Author: Lisa Grossman / Source: Science News
SEATTLE — Astronomers may have discovered a new way that stars can die.
A mysteriously brief and bright burst whimsically called the “Cow” reveals an entirely new type of stellar death.The details of that stellar doom, however, remain hazy. Scientists are still debating whether the flare-up, spotted on June 16, 2018, was from an unusual type of star that was eaten by a black hole, or from an old, massive star exploding in a weird sort of supernova.
The Asteroid Terrestrial-impact Last Alert System telescope in Hawaii first detected the explosion, and gave the event the random name AT2018cow. “It was immediately dubbed, to avoid this mouthful of letters, the Cow,” said astronomer Daniel Perley in a news conference January 10 at the American Astronomical Society meeting.
Right away, the Cow was weird. The first observations showed that it came from a star-forming dwarf galaxy about 200 million light-years away in the constellation Hercules. But the Cow was particularly bright for being so far away, suggesting it was about 10 times the luminosity of a typical supernova and 100 billion times the luminosity of the sun. It also appeared suddenly, going from invisible to peak brightness in just two days, far faster than most ordinary supernovas.
“This combination of being very fast and very luminous is very unusual,” said Perley, of Liverpool John Moores University in England. “Many of us got very excited.”
Over the following months, a slew of telescopes rushed to follow up on the Cow in wavelengths of light spanning the electromagnetic spectrum, from long radio waves to short gamma rays. “The Cow has become one of the most intensely observed cosmic events in history,” said astronomer Anna Ho of Caltech at the meeting.
Those follow-up observations revealed that the Cow was surrounded by dense material moving at a 10th of the speed of light. The burst of light also lasted for several months, growing gradually dimmer across a range of wavelengths. Although it was dimming…
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