The Chinese LAMOST telescope has given scientists a better look at the Andromeda and Triangulum galaxies neighboring the Milky Way. Astronomers found several hundred previously unknown supergiant stars in them.
Supergiant stars and their evolution
Using the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), Chinese astronomers have discovered nearly 300 candidate supergiant stars in the Andromeda and Triangulum galaxies. This is reported in a research paper published October 25 on the arXiv preprint server.
Supergiants are evolved high-mass stars that are larger and brighter than main-sequence stars. The study of such objects is fundamental to improving our understanding of stellar evolution, but they are difficult to observe as they are relatively far away, tend to be born in binary or multiple systems, and are associated with dense clouds of interstellar material.
Especially, systematic surveys and studies of supergiants in the Local Group of galaxies may be relevant for gathering important clues to constrain theoretical models of stellar evolution. However, despite significant progress in the search for supergiants in neighboring Local Group galaxies, their census is still ongoing.
Number of supergiants in the Andromeda and Triangulum galaxies
A team of astronomers led by Hao Wu of Peking University in Beijing, China, has released the results of a new study that could significantly expand the list of known supergiants in the Milky Way’s neighborhood. They performed a systematic identification of supergiants in two Local Group galaxies: Messier 31 (Andromeda galaxy) and Messier 33 (Triangulum galaxy).
In total, Wu’s team identified 199 supergiant stars in the Andromeda galaxy and 84 in the Triangulum galaxy using a dataset from the LAMOST data release 10 (DR10). The astronomers pointed out that about 84% of the supergiant candidates in Andromeda successfully passed two independent selection criteria, indicating a high level of confidence in them as true supergiants in this galaxy. In the case of the Triangulum Galaxy, the figure is lower, at about 67%.
According to the paper, the sample of identified candidates in the Andromeda Galaxy consists of 134 yellow supergiants (YSGs), 62 blue supergiants (BSGs), and three red supergiants (RSGs). Within the Triangulum Galaxy, the researchers found 53 YSGs, 28 BSGs, and three RSGs.
Results of scientists’ work
In concluding the results, the authors of the paper emphasized the importance of their recently published work.
“So far, this is one of the largest supergiant samples of M31/M33 with full optical wavelength coverage. This sample is valuable for understanding the star formation and stellar evolution under different environments,” the scientists finalized.
Provided by phys.org
