A Russian-European team of scientists has discovered a possible new type of stars, born in the process of a catastrophic collision of white dwarfs.
Medium-sized stars complete their evolution by shedding their outer shells and turning into compact and faint white dwarfs. Due to their almost infinite lifetime, many of these objects persist in the Galaxy, and they often form binary systems. While spinning in pairs, white dwarfs can approach each other until a Type Ia supernova breaks out.
Such an event also occurred in the IRAS 00500 + 6713 system, but the explosion was not strong enough and could not completely destroy it. In place of the tandem of white dwarfs, a new stellar object remains, surrounded by a dense cloud of gas and dust. It was studied by a team of scientists led by Lydia Oskinova, who works at the University of Potsdam and the Kazan (Volga Region) Federal University. Their article was published in the journal Astronomy & Astrophysics.
The system was first noticed in 2019. Its central star, J005311, rotates rapidly and has a relatively high oxygen and carbon content. And the stellar wind emanating from it stands out with an incredible speed, reaching 16 thousand kilometers per second. New observations from the XMM-Newton space observatory have demonstrated that J005311 emits brightly in the X-ray range. Based on these data, the system is unusually rich in neon, silicon and sulfur, and its nebula is very hot, reaching temperatures in the millions of degrees.
It was not possible to determine the mass of the star, although according to indirect indications, scientists estimated it at more than 1.4 solar - above the upper limit of the mass of white dwarfs. Apparently, it became the product of a merger of a pair of white dwarfs, at least one of which was oxygen-neon-magnesium (such dwarfs remain after the death of stars about 10 solar masses).
The explosion could not destroy the system completely, but led to the release of large quantities of matter and left behind a new star. “IRAS 00500 + 6713 is a new type of stellar objects. We are not aware of any other similar objects with similar properties, - says Oskinova. "You can call him a very unusual star." The authors hope to better study the exotic object with the new JWST space telescope, which is preparing to launch in 2021.