Astronomers have found comet tails from giant stars

In one of the young star clusters of the Milky Way, scientists from the UK found stars with tails, like comets.

Using data from the ALMA observatory, astronomers discovered comet-like stars in the Westerlund 1 young star cluster. New observations are described in an article for Astronomy & Astrophysics.

The cluster, discovered by the Swedish astronomer Bengt Westerlund in 1961, is about 15 thousand light years away, in the direction of the constellation Altar. This is one of the most massive star clusters of the Milky Way. It consists of about 200 thousand stars and is relatively young (by astronomical standards) – it is about three million years old. Compared to the Sun, which is already 4.6 billion, this cluster is just a baby.

The cluster Westerlund 1 contains many massive stars, many of which are unusual and rare. This object got its name due to the star Westerlund 1-26 – the first one discovered in the cluster.

This image of the Westerlund 1 cluster was produced using data collected by ALMA combined with Hubble telescope data / © ESO / ALMA / NAOJ / NRAO / Fenech et al.
Westerlund 1-26 is a red supergiant, sometimes classified as a hypergiant, with a radius of more than 1500 times greater than that of the sun. If this star were located where the sun is located in the solar system, it would be greater than the orbit of Jupiter.

New observations of Westerlund 1 by radio astronomer Daniel Marie Fenech of University College London showed that some of the giant stars in the cluster have comet-like tails.

These tails are formed in dense merciless winds emanating from the inhabitants of the star cluster, which carry their material out. Outwardly, this phenomenon is reminiscent of how comets form their beautiful tails.

“Comet tails in the solar system are directed in the opposite direction from the nucleus of their comets due to the wind of particles flying from the sun. Therefore, cometary tails are always directed in the opposite direction from the Sun, the astronomer explains. – Similarly, the tails of huge red stars, which can be seen in the ALMA image, point in the opposite direction from the cluster core. Most likely, they appeared as a result of the impact of cluster winds created by hundreds of hot and massive stars closer to the center of Westerlund 1. These massive structures cover vast distances and mark the amazing effect that the environment can have on the formation and development of stars. ”