RR Lyrae are among the oldest stars in our galaxy and have physical properties that cause them to expand and contract in a regular cycle, allowing them to be used as a standard for measuring galactic distances.
A new study from the University of California, Santa Cruz, in the US, will be presented at the American Astronomical Society meeting, which will be held in Seattle this week.
Observing the new RR Lyrae stars allowed the team to map the outer boundary of the Milky Way’s halo, which is much larger than its disk and about 100,000 light-years across, according to Raja Guathakurta, an astrophysicist at the university.
The Milky Way and its neighboring galaxy, Andromeda, are so massive that there is almost no space between the two galaxies, even though the latter is about 2.5 million light-years away from our galaxy.
The solar system is located in one of the spiral arms of the disk of the Milky Way, at the center of which is a central bulge, and around this halo containing the oldest stars and extending hundreds of thousands of light-years across the globe. directione.
The halo is the hardest part to study because the outer boundary is so far away and there are so few stars compared to the high density of the disk and bulge.
The findings are based on data from the Virgo Cluster Next Generation Survey (NGVS), a program that uses the Canada-France-Hawaii Telescope (CFHT) to study a group of galaxies outside the Milky Way.
The researchers had to dig through the data in detail to uncover RR Lyrae stars among all those available in the NGVS, whose measurements are of “excellent quality,” allowing them to obtain “the most reliable and accurate characterization of RR Lyrae at these distances.”
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