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Gluttonous cosmic 'black widow' is heaviest-known neutron star
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‘Black widow’: A spinning-neutron star periodically swings its radio (green) and gamma-ray (magenta) beams past Earth in this artist's concept of a black-widow pulsar. The pulsar heats the facing side of its stellar partner to temperatures twice as hot as the sun's surface and slowly evaporates it. (Reuters/Goddard Space Flight Center/NASA)
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stronomers have observed the most-massive known example of an object called a neutron star, one classified as a "black widow" that got particularly hefty by gobbling up most of the mass of a stellar companion trapped in an unhappy cosmic marriage.
The researchers said the neutron star, wildly spinning at 707 times per second, has a mass about 2.35 times greater than that of our sun, putting it perhaps at the maximum possible for such objects before they would collapse to form a black hole.
A neutron star is the compact collapsed core of a massive star that exploded as a supernova at the end of its life cycle. The one described by the researchers is a highly magnetized type of neutron star called a pulsar that unleashes beams of electromagnetic radiation from its poles. As it spins, these beams appear from the perspective of an observer on Earth to pulse -- akin to a lighthouse's rotating light.
Only one other neutron star is known to spin more quickly than this one.
"The heavier the neutron star, the denser the material in its core," said Roger Romani, director of Stanford University's Center for Space Science and Astrophysics and a coauthor of the research published this week in the Astrophysical Journal Letters.
"So as the heaviest-neutron star known, this object presents the densest material in the observable universe. If it was any heavier it should collapse to a black hole, and then the stuff inside would be behind the event horizon, forever sealed off from any observation," Romani added.
A black hole's event horizon is the point of no return beyond which anything including light gets sucked in irretrievably.
