Massive stellar superflare in detail at 400 light-years

28 Apr. (EUROPE PRESS) –

A team of Japanese astronomers used simultaneous observations on the ground and in space to capture a more complete picture of a superflare on a star.

The observed flare began with a very massive, high velocity prominence eruption. These results give us a better idea of how superflares and stellar prominence eruptions occur.

Some stars have been seen releasing superflares more than 10 times larger than the largest solar flare ever seen on the Sun. The hot ionized gas released by solar flares can influence the environment around Earth, known as space weather. The most powerful superflares should have an even greater impact on the evolution of any planets that form around the star, or on the evolution of any life that forms on those planets. But the details of how superflares and prominence eruptions occur in stars are unclear.

According to the NAOJ (National Astronomical Observatory of Japan), a team led by Shun Inoue at Kyoto University used the Seimei 3.8m Telescope in Japan and the Transiting Exoplanet Survey Satellite (TESS) to monitor the V1355 Orionis binary star system, which is known to release frequently large-scale superflares. V1355 Orionis is located 400 light-years away in the constellation Orion.

The team managed to capture a superflare with continuous observations of high temporal resolution. Data analysis shows that the superflare originated with a phenomenon known as prominence eruption.

Calculating the velocity of the eruption requires making some assumptions about things that are not directly observable, but even the most conservative estimates far exceed the escape velocity of the star (347 km/s), indicating that the prominent eruption was capable of to break free of the star’s gravity and becoming coronal mass ejections (CMEs). The eruption from the prominence was also one of the most massive ever observed, transporting billions of tons of material.