Hypervelocity Star Candidates in the SEGUE G and K Dwarf Sample

Schneider, Donald P.; Beers, Timothy C.; Lee, Young Sun; Allende-Prieto, C.; Palladino, L. E.; Schlesinger, Katharine J.; Holley-Bockelmann, Kelly
Bibliographical reference

The Astrophysical Journal, Volume 780, Issue 1, article id. 7, 7 pp. (2014).

Advertised on:
1
2014
Number of authors
7
IAC number of authors
1
Citations
44
Refereed citations
42
Description
We present 20 candidate hypervelocity stars from the Sloan Extension for Galactic Understanding and Exploration (SEGUE) G and K dwarf samples. Previous searches for hypervelocity stars have only focused on large radial velocities; in this study, we also use proper motions to select the candidates. We determine the hypervelocity likelihood of each candidate by means of Monte Carlo simulations, considering the significant errors often associated with high proper motion stars. We find that nearly half of the candidates exceed their escape velocities with at least 98% probability. Every candidate also has less than a 25% chance of being a high-velocity fluke within the SEGUE sample. Based on orbits calculated using the observed six-dimensional positions and velocities, few, if any, of these candidates originate from the Galactic center. If these candidates are truly hypervelocity stars, they were not ejected by interactions with the Milky Way's supermassive black hole. This calls for a more serious examination of alternative hypervelocity-star ejection scenarios.
Related projects
spectrum of mercury lamp
Chemical Abundances in Stars
Stellar spectroscopy allows us to determine the properties and chemical compositions of stars. From this information for stars of different ages in the Milky Way, it is possible to reconstruct the chemical evolution of the Galaxy, as well as the origin of the elements heavier than boron, created mainly in stellar interiors. It is also possible to
Carlos
Allende Prieto