Astronomers for the second time in history, failed to see ultraviolet light, remaining after an explosion of a white dwarf, reported in an article published in The Astrophysical Journal. Thanks to him, scientists will be able to figure out what causes such events and also to clarify, how are the heavy metals such as iron.
White dwarf is considered to be the remnant of a star which has completed its normal life cycle and dumped in the evolution of the outer shell. In fact, it is the former core with extremely high density and gravity that can accretional substance. Primarily this happens in binary systems where a white dwarf has a binary companion, which may become the donor of matter. When the mass of the star exceeds the Chandrasekhar limit — 1.44 times the mass of the Sun — is the thermonuclear detonation of a substance star, completely destroying a star (astronomers klassificeret this event as a supernova explosion of type Ia).
Despite the fact that type Ia supernovas have long been known to scholars and even used as “standard candles” in measuring distances to galaxies in the scientific community there is still no consensus on the exact mechanism of the explosion and nature of the companions are white dwarfs. To clarify can research in different bands of the electromagnetic spectrum including the ultraviolet.
Astrophysicist Adam Miller (Adam Miller) from northwestern University, along with colleagues reported the discovery of ultraviolet light, remaining after an explosion of a white dwarf in the galaxy, which is 140 million light-years from Earth. The event, dubbed SN2019yvq, it was the Palomar Observatory in December 2019. First, scientists saw a flash of relatively dim magnitude is 18.5, and then continued observations in the ultraviolet range with a telescope Swift.
Ultraviolet afterglow, which persisted for two days, indicates that the substance is a white dwarf or close to it was very very hot — the temperature was 3-4 times higher than the temperature of the Sun — though usually white dwarfs with time, on the contrary, gradually cool down.
The authors considered four potential scenarios that explain the observed features of the spectrum SN2019yvq. According to the first, the white dwarf has absorbed the substance of its companion star, which led to the emergence of instability and explosion, and the remains of a white dwarf and a companion star collided and caused a flash of ultraviolet radiation.
In the second scenario, the hot Nickel isotope 56Ni in the core of a white dwarf mixed with its outer layers, causing the outer shell of the star has warmed up more than usual. In the third scenario, the UV afterglow could remain after the dual explosion, when the helium detonation on the surface of a white dwarf sent out a shock wave that triggered the nuclear burning of carbon in the subsoil thereof. And finally, the last explanation involves the merger of two white dwarfs, which provokes an explosion and the collision of residual material, shining in the ultraviolet range.
Over time thrown into space, the matter will be gradually removed from the source, and astronomers hope that in a year the cloud of gas and dust is so thin that they will be able to see the Central area of the explosion and determine what was the cause of the outbreak. When the authors find the answer to this question, they will be able to understand how to form the iron cores of rocky planets, as explosions type Ia supernovas are the main suppliers of iron in space.
Most stars, including our Sun, at the end of evolution will become white dwarfs, these objects are particularly interesting to scientists. Recently, they found evidence of the existence of a small dense body in close orbit of the white dwarf, which is extremely rare situation. In addition, astronomers have previously been able to see the unique white dwarf, which was formed in the merger of the two into one.