Distances with <4% precision from type Ia supernovae in young star-forming environments

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Science  27 Mar 2015:
Vol. 347, Issue 6229, pp. 1459-1462
DOI: 10.1126/science.1261475

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A place where stars are more predictable

Astrophysicists use reference objects of known brightness to determine distances. For example, type Ia supernova (SN Ia) always reach nearly the same peak brightness. This is because they explode when the progenitor white dwarf exceeds its supportable mass threshold. Kelly et al. find that a particular subset of SN Ia—those in environments with high ultraviolet surface brightness and star-formation density—can calibrate distances even more tightly. It seems that only one or two intrinsic parameters may drive the apparent relationship between luminosity, color, and fading with time.

Science, this issue p. 1459


The luminosities of type Ia supernovae (SNe), the thermonuclear explosions of white-dwarf stars, vary systematically with their intrinsic color and the rate at which they fade. From images taken with the Galaxy Evolution Explorer (GALEX), we identified SNe Ia that erupted in environments that have high ultraviolet surface brightness and star-formation surface density. When we apply a steep model extinction law, we calibrate these SNe using their broadband optical light curves to within ~0.065 to 0.075 magnitude, corresponding to <4% in distance. The tight scatter, probably arising from a small dispersion among progenitor ages, suggests that variation in only one progenitor property primarily accounts for the relationship between their light-curve widths, colors, and luminosities.

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