Astronomers witness formation of massive star over 18 years

Astronomers observed formation of a massive star, called W75N(B)-VLA 2, over the period of 18 years.

Pair of images of a young star, made 18 years apart, has revealed a dramatic difference that is providing astronomers with a unique, "real-time' look at how massive stars develop in the earliest stages of their formation.

The astronomers used the National Science Foundation's Karl G. Jansky Very Large Array (VLA) to study a massive young star, which was some 4200 light-years from Earth. They compared an image made in 2014 with an earlier VLA image from 1996.

The scientists believed that the young star was forming in a dense, gaseous environment, and was surrounded by a doughnut-shaped, dusty torus.

The star had episodes in which it ejected a hot, ionized wind for several years. At first, that wind can expand in all directions, and so forms a spherical shell around the star. Later, the wind hits the dusty torus, which slows it. Wind expanding outward along the poles of the torus, where there was less resistance, moves more quickly, resulting in an elongated shape for the outflow.

W75N(B)-VLA 2 was estimated to be about 8 times more massive than the Sun. The more-uniform outflows are seen in massive young stars in the first few thousand years of their lives, the stage at which W75N(B)-VLA 2 was thought to be.