astronomy & space stuff
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linuxgeek
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AURORA WEEKEND: Auroras in Nebraska? California? Arizona? Believe it. On Saturday night, May 14th, Northern Lights rippled across the United States during an intense geomagnetic storm. The display was triggered by a solar coronal mass ejection (CME) hitting Earth's magnetic field. So much for the quiet sun.
http://www.spaceweather.com/aurora/images2005/15may05d/brumm1_strip.jpg
Above: Red auroras filled the skies above Marinette, Wisconsin on May 15th. "The reds actually painted the foreground of the picture without enhancement ... awesome," says photographer Rob Brumm.
http://www.spaceweather.com/aurora/images2005/15may05d/brumm1_strip.jpg
Above: Red auroras filled the skies above Marinette, Wisconsin on May 15th. "The reds actually painted the foreground of the picture without enhancement ... awesome," says photographer Rob Brumm.
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Planets with Two Suns Likely Common
In the Star Wars saga, the Skywalker clan has its roots on Tatooine – a desert-covered planet revolving around two suns. A theoretical investigation has explored the likelihood for worlds like this to exist.
And it looks like the nearest Tatooine may be closer than a galaxy far, far away.
That’s because more than half of the stars in our galaxy have a stellar companion. And yet, of the 130 or so currently known exoplanets (none of which are Earth-like), only about 20 of them are around so-called binaries. The percentage may grow higher. The current ratio is affected by an observational bias: planet hunters tend to avoid binaries because the star-star interactions can hide the planet signatures.
Scientists discussed the issue earlier this month at a gathering of exoplanet hunters at the Space Telescope Science Institute in Baltimore.
Bad to good
"A few years ago, it was thought that [binaries] were a very bad site to search for planets," says Michel Mayor of the Observatoire de Geneve. "So we carefully eliminated all binary stars from our sample."
But planets may be just as likely around binaries as around single stars. Recent numerical simulations have shown that Earth-like planets, known as terrestrials, form readily in double star systems.
"The most significant thing we found is that terrestrial planets around certain close and wide binaries can look similar to planets around a single star," said Jack Lissauer of the NASA Ames Research Center.
Wide binaries are those in which the two stars are separated by several astronomical units (AU), which is the distance between the Sun and the Earth. Planets could orbit around one of the pair, or each separately. So far, all the stellar binaries with exoplanets are wide binaries.
But close binaries, where the stars are less than about an AU apart, can potentially have planets in orbit around both stars – presumably as is the case for Tatooine. These planets, however, will be much harder to detect.
Lissauer and his collaborators have explored what binary star systems are favorable for planet formation. These limits could be useful in future planet searches.
Simulations
The researchers used computer models that start with 14 large planet "embryos" and 140 smaller planetesimals in orbit around one star or both stars of a binary. Evolution of this material is influenced by gravity and collisions. The models are followed for the equivalent of about one billion years.
"All of our simulations have been able to form terrestrial planets," said Ames researcher Elisa Quintana, who presented a poster on these results at the symposium.
But not all of the models produce planets around 1 AU, which is often thought to be the most likely habitable zone for life. Quintana varied how the two stars revolve around each other to see what configurations allowed for stable planet orbits inside 1 AU.
For wide binaries, Earth-like planets formed as long as the two stars came no closer than 7 AU. Quintana said that about 50 percent of known binaries meet this constraint.
The research group also ran simulations that mimicked Alpha Centauri – the nearest binary system to Earth, where the closest the two stars come is about 11 AU. The secondary star apparently acts like Jupiter does in our solar system – limiting how far out planets can form. The results showed several terrestrial planets were possible around either of the stars.
Planets have not yet been seen in the Alpha Centauri system, but small mass planets cannot yet be ruled out.
For close binaries, if the two stars are about 0.1 AU apart, the planets that form are indistinguishable from those seen in simulations with only one star. But as this separation increases, or the orbit becomes highly non-circular, it is harder for Earth-like planets to exist.
"Perturbations from the stellar motions can eject matter into space or into one of the stars," Quintana said.
The simulation results can inform observers which binaries might be better targets for their telescopes.
Observational hurdles
That said, it will not be easy to see a planet around a binary, especially those where the stars are close to each other. Most planets have been found by the radial velocity technique that searches for Doppler shifts in the light spectra of stars.
"Finding the wobble from a planet in a stellar spectrum is hard enough without having another star orbiting the one you are looking at," Quintana said.
An alternative way of detecting planets is to look for the eclipse, or transit, of a planet in front of a star. Lissauer said that transiting searches could potentially discover planets around close binaries, but "there are complications."
For one thing, two stars are putting out light, so the eclipse of one star is less noticeable. Also, the transit searches look for certain patterns of dimming and brightening of a star. If there are two stars in a tight orbit, this pattern will be different, so special algorithms will be needed.
But there are situations where a binary could provide an advantage for detecting planets. If the two stars eclipse each other, a planet could change when this eclipse happens.
"If the timing of the eclipses is not periodic, maybe a planet is to blame," Lissauer said.
Besides the possibility of transit timing, eclipsing binaries make good targets because planets – if they exist – will likely orbit in the same plane as the two stars – meaning they will also eclipse the stars at some point.
Which of these detection methods will be most likely to find the first Tatooine-like planet? Lissauer is unwilling to say.
"Predictions are tricky because they deal with the future," he joked.
Planets with Two Suns Likely Common
In the Star Wars saga, the Skywalker clan has its roots on Tatooine – a desert-covered planet revolving around two suns. A theoretical investigation has explored the likelihood for worlds like this to exist.
And it looks like the nearest Tatooine may be closer than a galaxy far, far away.
That’s because more than half of the stars in our galaxy have a stellar companion. And yet, of the 130 or so currently known exoplanets (none of which are Earth-like), only about 20 of them are around so-called binaries. The percentage may grow higher. The current ratio is affected by an observational bias: planet hunters tend to avoid binaries because the star-star interactions can hide the planet signatures.
Scientists discussed the issue earlier this month at a gathering of exoplanet hunters at the Space Telescope Science Institute in Baltimore.
Bad to good
"A few years ago, it was thought that [binaries] were a very bad site to search for planets," says Michel Mayor of the Observatoire de Geneve. "So we carefully eliminated all binary stars from our sample."
But planets may be just as likely around binaries as around single stars. Recent numerical simulations have shown that Earth-like planets, known as terrestrials, form readily in double star systems.
"The most significant thing we found is that terrestrial planets around certain close and wide binaries can look similar to planets around a single star," said Jack Lissauer of the NASA Ames Research Center.
Wide binaries are those in which the two stars are separated by several astronomical units (AU), which is the distance between the Sun and the Earth. Planets could orbit around one of the pair, or each separately. So far, all the stellar binaries with exoplanets are wide binaries.
But close binaries, where the stars are less than about an AU apart, can potentially have planets in orbit around both stars – presumably as is the case for Tatooine. These planets, however, will be much harder to detect.
Lissauer and his collaborators have explored what binary star systems are favorable for planet formation. These limits could be useful in future planet searches.
Simulations
The researchers used computer models that start with 14 large planet "embryos" and 140 smaller planetesimals in orbit around one star or both stars of a binary. Evolution of this material is influenced by gravity and collisions. The models are followed for the equivalent of about one billion years.
"All of our simulations have been able to form terrestrial planets," said Ames researcher Elisa Quintana, who presented a poster on these results at the symposium.
But not all of the models produce planets around 1 AU, which is often thought to be the most likely habitable zone for life. Quintana varied how the two stars revolve around each other to see what configurations allowed for stable planet orbits inside 1 AU.
For wide binaries, Earth-like planets formed as long as the two stars came no closer than 7 AU. Quintana said that about 50 percent of known binaries meet this constraint.
The research group also ran simulations that mimicked Alpha Centauri – the nearest binary system to Earth, where the closest the two stars come is about 11 AU. The secondary star apparently acts like Jupiter does in our solar system – limiting how far out planets can form. The results showed several terrestrial planets were possible around either of the stars.
Planets have not yet been seen in the Alpha Centauri system, but small mass planets cannot yet be ruled out.
For close binaries, if the two stars are about 0.1 AU apart, the planets that form are indistinguishable from those seen in simulations with only one star. But as this separation increases, or the orbit becomes highly non-circular, it is harder for Earth-like planets to exist.
"Perturbations from the stellar motions can eject matter into space or into one of the stars," Quintana said.
The simulation results can inform observers which binaries might be better targets for their telescopes.
Observational hurdles
That said, it will not be easy to see a planet around a binary, especially those where the stars are close to each other. Most planets have been found by the radial velocity technique that searches for Doppler shifts in the light spectra of stars.
"Finding the wobble from a planet in a stellar spectrum is hard enough without having another star orbiting the one you are looking at," Quintana said.
An alternative way of detecting planets is to look for the eclipse, or transit, of a planet in front of a star. Lissauer said that transiting searches could potentially discover planets around close binaries, but "there are complications."
For one thing, two stars are putting out light, so the eclipse of one star is less noticeable. Also, the transit searches look for certain patterns of dimming and brightening of a star. If there are two stars in a tight orbit, this pattern will be different, so special algorithms will be needed.
But there are situations where a binary could provide an advantage for detecting planets. If the two stars eclipse each other, a planet could change when this eclipse happens.
"If the timing of the eclipses is not periodic, maybe a planet is to blame," Lissauer said.
Besides the possibility of transit timing, eclipsing binaries make good targets because planets – if they exist – will likely orbit in the same plane as the two stars – meaning they will also eclipse the stars at some point.
Which of these detection methods will be most likely to find the first Tatooine-like planet? Lissauer is unwilling to say.
"Predictions are tricky because they deal with the future," he joked.
linuxgeek
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GOODBYE... and thanks for the auroras. Sunspot 759, the source of the May 15th geomagnetic storm, is about to disappear. It's being carried over the western limb of the Sun by the star's 27-day rotation. Any further eruptions from this 'spot will not be directed at Earth.
http://www.spaceweather.com/swpod2005/19may05/palmer.jpg
Above: Departing sunspot 759, photographed on May 18th by Gary Palmer of Los Angeles, CA.
http://www.spaceweather.com/swpod2005/19may05/palmer.jpg
Above: Departing sunspot 759, photographed on May 18th by Gary Palmer of Los Angeles, CA.
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FLOWER MOON: According to folklore, tonight's full moon is called the "Flower Moon." Why? Full moons in May shine down on the abundant flowers of late Spring. Step outside at sunset and watch the Flower Moon rise in the east--it's beautiful.
Be alert also for colorful coronas and rings around the moon, as in this May 19th picture from Andy Skinner of Yosemite Valley, Calfornia:
http://www.spaceweather.com/swpod2005/21may05/skinner.jpg
"On my way home from work, I saw this richly colored corona and began searching for something to block the moon," recalls Skinner. "A dead pine tree did the trick."
Be alert also for colorful coronas and rings around the moon, as in this May 19th picture from Andy Skinner of Yosemite Valley, Calfornia:
http://www.spaceweather.com/swpod2005/21may05/skinner.jpg
"On my way home from work, I saw this richly colored corona and began searching for something to block the moon," recalls Skinner. "A dead pine tree did the trick."
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http://www.universetoday.com/am/uploads/2005-0524voyager-lg.jpg
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Voyager 1 Enters the Heliosheath
Summary - (May 24, 2005) NASA's Voyager 1 spacecraft has traveled so far in our Solar System that it's reached the heliosheath. This is an area just past the termination shock region, where the solar wind crashes into the thin interstellar gas of the galaxy. It was difficult to detect exactly when Voyager 1 passed through the termination shock and into the heliosheath, because we have no data about interstellar space yet, just calculations.
NASA's Voyager 1 spacecraft has entered the solar system's final frontier. It is entering a vast, turbulent expanse where the Sun's influence ends and the solar wind crashes into the thin gas between stars.
"Voyager 1 has entered the final lap on its race to the edge of interstellar space," said Dr. Edward Stone, Voyager project scientist at the California Institute of Technology in Pasadena. Caltech manages NASA's Jet Propulsion Laboratory in Pasadena, which built and operates Voyager 1 and its twin, Voyager 2.
In November 2003, the Voyager team announced it was seeing events unlike any in the mission's then 26-year history. The team believed the unusual events indicated Voyager 1 was approaching a strange region of space, likely the beginning of this new frontier called the termination shock region. There was considerable controversy over whether Voyager 1 had indeed encountered the termination shock or was just getting close.
The termination shock is where the solar wind, a thin stream of electrically charged gas blowing continuously outward from the Sun, is slowed by pressure from gas between the stars. At the termination shock, the solar wind slows abruptly from a speed that ranges from 700,000 to 1.5 million miles per hour and becomes denser and hotter. The consensus of the team is that Voyager 1, at approximately 8.7 billion miles from the Sun, has at last entered the heliosheath, the region beyond the termination shock.
Predicting the location of the termination shock was hard, because the precise conditions in interstellar space are unknown. Also, changes in the speed and pressure of the solar wind cause the termination shock to expand, contract and ripple.
The most persuasive evidence that Voyager 1 crossed the termination shock is its measurement of a sudden increase in the strength of the magnetic field carried by the solar wind, combined with an inferred decrease in its speed. This happens whenever the solar wind slows down.
In December 2004, the Voyager 1 dual magnetometers observed the magnetic field strength suddenly increasing by a factor of approximately 2-1/2, as expected when the solar wind slows down. The magnetic field has remained at these high levels since December. NASA's Goddard Space Flight Center, Greenbelt, Md., built the magnetometers.
Voyager 1 also observed an increase in the number of high-speed electrically charged electrons and ions and a burst of plasma wave noise before the shock. This would be expected if Voyager 1 passed the termination shock. The shock naturally accelerates electrically charged particles that bounce back and forth between the fast and slow winds on opposite sides of the shock, and these particles can generate plasma waves.
"Voyager's observations over the past few years show the termination shock is far more complicated than anyone thought," said Dr. Eric Christian, Discipline Scientist for the Sun-Solar System Connection research program at NASA Headquarters, Washington.
The result is being presented today at a press conference in the Morial Convention Center, New Orleans, during the 2005 Joint Assembly meeting of Earth and space science organizations.
For their original missions to Jupiter and Saturn, Voyager 1 and sister spacecraft Voyager 2 were destined for regions of space far from the Sun where solar panels would not be feasible, so each was equipped with three radioisotope thermoelectric generators to produce electrical power for the spacecraft systems and instruments. Still operating in remote, cold and dark conditions 27 years later, the Voyagers owe their longevity to these Department of Energy-provided generators, which produce electricity from the heat generated by the natural decay of plutonium dioxide.
src
Voyager 1 Enters the Heliosheath
Summary - (May 24, 2005) NASA's Voyager 1 spacecraft has traveled so far in our Solar System that it's reached the heliosheath. This is an area just past the termination shock region, where the solar wind crashes into the thin interstellar gas of the galaxy. It was difficult to detect exactly when Voyager 1 passed through the termination shock and into the heliosheath, because we have no data about interstellar space yet, just calculations.
NASA's Voyager 1 spacecraft has entered the solar system's final frontier. It is entering a vast, turbulent expanse where the Sun's influence ends and the solar wind crashes into the thin gas between stars.
"Voyager 1 has entered the final lap on its race to the edge of interstellar space," said Dr. Edward Stone, Voyager project scientist at the California Institute of Technology in Pasadena. Caltech manages NASA's Jet Propulsion Laboratory in Pasadena, which built and operates Voyager 1 and its twin, Voyager 2.
In November 2003, the Voyager team announced it was seeing events unlike any in the mission's then 26-year history. The team believed the unusual events indicated Voyager 1 was approaching a strange region of space, likely the beginning of this new frontier called the termination shock region. There was considerable controversy over whether Voyager 1 had indeed encountered the termination shock or was just getting close.
The termination shock is where the solar wind, a thin stream of electrically charged gas blowing continuously outward from the Sun, is slowed by pressure from gas between the stars. At the termination shock, the solar wind slows abruptly from a speed that ranges from 700,000 to 1.5 million miles per hour and becomes denser and hotter. The consensus of the team is that Voyager 1, at approximately 8.7 billion miles from the Sun, has at last entered the heliosheath, the region beyond the termination shock.
Predicting the location of the termination shock was hard, because the precise conditions in interstellar space are unknown. Also, changes in the speed and pressure of the solar wind cause the termination shock to expand, contract and ripple.
The most persuasive evidence that Voyager 1 crossed the termination shock is its measurement of a sudden increase in the strength of the magnetic field carried by the solar wind, combined with an inferred decrease in its speed. This happens whenever the solar wind slows down.
In December 2004, the Voyager 1 dual magnetometers observed the magnetic field strength suddenly increasing by a factor of approximately 2-1/2, as expected when the solar wind slows down. The magnetic field has remained at these high levels since December. NASA's Goddard Space Flight Center, Greenbelt, Md., built the magnetometers.
Voyager 1 also observed an increase in the number of high-speed electrically charged electrons and ions and a burst of plasma wave noise before the shock. This would be expected if Voyager 1 passed the termination shock. The shock naturally accelerates electrically charged particles that bounce back and forth between the fast and slow winds on opposite sides of the shock, and these particles can generate plasma waves.
"Voyager's observations over the past few years show the termination shock is far more complicated than anyone thought," said Dr. Eric Christian, Discipline Scientist for the Sun-Solar System Connection research program at NASA Headquarters, Washington.
The result is being presented today at a press conference in the Morial Convention Center, New Orleans, during the 2005 Joint Assembly meeting of Earth and space science organizations.
For their original missions to Jupiter and Saturn, Voyager 1 and sister spacecraft Voyager 2 were destined for regions of space far from the Sun where solar panels would not be feasible, so each was equipped with three radioisotope thermoelectric generators to produce electrical power for the spacecraft systems and instruments. Still operating in remote, cold and dark conditions 27 years later, the Voyagers owe their longevity to these Department of Energy-provided generators, which produce electricity from the heat generated by the natural decay of plutonium dioxide.
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AURORA WATCH: Earth is slipping into a solar wind stream flowing from a coronal hole on the sun; so far the encounter has done little to spark auroras. There's still hope for some geomagnetic activity this weekend, however, because a coronal mass ejection (CME, movie) is heading toward Earth, due to arrive on May 28th or 29th. The CME is not a big one, but it might spark high latitude auroras over, say, Canada and Scandinavia.
ACTIVE SUNSPOT: The CME now en route to Earth was propelled in our direction by an explosion near sunspot 767. This fast-growing sunspot has an unstable magnetic field that harbors energy for more eruptions. M-class flares are possible this weekend.
http://www.spaceweather.com/swpod2005/28may05/weber_strip.jpg
Above: Sunspot 767 photographed on May 27th by Eva Seidenfaden and Markus Weber of Trier, Germany.
http://www.spaceweather.com/images2005/28may05/midi140.gif
ACTIVE SUNSPOT: The CME now en route to Earth was propelled in our direction by an explosion near sunspot 767. This fast-growing sunspot has an unstable magnetic field that harbors energy for more eruptions. M-class flares are possible this weekend.
http://www.spaceweather.com/swpod2005/28may05/weber_strip.jpg
Above: Sunspot 767 photographed on May 27th by Eva Seidenfaden and Markus Weber of Trier, Germany.
http://www.spaceweather.com/images2005/28may05/midi140.gif
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WEAK IMPACT: A coronal mass ejection (CME, movie) hit Earth's magnetic field today, May 29th at 0930 GMT, but the impact was weak. It did not trigger a strong geomagnetic storm. Nevertheless, faint auroras were seen over Canada:
http://www.spaceweather.com/aurora/images2005/29may05/harry1_strip.jpg
"There was a faint reddish glow in the night sky so I got my camera and took a few shots," says photographer Laurence Harry of Nanaimo, British Columbia. "I soon realized it was the aurora borealis."
http://www.spaceweather.com/aurora/images2005/29may05/harry1_strip.jpg
"There was a faint reddish glow in the night sky so I got my camera and took a few shots," says photographer Laurence Harry of Nanaimo, British Columbia. "I soon realized it was the aurora borealis."
linuxgeek
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ALERT: If it's dark where you live, go outside and look for auroras. A strong geomagnetic storm is underway.
http://www.sec.noaa.gov/rt_plots/kp_3d_200505301515.gif
"Neighbourhood dogs were barking very noisily around the village. I went outside to found green lights all over the sky," says Yuichi Takasaka of New Aiyansh, British Columbia. He took this picture early this morning:
http://www.spaceweather.com/aurora/images2005/30may05/takasaka1.jpg
The ongoing storm is fueled by the interplanetary magnetic field (IMF), which has been tipping south for many hours. South-tipping IMFs are a key ingredient of good auroral displays.
http://www.sec.noaa.gov/rt_plots/kp_3d_200505301515.gif
"Neighbourhood dogs were barking very noisily around the village. I went outside to found green lights all over the sky," says Yuichi Takasaka of New Aiyansh, British Columbia. He took this picture early this morning:
http://www.spaceweather.com/aurora/images2005/30may05/takasaka1.jpg
The ongoing storm is fueled by the interplanetary magnetic field (IMF), which has been tipping south for many hours. South-tipping IMFs are a key ingredient of good auroral displays.
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linuxgeek
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WOW: May was a good month for auroras. The action began on May 15th when a coronal mass ejection (CME) hit Earth's magnetic field and sent auroras rippling across the United States. Beautiful lights were seen as far south as Arizona and California.
A lesser CME hit Earth on May 29th. Auroras didn't spread as far south as California, but they did reach, e.g., Wisconsin where "the show was impressive," says photographer Jeffrey R Hapeman. He took this picture at Lac du Flambeau:
http://www.spaceweather.com/aurora/images2005/29may05/Hapeman1_strip.jpg
Could June be just as good? The outlook this week: no auroras. But that's how May started, too. Stay tuned.
A lesser CME hit Earth on May 29th. Auroras didn't spread as far south as California, but they did reach, e.g., Wisconsin where "the show was impressive," says photographer Jeffrey R Hapeman. He took this picture at Lac du Flambeau:
http://www.spaceweather.com/aurora/images2005/29may05/Hapeman1_strip.jpg
Could June be just as good? The outlook this week: no auroras. But that's how May started, too. Stay tuned.
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SOLAR ACTIVITY: Astronomers are monitoring the sun's limb, which has been beautifully active this week. Yesterday in Los Angeles, California, Didier Favre photographed a prominence five times taller than the entire planet Earth:
http://www.spaceweather.com/swpod2005/02jun05/favre1_strip.jpg
Prominences are regions of hot, dense gas held aloft by solar magnetic force fields. Occasionally they collapse and explode. More often they remain aloft for days (even weeks), eventually sinking gently back into the sun. Several prominences are visible on the sun today.
http://www.spaceweather.com/swpod2005/02jun05/favre1_strip.jpg
Prominences are regions of hot, dense gas held aloft by solar magnetic force fields. Occasionally they collapse and explode. More often they remain aloft for days (even weeks), eventually sinking gently back into the sun. Several prominences are visible on the sun today.
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White Dwarfs in a Death Spiral
Summary - (May 31, 2005) New observations from the Chandra X-Ray Observatory have discovered two white dwarf stars orbiting one another at a tremendous speed - they're only 80.000 km (50,000 miles) apart! The rate at which they're orbiting is decreasing by 1.2 milliseconds every year, which means they're destined to eventually collide. What's important about this find is that the stars are probably creating gravity waves, as predicted by Einstein, and these gravity waves should increase as they get closer and closer.
http://www.universetoday.com/am/uploads/2005-0531spiral-full.jpg
Full Story - A scientist using NASA's Chandra X-ray Observatory has found evidence that two white dwarf stars are orbiting each other in a death grip, destined to merge. The data indicate that gravitational waves are carrying energy away from the star system at a prodigious rate - making it a prime candidate for future missions designed to directly detect these subtle ripples in space-time.
Einstein's General Theory of Relativity predicts that a binary star system should emit gravitational waves, which rush away at the speed of light and cause the stars to move closer together. The orbital period of this system, known as RX J0806.3+1527, or J0806, is decreasing by 1.2 milliseconds every year, a rate consistent with theory.
The white dwarf pair in J0806 might have the smallest orbit of any known binary system with the stars only about 50,000 miles apart, a fifth of the distance from the Earth to the Moon. As the stars swirl closer together, traveling in excess of a million miles per hour, the production of gravitational waves increases.
"If confirmed, J0806 could be one of the brightest sources of gravitational waves in our Galaxy," said Tod Strohmayer of NASA's Goddard Space Flight Center of Greenbelt, Md., who presents his results today at the American Astronomical Society meeting in Minneapolis, Minn. "It could be among the first to be detected directly with an upcoming space mission called LISA, the Laser Interferometer Space Antenna."
White dwarfs are remnants of stars like our Sun that have used up all their fuel. Along with neutron stars and black holes, white dwarfs are called compact objects because they pack a lot of mass into a small volume. The white dwarfs in the J0806 system each have an estimated mass half that of the Sun, yet are only about the size of Earth.
Optical and X-ray observations of J0806 show periodic variations with a period of 321.5 seconds - barely more than five minutes. The observed five-minute period in J0806 is most likely the orbital period of the white dwarf system. However the possibility that it represents the spin of one of its white dwarfs cannot yet be completely ruled out.
"It's either the most compact binary known or one of the most unusual systems we've ever seen," said Strohmayer. "Either way it's got a great story to tell."
Strohmayer's Chandra X-ray observations, which will be published in an upcoming issue of The Astrophysical Journal, tighten orbital decay estimates made through optical observations in recent years independently by teams led by GianLuca Israel of the Astronomical Observatory of Rome and by Pasi Hakala of the University of Helsinki.
NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate, Washington. Northrop Grumman of Redondo Beach, Calif., was the prime development contractor for the observatory. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.
Additional information and images are available at: http://chandra.harvard.edu and http://chandra.nasa.gov
White Dwarfs in a Death Spiral
Summary - (May 31, 2005) New observations from the Chandra X-Ray Observatory have discovered two white dwarf stars orbiting one another at a tremendous speed - they're only 80.000 km (50,000 miles) apart! The rate at which they're orbiting is decreasing by 1.2 milliseconds every year, which means they're destined to eventually collide. What's important about this find is that the stars are probably creating gravity waves, as predicted by Einstein, and these gravity waves should increase as they get closer and closer.
http://www.universetoday.com/am/uploads/2005-0531spiral-full.jpg
Full Story - A scientist using NASA's Chandra X-ray Observatory has found evidence that two white dwarf stars are orbiting each other in a death grip, destined to merge. The data indicate that gravitational waves are carrying energy away from the star system at a prodigious rate - making it a prime candidate for future missions designed to directly detect these subtle ripples in space-time.
Einstein's General Theory of Relativity predicts that a binary star system should emit gravitational waves, which rush away at the speed of light and cause the stars to move closer together. The orbital period of this system, known as RX J0806.3+1527, or J0806, is decreasing by 1.2 milliseconds every year, a rate consistent with theory.
The white dwarf pair in J0806 might have the smallest orbit of any known binary system with the stars only about 50,000 miles apart, a fifth of the distance from the Earth to the Moon. As the stars swirl closer together, traveling in excess of a million miles per hour, the production of gravitational waves increases.
"If confirmed, J0806 could be one of the brightest sources of gravitational waves in our Galaxy," said Tod Strohmayer of NASA's Goddard Space Flight Center of Greenbelt, Md., who presents his results today at the American Astronomical Society meeting in Minneapolis, Minn. "It could be among the first to be detected directly with an upcoming space mission called LISA, the Laser Interferometer Space Antenna."
White dwarfs are remnants of stars like our Sun that have used up all their fuel. Along with neutron stars and black holes, white dwarfs are called compact objects because they pack a lot of mass into a small volume. The white dwarfs in the J0806 system each have an estimated mass half that of the Sun, yet are only about the size of Earth.
Optical and X-ray observations of J0806 show periodic variations with a period of 321.5 seconds - barely more than five minutes. The observed five-minute period in J0806 is most likely the orbital period of the white dwarf system. However the possibility that it represents the spin of one of its white dwarfs cannot yet be completely ruled out.
"It's either the most compact binary known or one of the most unusual systems we've ever seen," said Strohmayer. "Either way it's got a great story to tell."
Strohmayer's Chandra X-ray observations, which will be published in an upcoming issue of The Astrophysical Journal, tighten orbital decay estimates made through optical observations in recent years independently by teams led by GianLuca Israel of the Astronomical Observatory of Rome and by Pasi Hakala of the University of Helsinki.
NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate, Washington. Northrop Grumman of Redondo Beach, Calif., was the prime development contractor for the observatory. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.
Additional information and images are available at: http://chandra.harvard.edu and http://chandra.nasa.gov
linuxgeek
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Strange Ozone Hole this Year
Summary - (Jun 3, 2005) Even through large levels of ozone were destroyed in the Earth's atmosphere this winter, NASA's Aura spacecraft detected that the ozone layer is actually looking quite healthy above the arctic, and did its job stopping harmful ultraviolet radiation. This strange paradox is explained by a very unusual winter in the Arctic, where stratospheric winds brought in large quantities of ozone from the Earth's middle latitudes. This was the first winter monitored by Aura, which was launched in 2004.
http://www.universetoday.com/am/uploads/2005-0603ozone-full.jpg
Full Story - Despite near-record levels of chemical ozone destruction in the Arctic this winter, observations from NASA's Aura spacecraft showed that other atmospheric processes restored ozone amounts to near average and stopped high levels of harmful ultraviolet radiation from reaching Earth's surface.
Analyses from Aura's Microwave Limb Sounder indicated Arctic chemical ozone destruction this past winter peaked at near 50 percent in some regions of the stratosphere, a region of Earth's atmosphere that begins about 8 to 12 kilometers (5 to 7 miles) above Earth's poles. This was the second highest level ever recorded, behind the 60 percent level estimated for the 1999-2000 winter. Data from another instrument on Aura, the Ozone Monitoring Instrument, found the total amount of ozone over the Arctic this past March was similar to other recent years when much less chemical ozone destruction occurred. So what tempered the ozone loss? The answer appears to lie in this year's unusual Arctic atmospheric conditions.
"This was one of the most unusual Arctic winters ever," said scientist Dr. Gloria Manney of NASA's Jet Propulsion Laboratory, Pasadena, Calif., who led the Microwave Limb Sounder analyses. "Arctic lower stratospheric temperatures were the lowest on record. But other conditions like wind patterns and air motions were less conducive to ozone loss this year."
While the Arctic polar ozone was being chemically destroyed toward the end of winter, stratospheric winds shifted and transported ozone-rich air from Earth's middle latitudes into the Arctic polar region, resulting in little net change in the total amount of ozone. As a result, harmful ultraviolet radiation reaching Earth's surface remained at near-normal levels.
Imagery and an animation depicting the Microwave Limb Sounder and Ozone Monitoring Instrument 2005 Arctic ozone observations may be viewed at:
http://www.nasa.gov/vision/earth/lookingatearth/ozone-aura.html
Extensive ozone loss occurs each winter over Antarctica (the "ozone hole") due to the extreme cold there and its strong, long-lived polar vortex (a band of winds that forms each winter at high latitudes). This vortex isolates the region from middle latitudes. In contrast, the Arctic winter is warmer and its vortex is weaker and shorter-lived. As a result, Arctic ozone loss has always been lower, more variable and much more difficult to quantify.
This was the first Arctic winter monitored by Aura, which was launched in July 2004. Aura's Microwave Limb Sounder is contributing to our understanding of the processes that cause Arctic wind patterns to push ozone-rich air to the Arctic lower stratosphere from higher altitudes and lower latitudes. Through Aura's findings, scientists can differentiate chemical ozone destruction from ozone level changes caused by air motions, which vary dramatically from year to year.
"Understanding Arctic ozone loss is critical to diagnosing the health of Earth's ozone layer," said Dr. Phil DeCola, Aura program scientist at NASA Headquarters, Washington. "Previous attempts to quantify Arctic ozone loss have suffered from a lack of data. With Aura, we now have the most comprehensive, simultaneous, global daily measurements of many of the key atmospheric gases needed to understand and quantify chemical ozone destruction."
Ozone loss in Earth's stratosphere is caused primarily by chemical reactions with chlorine from human-produced compounds like chlorofluorocarbons. When stratospheric temperatures drop below minus 78 degrees Celsius (minus 108 degrees Fahrenheit), polar stratospheric clouds form. Chemical reactions on the surfaces of these clouds activate chlorine, converting it into forms that destroy ozone when exposed to sunlight.
The data obtained by Aura were independently confirmed by instruments participating in NASA's Polar Aura Validation Experiment, which flew underneath Aura as it passed over the polar vortex. The experiment, flown on NASA's DC-8 flying laboratory from NASA's Dryden Flight Research Center, Edwards, Calif., carried 10 instruments to measure temperatures, aerosols, ozone, nitric acid and other gases. The experiment was carried out in January and February 2005.
Aura is the third and final major Earth Observing System satellite. Aura carries four instruments: the Ozone Monitoring Instrument, built by the Netherlands and Finland in collaboration with NASA; the High Resolution Dynamics Limb Sounder, built by the United Kingdom and the United States; and the Microwave Limb Sounder and Tropospheric Emission Spectrometer, both built by JPL. Aura is managed by NASA's Goddard Space Flight Center, Greenbelt, Md.
For more information on Aura on the Internet, visit: http://aura.gsfc.nasa.gov/
For more information on the Microwave Limb Sounder on the Internet, visit: http://mls.jpl.nasa.gov/
Strange Ozone Hole this Year
Summary - (Jun 3, 2005) Even through large levels of ozone were destroyed in the Earth's atmosphere this winter, NASA's Aura spacecraft detected that the ozone layer is actually looking quite healthy above the arctic, and did its job stopping harmful ultraviolet radiation. This strange paradox is explained by a very unusual winter in the Arctic, where stratospheric winds brought in large quantities of ozone from the Earth's middle latitudes. This was the first winter monitored by Aura, which was launched in 2004.
http://www.universetoday.com/am/uploads/2005-0603ozone-full.jpg
Full Story - Despite near-record levels of chemical ozone destruction in the Arctic this winter, observations from NASA's Aura spacecraft showed that other atmospheric processes restored ozone amounts to near average and stopped high levels of harmful ultraviolet radiation from reaching Earth's surface.
Analyses from Aura's Microwave Limb Sounder indicated Arctic chemical ozone destruction this past winter peaked at near 50 percent in some regions of the stratosphere, a region of Earth's atmosphere that begins about 8 to 12 kilometers (5 to 7 miles) above Earth's poles. This was the second highest level ever recorded, behind the 60 percent level estimated for the 1999-2000 winter. Data from another instrument on Aura, the Ozone Monitoring Instrument, found the total amount of ozone over the Arctic this past March was similar to other recent years when much less chemical ozone destruction occurred. So what tempered the ozone loss? The answer appears to lie in this year's unusual Arctic atmospheric conditions.
"This was one of the most unusual Arctic winters ever," said scientist Dr. Gloria Manney of NASA's Jet Propulsion Laboratory, Pasadena, Calif., who led the Microwave Limb Sounder analyses. "Arctic lower stratospheric temperatures were the lowest on record. But other conditions like wind patterns and air motions were less conducive to ozone loss this year."
While the Arctic polar ozone was being chemically destroyed toward the end of winter, stratospheric winds shifted and transported ozone-rich air from Earth's middle latitudes into the Arctic polar region, resulting in little net change in the total amount of ozone. As a result, harmful ultraviolet radiation reaching Earth's surface remained at near-normal levels.
Imagery and an animation depicting the Microwave Limb Sounder and Ozone Monitoring Instrument 2005 Arctic ozone observations may be viewed at:
http://www.nasa.gov/vision/earth/lookingatearth/ozone-aura.html
Extensive ozone loss occurs each winter over Antarctica (the "ozone hole") due to the extreme cold there and its strong, long-lived polar vortex (a band of winds that forms each winter at high latitudes). This vortex isolates the region from middle latitudes. In contrast, the Arctic winter is warmer and its vortex is weaker and shorter-lived. As a result, Arctic ozone loss has always been lower, more variable and much more difficult to quantify.
This was the first Arctic winter monitored by Aura, which was launched in July 2004. Aura's Microwave Limb Sounder is contributing to our understanding of the processes that cause Arctic wind patterns to push ozone-rich air to the Arctic lower stratosphere from higher altitudes and lower latitudes. Through Aura's findings, scientists can differentiate chemical ozone destruction from ozone level changes caused by air motions, which vary dramatically from year to year.
"Understanding Arctic ozone loss is critical to diagnosing the health of Earth's ozone layer," said Dr. Phil DeCola, Aura program scientist at NASA Headquarters, Washington. "Previous attempts to quantify Arctic ozone loss have suffered from a lack of data. With Aura, we now have the most comprehensive, simultaneous, global daily measurements of many of the key atmospheric gases needed to understand and quantify chemical ozone destruction."
Ozone loss in Earth's stratosphere is caused primarily by chemical reactions with chlorine from human-produced compounds like chlorofluorocarbons. When stratospheric temperatures drop below minus 78 degrees Celsius (minus 108 degrees Fahrenheit), polar stratospheric clouds form. Chemical reactions on the surfaces of these clouds activate chlorine, converting it into forms that destroy ozone when exposed to sunlight.
The data obtained by Aura were independently confirmed by instruments participating in NASA's Polar Aura Validation Experiment, which flew underneath Aura as it passed over the polar vortex. The experiment, flown on NASA's DC-8 flying laboratory from NASA's Dryden Flight Research Center, Edwards, Calif., carried 10 instruments to measure temperatures, aerosols, ozone, nitric acid and other gases. The experiment was carried out in January and February 2005.
Aura is the third and final major Earth Observing System satellite. Aura carries four instruments: the Ozone Monitoring Instrument, built by the Netherlands and Finland in collaboration with NASA; the High Resolution Dynamics Limb Sounder, built by the United Kingdom and the United States; and the Microwave Limb Sounder and Tropospheric Emission Spectrometer, both built by JPL. Aura is managed by NASA's Goddard Space Flight Center, Greenbelt, Md.
For more information on Aura on the Internet, visit: http://aura.gsfc.nasa.gov/
For more information on the Microwave Limb Sounder on the Internet, visit: http://mls.jpl.nasa.gov/
linuxgeek said:
Linux, are these winds the same ones that have disrupted the high-tension grid in upper latitudes, i.e. Canada? I remember reading about these a few years ago, driving power grids crazy with low-voltage DC signals (1-2VDC) injected across transformers, burning them out. Are we in for a dark summer?
linuxgeek
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Gringao said:
they are one of the thing which will trigger the Geomagnetic Storms which can screw with the power grids. Hits by CME from solar flares can trigger strong storms which will do it also.
http://sec.noaa.gov/NOAAscales/
Ishmael
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linuxgeek said:
Well me for sure linux. Somehow the thought of an infinite number of universes floating around like bubbles in a glass of beer satisfies my belief in unintended consequences.
It also satifies my belief that it can all end tomorrow, universally speaking. The ancients attribute the end to the 'wrath of God' or some other event which, if only we are 'pure' enough, we can avoid. If SS theory is correct, the end of our universe is nothing more than the collision of two bubbles in that glass of beer (our bubble being one of the two) and in the destruction of the two, a new universe is created. The point there being that the bubbles can meet tomorrow and the life expectancy of the sun is pretty much a moot point. (The math is a little more subtle than that in that absorption and dispersion can occur but entropy is conserved.)
It all happens on the 11th dimension.
Ishmael
Last edited:
linuxgeek
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SUNSPOT WATCH: Two big sunspots, 775 and 776, have been growing this week, and they now have complex magnetic fields that harbor energy for M- or X-class solar flares. Stay tuned for possible solar activity.
http://www.spaceweather.com/images2005/09jun05/midi360_anim.gif
Above: A 5-day animation of sunspots 775 and 776, spanning June 5th - 9th. Credit: SOHO
http://www.spaceweather.com/images2005/09jun05/midi140.gif
http://www.spaceweather.com/images2005/09jun05/midi360_anim.gif
Above: A 5-day animation of sunspots 775 and 776, spanning June 5th - 9th. Credit: SOHO
http://www.spaceweather.com/images2005/09jun05/midi140.gif
