Dying Star Emits a Whisper

Caltech News tagged with “astronomy + exoplanets + JPL + planetary_science”

A Caltech-led team of researchers has observed the peculiar death of a massive star that exploded in a surprisingly faint and rapidly fading supernova. These observations suggest that the star has an unseen companion, gravitationally siphoning away the star’s mass to leave behind a stripped star that exploded in a quick supernova. The explosion is believed to have resulted in a dead neutron star orbiting around its dense and compact companion, suggesting that, for the first time, scientists have witnessed the birth of a compact neutron star binary system.The research was led by graduate student Kishalay De and is described in a paper appearing in the October 12 issue of the journal Science. The work was done primarily in the laboratory of Mansi Kasliwal (MS ’07, PhD ’11), assistant professor of astronomy. Kasliwal is the principal investigator of the Caltech-led Global Relay of Observatories Watching Transients Happen (GROWTH) project.When a massive star—at least eight times the mass of the sun—runs out of fuel to burn in its core, the core collapses inwards upon itself and then rebounds outward in a powerful explosion called a supernova. After the explosion, all of the star’s outer layers have been blasted away, leaving behind a dense neutron star—about the size of a small city but containing more mass than the sun. A teaspoon of a neutron star would weigh as much as a mountain.During a supernova, the dying star blasts away all of the material in its outer layers. Usually, this is a few times the mass of the sun. However, the event that Kasliwal and her colleagues observed, dubbed iPTF 14gqr, ejected matter only one fifth of the mass of the sun.”We saw this massive star’s core collapse, but we saw remarkably little mass ejected,” Kasliwal says. “We call this an ultra-stripped envelope supernova and it has …

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