[astro-ph/0611902] Spectropolarimetric diagnostics of thermonuclear supernova explosions

Authors:  Lifan Wang, Dietrich Baade, Ferdinando Patat
Abstract:  Even at extragalactic distances, the shape of supernova ejecta can be effectively diagnosed by spectropolarimetry. We present here results for 17 Type Ia supernovae that allow a statistical study of the correlation among the geometric structures and other observable parameters of Type Ia supernovae. These observations suggest that their ejecta typically consist of a smooth, central iron rich core and an outer layer with chemical asymmetries. The degree of this peripheral asphericity is correlated with the light-curve decline rate of Type Ia supernovae. These observations lend strong support to delayed-detonation models of Type Ia supernovae.
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Tommy Anderberg
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Joined: November 24 2005
Affiliation: independent

[astro-ph/0611902] Spectropolarimetric diagnostics of thermo

Post by Tommy Anderberg » December 01 2006

From ESO's press release:
"Our study reveals that explosions of Type Ia supernovae are really three-dimensional phenomena," he adds. "The outer regions of the blast cloud is asymmetric, with different materials found in 'clumps', while the inner regions are smooth."

The research team first spotted this asymmetry in 2003, as part of the same observational campaign (ESO PR 23/03 and ESO PR Photo 26/05). The new, more extensive results show that the degree of polarisation and, hence, the asphericity, correlates with the intrinsic brightness of the explosion. The brighter the supernova, the smoother, or less clumpy, it is.

"This has some impact on the use of Type Ia supernovae as standard candles," says Ferdinando Patat. "This kind of supernovae is used to measure the rate of acceleration of the expansion of the Universe, assuming these objects behave in a uniform way. But asymmetries can introduce dispersions in the quantities observed."

"Our discovery puts strong constraints on any successful models of thermonuclear supernova explosions," adds Wang.
I expect Middleditch (astro-ph/0608386) and Vishwakarma (astro-ph/0511628) will be all over this one. What I would like to know is: how much impact is "some impact"?

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