Newly discovered feature in our galaxy has baffled the scientific community – Science Enséñame

Astronomical events seem to be all the rage, and thanks to the hard work of scientists who focus on studying space and our galaxy in particular, some truly amazing results have been achieved, as recently reported by a group of researchers.

Discovery

Recently, researchers from the University of California, Santa Cruz, California, USA, discovered 200 new distant stars called “RR Lyrae Stars” in the stellar halo of the Milky Way galaxy.

The most distant star is located on the periphery of the outer halo of our galaxy, and is located more than a million light-years from our planet, or about half the distance between us and our neighboring galaxy Andromeda (2.5 million light-years away).

The newly discovered stars are considered “standard candles” because of the pulsations they emit and the intensity of their brightness. Thanks to these properties, astronomers were able to determine the outer limits of the galaxy’s halo.

To give you a better understanding of the halos that make up the Milky Way, we share the following image with you:

An image of the inner and outer halos of the Milky Way galaxy. The halo is a spherical cloud of stars surrounding the galaxy. (Image credits: NASA, ESA, and A. Field) [STScI])

Professor Raja Guthakurta commented that the Milky Way and Andromeda are so huge that there is hardly any distance between them. He added that the stellar halo of our galaxy is larger than the disk, which is about 100,000 light years in diameter.

Our home is located in one of the spiral arms of the disk. In the center of the disk is a central bulge, around which the halo containing the oldest stars in the Milky Way extends thousands of light-years around it.

The researcher also commented that the halo is the most difficult region to study, as its borders are very far away, in addition to the number of stars in it is very small, compared to the regions close to the disk and prominence. The halo is composed of dark matter and has the largest percentage of the mass of the galaxy.

“The halo is the most difficult part to study because the outer boundary is so far away,” said Guhathakurta. “Stars are very rare compared to the high stellar density of the disk and bulge, but the halo is dominated by dark matter and actually contains most of the galaxy’s mass.”

One of Professor Guhathakurta’s students, Yuting Venga, who led the study, presented his findings in two papers at the American Astronomical Society meeting in Seattle in January 2023.

According to the data previously calculated by student Feng, the stellar halo should extend about 300 kiloparsecs, or about a million light-years from the center of the galaxy (scientists measure distances between galaxies in kiloparsecs, which equal 3,260 light-years).

The bright RR Lyrae stars discovered by Ling and colleagues were found to be between 20 and 320 kiloparsecs away.

The student added that the variable stars acted as reliable trackers to accurately estimate distances and that the observations made confirmed theoretical calculations of the size of the halo, a very important result.

The published study is based on various observations made with MegaPrime/MegaCam, a collaboration between CFHT and CEA/IRFU, at the Canada-France-Hawaii Telescope (CFHT), operated by the National Research Council (NRC) of Canada, the National Institute of Universe Sciences of the National Centre for Scientific Research (CNRS) of France, and the University of Hawaii.

The original article was published in Official website of the University of California, Santa Cruz.