(ORDO NEWS) — For the first time, astronomers have discovered a binary star system in the Milky Way, which in the future will give rise to an outbreak of the so-called kilonova as a result of the merger of two neutron stars.
“Astronomers have long been trying to understand the conditions under which stellar systems are formed that can generate kilonova outbursts.
The discovery of the star system SGR 0755-2933 indicates that in some cases one of the neutron stars, whose pairs generate such cosmic cataclysms, occurs without a classic supernova explosion “, – said Andre-Nicolas Chen, a researcher at NOIRLab, quoted by the press service of the laboratory.
The so-called kilonovae are powerful cosmic flares resulting from the collision of two neutron stars.
For a long time they remained the subject of theoretical discussions, but three years ago, the gravitational observatories LIGO and ViRGO recorded space-time fluctuations generated by a similar event in the nearby galaxy NGC 4993, which is only 140 million light years away from the Milky Way.
As Shen and his colleagues note, the discovery of the kilonova in the galaxy NGC 4993 has generated a lot of controversy about how these cataclysms arise and in which regions of space it is best to look for them.
In particular, scientists cannot yet say exactly how pairs of neutron stars are formed that can generate kilonova outbursts, and whether they can arise inside binary star systems as a result of supernova explosions.
Rare double star
Shen and his colleagues discovered the closest example of a candidate star system to Earth while analyzing images of the Milky Way taken by the Swift orbital observatory, which monitors X-ray and gamma-ray flares.
Recently, its instruments picked up intermittent flashes of X-rays from an object relatively close to Earth in the constellation of Puppis.
Subsequent observations of the “blinks” of this star system, named SGR 0755-2933, indicated that it is still a double star, unique in the Milky Way, consisting of a neutron star and a blue giant that is actively shedding its outer shells.
Both objects are at a short distance from each other and rotate around a common center of mass in just 59 days.
As Shen and his colleagues explain, the uniqueness of SGR 0755-2933 lies in the fact that the neutron star has an unusually “round” orbit, which is not typical for such luminaries.
According to astronomers, this indicates that the neutron star arose as a result of an unusually weak supernova explosion, shortly before which most of the matter of its progenitor was “tightened” by the attraction of the second star of the SGR 0755-2933 system.
In the near cosmic future, this luminary will also turn into a neutron star, whose merger with its neighbor will lead to a kilonova outburst.
Further observations of SGR 0755-2933, astronomers hope, will help them understand when this will happen and how often such star systems form.
Understanding this is important for studying how the “seeding” of the Universe with heavy elements took place, the astronomers summed up.
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