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When Stars Explode

Object of Study– What we’re looking at in class

February 27, 2018

Prof. Alison Crocker’s astrophysics class (Physics 364) covers the physics behind how stars form, remain in equilibrium for most of their lives, and then, sometimes, spectacularly explode or implode when nuclear reactions are exhausted.

Students recently learned about the Eddington limit, which poses an upper limit on the photon luminosity a star may emit before becoming dynamically unstable and ejecting its outer layers as a stellar wind.

High-mass stars undergo such a furious pace of nuclear reactions at their core that they surpass the Eddington limit in their luminous output. The image shown here is of a star known as WR (Wolf-Rayet) 134—the brightest star below the center of the image—illuminating material it has previously ejected.  WR 134 probably started out as a star about 45 times the mass of our sun, but has lost so much material it is now closer to 19 times the solar mass.

This image was taken by the 4 m Mayall telescope at Kitt Peak National Observatory, using filters to isolate emission from the 656 nm hydrogen line and the 673 nm doubly ionized sulfur line. These emission lines reveal the distribution of ionized gas in the nebula.