Abstract

Mondal
The origin of the very metal-rich stars near the sun
Stars of all ages are found near the sun- young and old, with abundances up to about [Fe/H] = 0.5. The most metal-rich stars with [Fe/H] > 0.1, could not have formed near the sun, because the ISM near the sun is not so metal-rich. It is widely believed that they formed in the inner Galaxy and migrated out to the solar neighborhood via radial migration. The migration process moves stars from near-circular orbits at one radius to near-circular orbits at another (mostly larger) radius via transient spiral structures, and their vertical dispersion is lower after the migration, due to the conservation of z-action. From the APOGEE, GALAH, and Gaia surveys, we study the abundances and motions of stars with [Fe/H] > 0.1 near the sun. We look for chemical and dynamical properties of > these stars that give insights into their possible origin in the inner Galaxy. From their (Vphi, VR) distribution, some of these metal-rich stars are associated with the Hercules moving group of stars, trapped by the Galactic bar in stable orbits. These orbits carry the stars out into the solar neighborhood. Our analysis supports this view. Unlike the stars of near-solar abundance, we find no change in orbital eccentricity distribution for the metal-rich stars. These stars have had a common dynamical history since their birth in the inner Galaxy.

Mondal

The origin of the very metal-rich stars near the sun

Stars of all ages are found near the sun- young and old, with abundances up to about [Fe/H] = 0.5. The most metal-rich stars with [Fe/H] > 0.1, could not have formed near the sun, because the ISM near the sun is not so metal-rich. It is widely believed that they formed in the inner Galaxy and migrated out to the solar neighborhood via radial migration. The migration process moves stars from near-circular orbits at one radius to near-circular orbits at another (mostly larger) radius via transient spiral structures, and their vertical dispersion is lower after the migration, due to the conservation of z-action.
From the APOGEE, GALAH, and Gaia surveys, we study the abundances and motions of stars with [Fe/H] > 0.1 near the sun. We look for chemical and dynamical properties of > these stars that give insights into their possible origin in the inner Galaxy. From their (Vphi, VR) distribution, some of these metal-rich stars are associated with the Hercules moving group of stars, trapped by the Galactic bar in stable orbits. These orbits carry the stars out into the solar neighborhood. Our analysis supports this view. Unlike the stars of near-solar abundance, we find no change in orbital eccentricity distribution for the metal-rich stars. These stars have had a common dynamical history since their birth in the inner Galaxy.

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Abstract