Accretion bursts discovered in young variable stars

arXiv: Accretion burst discovered in young variable star Sgr V1741 Astronomers have discovered an accretion burst that occurred around the young variable star Sgr V1741. The research results were published on the preprint server arXiv. V1741 Sgr (also known as SPICY 71482 and Gaia22dtk) is a classical T Taurus variable star located near the young star cluster NGC 6530 (Lagoon Nebula). The nature of the source as a variable was first identified in 1957, and after several years of stability, the flare was first detected in mid-2022 and observed by ESA’s Gaia satellite. The results of the study suggest that V1741 Sgr may be a young stellar object (YSO) characterized by an episodic accretion process. YSO accretion eruptions are divided into two groups: EX Lup (also known as EXors) and FU Ori eruptions (or FUors). EXor has an amplitude of several orders of magnitude and lasts from a few months to a year or two. FUor is more extreme and rare, reaching 5-6 points in amplitude and can persist for decades to centuries. The study showed that Sgr burst V1741 is a medium-amplitude His EX-Lup event, with magnitude around 3.0 in the optical range and magnetic magnitude 1-2 in the infrared range. The spectrum of the flare shows strong atomic and molecular emission, as well as an increase in brightness across the observable range. The most noticeable change was the appearance of the titanium oxide and its subsequent absorption lines. This may be due to cooling of the circumstellar gas. Additionally, Sgr V1741 turned out to be a K2 spectral-class star less than 3 million years old and about 4,100 light-years away.