IAA-CSIC/HITS: Galaxy Histories Reconstructed from Star Motions

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IAA-CSIC/HITS: Galaxy Histories Reconstructed from Star Motions

Post by bystander » Fri Jan 05, 2018 2:39 am

Library of Galaxy Histories Reconstructed from Motions of Stars
Institute of Astrophysics of Andalusia (IAA) | High Council of Scientific Research (CSIC)
Heidelberg Institute for Theoretical Studies (HITS) | 2018 Jan 03

The CALIFA survey allows to map the orbits of the stars of a sample of 300 galaxies, a fundamental information to know how they formed and evolved

Just like the Sun is moving in our galaxy, the Milky Way, all the stars in galaxies are moving, but with very different orbits: some of the stars have strong rotations, while others may be moving randomly with no clear rotation. Comparing the fraction of stars on different orbits we can find out how galaxies form and evolve. An international team of astronomers has derived directly, for the first time, the orbital distribution of a galaxy sample, containing more than 300 galaxies of the local universe. The results, published in Nature Astronomy, are based on the CALIFA survey, a project developed at Calar Alto Observatory and conceived from the Institute of Astrophysics of Andalusia (IAA-CSIC).

Galaxies are the largest structures in the universe, and scientist study how they evolve to understand the history of the universe. Galaxy formation entails the hierarchical assembly of halos of dark matter (a type of matter that has not been directly observed and whose existence and properties are inferred from its gravitational effects), along with the condensation of normal matter at the halos’ center, where stellar formation takes place. Stars that formed from a settled, thin gas disk and then lived though dynamically quiescent times will present near circular orbits, while stars with random motions are the result of turbulent environments, either at birth or later, with galactic mergers.

Thus, the motions of stars in a galaxy are like a history book; they record the information about their birth and growth environment, and it may tell us how the galaxy was formed. ...

The Stellar Orbit Distribution in Present-Day Galaxies Inferred from the CALIFA Survey - Ling Zhu et al
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