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View Full Version : Researchers Find a Supernova, Before it Exploded



Fraser
2008-Feb-14, 09:00 PM
The problem with supernovae is that you never know where they're going to happen. Your only clue is the bright flash in the sky, and then it's too late. But a team of European researchers think they were lucky enough to have spotted the precursor to supernova.

More... (http://www.universetoday.com/2008/02/14/researchers-find-a-supernova-before-it-exploded/)

Noclevername
2008-Feb-14, 09:59 PM
But followup observations from Chandra show that the X-ray source is gone. Whatever was at that location isn't there any more. Perhaps it did indeed vaporize in a supernova explosion.

Oh, that was just the signature of the Space Modulator activation sequence... Oops, I've said too much.

trinitree88
2008-Feb-15, 12:54 PM
The problem with supernovae is that you never know where they're going to happen. Your only clue is the bright flash in the sky, and then it's too late. But a team of European researchers think they were lucky enough to have spotted the precursor to supernova.

More... (http://www.universetoday.com/2008/02/14/researchers-find-a-supernova-before-it-exploded/)

Fraser. There is another way to detect a precursor going supernova. It's giant stars ~ 8-25+ solar masses that are the precursors to core collapse Type 2's. One class of these is R Corona Borealis type stars. These are known as reverse novae, as they periodically dim by several magnitudes and then slowly return to their optical brightness. As they dim in visible, they brighten in infrared, so the total bolometric magnitude remains ~ constant.
This has been attributed to them blowing off ejecta rich in carbon, quenching the visible output, and the grains re-emit in the infrared. As they age and switch to ever heavier isotopes for fusion fuel, they become less efficient, leaking a larger and larger proportion of their energy away as neutrinos, and generating less heat per fusion due to the curve of binding energy. Their runaway fuel-consuming antics should produce a distinct signature during successive rebrightenings, as massive floods of neutrinos stream away through the outer cold carbon layers...a warning that the final years before supernova...less than 10 by most models,.. are imminent. ("R Corona Borealis, Infrared Enigma", Williams College, AAPT meeting Spring 1993). Shortly after this an R Cor Bor observing program was begun at ,I believe ,Southwest Louisiana State...so they might have some data to check out. pete

antoniseb
2008-Feb-15, 01:39 PM
There is another way to detect a precursor going supernova...

The way you describe is pretty interesting, though for the time being, being able to see Type 1a precursors seems more critical to our immediate needs for adding credibility to the current model of the universe.

Jerry
2008-Feb-16, 04:05 PM
This isn't a slam dunk, though. A higher-quality optical image shows the binary system to be in a slightly different position from where the supernova detonated. So maybe this system isn't the precursor after all.
Close only counts in cosmic rays, radio waves, and horseshoes.

When higher resolution images place the X-ray source in a 'slightly different position' nil points are scored for a theory that says that the X-rays are the signature of white dwarf accretion. In fact if anything, it proves exactly the opposite: This kind of X-ray event can occur in different positions from a supernova star, and even disappear after the event. Therefore future searches must be extremely careful not to 'cherry pick' random correlations and claim a victory for the accreting white dwarf theory.

This article takes the wrong message, an optomistic message to the public about the accreting white dwarf theory of supernova Ia explosions. Much of the evidence we have observed in the last decade points in other directions: the polarity of the light, the shape of the fireballs, the null evidence of X-ray accretion in other searches; and the wide diversity in near-local supernova Ia magnitudes: All of this evidence is running contrary to the accreting white dwarf theory.

Science is not like football: The high definition film has the final say, not the referee.

Jerry
2008-Feb-18, 09:10 PM
A case in point:

Limits on the X-ray and optical luminosity of the progenitor of the type Ia supernova SN2007sr

http://xxx.lanl.gov/PS_cache/arxiv/pdf/0802/0802.2239v1.pdf


We present HST/WFPC2, GALEX and Chandra observations of the position of the type Ia supernova SN2007sr in the Antennae galaxies, taken before the explosion. No source is found in any of the observations, allowing us to put interesting constraints on the progenitor luminosity...

The X-ray limit is comparable to the brightest supersoft X-ray sources in the Galaxy, the LMC and the SMC and significantly below the luminosities of the brightest supersoft and quasi-soft X-ray sources found in nearby galaxies, ruling these out as progenitors of this type Ia supernova.

Accretion of matter by a white dwarf star to the Chandrashker limit is an important assumption in supernova science. Without evidence of accretion, there is no reason to suppose that the mass explodes within a narrow range of masses...and a correspondingly narrow range of magnitudes.