Gaia Reveals a Metal-rich, in situ Component of the Local Stellar Halo
Top Cited Papers
- 16 August 2017
- journal article
- research article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 845 (2), 101
- https://doi.org/10.3847/1538-4357/aa7d0c
Abstract
We use the first Gaia data release, combined with the RAVE and APOGEE spectroscopic surveys, to investigate the origin of halo stars within kpc from the Sun. We identify halo stars kinematically as moving at a relative speed of at least 220 km s−1 with respect to the local standard of rest. These stars are generally less metal-rich than the disk, but surprisingly, half of our halo sample is comprised of stars with . The orbital directions of these metal-rich halo stars are preferentially aligned with the disk rotation, in sharp contrast with the intrinsically isotropic orbital distribution of the metal-poor halo stars. We find similar properties in the Latte cosmological zoom-in simulation of a Milky Way-like galaxy from the FIRE project. In Latte, metal-rich halo stars formed primarily inside of the solar circle, whereas lower-metallicity halo stars preferentially formed at larger distances (extending beyond the virial radius). This suggests that metal-rich halo stars in the solar neighborhood actually formed in situ within the Galactic disk, rather than having been accreted from satellite systems. These stars, currently on halo-like orbits, therefore have likely undergone substantial radial migration/heating.Keywords
This publication has 116 references indexed in Scilit:
- DWARFS GOBBLING DWARFS: A STELLAR TIDAL STREAM AROUND NGC 4449 AND HIERARCHICAL GALAXY FORMATION ON SMALL SCALESThe Astrophysical Journal Letters, 2012
- THE ONGOING ASSEMBLY OF A CENTRAL CLUSTER GALAXY: PHASE-SPACE SUBSTRUCTURES IN THE HALO OF M87The Astrophysical Journal, 2012
- THE GENESIS OF THE MILKY WAY'S THICK DISK VIA STELLAR MIGRATIONThe Astrophysical Journal, 2011
- The Ages of StarsAnnual Review of Astronomy and Astrophysics, 2010
- Two distinct halo populations in the solar neighborhoodAstronomy & Astrophysics, 2010
- RUNAWAY STARS, HYPERVELOCITY STARS, AND RADIAL VELOCITY SURVEYSThe Astrophysical Journal, 2009
- Validation of the new Hipparcos reductionAstronomy & Astrophysics, 2007
- The Geneva-Copenhagen survey of the Solar neighbourhoodAstronomy & Astrophysics, 2004
- GAIA: Composition, formation and evolution of the GalaxyAstronomy & Astrophysics, 2001
- The Age of Globular Clusters in Light ofHipparcos: Resolving the Age Problem?The Astrophysical Journal, 1998