A star flash, whose power is almost 10 times the power of the brightest flash ever seen on the Sun, occurred on a supercold star about the size of Jupiter.
This star has received the status of the coldest and the tiniest star on which a white superflash was ever recorded – and according to some definitions, it may not even fall into the class of stars and be a substellar object called the brown dwarf.
The activity of small-mass stars decreases rapidly with decreasing mass, and we expect the chromosphere (the envelope of the star in which the flashes are born) becomes colder and loses the tendency to form flares. The fact that we are seeing a flash of white light on this star of extremely small mass indicates a relatively high magnetic activity of stars of such small masses.
-The main author of the new study, James Jackman, a doctoral student at Warwick University, United Kingdom
This star, attributed by astronomers to dwarfs of spectral class L, is located about 250 light-years from us and is called ULAS J224940.13-011236.9. The star is only about one tenth the size of our Sun, which is roughly equivalent to the size of Jupiter in the solar system. This star was previously inaccessible for observation, because it is very dim, but during a survey of the surrounding stars, astronomers from the University of Warwick were able to notice this star just at the moment when an unexpectedly powerful flash erupted on it.
The dwarfs of the spectral class L mainly radiate in the IR range, so the Jackman team was not difficult to determine that a high-energy flash occurs on the star they observe, accompanied, in addition to IR radiation, by radiation in the UV and optical ranges of the electromagnetic spectrum. Using the Next Generation Transit Survey (NGTS) instrument of the Paranal Observatory, Chile, as well as additional data obtained using Two Micron All Sky Survey (2MASS) and Wide-field Infrared Survey Explorer (WISE) sky surveys, the scientists collected a star observatory of this star over 146 nights.
According to the analysis of these data by the researchers, the outbreak occurred on August 13, 2017 and had a capacity of about 80 billion tons of TNT equivalent, which is 10 times the energy of the Carrington event of 1859 – the most powerful solar flare ever registered by science.
Jackman and his colleagues see further development of their research for other low-mass stars, which are subject to powerful flares, in order to get even more information about the lower mass limit, at which the star becomes inactive.
A tiny, dim star the size of Jupiter has broken out an incredibly powerful flash
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