Surviving supernova explodes across the galaxy

(ORDO NEWS) — Astronomers have discovered a star that survived a supernova explosion. However, the catastrophe gave the luminary great speed and sent it on a journey through the galaxy.

The achievement is described in a scientific article published in the Monthly Notices of the Royal Astronomical Society.

Vesti.Ru talked in detail about white dwarfs. Recall that these are the cores of small burnt-out stars. Thermonuclear reactions no longer take place in them, and they gradually cool down.

However, such a veteran can still mess things up if he builds up his mass. To do this, the white dwarf needs a partner star that forms a close pair with it.

A white dwarf can gain mass gradually, tearing off matter from its companion by its gravity and assigning it to itself. And if his partner is also a white dwarf, two sworn friends can collide and merge into one large white dwarf.

Both scenarios are fraught with the same sad outcome. As soon as the mass of the white dwarf exceeds a certain limit, a thermonuclear explosion occurs. Such catastrophes are called Type Ia supernovae.

Not so long ago, scientists thought that this unlucky celestial bodies would inevitably turn into dust. But in recent years, several white dwarfs have been discovered that seem to have survived the heat of the fusion. These are, for example, LP 40-365 and D6-2.

Each such story of a miraculous salvation for astronomers is literally worth its weight in gold. They strive to understand how the luminaries manage to survive in a cosmic cataclysm, which until recently seemed absolutely impossible.

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And now, it looks like scientists have found another “survivor”. This is the white dwarf SDSSJ1240 + 6710.

This star was discovered back in 2015. At the same time, astronomers drew attention to its strange chemical composition. In the atmosphere of this star there is no hydrogen and helium, but there is a lot of oxygen and a solid amount of neon, magnesium and silicon. This fact already hints that the white dwarf has been in a thermonuclear hell. But other explanations, too, could not be ruled out.

The authors of the new study collected additional data on the composition of SDSSJ1240 + 6710 using the renowned Hubble. As a result, astronomers found lines of carbon, sodium and aluminum in the spectrum of the star. These elements are abundantly formed at the onset of a Type Ia supernova, a thermonuclear explosion that blasts white dwarfs into dust. At the same time, experts did not find traces of titanium, iron, cobalt and nickel – metals that form at a later stage of such an outbreak.

The conclusion suggests itself that the thermonuclear explosion, which was supposed to destroy SDSSJ1240 + 6710, began, but did not end.

To test this hypothesis, the authors turned to data from the Gaia orbiting telescope. They made it possible to determine the mass and speed of the star.

So it turned out that SDSSJ1240 + 6710 is unusually light even for a white dwarf: only 40% of the mass of the Sun. But his speed is very solid: 250 kilometers per second. This is far from a record, but still the star must have a reason to accelerate this way.

All of these facts indicate that SDSSJ1240 + 6710 is a “failed” Type Ia supernova. In a thermonuclear catastrophe, he lost a significant part of his mass, underwent a change in composition and received a hefty kick that sent him on a journey across the Galaxy. But compared to the prospect of becoming cosmic dust, this is an enviable fate.

Scientists have yet to uncover the secret of the miraculous rescue of SDSSJ1240 + 6710. By the way, they already have several versions. Interestingly, the characteristics of this white dwarf are unlike the other survivors LP 40-365 and D6-2. The authors note that there seems to be a whole “zoo” of such objects, and we are just starting to get acquainted with them.

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