Monday, February 12, 2007

How To Ingite A Cosmic Lighthouse

Researchers have been able to show that all supernovae of a certain type explode with the same mass and the same energy - the brightness depends only on how much nickel the supernova contains. This knowledge has allowed the researchers to calibrate the brightness of supernovae with greater precision. This means that in the future, they will use the brightness of a supernova that they are observing through their telescopes to determine more accurately how far away from the Earth the cosmic lighthouse is emitting its rays.

The arrow points to the supernova 2002bo, the explosion of a white dwarf in the galaxy NGC 3190 in the Leo constellation--60 million light years away from earth.Image: Benetti et al., MNRAS 384:261-278 (2004)

All supernovae have low-velocity cores of stable iron-group elements. Outside this core, nickel-56 dominates the supernova ejecta. The outer extent of the iron-group material depends on the amount of nickel-56 and coincides with the inner extent of silicon, the principal product of incomplete burning. The outer extent of the bulk of silicon is similar in all supernovae, having an expansion velocity of 11,000 kilometers per second and corresponding to a mass of slightly over one solar mass. This indicates that all the supernovae considered here burned similar masses and suggests that their progenitors had the same mass. link

A Common Explosion Mechanism for Type Ia Supernovae. 2007. P.A. Mazzali et al. Science.

Hey, Where's Capt. Kirk!?