期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 447, 期 2, 页码 2046-2058出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stu2574
关键词
Galaxy: abundances; Galaxy: halo; Galaxy: kinematics and dynamics
资金
- British Marshall Scholarship program
- King's College, Cambridge Studentship
- NSF [OIA-1124403]
- Australian Astronomical Observatory
- Leibniz-Institut fuer Astrophysik Potsdam (AIP)
- Australian National University
- Australian Research Council
- French National Research Agency
- German Research Foundation [SPP 1177, SFB 881]
- European Research Council [ERC-StG 240271 Galactica]
- Istituto Nazionale di Astrofisica at Padova
- Johns Hopkins University
- National Science Foundation of the USA [AST-0908326]
- W. M. Keck foundation
- Macquarie University
- Netherlands Research School for Astronomy
- Natural Sciences and Engineering Research Council of Canada
- Slovenian Research Agency
- Swiss National Science Foundation
- Science & Technology Facilities Council of the UK
- Opticon
- Strasbourg Observatory
- University of Groningen, Heidelberg
- University of Groningen, Sydney
- Science and Technology Facilities Council [ST/K000985/1, ST/K000977/1] Funding Source: researchfish
- STFC [ST/K000985/1, ST/K000977/1] Funding Source: UKRI
- Office Of The Director
- Office of Integrative Activities [1124403] Funding Source: National Science Foundation
We aim to characterize high-velocity (HiVel) stars in the solar vicinity both chemically and kinematically using the fourth data release of the RAdial Velocity Experiment (RAVE). We used a sample of 57 HiVel stars with Galactic rest-frame velocities larger than 275 km s(-1). With 6D position and velocity information, we integrated the orbits of the HiVel stars and found that, on average, they reach out to 13 kpc from the Galactic plane and have relatively eccentric orbits consistent with the Galactic halo. Using the stellar parameters and [alpha/Fe] estimates from RAVE, we found the metallicity distribution of the HiVel stars peak at [M/H] = -1.2 dex and is chemically consistent with the inner halo. There are a few notable exceptions that include a hypervelocity star candidate, an extremely HiVel bound halo star, and one star that is kinematically consistent with the halo but chemically consistent with the disc. High-resolution spectra were obtained for the metal-rich HiVel star candidate and the second highest velocity star in the sample. Using these high-resolution data, we report the discovery of a metal-rich halo star that has likely been dynamically ejected into the halo from the Galactic thick disc. This discovery could aid in explaining the assembly of the most metal-rich component of the Galactic halo.
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