Astronomers have discovered a quadruple star system that can cause supernova explosions

(ORDO NEWS) — A quadruple star system discovered in 2017 and recently observed by Canterbury University’s Mount John Observatory could represent a new conduit through which thermonuclear supernova explosions could occur in the universe, according to results published May 13 in the journal Nature Astronomy by an international team of astronomers.

The rare binary binary star system HD74438 was discovered in the constellation Parus in 2017 by the Gaia-ESO Survey, which characterized more than 100,000 stars in our Milky Way Galaxy.

Follow-up observations were made over several years to accurately track the orbits of stars in a quadruple star system. The observations were made with high-resolution spectrographs at the University of Canterbury Observatory on Mount John in New Zealand and the South African Large Telescope in South Africa.

Astronomers have been able to determine that this quadruple is made up of four gravitationally bound stars: a short period binary system of stars orbiting another short period binary system of stars with a longer orbital period (2+2 configuration).

This quad system is a member of the young open star cluster IC 2391, making it the youngest (only 43 million years) spectroscopic quad system discovered to date in the Milky Way Galaxy and one of the quad systems with the shortest outer orbital period (six years ).

In the published paper, the authors showed that the gravitational influence of the outer binary changes the orbits of the inner binary, causing it to become more eccentric.

Current simulations of the future evolution of this system show that such gravitational dynamics could lead to one or more collisions and mergers, resulting in the formation of evolved dead stars (white dwarfs) with masses just below the Chandrasekhar limit. As a result of mass transfer or merger, these white dwarf stars can produce a thermonuclear supernova explosion.

It is now recognized that binary stars play an important role in a large number of astrophysical events, and mergers of binars are responsible for the recent discovery of gravitational wave radiation.

Binary stars also allow us to derive fundamental stellar parameters such as masses, radii and luminosities with greater accuracy than single stars. They are gems on which various themes of astrophysics rely.

Star quadruples make up only an insignificant part (a few percent) of all multiple systems. The complex evolution of such high-order multiples involves mass transfer and collisions, leading to mergers that are also possible progenitors of thermonuclear supernovae.

These supernovae are the standard candles for fixing the scale of the universe’s distances, although the evolutionary channel(s) leading to the origins of such supernova explosions is still much debated.


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