In one of the young star clusters of the Milky Way, scientists from the UK have discovered stars with tails like comets.
Using data from the ALMA observatory, astronomers have discovered comet-like stars in the young star cluster Westerlund 1. New observations are described in an article for the journal Astronomy & Astrophysics.
The cluster, discovered by Swedish astronomer Bengt Westerlund in 1961, lies about 15,000 light-years away towards the constellation Altar. It is one of the most massive star clusters in the Milky Way. It consists of about 200 thousand stars and is relatively young (by astronomical standards) - about three million years old. Compared to the Sun, which is already 4.6 billion, this cluster is just a baby.
The Westerlund 1 cluster contains many massive stars, many of which are unusual and rare. This object got its name from Westerlund 1-26, the first star discovered in the cluster.
This image of the Westerlund 1 cluster was produced using data collected by ALMA combined with data from the Hubble telescope / © 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 that of the Sun. If this star were located where the Sun is located in the solar system, it would be larger than the orbit of Jupiter.
New observations of Westerlund 1 by radio astronomer Daniel Marie Fenech of University College London have shown that some of the giant stars in the cluster have comet-like "tails."
These tails are formed in dense, relentless winds emanating from the inhabitants of the star cluster, which carry their material outward. Outwardly, this phenomenon resembles 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 direction opposite to the Sun, the astronomer explains. “Likewise, the tails of the huge red stars seen in the ALMA image point away from the cluster's core. Most likely, they appeared as a result of cluster winds created by hundreds of hot and massive stars closer to the center of Westerlund 1. These massive structures cover huge distances and represent the amazing effect that the environment can have on the formation and development of stars."