Posted on 03/27/2003 5:51:09 AM PST by Sabertooth
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Hubble Chronicles Mysterious Outburst with 'Eye-Popping' Pictures By Robert Roy Britt Senior Science Writer posted: 02:00 pm ET 26 March 2003 |
An eruptive star that brightened to 600,000 times its initial intensity and briefly outshone all others in the Milky Way Galaxy has astronomers amazed and puzzled over what happened.
The star's light bounces off surrounding dust clouds, creating a spectacular "light echo" in a series of new images from the Hubble Space Telescope. The echo is seen to grow over time as the light races out to fresh layers of material, presumed to have been cast into space long ago by one or more eruptions of the star. The light bounces off that dust and is reflected toward Earth.
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That is not the strange part.
The star, named V838 Monocerotis, has suddenly grown so big that if placed in the center of our solar system it would engulf Jupiter.
Oddly, it isn't hot and eruptive in the manner of a supernova or nova, both of which toss off outer layers in explosive fits. Instead, V838 Mon, as astronomers call it, achieved remarkable brilliance while swelling to gargantuan size and remaining cool at its surface.
"A supernova would have been much brighter than V838 Mon, so that is ruled out," said Howard Bond, a Space Telescope Science Institute researcher who led the observations. "V838 Mon was roughly as bright as an ordinary nova, but its behavior was very different."
When a nova ejects its outer layers, a hot core is exposed, Bond explained. V838 Mon did not explosively eject its outer envelope, so it remained cool throughout the event, which was observed from April to December 2002.
"In fact, at present it is one of the coolest stars known," Bond told SPACE.com.
The surface of V838 Mon is about 3,600 degrees Fahrenheit (2,000 degrees Celsius), less than half that at the surface of the Sun. The observations will be detailed in the March 27 issue of the journal Nature.
'Eye-popping'
The pictures were publicly released today, but astronomers have been cooing over them for nearly three months.
"These are eye-popping images," said Karen Kwitter, a Williams College astronomer who was not involved in the study. "I couldn't believe it at first. Astronomers are not used to seeing stars change on such a short time scale."
Scientists don't know how long ago or how often the star might have erupted, apparently filling the space around it with dust. This material is thought to be racing away from the star, but not near as fast as the fresh burst of light that illuminates the dust and continually overtakes new regions of it to create the expanding light echo.
The visible structure around V838 Mon grows from 4 to 7 light-years during the sequence. Bond said if the dust is expanding at 223,700 mph (100 kilometers per second), then some of it was hurled into space about 20,000 years ago.
"We are still working out the detailed structure of the dust, which will take more observations as the echoes continue to evolve," he said. "So we're not yet sure whether there are multiple shells that indicate multiple outbursts."
The star has now been observed with ground-based observatories, too, but researchers still don't know what sort of celestial animal they are dealing with. They suspect the star might have flung a relatively small portion of its outer shell into space, then expanded and cooled.
"We don't understand the outburst or its cause, Sumner Starrfield, an Arizona State University astronomer, said in a January interview at a meeting of the American Astronomical Society, where the images were previewed.
"This object got bigger and brighter and cooler, but we don't know why," Starrfield said today. "Right now we know the effects and we're trying to use the effects to determine the cause."
Second star
Starrfield and colleague R. Mark Wagner of the University of Arizona, looking at V838 Mon from the ground, did learn that it has a smaller, hotter companion. Because the smaller star is of a common type, the researchers were able to use its brightness to estimate a distance to the pair, which they put at 20,000 light-years or more.
That means the currently observed outburst actually took place 20,000 years ago, and the light from the developing echo is just now arriving here. Because of the great distance, the light diminished to the point that the star was visible from Earth only with binoculars or telescopes.
The light echo is expected to continue growing for another decade or so, Earth time, so further study is planned.
"This research will likely have significant impact on our understanding of the late phases of stellar evolution," said Phil Ianna of the National Science Foundation, which helped fund the research. Kwitter, the Williams College astronomer, agreed with the scientists who studied V838 Mon and determined only that it is a strange beast.
"To create an outburst as sudden and as luminous as V838 Mon's, you have to do something pretty significant to the star," Kwitter said. "Right now we have no idea what. There are some interesting theories involving binary companion interactions or planet swallowing that may turn out to be relevant, but the truth is that nobody knows yet why this happened." Kwitter said the light echo, one of only a few that have ever been examined, may be a relatively common phenomenon that just has not been spotted very often because it doesn't last long. "It's like a flower that blooms for 1 second," she suggested. "What are the odds that you're looking right at it the moment it opens? If you had blinked or glanced at it 5 seconds earlier or later, you'd have missed it."
Let me know if you'd like to be on my Science/Crevo list.
"The star, named V838 Monocerotis, has suddenly grown so big ... "So, Monica (for short) has blown, and gives evidence of having blown before, is getting big, and there is suspicion of planet swallowing. There may be something to this astrology after all."There are some interesting theories involving binary companion interactions or planet swallowing that may turn out to be relevant ..."
Well, giving credit where credit is due--a few centuries back they invented the zero (0) and we still use 'arabic numerals' instead of Roman ones.
For a while there they were decent astronomers and 'alchemists'. Many star names derive from arabic, for example. Also the roots of algebra (the word itself has an arabic origin). Other than that, not much, especially in the last 500 years or so.
--Boris
NONE!!!
What does this have to do with the thread?
NOTHING!!!
Didn't they give us the zero?
Averroes (Consider the source, but this article isn't stating anything controversial.)
Yeah right. And my name's Buck Rogers. Must be the April 1st issue of Space.com :)
I realize they are speaking in relative terms to other star temperatures but no human would feel those are cool readings from a personal perspective. Those photos are definitely cool though. :)
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