25 August 2011
David Shiga
http://www.newscientist.com/article/dn20832-astrophile-the-diamond-as-big-as-a-planet.html
Cruising through the Milky Way in your reconnaissance craft, your sensors pick up a powerful radio beacon. Altering your course to take a closer look, you find not a ship in distress, but an ultradense sphere of neutrons, packing a sun's worth of mass into something the size of a city.
This dead remnant of a star glows red like a hot ember, and is spinning 173 times per second, emitting powerful radio beams that sweep across the sky as it rotates. While such pulsars are striking, they are nothing out of the ordinary, so you are about to resume your original course when your eye catches something sparkling near the dim red glow.
A closer look reveals it to be an orb with the mass of Jupiter and about half as wide. Sensors indicate it's made of – wait, this can't be right – diamond! Your instruments don't lie. You've just stumbled upon a 1031-carat diamond.
Glitter ball
Fanciful as it may sound, a team led by Matthew Bailes of Swinburne University of Technology in Melbourne, Australia may have made a similar discovery – via telescope, not a starship.
Their radio survey of the sky detected the pulsar in December 2009, using the CSIRO Parkes radio telescope in New South Wales, Australia. A month later, follow-up observations with the Lovell radio telescope in Cheshire, UK, revealed periodic variations in the pulsar's signals, indicating the existence of an orbiting companion with the mass of a planet.
That in itself was a rare find: of the 1800 or so pulsars known, only two had previously been found to harbour planets. Further analysis pointed to an even more astonishing possibility – a diamond planet.
The variations in the pulsar's signals, which stem from the planet's gravity tugging on the pulsar, revealed that the planet's mass is roughly equal to Jupiter's and that it orbits the pulsar at a distance of 600,000 kilometres, 1.5 times the distance of the moon from Earth.
Danger zone
The latter point is crucial. The planet orbits so close to the pulsar that it skirts the danger zone within which the star's gravity would rip it apart.
Wait a minute, though. If it were a gas giant the size of Jupiter, part of its atmosphere would actually be inside the gravitational destruction zone, and the planet would not have survived long enough for Bailes's team to detect it. So it must be less than about 60,000 kilometres in diameter, roughly 40 per cent of Jupiter's width.
That in turn means it is much more compact than Jupiter, which has an average density only slightly greater than water.
The extremely fast rotation of the pulsar supports this conclusion. Pulsars that rotate many times each second are thought to spin up to such tremendous speeds as a result of stealing matter from a companion star. But there is no sign of such a massive companion today, so the planet is likely all that's left of a star that was whittled down by the pulsar.
Hard-core bling
The core of a stripped down star would be mostly carbon, with a dash of oxygen. With the mass of Jupiter, such an object would be under high pressure because of its own gravity. And this would cause it to crystallise – most likely into diamond, just as carbon does deep inside the Earth.
If it is a diamond, does the planet glitter like an Earthly gem? "It's highly speculative, but if you shine a light on it, I can't see any reason why it wouldn't sparkle like a diamond," says Travis Metcalfe of the National Center for Atmospheric Research in Boulder, Colorado. He previously found a white dwarf – the remnant of an old star – with a carbon-crystal core that was under higher pressure than the new planet, producing a crystalline structure distinct from diamond.
Moshe Mosbacher, president of the Diamond Dealers Club in New York says he has "no clue" how much a diamond of this size would fetch, without first knowing its quality. But he is intrigued. "If there's some way to transport it to New York and cut it, it doesn't make a difference if it's from inner space or outer space."
Showing posts with label Milky Way. Show all posts
Showing posts with label Milky Way. Show all posts
Tuesday, September 6, 2011
Friday, November 26, 2010
Giant Bubbles Found in Space
http://news.discovery.com/space/gamma-ray-bubbles-black-hole.html
Giant Bubbles Found in Space
An ancient eruption of a supermassive black hole may have inflated the mysteriously huge bubbles that span 50,000 light-years.
Irene Klotz
Wed Nov 10, 2010
THE GIST
Astronomers discover new type of object -- huge bubbles of gamma rays stemming from the heart of the galaxy.
The two bubbles could have been inflated by a past eruption from the supermassive black hole at the center of the Milky Way.
The bubbles span 50,000 light-years across the sky.
An ancient eruption of a supermassive black hole in the Milky Way may have inflated two huge bubbles of gamma rays which were just now discovered and are considered a new type of astronomical object.
"It shows, once again, that the universe is full of surprises," said Jon Morse, director of astrophysics at NASA headquarters.
Combined, the bubbles, which are aligned at the center of the Milky Way, span a vast distance of about 50,000 light-years. The structures are very distinct, with defined edges, and have as much energy in them as 100,000 supernova.
They were found with NASA's Fermi Gamma-Ray Telescope, which surveys the sky every three hours for the highest-energy light.
Among the 1,500 sources of gamma rays Fermi has mapped so far, nothing resembles the bubble-shaped structures, which stretch across more than half of the visible sky, from the constellation Virgo to the constellation Grus.
"You have to ask where could energy like that come from," said astronomer Doug Finkbeiner, with the Harvard-Smithsonian Center for Astrophysics.
Hints of the bubbles appeared years earlier in X-ray surveys and in maps of the cosmic microwave background radiation stemming from the Big Bang explosion.
"We had a hypothesis before Fermi launched that there should be some gamma ray emission in this part of the sky. We were thinking something a bit more modest, maybe something within 10 or 20 or 30 degrees of the center, not these giant structures reaching all the way up to 50 degrees," Finkbeiner said.
Scientists have two possible explanations for the Fermi bubbles. Theory one: a burst of star-formation at the center of the galaxy generated short-lived massive stars with energetic winds that blasted high-energy particles out into space.
Finkbeiner points out that it would take some time to accumulate as much energy as what's inside the bubbles, however. He favors an alternative theory: an outburst from the supermassive black hole lurking in the center of the galaxy.
In other galaxies, astronomers have seen evidence for jets of particles triggered by matter that is being pulled into a black hole, objects that have so much gravitational pull that not even light can escape their grasp.
There's no evidence that the Milky Way's central black hole, which is about 400 million times more massive than our sun, has jets, but astronomers suspect it might have in the past.
"We know it didn't get to be that big by sitting there quietly all the time. It certainly has had big accretion events in the past, where material falls on it and then some of that material comes back out as high-energy particles blasted out in the form of a jet," Finkbeiner said.
"We've never really seen very good evidence of it. This might be the first evidence for a major outburst of the black hole at the center of the galaxy. When it's going full-blast … it would not actually take an enormous amount of time -- maybe 10,000 or 100,000 years -- for it to produce enough energy to create these structures," Finkbeiner said.
"This result is very exciting," added Fermi scientist Simona Murgia, with the SLAC National Accelerator Laboratory in Menlo Park, Calif. "These features could reveal unexpected and very important physical processes in our galaxy that until now we knew nothing about despite the fact that these features could possibly be almost as large as the Milky Way and might have been around for millions of years."
The discovery was unveiled during a teleconference with reporters on Tuesday and is the subject of an upcoming paper in The Astrophysical Journal.
Giant Bubbles Found in Space
An ancient eruption of a supermassive black hole may have inflated the mysteriously huge bubbles that span 50,000 light-years.
Irene Klotz
Wed Nov 10, 2010
THE GIST
Astronomers discover new type of object -- huge bubbles of gamma rays stemming from the heart of the galaxy.
The two bubbles could have been inflated by a past eruption from the supermassive black hole at the center of the Milky Way.
The bubbles span 50,000 light-years across the sky.
An ancient eruption of a supermassive black hole in the Milky Way may have inflated two huge bubbles of gamma rays which were just now discovered and are considered a new type of astronomical object.
"It shows, once again, that the universe is full of surprises," said Jon Morse, director of astrophysics at NASA headquarters.
Combined, the bubbles, which are aligned at the center of the Milky Way, span a vast distance of about 50,000 light-years. The structures are very distinct, with defined edges, and have as much energy in them as 100,000 supernova.
They were found with NASA's Fermi Gamma-Ray Telescope, which surveys the sky every three hours for the highest-energy light.
Among the 1,500 sources of gamma rays Fermi has mapped so far, nothing resembles the bubble-shaped structures, which stretch across more than half of the visible sky, from the constellation Virgo to the constellation Grus.
"You have to ask where could energy like that come from," said astronomer Doug Finkbeiner, with the Harvard-Smithsonian Center for Astrophysics.
Hints of the bubbles appeared years earlier in X-ray surveys and in maps of the cosmic microwave background radiation stemming from the Big Bang explosion.
"We had a hypothesis before Fermi launched that there should be some gamma ray emission in this part of the sky. We were thinking something a bit more modest, maybe something within 10 or 20 or 30 degrees of the center, not these giant structures reaching all the way up to 50 degrees," Finkbeiner said.
Scientists have two possible explanations for the Fermi bubbles. Theory one: a burst of star-formation at the center of the galaxy generated short-lived massive stars with energetic winds that blasted high-energy particles out into space.
Finkbeiner points out that it would take some time to accumulate as much energy as what's inside the bubbles, however. He favors an alternative theory: an outburst from the supermassive black hole lurking in the center of the galaxy.
In other galaxies, astronomers have seen evidence for jets of particles triggered by matter that is being pulled into a black hole, objects that have so much gravitational pull that not even light can escape their grasp.
There's no evidence that the Milky Way's central black hole, which is about 400 million times more massive than our sun, has jets, but astronomers suspect it might have in the past.
"We know it didn't get to be that big by sitting there quietly all the time. It certainly has had big accretion events in the past, where material falls on it and then some of that material comes back out as high-energy particles blasted out in the form of a jet," Finkbeiner said.
"We've never really seen very good evidence of it. This might be the first evidence for a major outburst of the black hole at the center of the galaxy. When it's going full-blast … it would not actually take an enormous amount of time -- maybe 10,000 or 100,000 years -- for it to produce enough energy to create these structures," Finkbeiner said.
"This result is very exciting," added Fermi scientist Simona Murgia, with the SLAC National Accelerator Laboratory in Menlo Park, Calif. "These features could reveal unexpected and very important physical processes in our galaxy that until now we knew nothing about despite the fact that these features could possibly be almost as large as the Milky Way and might have been around for millions of years."
The discovery was unveiled during a teleconference with reporters on Tuesday and is the subject of an upcoming paper in The Astrophysical Journal.
Thursday, February 19, 2009
Alien Census
http://www.sciam.com/article.cfm?id=how-much-intelligent-alien-life
February 10, 2009
Alien Census: Can We Estimate How Much Life Is Out There?
New study looks to tabulate the extent of intelligent extraterrestrial life
By John Matson
One day in 1950, nuclear physicist Enrico Fermi posed a question to a few colleagues he was lunching with at Los Alamos National Laboratory that would become known as the Fermi Paradox: If the Milky Way is indeed teeming with alien civilizations, as many theories suggest, where are they? Shouldn't we see evidence of their existence? Nearly 60 years later, the question remains just as vexing. After all, decades of searching for extraterrestrial radio signals or evidence of alien civilizations have come up empty.
Nevertheless, search for extraterrestrial intelligence (SETI) programs soldier on. And the hunt for any alien life, even in microbial form, is ramping up quickly with instruments probing Mars and other likely nearby candidates in greater detail and with the regular detection of new planets outside our solar system. In the absence of hard evidence for intelligent extraterrestrial life, some researchers have set out to estimate just how much might be out there. The hope is that they can justify the continuation of SETI searches or even refine them and thus up the odds of finding ET, perhaps someday rendering the Fermi Paradox moot.
In a recent paper published online by the International Journal of Astrobiology, graduate student Duncan Forgan of the Royal Observatory, Edinburgh, in Scotland set up a numerical model of the universe under different scenarios of biogenesis. His model relies on current observational knowledge of stars and planetary systems, as well as some assumptions about the viability of life and its ability to evolve into an advanced, intelligent form. If life can only arise under a narrow set of initial conditions, Forgan estimates there should be 361 advanced, stable civilizations in the Milky Way. If life can spread from one planet to another through biological molecules embedded in asteroids, though, the number jumps to nearly 38,000. (Even given a densely populated galaxy, Forgan notes, there is no guarantee of immediate mutual contact.)
Forgan's model makes use of the Monte Carlo method, by which the starting variables in a system are randomized over repeated simulations to allow for uncertainties in their values. By averaging the results from 100 such simulations, Forgan's analysis yields an estimate that accounts for variations in inputs.
But some in the field argue that estimates of the extent of extraterrestrial intelligence cannot carry any degree of accuracy, given the gaps in our knowledge. Such numerical estimates are "still subject to all the other uncertainties and all the other imponderables" regarding the origins of life, says planetary scientist Ian Crawford of Birkbeck College at the University of London. "We have to admit that we're hugely ignorant of many of the pieces of information that we would need to know before we could realistically estimate the prevalence of intelligent life elsewhere in the galaxy."
Mark Burchell, a professor of space sciences at the University of Kent in England, says that astronomically speaking, our knowledge base is fairly refined. "But the biological and social aspects of the equation remain speculative," he said in an e-mail. "As Forgan points out, we are limited to single-event observations (life on Earth) to make sweeping general predictions (life elsewhere)."
Forgan acknowledges that the analysis suffers from some uncertainties, stemming in part from a small and somewhat biased data set on planets outside the solar system. Some 300 planetary systems have been found since 1995, when the first planet orbiting a normal star other than the sun was discovered. But the detection methods employed in this effort tend to find planets that are quite large and hot. The European COROT satellite and NASA's forthcoming Kepler spacecraft, however, should be able to locate more Earth-like worlds in the coming years with dedicated, sensitive monitoring of dips in stellar brightness that occur when a planet passes in front of a star. Forgan says that "Earth-mass, rocky planets are still the best bet for habitability," so such discoveries would significantly affect his conclusions.
He also notes that the numbers, subject as they are to uncertainties, should not be considered the sole outcome of his paper. Simply refining models of where and when life should arise, he says, might improve SETI searches. "Searching for life in the galaxy is the ultimate needle in the haystack," Forgan says, and any guidance as to where and when to search for that needle should be useful.
But Crawford thinks such analyses won't affect the status quo. "We've got no option but to keep looking; there's nothing else we can do," he says. "All the SETI searches can do is what they've been doing for the last 40 years and keep listening."
February 10, 2009
Alien Census: Can We Estimate How Much Life Is Out There?
New study looks to tabulate the extent of intelligent extraterrestrial life
By John Matson
One day in 1950, nuclear physicist Enrico Fermi posed a question to a few colleagues he was lunching with at Los Alamos National Laboratory that would become known as the Fermi Paradox: If the Milky Way is indeed teeming with alien civilizations, as many theories suggest, where are they? Shouldn't we see evidence of their existence? Nearly 60 years later, the question remains just as vexing. After all, decades of searching for extraterrestrial radio signals or evidence of alien civilizations have come up empty.
Nevertheless, search for extraterrestrial intelligence (SETI) programs soldier on. And the hunt for any alien life, even in microbial form, is ramping up quickly with instruments probing Mars and other likely nearby candidates in greater detail and with the regular detection of new planets outside our solar system. In the absence of hard evidence for intelligent extraterrestrial life, some researchers have set out to estimate just how much might be out there. The hope is that they can justify the continuation of SETI searches or even refine them and thus up the odds of finding ET, perhaps someday rendering the Fermi Paradox moot.
In a recent paper published online by the International Journal of Astrobiology, graduate student Duncan Forgan of the Royal Observatory, Edinburgh, in Scotland set up a numerical model of the universe under different scenarios of biogenesis. His model relies on current observational knowledge of stars and planetary systems, as well as some assumptions about the viability of life and its ability to evolve into an advanced, intelligent form. If life can only arise under a narrow set of initial conditions, Forgan estimates there should be 361 advanced, stable civilizations in the Milky Way. If life can spread from one planet to another through biological molecules embedded in asteroids, though, the number jumps to nearly 38,000. (Even given a densely populated galaxy, Forgan notes, there is no guarantee of immediate mutual contact.)
Forgan's model makes use of the Monte Carlo method, by which the starting variables in a system are randomized over repeated simulations to allow for uncertainties in their values. By averaging the results from 100 such simulations, Forgan's analysis yields an estimate that accounts for variations in inputs.
But some in the field argue that estimates of the extent of extraterrestrial intelligence cannot carry any degree of accuracy, given the gaps in our knowledge. Such numerical estimates are "still subject to all the other uncertainties and all the other imponderables" regarding the origins of life, says planetary scientist Ian Crawford of Birkbeck College at the University of London. "We have to admit that we're hugely ignorant of many of the pieces of information that we would need to know before we could realistically estimate the prevalence of intelligent life elsewhere in the galaxy."
Mark Burchell, a professor of space sciences at the University of Kent in England, says that astronomically speaking, our knowledge base is fairly refined. "But the biological and social aspects of the equation remain speculative," he said in an e-mail. "As Forgan points out, we are limited to single-event observations (life on Earth) to make sweeping general predictions (life elsewhere)."
Forgan acknowledges that the analysis suffers from some uncertainties, stemming in part from a small and somewhat biased data set on planets outside the solar system. Some 300 planetary systems have been found since 1995, when the first planet orbiting a normal star other than the sun was discovered. But the detection methods employed in this effort tend to find planets that are quite large and hot. The European COROT satellite and NASA's forthcoming Kepler spacecraft, however, should be able to locate more Earth-like worlds in the coming years with dedicated, sensitive monitoring of dips in stellar brightness that occur when a planet passes in front of a star. Forgan says that "Earth-mass, rocky planets are still the best bet for habitability," so such discoveries would significantly affect his conclusions.
He also notes that the numbers, subject as they are to uncertainties, should not be considered the sole outcome of his paper. Simply refining models of where and when life should arise, he says, might improve SETI searches. "Searching for life in the galaxy is the ultimate needle in the haystack," Forgan says, and any guidance as to where and when to search for that needle should be useful.
But Crawford thinks such analyses won't affect the status quo. "We've got no option but to keep looking; there's nothing else we can do," he says. "All the SETI searches can do is what they've been doing for the last 40 years and keep listening."
Saturday, January 10, 2009
Milky Way 50 Percent Larger
http://blog.wired.com/wiredscience/2009/01/milkyway.htmMilky Way 50 Percent Larger, Astronomers Discover
By Alexis Madrigal
January 05, 2009
Artist's conceptions of the Milky Way might give you the impression that astronomers have a precise notion of what our galaxy looks like, but you'd be wrong. In fact, new observations suggest that our home galaxy has been vastly underestimated.Those spiraling arms? Some scientists think it only has two, not four. Its size? For years, we thought that the Milky Way was substantially smaller than our closest galactic neighbor, the Andromeda Galaxy.
Now, new measurements of how quickly our galaxy is rotating have led a team of Harvard astrophysicists to conclude that our galaxy is 50 percent more massive than previously thought, and likely does have four arms.
"We should certainly think of the Milky Way no longer as the little sister of the local group," said Mark Reid of the Harvard-Smithsonian Center for Astrophysics. "We should think of the Milky Way and Andromeda as more like fraternal twins."
The question of what exactly our galaxy looks like is more difficult to solve than you might think. We're inside the galaxy, so we can't get direct perspective on our home. The best method is to measure how quickly the galaxy is rotating and back out to the amount of mass that would have to exist in the structure to generate that velocity.
Using the Very Large Baseline Array of radio telescopes, Reid's team found that the Milky Way is rotating at about 600,000 miles an hour, 100,000 miles per hour faster than previous estimates. When you do the math, that translates into the 50 percent mass increase his team reported in a press conference at the American Astronomical Society meeting Monday. One major consequence of a heavier Milky Way is that we're likely to collide with the Andromeda Galaxy sooner, Reid said.
The new measurements also seem to indicate that the galaxy must have the four arms that astronomers had long assumed before Spitzer Space Telescope observations last year called that into question.
"By measuring distances to regions of very massive star formation, we can start to trace out the spiral arms of the Milky Way and begin to constrain how tightly wound the arms are and trace out how many of them there are," Reid said.
With the new array of radio telescopes, the team has been able to make more precise measurements than ever before.
"We're using trigonometric parallax. It's essentially what surveyors do here on Earth," he said. "If you know the length of one leg of the triangle and the angles between the legs, you can calculate all the lengths."
In this case, they make an observation of the same region at two different times of the year, creating a triangle out of the earth's two positions and the star itself.
As for the discrepancy with the Spitzer's findings about the number of arms our galaxy has, Reid explained that he thought the old stars measured by the other group of astronomers only showed up in two of the arms, while his young stars showed up everywhere. Why only two of the galaxy's four arms would contain older stars would take further research into the galaxy's makeup.
"The central question here is: What does the Milky Way really look like?" Reid said.
Tuesday, December 16, 2008
Black hole at the heart of the Milky Way
http://www.timesonline.co.uk/tol/news/uk/science/article5316001.eceDecember 9, 2008
Astronomers confirm black hole at the heart of the Milky Way
The nature of the black hole can be inferred from the pattern of motion of the stars that surround it
Mark Henderson, Science Editor
A swarm of stars orbiting a vast black hole at the centre of the Milky Way has been mapped with remarkable precision, providing astronomers with their most detailed look yet at the heart of our galaxy.
Observations by the European Southern Observatory (ESO) in Chile has found the strongest evidence yet for a supermassive black hole at the galaxy’s core, as well as charting the immense gravitational effects this has on the surrounding stars.
Over 16 years, the orbits of 28 stars in the Milky Way’s central region have been meticulously tracked by astronomers, allowing them to study the hidden black hole that influences their movements.
The black hole, known as Sagittarius A* (pronounced “Sagittarius A-star”), cannot be seen directly, but its nature can be inferred from the pattern of motion of the stars that surround it. Details of the research are published in the Astrophysical Journal.
Reinhard Genzel, of the Max Planck Institute for Extraterrestrial Physics in Germany, who led the international study team, said: “Undoubtedly the most spectacular aspect of our long term study is that it has delivered what is now considered to be the best empirical evidence that supermassive black holes do really exist. The stellar orbits in the galactic centre show that the central mass concentration of four million solar masses must be a black hole, beyond any reasonable doubt.
“The centre of the galaxy is a unique laboratory where we can study the fundamental processes of strong gravity, stellar dynamics and star formation that are of great relevance to all other galactic nuclei, with a level of detail that will never be possible beyond our galaxy.”
His colleague Stefan Gillessen said: “The galactic centre harbours the closest supermassive black hole known. Hence, it is the best place to study black holes in detail.”
The observations have also allowed astronomers to pinpoint the Earth’s distance from the centre of the galaxy with greater precision, measuring it at 27,000 light years. Scientists have also been able to identify common properties among the stellar orbits at the galactic centre.
“The stars in the innermost region are in random orbits, like a swarm of bees,” Dr Gillessen said. “However, further out, six of the 28 stars orbit the black hole in a disc. In this respect the new study has also confirmed explicitly earlier work in which the disc had been found, but only in a statistical sense.
“Ordered motion outside the central light-month, randomly oriented orbits inside - that’s how the dynamics of the young stars in the galactic centre are best described.”
Wednesday, December 10, 2008
Key Molecule for Life Found
http://blog.wired.com/wiredscience/2008/11/sugar-molecule.html
Key Molecule for Life Found in Habitable Region of the Galaxy
By Clara Moskowitz
November 26, 2008
Astrobiology
A sugar molecule linked to the origin of life was discovered in a potentially habitable region of our galaxy.
The molecule, called glycolaldehyde, was spotted in a large star-forming area of space around 26,000 light-years from Earth in the less-chaotic outer regions of the Milky Way. This suggests the sugar could be common across the universe, which is good news for extraterrestrial-life seekers.
"This is an important discovery as it is the first time glycolaldehyde, a basic sugar, has been detected towards a star-forming region where planets that could potentially harbor life may exist," Serena Viti of University College London said in a press release.
Previously, glycolaldehyde had only been observed toward the center of the galaxy, where conditions are thought to be too extreme to host habitable planets.
Glycolaldehyde is a key ingredient for life. It helps to build Ribonucleic acid (RNA), which is thought to be the central molecule involved in the origin of life on Earth. Glycolaldehyde is a monosaccharide sugar, the basic unit of carbohydrates. It can react with the chemical propenal to form ribose, the building block of RNA.
"The discovery of an organic sugar molecule in a star forming region of space is very exciting and will provide incredibly useful information in our search for alien life,” said Keith Mason, chief executive of the England’s Science and Technology Facilities Council.
The finding, made with the IRAM radio telescope in France, was announced Tuesday and will be published in the Astrophysical Journal Letters.
Key Molecule for Life Found in Habitable Region of the Galaxy
By Clara Moskowitz
November 26, 2008
Astrobiology
A sugar molecule linked to the origin of life was discovered in a potentially habitable region of our galaxy.
The molecule, called glycolaldehyde, was spotted in a large star-forming area of space around 26,000 light-years from Earth in the less-chaotic outer regions of the Milky Way. This suggests the sugar could be common across the universe, which is good news for extraterrestrial-life seekers.
"This is an important discovery as it is the first time glycolaldehyde, a basic sugar, has been detected towards a star-forming region where planets that could potentially harbor life may exist," Serena Viti of University College London said in a press release.
Previously, glycolaldehyde had only been observed toward the center of the galaxy, where conditions are thought to be too extreme to host habitable planets.
Glycolaldehyde is a key ingredient for life. It helps to build Ribonucleic acid (RNA), which is thought to be the central molecule involved in the origin of life on Earth. Glycolaldehyde is a monosaccharide sugar, the basic unit of carbohydrates. It can react with the chemical propenal to form ribose, the building block of RNA.
"The discovery of an organic sugar molecule in a star forming region of space is very exciting and will provide incredibly useful information in our search for alien life,” said Keith Mason, chief executive of the England’s Science and Technology Facilities Council.
The finding, made with the IRAM radio telescope in France, was announced Tuesday and will be published in the Astrophysical Journal Letters.
Tuesday, April 8, 2008
Mini-black hole is smallest ever but still strong
http://news.yahoo.com/s/nm/20080401/sc_nm/space_blackhole_dc
Mini-black hole is smallest ever but still strong
Tue Apr 1, 2008
NASA scientists have identified the smallest black hole ever found -- less than four times the mass of our sun and about the size of a large city.
But the mini-black hole, dubbed J1650, could still stretch a person into a "strand of spaghetti" with its pull, the researchers told a meeting in Los Angeles.
"This black hole is really pushing the limits. For many years astronomers have wanted to know the smallest possible size of a black hole, and this little guy is a big step toward answering that question," Nikolai Shaposhnikov of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in a statement.
It would likely be stronger than bigger black holes found at the centers of galaxies. Shaposhnikov said if someone ventured too close to J1650, its gravity would "stretch your body into a strand of spaghetti."
Like other black holes, it was formed by a star that ran out of fuel and shut down, collapsing due to its own gravity.
Shaposhnikov and his Goddard colleague Lev Titarchuk used NASA's Rossi X-ray Timing Explorer satellite and a new method to estimate the size of the black hole, found in a system in the southern constellation Ara, in our own Milky Way Galaxy.
It measures the oscillation of hot gas piling up near the black hole as it sucks in matter, they told a meeting in Los Angeles of the American Astronomical Society High-Energy Astrophysics Division.
The new black hole has a mass of 3.8 Suns and would be about 15 miles across, they estimate. "This makes the black hole one of the smallest objects ever discovered outside our solar system," Shaposhnikov said.
The smallest black hole previously identified was GRO 1655-40, with a mass of about 6.3 Suns.
"Amazingly, equations from Albert Einstein predict that a black hole with 3.8 times the mass of our Sun would be only 15 miles across -- the size of a city," NASA said in a statement.
A collapsing star that was much smaller than J1650 would likely form a neutron star and not a black hole, the researchers said.
(Reporting by Maggie Fox; Editing by Will Dunham and Bill Trott)
Mini-black hole is smallest ever but still strong
Tue Apr 1, 2008
NASA scientists have identified the smallest black hole ever found -- less than four times the mass of our sun and about the size of a large city.
But the mini-black hole, dubbed J1650, could still stretch a person into a "strand of spaghetti" with its pull, the researchers told a meeting in Los Angeles.
"This black hole is really pushing the limits. For many years astronomers have wanted to know the smallest possible size of a black hole, and this little guy is a big step toward answering that question," Nikolai Shaposhnikov of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in a statement.
It would likely be stronger than bigger black holes found at the centers of galaxies. Shaposhnikov said if someone ventured too close to J1650, its gravity would "stretch your body into a strand of spaghetti."
Like other black holes, it was formed by a star that ran out of fuel and shut down, collapsing due to its own gravity.
Shaposhnikov and his Goddard colleague Lev Titarchuk used NASA's Rossi X-ray Timing Explorer satellite and a new method to estimate the size of the black hole, found in a system in the southern constellation Ara, in our own Milky Way Galaxy.
It measures the oscillation of hot gas piling up near the black hole as it sucks in matter, they told a meeting in Los Angeles of the American Astronomical Society High-Energy Astrophysics Division.
The new black hole has a mass of 3.8 Suns and would be about 15 miles across, they estimate. "This makes the black hole one of the smallest objects ever discovered outside our solar system," Shaposhnikov said.
The smallest black hole previously identified was GRO 1655-40, with a mass of about 6.3 Suns.
"Amazingly, equations from Albert Einstein predict that a black hole with 3.8 times the mass of our Sun would be only 15 miles across -- the size of a city," NASA said in a statement.
A collapsing star that was much smaller than J1650 would likely form a neutron star and not a black hole, the researchers said.
(Reporting by Maggie Fox; Editing by Will Dunham and Bill Trott)
Wednesday, March 12, 2008
Real Death Star Could Strike Earth
http://www.space.com/scienceastronomy/080310-mm-grb-us.html
Real Death Star Could Strike Earth
Charles Q. Choi
SPACE.com
Mon Mar 10, 2008
A beautiful pinwheel in space might one day blast Earth with death rays, scientists now report.
Unlike the moon-sized Death Star from Star Wars, which has to get close to a planet to blast it, this blazing spiral has the potential to burn worlds from thousands of light-years away.
"I used to appreciate this spiral just for its beautiful form, but now I can't help a twinge of feeling that it is uncannily like looking down a rifle barrel," said researcher Peter Tuthill, an astronomer at the University of Sydney.
The fiery pinwheel in space in question has at its heart a pair of hot, luminous stars locked in orbit with each other. As they circle one another, plumes of streaming gas driven from the surfaces of the stars collide in the intervening space, eventually becoming entangled and twisted into a whirling spiral by the orbits of the stars.
Short fuse
The pinwheel, named WR 104, was discovered eight years ago in the constellation Sagittarius. It rotates in a circle "every eight months, keeping precise time like a jewel in a cosmic clock," Tuthill said.
Both the massive stars in WR 104 will one day explode as supernovae. However, one of the pair is a highly unstable star known as a Wolf-Rayet, the last known stable phase in the life of these massive stars right before a supernova.
"Wolf-Rayet stars are regarded by astronomers as ticking bombs," Tuthill explained. The 'fuse' for this star "is now very short — to an astronomer — and it may explode any time within the next few hundred thousand years."
When the Wolf-Rayet goes supernova, "it could emit an intense beam of gamma rays coming our way," Tuthill said. "If such a 'gamma ray burst' happens, we really do not want Earth to be in the way."
Since the initial blast would travel at the speed of light, there would be no warning of its arrival.
Firing line
Gamma ray bursts are the most powerful explosions known in the universe. They can loose as much energy as our sun during its entire 10 billion year lifetime in anywhere from milliseconds to a minute or more.
The spooky thing about this pinwheel is that it appears to be a nearly perfect spiral to us, according to new images taken with the Keck Telescope in Hawaii. "It could only appear like that if we are looking nearly exactly down on the axis of the binary system," Tuthill said.
The findings are detailed in the March 1 issue of Astrophysical Journal.
Unfortunately for us, gamma ray bursts seem to be shot right along the axis of systems. In essence, if this pinwheel ever releases a gamma ray burst, our planet might be in the firing line.
"This is the first object that we know of that might release a gamma ray burst at us," said astrophysicist Adrian Melott at the University of Kansas in Lawrence, who did not participate in this study. "And it's close enough to do some damage."
This pinwheel is about 8,000 light years away, roughly a quarter of the way to the center of the Milky Way Galaxy. While this might seem far, "earlier research has suggested that a gamma ray burst — if we are unfortunate enough to be caught in the beam — could be harmful to life on Earth out to these distances," Tuthill said.
What might happen
Although the pinwheel can't blast Earth apart like the Death Star from Star Wars — at least not from 8,000 light years away — it could still cause mass extinction or possibly even threaten life as we know it on our planet.
Gamma rays would not penetrate Earth's atmosphere well to burn the ground, but they would chemically damage the stratosphere. Melott estimates that if WR 104 were to hit us with a burst 10 seconds or so long, its gamma rays could deplete about 25 percent of the world's ozone layer, which protects us from damaging ultraviolet rays. In comparison, the recent human-caused thinning of the ozone layer, creating "holes" over the polar regions, have only been depletions of about 3 to 4 percent, he explained.
"So that would be very bad," Melott told SPACE.com. "You'd see extinctions. You might see food chain collapses in the oceans, might see agricultural crises with starvation."
Gamma ray bursts would also trigger smog formation that could blot out sunlight and rain down acid. However, at 8,000 light-years away, "there's probably not a large enough effect there for much of a darkening effect," Melott estimated. "It'd probably cut off 1 or 2 percent of total sunlight. It might cool the climate somewhat, but it wouldn't be a catastrophic ice age kind of thing."
Cosmic ray danger
One unknown about gamma ray bursts is how many particles they spew as cosmic rays.
"Normally the gamma ray bursts we see are so far away that magnetic fields out in the universe deflect any cosmic rays we might observe from them, but if a gamma ray burst was pretty close, any high-energy particles would blast right through the galaxy's magnetic field and hit us," Melott said. "Their energies would be so high, they would arrive at almost the same time as the light burst."
"The side of the Earth facing the gamma ray burst would experience something like getting irradiated by a not-too-distant nuclear explosion, and organisms on that side might see radiation sickness. And the cosmic rays would make the atmospheric effects of a gamma ray burst worse," Melott added. "But we just don't know how many cosmic rays gamma ray bursts emit, so that's a danger that's not really understood."
It remains uncertain just how wide the beams of energy that gamma ray bursts release are. However, any cone of devastation from the pinwheel would likely be several hundred square light-years wide by the time it reached Earth, Melott estimated. Tuthill told SPACE.com "it would be pretty much impossible to for anyone to get far enough to be out of the beam in a spaceship if it really is coming our way."
Don't worry
Still, Tuthill noted this pinwheel might not be the death of us.
"There are still plenty of uncertainties — the beam could pass harmlessly to the side if we are not exactly on the axis, and nobody is even sure if stars like WR 104 are capable of producing a fully-fledged gamma-ray burst in the first place," he explained.
Future research should focus on whether WR 104 really is pointed at Earth and on better understanding how supernovae produce gamma ray bursts.
Melott and others have speculated that gamma ray bursts might have caused mass extinctions on Earth. But when it comes to whether this pinwheel might pose a danger to us, "I would worry a lot more about global warming," Melott said.
Real Death Star Could Strike Earth
Charles Q. Choi
SPACE.com
Mon Mar 10, 2008
A beautiful pinwheel in space might one day blast Earth with death rays, scientists now report.
Unlike the moon-sized Death Star from Star Wars, which has to get close to a planet to blast it, this blazing spiral has the potential to burn worlds from thousands of light-years away.
"I used to appreciate this spiral just for its beautiful form, but now I can't help a twinge of feeling that it is uncannily like looking down a rifle barrel," said researcher Peter Tuthill, an astronomer at the University of Sydney.
The fiery pinwheel in space in question has at its heart a pair of hot, luminous stars locked in orbit with each other. As they circle one another, plumes of streaming gas driven from the surfaces of the stars collide in the intervening space, eventually becoming entangled and twisted into a whirling spiral by the orbits of the stars.
Short fuse
The pinwheel, named WR 104, was discovered eight years ago in the constellation Sagittarius. It rotates in a circle "every eight months, keeping precise time like a jewel in a cosmic clock," Tuthill said.
Both the massive stars in WR 104 will one day explode as supernovae. However, one of the pair is a highly unstable star known as a Wolf-Rayet, the last known stable phase in the life of these massive stars right before a supernova.
"Wolf-Rayet stars are regarded by astronomers as ticking bombs," Tuthill explained. The 'fuse' for this star "is now very short — to an astronomer — and it may explode any time within the next few hundred thousand years."
When the Wolf-Rayet goes supernova, "it could emit an intense beam of gamma rays coming our way," Tuthill said. "If such a 'gamma ray burst' happens, we really do not want Earth to be in the way."
Since the initial blast would travel at the speed of light, there would be no warning of its arrival.
Firing line
Gamma ray bursts are the most powerful explosions known in the universe. They can loose as much energy as our sun during its entire 10 billion year lifetime in anywhere from milliseconds to a minute or more.
The spooky thing about this pinwheel is that it appears to be a nearly perfect spiral to us, according to new images taken with the Keck Telescope in Hawaii. "It could only appear like that if we are looking nearly exactly down on the axis of the binary system," Tuthill said.
The findings are detailed in the March 1 issue of Astrophysical Journal.
Unfortunately for us, gamma ray bursts seem to be shot right along the axis of systems. In essence, if this pinwheel ever releases a gamma ray burst, our planet might be in the firing line.
"This is the first object that we know of that might release a gamma ray burst at us," said astrophysicist Adrian Melott at the University of Kansas in Lawrence, who did not participate in this study. "And it's close enough to do some damage."
This pinwheel is about 8,000 light years away, roughly a quarter of the way to the center of the Milky Way Galaxy. While this might seem far, "earlier research has suggested that a gamma ray burst — if we are unfortunate enough to be caught in the beam — could be harmful to life on Earth out to these distances," Tuthill said.
What might happen
Although the pinwheel can't blast Earth apart like the Death Star from Star Wars — at least not from 8,000 light years away — it could still cause mass extinction or possibly even threaten life as we know it on our planet.
Gamma rays would not penetrate Earth's atmosphere well to burn the ground, but they would chemically damage the stratosphere. Melott estimates that if WR 104 were to hit us with a burst 10 seconds or so long, its gamma rays could deplete about 25 percent of the world's ozone layer, which protects us from damaging ultraviolet rays. In comparison, the recent human-caused thinning of the ozone layer, creating "holes" over the polar regions, have only been depletions of about 3 to 4 percent, he explained.
"So that would be very bad," Melott told SPACE.com. "You'd see extinctions. You might see food chain collapses in the oceans, might see agricultural crises with starvation."
Gamma ray bursts would also trigger smog formation that could blot out sunlight and rain down acid. However, at 8,000 light-years away, "there's probably not a large enough effect there for much of a darkening effect," Melott estimated. "It'd probably cut off 1 or 2 percent of total sunlight. It might cool the climate somewhat, but it wouldn't be a catastrophic ice age kind of thing."
Cosmic ray danger
One unknown about gamma ray bursts is how many particles they spew as cosmic rays.
"Normally the gamma ray bursts we see are so far away that magnetic fields out in the universe deflect any cosmic rays we might observe from them, but if a gamma ray burst was pretty close, any high-energy particles would blast right through the galaxy's magnetic field and hit us," Melott said. "Their energies would be so high, they would arrive at almost the same time as the light burst."
"The side of the Earth facing the gamma ray burst would experience something like getting irradiated by a not-too-distant nuclear explosion, and organisms on that side might see radiation sickness. And the cosmic rays would make the atmospheric effects of a gamma ray burst worse," Melott added. "But we just don't know how many cosmic rays gamma ray bursts emit, so that's a danger that's not really understood."
It remains uncertain just how wide the beams of energy that gamma ray bursts release are. However, any cone of devastation from the pinwheel would likely be several hundred square light-years wide by the time it reached Earth, Melott estimated. Tuthill told SPACE.com "it would be pretty much impossible to for anyone to get far enough to be out of the beam in a spaceship if it really is coming our way."
Don't worry
Still, Tuthill noted this pinwheel might not be the death of us.
"There are still plenty of uncertainties — the beam could pass harmlessly to the side if we are not exactly on the axis, and nobody is even sure if stars like WR 104 are capable of producing a fully-fledged gamma-ray burst in the first place," he explained.
Future research should focus on whether WR 104 really is pointed at Earth and on better understanding how supernovae produce gamma ray bursts.
Melott and others have speculated that gamma ray bursts might have caused mass extinctions on Earth. But when it comes to whether this pinwheel might pose a danger to us, "I would worry a lot more about global warming," Melott said.
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