Superflare detected on an ultracool star

Using Xinglong observatory's Ground-based Wide Angle Cameras (GWAC), astronomers from China and France have detected a new superflare of an ultracool star known as SDSS J013333.08+003223.7.

The newly found event, designated GWAC 181229A, appears to be one of the most powerful flares on ultracool stars so far discovered.


Ultracool dwarfs (UCDs) are stellar or sub-stellar objects of spectral class M with effective temperatures below 2,700 K and masses not exceeding 0.3 solar masses.

In general, they have weak chromospheric emission and are dim in X-rays, however, they sometimes exhibit flaring activity in various wavelengths.

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Credit: Xin et al., 2020.

Finding Charts of GWAC 181229A detected by GWAC. All these images were obtained by GWAC at the same night, and all the observation times are marked.

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This artist’s impression video shows an imagined view from the surface one of the three planets orbiting an ultracool dwarf star just 40 light-years from Earth that were discovered using the TRAPPIST telescope at ESO’s La Silla Observatory.

These worlds have sizes and temperatures similar to those of Venus and Earth and may be the best targets found so far for the search for life outside the Solar System.

They are the first planets ever discovered around such a tiny and dim star.

Astronomers have found a system of seven Earth-sized planets just 40 light-years away.

Using ground and space telescopes, including ESO’s Very Large Telescope, the planets were all detected as they passed in front of their parent star, the ultracool dwarf star known as TRAPPIST-1.

Three of the planets lie in the habitable zone and could harbour oceans of water on their surfaces, increasing the possibility that the star system could play host to life.

This system has both the largest number of Earth-sized planets yet found and the largest number of worlds that could support liquid water on their surfaces.