Why is this strange metal star popping out of the Milky Way?

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About 2,000 light-years away from Earth, there are stars flying toward the edge of the Milky Way. This particular star, known as LP 40-365, is one of the unique varieties of fast-moving stars that survived in chunks after a giant stellar explosion.

“This star is moving so fast that it almost certainly leaves the galaxy …[it’s] Says JJ Hermes, an assistant professor of astronomy at Boston University’s Faculty of Arts and Sciences. But why is this flying object speeding up from the Milky Way? Because it is a fragment from a past explosion. A cosmic event known as a supernova — it’s still moving forward.

“Surviving through a partial explosion is very cool and unique. It’s only in the last few years that we’ve begun to think that this kind of star may exist,” said a former BU student. Says Odelia Putterman, who worked at. In the Hermes lab.

In a new treatise published in Astrophysical Journal Letter, Hermes and Putterman reveal new observations about this remaining “star debris” that gives insight into other stars with a similar devastating past.

Patterman and Hermes analyzed data from NASA’s Hubble Space Telescope and the Transiting Exoplanet Exploration Satellite (TESS). This satellite explores the sky and collects light information about nearby and distant stars. Examining different types of optical data from both telescopes, researchers and their collaborators found that LP 40-365 was not only thrown out of the galaxy, but also based on the brightness pattern of the data. I discovered that it was spinning on the way. ..

“The stars are basically slingshot from the explosion, and we [observing] It spins along the way, “says Putterman, the second author of the treatise.

“We dug a little deeper to understand why the star is that star. [was repeatedly] Bright and dark, the simplest explanation is that we are looking at something [its] The surface rotates every 9 hours and becomes visible or invisible. ” Rotational speed, Hermes says. All stars rotate — even our sun slowly rotates around its axis every 27 days. However, for a fragment of a star that survived a supernova, 9 hours is considered relatively slow.

Supernovae occur when a white dwarf becomes too large to support itself, eventually causing an energy explosion in the universe. Finding the rotational speed of a star like LP40-365 after a supernova can give a clue to the original two-star system from which it came. In the universe, it is common for stars to come in close pairs as follows: White dwarf, A dense star that forms towards the end of the star’s life. If one of the white dwarfs gives too much mass to the other, the dumped star can self-destruct and become a supernova. According to researchers, supernovae are commonplace in galaxies and can occur in a variety of ways, but they are usually very hard to see. This makes it difficult to know which star implosed and which star dropped too much mass on that star’s partner.

Based on the relatively slow rotation speed of LP 40-365, Hermes and Putterman once orbited each other at high speeds, and it was the debris from the stars that self-destructed after being supplied with a large amount of mass by their partners. I’m more sure there is. The explosion slingshot both stars, as the stars were orbiting each other very quickly and closely, and now we only see LP40-365.

“this [paper] “We add another layer of knowledge about the role these stars played when supernovae occurred and what could happen after the explosion. What’s happening with this particular star?” By understanding, you can begin to understand what is happening with many other similar stars. Stars from similar situations. ”

“These are very strange stars,” says Hermes. Stars like LP 40–365 are not only some of the fastest stars known to astronomers, but also the most metal-rich stars. Performer Detected so far.Our sun-like stars are made up of helium and hydrogen, but the surviving stars are Supernova “What we see is a by-product of the violent nuclear reaction that occurs when a star explodes,” so Hermès is mainly composed of metallic materials to study such star debris. Especially attractive.

Blistering Stars in the Universe: Rare Insights into Star Evolution

For more information:
JJ Hermes et al, 8.9 hr Rotation in the Partly Burned Runaway Stellar Remnant LP 40-365 (GD 492), Astrophysical Journal Letter (2021). DOI: 10.3847 / 2041-8213 / ac00a8

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