Henry A. Rowland Department of Physics and Astronomy’s Center for Astrophysical Sciences. “A couple of decades ago, it was also found that NGC 6791 contains a handful of very hot but somewhat dim stars, called hot subdwarfs. The presence of such stars in an open cluster is rare, though not unique.”

Why are these hot subdwarfs an anomaly? The facts about star clusters as we know them are that globular clusters are notoriously metal poor, while open clusters are metal rich. "The massive stars that create much of the metals live for only a short time, and when they die, they spit out or eject the metals they have created." says the team. "The expelled metals become part of the raw material out of which the next stars are formed. Thus, there is a relationship between the age of a star and how much metal it contains: old stars have a lower metallicity than do younger ones. Less massive stars live longer than higher mass stars, so low mass stars from early generations still survive today and are studied extensively."

A team led by Platais and Kyle Cudworth from The University of Chicago’s Yerkes Observatory set out to solve the mystery of NGC 6791 by taking a census of its stars. Their findings revealed several luminous stars in the horizontal branch of the HR diagram... Stars that would normally be found in a globular clusters. The hot subdwarfs were confirmed to be genuine cluster members, but they now "appear to be simply the bluest horizontal branch stars". What's wrong with this picture? NGC 6791 contains simultaneously both red and very blue horizontal branch stars - making it both old and metal rich. Quite simply put, studying star clusters is key to understanding stellar evolution - unless the cluster starts breaking the rules.

“Star clusters are the building blocks of galaxies and we believe that all stars, including our own sun, are born in clusters. NGC 6791 is a real oddball among about 2,000 known open and globular star clusters in the Milky Way and as such provides a new challenge and a new opportunity, to our understanding of how stars form and evolve,” said Platais, who presented this work last week at the 218th meeting of the American Astronomical Society in Boston.

So... what about star clusters in other galaxies? Three hybrids have been discovered (2005) in the Andromeda Galaxy - M31WFS C1, M31WFS C2, and M31WFS C3. They have the same basic population and metallicity of a globular cluster, but they're expanded hundreds of light years across and are equally less dense. Are they extended? Or perhaps a dwarf spheroidal galaxy? They don't exist (as far as we know) in the Milky Way, but there's always a possibility these hybrid clusters may call other galaxies home.

Until then, we'll just keep learning.

Original Story Source: John Hopkins University. NGC 6791 - Credit: NASA, ESA, and L. Bedin (STScI)

Free Books! National Academies Press Offers More Than 4,000 Titles

Contributed by Tammy Plotner

Are you hungry for knowledge? Well, if you've got a filet mignon appetite and a hamburger budget, then get in line as the National Academies Press is offering free PDF downloads of more than 4,000 titles from its exhaustive library!

The mission of the National Academies Press (NAP) - publisher for the National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council - is to distribute the institutions' content as widely as possible while maintaining its financial security. The project began in 1994 when the NAP began delivering content to developing countries, and even then 65% of the files were free.

"Our business model has evolved so that it is now financially viable to put this content out to the entire world for free," said Barbara Kline Pope, executive director for the National Academies Press. "This is a wonderful opportunity to make a positive impact by more effectively sharing our knowledge and analyses."

Just a quick browse through the titles shows such a wealth of information that one could spend hours choosing alone! You'll find Agriculture, Earth Sciences, Forensics, Biology, Computers, Education, Health, Industry, Math, and yes... Space and Aeronautics, just to name a few. Based on the performance of NAP’s current free PDFs, projections suggest this change will enhance distribution of PDF reports from about 700,000 downloads per year to more than 3 million by 2013.

Where do you get 'em? Just head toward the NAP Website and have fun!

Original Story Source: Nation Acadamies News and illustration by School Clip Art.

Coming To A Theatre Near You... Extreme Neutron Stars!

Written by Tammy Plotner

They came into existence violently... Born at the death of a massive star. They are are composed almost entirely of neutrons, barren of electrical charge and with a slightly larger mass than protons. They are quantum degenerates with an average density typically more than one billion tons per teaspoonful - a state which can never be created here on Earth. And they are absolutely perfect for study of how matter and exotic particles behave under extreme conditions. We welcome the neutron star...

In 1934 Walter Baade and Fritz Zwicky proposed the existence of the neutron star, only a year after the discovery of the neutron by Sir James Chadwick. But it took another 30 years before the first neutron star was actually observed. Up until now, neutron stars have had their mass accurately measure to about 1.4 times that of Sol. Now a group of astronomers using the Green Bank Radio Telescope found a neutron star that has a mass of nearly twice that of the Sun. How can they make estimates so precise? Because the extreme neutron star in question is actually a pulsar - PSR J1614-2230. With heartbeat-like precision, PSR J1614-2230 sends out a radio signal each time it spins on its axis at 317 times per second.

According to the team; "What makes this discovery so remarkable is that the existence of a very massive neutron star allows astrophysicists to rule out a wide variety of theoretical models that claim that the neutron star could be composed of exotic subatomic particles such as hyperons or condensates of kaons."

The presence of this extreme star poses new questions about its origin... and its nearby white dwarf companion. Did it become so extreme from pulling material from its binary neighbor - or did it simply become that way through natural causes? According to Professor Lorne Nelson (Bishop's University) and his colleagues at MIT, Oxford, and UCSB, the neutron star was likely spun up to become a fast-rotating (millisecond) pulsar as a result of the neutron star having cannibalized its stellar companion many millions of years ago, leaving behind a dead core composed mostly of carbon and oxygen. According to Nelson, "Although it is common to find a high fraction of stars in binary systems, it is rare for them to be close enough so that one star can strip off mass from its companion star. But when this happens, it is spectacular."

Through the use of theoretical models, the team hopes to gain insight as to how binary systems evolve over the entire lifetime of the Universe. With today's extreme super-computing powers, Nelson and his team members were able to calculate the evolution of more than 40,000 plausible starting cases for the binary and determine which ones were relevant. As they describe at this week's CASCA meeting in Ontario, Canada, they found many instances where the neutron star could evolve higher in mass at the expense of its companion, but as Nelson says, "It isn't easy for Nature to make such high-mass neutron stars, and this probably explains why they are so rare."

Original story source at Illustration courtesy of NASA.