Detection efficiency for a two-line DWD where both stars have a similar flux contribution. Credit: arXiv (2024). DOI: 10.48550/arxiv.2407.02594
An international team of astronomers reports the discovery of 34 rare double-row white dwarf binary systems using the Intermediate Dispersion Spectrograph and Imaging System (ISIS) on the William Herschel Telescope (WHT). The finding was detailed in a research paper published on the preprint server arXiv.
Astronomers are interested in finding and studying binary white dwarfs (DWDs), as their mergers are believed to produce new white dwarfs of higher mass. It is hypothesized that some high-mass white dwarfs in the solar neighborhood may be products of DWD mergers.
Until now, most binaries, including DWDs, have been detected by Doppler shifts in their spectral lines; therefore, these systems are called spectroscopic binaries. Observations show that in some spectroscopic binaries, spectral lines from both stars are visible, and these lines are alternately double and single. These systems are known as spectroscopic two-line binaries (SB2).
The number of known SB2 white dwarf systems with well-measured masses and orbital parameters is still relatively small. Finding new objects of this type could be crucial to advancing our knowledge of binary white dwarfs in general.
A group of astronomers led by James Munday of the University of Warwick, UK, has inspected 117 candidate DWD binaries with ISIS, hoping to confirm their SB2 DWD nature.
“Our search of 117 candidates that were randomly selected from a magnitude-restricted sample of 399 yielded a detection efficiency of 29 percent with 34 systems exhibiting a dual signature,” the researchers wrote in the paper.
The detected SB2 DWDs have masses ranging from 0.85 to 1.55 solar masses and orbital periods between 0.4 and 13.5 days. All of these systems are located within 580 light-years of Earth with the nearest at a distance of only 83 light-years.
The observations revealed that the masses of the hottest component in the reported binaries range from 0.4-0.75 solar masses with an average mass of about 0.53 solar masses. The cooler companions have an average mass of approximately 0.45 solar masses.
The authors of the paper noted that the most massive of the two-row DWDs discovered, designated WDJ181058.67+311940.94, exceeds the so-called Chandrasekhar limit – the maximum mass of a stable white dwarf star, which is generally accepted to be about 1.4 solar masses.
Therefore, it is expected that this system, located about 160 light years away, may experience a Type Ia supernova explosion in the near future or may merge to form an ultramassive white dwarf. However, further observations of this system are required to provide time estimates regarding its fate.
More information:
James Munday et al, The DBL Survey I: discovery of 34 two-line white dwarf binaries, arXiv (2024). DOI: 10.48550/arxiv.2407.02594
Magazine Information:
arXiv
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citation: Astronomers discover dozens of double-lined white dwarf binaries (2024, July 11) Retrieved July 11, 2024 from https://phys.org/news/2024-07-astronomers-dozens-lined-white-dwarf.html
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