Chinese astronomers conducted extensive searches for hyperfast stars in the Milky Way. These stars are also important objects that help us accurately measure distances in our galaxy using variable luminaries of the PR Lira class. They have regular and especially predictable pulsations, acting as a "unit of cosmic measurement." This research was published in The Astrophysical Journal (AstroJournal).
Hypervelocity stars move so fast that they move independently of galactic gravitational forces. If the escape velocity for the Milky Way is approximately 550 km/h, then at such objects they can exceed 1000 km/h. Their appearance and subsequent formation are often due to the black hole at the center of the galaxy - Sagittarius A and its interaction.
Astronomers from Beijing University, led by Haochju Fu, decided to search for such hyperfast objects through PR Lira stars. These objects are mainly characteristic of the galaxy and thick disk of the Milky Way, as well as old giant stars in spherical clusters. They allow accurate and reliable measurement of these distances for studying brightness, pulsation period, and chemical composition.
Through special work by government astronomers and analysis of two large catalogs, he managed to identify 87 of the most reliable hyperfast stars from samples shortened to 165 candidates. The transverse speed of seven of them exceeded 800 km/h. Thus, they are located in the region of neighboring dwarf galaxies, such as the Large and Small Magellanic Clouds, close to the center of the Milky Way.
New indicators of unusual "fugitives" could be identified in the future based on Gaia satellite and new spectroscopic observations. The research that helped to understand the trajectories and origins of these escapees will undoubtedly be important for studying the galactic center and mapping the gravitational potential of the Milky Way. This is important in determining the distribution of dark matter, which is one of the most mysterious components in modern astrophysics.
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