Science and Tech

Hubble tracks ‘blue marauder’ among the stars

Evolution of a 'blue marauder' star system

Evolution of a ‘blue marauder’ star system – NASA, ESA, LEAH HUSTAK (STSCI)

Jan. 14 () –

The NASA/ESA Hubble Space Telescope explored a rare class of star, called a ‘blue marauder’, by peering deep into the open star cluster M67, about 2,800 light years away.

Forensic analyzes using Hubble data show that the star has had a tumultuous life, mixing with two other gravitationally bound stars in a remarkable triple star system. The star is related to the so-called ‘blue stragglers’, which are hotter, brighter and bluer than expected because they are probably the result of mergers between stars.

The blue marauder spins much faster than expectedunusual behavior that led to his identification. Otherwise, it appears to be a normal Sun-like star. The term “blue” is a misnomer because the star’s color blends with that of all the other solar-mass stars in the cluster. Therefore, it is like “lurking” among the common stellar population.

The spin speed is evidence that the star must have absorbed material from a companion star, causing its rotation to accelerate. The star’s high spin speed was discovered with NASA’s retired Kepler space telescope. While normal Sun-like stars usually take about 30 days to complete one rotation, the Marauder takes just four days.

How this star came to be like this is a “super complicated evolutionary history”, Emily Leiner of the Illinois Institute of Technology in Chicago said in a statement. “This star is really exciting because it is an example of a star that has interacted in a triple star system.” The blue marauder originally rotated more slowly and orbited a binary system consisting of two Sun-like stars.

About 500 million years ago, the two stars of that binary system merged, creating a single, much more massive star. This colossus soon swelled into a giant star, pouring some of its own material onto the blue marauder and spinning it in the process. Today we observe that the blue stalker is orbiting a white dwarf star, the burned remains of the massive merger.

“We know that these multiple star systems are quite common and that they are going to lead to really interesting results,” Leiner explained. “Simply, We still don’t have a model that can reliably connect all those stages of evolution.. “Triple star systems represent about 10 percent of the population of Sun-like stars. But being able to reconstruct this evolutionary history is a challenge.”

Hubble observed the companion white dwarf star orbiting the stalker. Using ultraviolet spectroscopy, Hubble discovered that the white dwarf is very hot (up to 12,700 degrees Celsius, or about three times the surface temperature of the Sun) and a heavyweight at 0.72 solar masses. According to theory, the hot white dwarfs in M67 should be only about 0.5 solar masses. This shows that the white dwarf It is the byproduct of the merger of two stars that were once part of a triple system.

“This is one of the only triple systems where we can tell such a detailed story about how it evolved,” Leiner said. “Triple systems are emerging as potentially very important for creating interesting and explosive end products. It’s really unusual to be able to put constraints on a system like the one we’re exploring.”

The results have been presented in the 245th session of the American Astronomical Society

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