CfA: Scientists Complete ELM Survey, Discover 98 Double White Dwarfs

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CfA: Scientists Complete ELM Survey, Discover 98 Double White Dwarfs

Post by bystander » Tue Feb 04, 2020 5:17 pm

Scientists Complete ELM Survey, Discover 98 Double White Dwarfs
Harvard Smithsonian Center for Astrophysics | 2020 Feb 04
Scientists at the Center for Astrophysics | Harvard & Smithsonian (CfA) have completed the Extremely Low Mass--also known as ELM--spectroscopic study of white dwarf stars in the Sloan Digital Sky Survey (SDSS). In process for more than a decade, the completed survey discovered 98 detached double white dwarf binaries.

"We targeted candidate low mass white dwarf stars and found that they are all ultra-compact binaries. It makes sense," said Dr. Warren Brown, astronomer at CfA and lead author on the survey. "The stars we studied lost so much of their mass during their evolution that they ended up as a low mass white dwarf."

White dwarf stars are the remnant core of a star, what is left over after the star has burned through its nuclear fuel. The stars catalogued in the ELM survey do not follow the traditional "rules" for the creation of white dwarfs.

"The universe isn't old enough to make such low mass white dwarfs on their own, and yet, here they are. That's because they have companions in close orbits. The universe can't make a low mass white dwarf unless it's part of a compact binary," said Brown. "The completed survey now represents more than half of the known detached double white dwarf binaries. This is a substantive piece of work that offers models for future studies and discoveries.” ...

The ELM Survey. VIII. Ninety-Eight Double White Dwarf Binaries ~ Warren R. Brown et al
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Ann
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Re: CfA: Scientists Complete ELM Survey, Discover 98 Double White Dwarfs

Post by Ann » Wed Feb 05, 2020 6:16 am

bystander wrote:
Tue Feb 04, 2020 5:17 pm
Scientists Complete ELM Survey, Discover 98 Double White Dwarfs
Harvard Smithsonian Center for Astrophysics | 2020 Feb 04
Scientists at the Center for Astrophysics | Harvard & Smithsonian (CfA) have completed the Extremely Low Mass--also known as ELM--spectroscopic study of white dwarf stars in the Sloan Digital Sky Survey (SDSS). In process for more than a decade, the completed survey discovered 98 detached double white dwarf binaries.

"We targeted candidate low mass white dwarf stars and found that they are all ultra-compact binaries. It makes sense," said Dr. Warren Brown, astronomer at CfA and lead author on the survey. "The stars we studied lost so much of their mass during their evolution that they ended up as a low mass white dwarf."

White dwarf stars are the remnant core of a star, what is left over after the star has burned through its nuclear fuel. The stars catalogued in the ELM survey do not follow the traditional "rules" for the creation of white dwarfs.

"The universe isn't old enough to make such low mass white dwarfs on their own, and yet, here they are. That's because they have companions in close orbits. The universe can't make a low mass white dwarf unless it's part of a compact binary," said Brown. "The completed survey now represents more than half of the known detached double white dwarf binaries. This is a substantive piece of work that offers models for future studies and discoveries.” ...

These low-mass white dwarf binaries are Algol system remnants.

Just sayin'. :yes:

Ann

P.S. I object to the colors of the stars in Mel Weiss' illustration. The small white dwarf is certainly not old enough to have cooled into a "yellow white dwarf", so its color in the illustration should be bluish. The larger star may or may not be blue.
Color Commentator