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trinitree88
2009-Oct-15, 06:58 PM
Bob Kirshner has carved out a nice career at Harvard University, where he has followed the evolution of extreme stars in ultraviolet spectroscopy and supernova theory. (Supernova Cosmology Project ). He caps a long view of the development of the use of SNe as standard candles with a view towards the future where we combine infrared assessments of dust extinction properties with optical light curves to better understand these objects. The present luminosity spread in type 1a's is at least a factor of three, notwithstanding polarimetric studies, and the latest analysis of past data bases indicates the different filters used on the different instruments plays a larger role than previously thought.. SEE:http://arxiv.org/PS_cache/arxiv/pdf/0910/0910.0257v1.pdf

Jerry
2009-Oct-26, 02:35 PM
http://arxiv.org/abs/0910.4403v1

Lifting the Dusty Veil II: A Large-Scale Study of the Galactic Infrared Extinction Law


Our analyses suggest that the observed relationship between extinction curve shape and Galactic longitude is due to an intrinsic dependence of the extinction law on Galactocentric radius.

A very curious result.

We really do not understand light extinction.

EricFD
2009-Oct-27, 01:33 AM
Interesting stuff! Thanks for the links.

Kwalish Kid
2009-Oct-27, 04:10 AM
The Kirshner article is a good review and covers the new research well. I wish it was written a while ago, it would have helped my thesis along!

The present luminosity spread in type 1a's is at least a factor of three
The original quote is, "Despite hope for a different result, and a theoretical argument why their luminosities should lie in a narrow range, Type Ia supernovae simply are not standard candles: they are known to vary over a factor of three in their intrinsic luminosity."

This comes in the context of discussing SNe Ia before 1993. At that time, the peak brightness to light curve relationship was established that could make SNe Ia effective standard candles. The current research is not the sort that could seriously place dark energy in doubt: it is looking for the equation of state of this energy, to see whether or not it is a cosmological constant or a scalar field.