2021-06-14

Researchers reveal the law of super flare activity based on LAMOST and TESS data

By yqqlm yqqlm

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The research results were published in the internationally renowned astronomy The journal “Astrophysical Journal Supplement” (2021, ApJS, 253, 35).

As early as 2000, American astronomer Cuntz and others put forward a theoretical model that the increase in star activity is caused by the interaction between the star and the surrounding planet’s magnetic field. In 2012, the Japanese scholar Hiroyuki Maehara and others found that the superflare events of sun-like stars (stars whose surface temperature and gravity are similar to the sun) in the Kepler data of the United States found that the burst rate of superflares of sun-like stars is similar to that of ordinary solar flares The rate has the same power law exponent result, and it is completely possible that a single star explodes into a superflare.

Starting from July 2019, TESS has carried out a one-year survey of the northern sky. At the same time, LAMOST has carried out a continuous spectral survey of the northern sky since 2012, and has obtained thousands of Spectral data of tens of thousands of stars. Researchers obtained 1272 superflares from 311 solar-like stars from TESS data. At the same time, 7454 sun-like stars captured by TESS were also matched in the spectral data of LAMOST. Using the spectral data of LAMOST, they measured the degree of chromosphere activity of these stars. It is worth mentioning that the chromosphere activity of a star is closely related to its sunspot, and the intensity of its activity is also roughly proportional to its magnetic field strength. In addition, TESS not only provides the possibility to search for superflares from the luminosity curve, but also provides an opportunity to estimate the proportion of sunspots on the surface of a star. The size of sunspots on the surface of a star is directly related to the star’s ability to explode superflares.

Researchers reveal the law of super flare activity based on LAMOST and TESS data

In Figure 2, researchers will explode Stars with superflares (red and yellow data points) are distinguished from stars without superflares (blue data points). They found that those stars with superflares have higher chromosphere activity than stars without superflares, and also have a higher proportion of surface sunspots. In addition, they found that sun-like stars with superflares have more intense chromosphere activity and greater sunspot coverage than the sun.

These results not only show that a single solar-like star has the possibility of independently producing superflares, but also that, combined with the sun’s activity, the probability of the sun bursting out of superflares and destroying the earth is very low. It is worth mentioning that with the advantage of LAMOST covering a large area of ​​the northern sky, their work combines TESS with LAMOST to further advance the comparative study of the similarity between stellar superflares and solar flares. Look for the possible correlation between stellar superflare burst rate and stellar evolution. In addition, from the statistical results, a small number of stars with high explosion rates and superflares with huge explosion energy are waiting for researchers to further study. In the future, researchers look forward to using LAMOST, including medium-resolution spectroscopy, to conduct more in-depth studies on this type of solar-like stars that explode superflares, and strive to have a more comprehensive and in-depth understanding of the physical mechanism of superflares.

Researchers reveal the law of super flare activity based on LAMOST and TESS data(1)