Powerful Flare Phenomena in Water Vapor Maser Lines in the Emerging Protostellar System with Protoplanetary Disks IRAS 16293-2422

Abstract

According to the detailed monitoring of the water maser at a frequency of 22.2 GHz from 2019 to 2021 in IRAS 16293-2422, two powerful phenomena that occurred at radial velocities of about 6 and 8 km s−1 were detected. Each flare phenomenon consisted of several separate flares lasting no more than a month. The existence of the several emitting maser spot configurations with very close radial velocities, located in the line of sight of the observer, were confirmed for the first time. This made possible to demonstrate the plausibility of the water maser activation hypothesis based on an increase in the amplification length of the maser due to several maser condensations. In both cases, powerful short flares were located on the top of less powerful, but more prolonged ones. Their radiation initiated the release of more powerful flares. The broad Doppler spectral lines of less powerful flares indicate that their masers are probably in a saturated state, while more powerful masers are in unsaturated state. New important parameters of water masers have been obtained, including flare amplitudes, maser line widths, H2O kinetic temperatures during flares, data on the relaxation time of the maser medium, and the fact of existence of a cascade amplification of the water maser in cases of powerful short flares. The possible localization of water masers at features near 6 and 8 km s−1 within the young gas and dust complex IRAS 16293-2422 is also discussed in this work.