W75N(B)-VLA2

W75N(B)-VLA2 is a massive protostar located in the Cygnus X region some 4,200 light-years from Earth, about 8 times more massive[2] and 300 times brighter than our Sun, observed in 1996 and 2014 by the Karl G. Jansky Very Large Array (VLA). In 2014 its stellar wind had changed from a compact spherical form to a larger thermal, ionized elliptical one outlining collimated motion, giving critical insight into the very early stages of the formation of a massive star.[1][3] Being able to observe its rapid growth as it happens (in real time in an astronomical context) is unique, according to Huib van Langevelde of Leiden University, one of the authors of a study of the object.

W75N(B)-VLA2 in 1996 (top) and in 2014

Star formation
Object classes
Interstellar medium Molecular cloud Bok globule Dark nebula Young stellar object Protostar Pre-main-sequence star T Tauri star Herbig Ae/Be star Herbig–Haro object
Theoretical concepts
Accretion Initial mass function Jeans instability Kelvin–Helmholtz mechanism Nebular hypothesis Planetary migration

The authors of the study believe W75N(B)-VLA2 is forming in a dense, gaseous environment, surrounded by a dusty torus. The star intermittently ejects a hot, ionized wind for several years. Initially the wind can expand in all directions and forms a spherical shell; later it hits the dusty torus, which slows it. There is less resistance along the poles of the torus, so the wind moves more quickly there, giving rise to an elongated shape.[2]