(ORDO NEWS) — An international team of astronomers has found that the recently discovered supernova SN 2018ivc belongs to a previously unknown class of similar cataclysms, which are generated by pairs of stars at medium distances from each other.
Supernovae are powerful explosions that are caused by the gravitational collapse of stars that have exhausted their reserves of hydrogen, as well as the merger of pairs of compact objects such as white dwarfs and neutron stars.
Over the past century, astronomers have identified many supernovae whose properties, including the strength and nature of the glow, differ due to the composition and size of the stars that gave birth to them.
An international team of astronomers led by Professor Keiichi Mayeda, Kyoto University (Japan), discovered a previously unknown type of supernovae generated by binary stars during observations of the SN 2018ivc flare that appeared in the night sky at the end of November 2018. Its source is located in the constellation Cetus at a distance of 3.2 million light years from Earth.
A new type of supernova
Initially, astronomers attributed it to one of the subtypes of supernovae of the second type (IIL), resulting from the gravitational collapse of large stars, but the very first observations indicated that this object may have unique properties.
Professor Mayeda and his colleagues confirmed their presence during many months of observations of SN 2018ivc using the ALMA microwave observatory installed in the Chilean part of the Atacama Desert.
Thus, the brightness of a supernova during the first year gradually decreased in the microwave part of the spectrum, but then it began to grow rapidly.
This came as a surprise to astronomers, since class IIL supernovae should not behave this way, so the researchers studied the remains of SN 2018ivc in detail.
Observations indicated that the flare was caused by a pair of stars distant from each other at an average distance for stars – they complete a revolution around each other in about 1800-1950 days.
One of these luminaries almost completely exhausted its reserves of hydrogen, as a result of which it threw off almost all the outer shells about 1.5 thousand years before the supernova explosion, after which the second luminary began to pull its remaining matter onto itself.
Ultimately, this led to the death of the first star, resulting in a powerful flash and shock wave, which now propagates through the previously ejected shells of the star and makes them glow.
Similarly, as scientists suggest, some other class IIL supernovae have arisen, whose properties do not quite fit into the ideas of astronomers about such cosmic cataclysms.
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