 of a supernova in the Milky Way. This composite view combines a 1985 radio image (blue) with a 2007 x-ray image (red), showing the 16 percent spread of the remnant during the interval. )
G1.9+0.3 is the new youngest remnant (debris cloud) of a supernova in the Milky Way. This composite view combines a 1985 radio image (blue) with a 2007 x-ray image (red), showing the 16 percent spread of the remnant during the interval.
Image: X-ray (NASA/CXC/NCSU/S.Reynolds et al.); Radio (NSF/NRAO/VLA/Cambridge/D.Green et al.)
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Astronomers have discovered traces of a star that went supernova about 140 years ago as viewed from Earth*, around the time of the U.S. Civil War and the publication of Charles Darwin's The Origin of Species. The expanding debris cloud, or remnant, known as G1.9+0.3, lies near the center of the Milky Way, about 25,000 light-years from Earth.
Besides making G1.9+0.3 the youngest supernova remnant known in our galaxy, the finding begins to fill a peculiar astronomical gap. Based on studies of other galaxies, researchers estimate that about three supernovae should pop off per century in the Milky Way. They knew of one recent remnant, Cassiopeia A, which went supernova around 1680 by Earth's watch.
Researchers first identified G1.9+0.3 as a supernova remnant in 1985, using the National Science Foundation's Very Large Array (VLA), a sprawling network of radio telescopes in Soccoro, N.M. They estimated its age at 400 to 1,000 years old, Earth-time.
More than 20 years later, in 2007, a team observing the remnant via NASA's orbiting Chandra X-Ray Observatory found that it had grown by a surprising 16 percent, implying that the object was younger than they thought. When researchers checked double-checked using VLA, they got the same result, published in twin papers in The Astrophysical Journal Letters and Monthly Notices of the Royal Astronomical Society.
Despite the supernova's timing, contemporaries of Lincoln and Darwin would have missed it, because dust and gas surrounding the dying star would have blocked the flash of visible light. The expanding gas cloud shines brightly, however, in radio and x-ray frequencies.
G1.9+0.3 may be the tip of the iceberg. "If the supernova rate estimates are correct, there should be the remnants of about 10 supernova explosions in the Milky Way that are younger than Cassiopeia A," said David Green of the University of Cambridge in England, leader of the VLA study, in a statement. "It's great to finally track one of them down."
*Clarification (5/15/08): The supernova marked by G1.9+0.3 would have occurred 25,000 years ago, but because of its distance from Earth, the supernova's light would have first become visible 140 years ago.
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11 Comments
Add CommentIf the star is 25k light years away and it went supernova 140 years ago, doesn't that would mean the explosion actually happened 25,140 years ago? If true then the title "Remains of a 140 year-old supernovae discovered" is technicaly misleading. If not, please help me understand this phenomina by explaining the difference.
Reply | Report Abuse | Link to thisI was just about to post the obvious when I saw the first comment to my right. Of course it does not make sense that the star is 25,000 light years away and that it is stated that we see it went supernova 140 years ago. The writers at Scientific American these days don't seem to know much science, but are merely pop science writers.
Reply | Report Abuse | Link to thisIt would have to be 25,000 years plus 140 years. I agree with the very first comment on the list.
Would a supernova cause the aurora borealis to dramatically increase and spread south to Virginia?
Reply | Report Abuse | Link to thisThere was such an event during the Civil War battle of Fredricksburg in December 1862?
140 yr old ? Try 25,140. If an object is 25,000 light years away the actual supernova happened 25,000 years before the light reached Earth.
Reply | Report Abuse | Link to thisBasic physics.
The SciAm writers "don't know much science"? Please. It's all very well to criticize the headline as "misleading," but notice that the number 25,140 would be equally misleading, since (a) it implies a precision not in the measurement, and (b) it assumes an "absolute age" for the supernova, when its age actually depends on the relative velocity of the observer. Although it's fine to remind the SciAm folks that casual readers need to have this sort of thing continually re-explained, no one with a science background could fail to understand what is meant: the supernova is interesting because of how recently it would have been observable on Earth.
Reply | Report Abuse | Link to thisHere is another quandry. If the timing is figured right, how is it that in 25+ thousand years of age, 16%observed expansion can be reconciled in 22yrs.
Reply | Report Abuse | Link to thisVery good point Tucker, everything is relative to observation.
Reply | Report Abuse | Link to thisre: h20jo53
Reply | Report Abuse | Link to thisIf you read the article - the original estimate of age was 400 to 1000 years - the size 'x' and distance are relative to that estimated age
The revised age is due to the revisit -- with the size growing 16% in 22 years the supernova must be younger (faster expansion) than previously estimated.
welcome to science -- conclusions and 'facts' are always 'provisional' and are only as good as the observations and theories used to determine them.
We do have some very solid theories, that have been firmly substantiated by experiment and observation... but there is still a lot of room for discovery!
I am astounded that SciAm is promulgated this "140 year old supernova" misconception. Since the center of The Galaxy is 25,000 light-years away. The New York Times got this right, so should you.
Reply | Report Abuse | Link to thisYEAH,YEAH,YEAH,BUT ANY REASONABLE THINKER WOULD KNOW THAT WE COULD NOT SEE IT UNTIL 140 YEARS AGO; GIVE YOUR BRILLIANCES A REST , PLEASE!
Reply | Report Abuse | Link to thisThis supernova caused the Krakatoa volcanic explosion in 1883. Supernova blast waves leave a nuclear signature and it would still be detectable. The 1908 Tunguska event was a supernova blast wave.
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