2023-12-01 12:53:30
A close-up image of Omega Centauri, in X-ray and optical light, shows the location of some of the spider pulsars. -NASA
MADRID, 1 Dic. (EUROPA PRESS) –
Data from NASA Chandra X-ray Observatory of the globular cluster Omega Centauri have revealed a group of dead stars known as “spider pulsars” destroying companion stars.
A pulsar is the dense, spinning core that remains after a massive star collapses in on itself to form a neutron star. Rapidly spinning neutron stars can produce beams of radiation. Like the beam of a rotating lighthouse, the radiation can be observed as a powerful source of pulsating radiation, or pulsar. Some pulsars spin tens to hundreds of times per second and are known as millisecond pulsars.
Spider pulsars are a special class of millisecond pulsars and They are named for the damage they inflict on small companion stars orbiting them.. Using winds of energetic particles blasting out from spider pulsars, the outer layers of the pulsar’s companion stars are methodically removed.
Astronomers recently discovered 18-millisecond pulsars at Omega Centauri, located about 17,700 light-years from Earth, using the Parkes and MeerKAT radio telescopes. Then, a pair of astronomers at the University of Alberta in Canada looked at Chandra data from Omega Centauri to see if any of the millisecond pulsars emit X-rays.
They found 11-millisecond pulsars emitting X-rays, and five of them were spider pulsars concentrated near the center of Omega Centauri. Next, the researchers combined the Omega Centauri data with Chandra observations of 26 spider-shaped pulsars in 12 other globular clusters, NASA reports.
There are two varieties of spider pulsars depending on the size of the star that is destroyed. “Redback” spider pulsars are damaging companion stars that weigh between one-tenth and one-half the mass of the Sun. Meanwhile, “black widow” spider pulsars are damaging companion stars with less than 5 percent of the mass. of the sun.
The team found a clear difference between the two classes of spider pulsars: redbacks are brighter in X-rays than black widows, confirming previous work. The team is the first to show a general correlation between X-ray brightness and the mass of spider-shaped pulsars, where pulsars that produce more X-rays combine with more massive companions. This provides clear evidence that the mass of the spider pulsar companion influences the X-ray dose the star receives.
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Spider pulsars are typically separated from their companions by only one to 14 times the distance between the Earth and the Moon. This proximity (cosmically speaking) makes the energetic particles of pulsars particularly harmful to their companion stars.
This finding is consistent with the theoretical models that scientists have developed. Because more massive stars produce a denser wind of particles, a stronger shock (producing brighter X-rays) occurs when their wind collides with the pulsar particles. The proximity of companion stars to their pulsars means that X-rays can cause significant damage to the stars, along with the pulsar’s wind.
The article describing these results is published Monthly Notices of the Royal Astronomical Society.
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