Journal article
Radial Velocities of RR Lyrae Stars in and around NGC 6441
The Astronomical journal, Vol.155(4), p.171
04/01/2018
DOI: 10.3847/1538-3881/aab42d
Abstract
Detailed elemental abundance patterns of metal-poor ([Fe/H] ∼ −1 dex) stars in the Galactic bulge indicate that a number of them are consistent with globular cluster (GC) stars and may be former members of dissolved GCs. This would indicate that a few per cent of the Galactic bulge was built up from destruction and/or evaporation of GCs. Here, an attempt is made to identify such presumptive stripped stars originating from the massive, inner Galaxy GC NGC 6441 using its rich RR Lyrae variable star (RRL) population. We present radial velocities of 40 RRLs centered on the GC NGC 6441. All 13 of the RRLs observed within the cluster tidal radius have velocities consistent with cluster membership, with an average radial velocity of 24 5 km s−1 and a star-to-star scatter of 11 km s−1. This includes two new RRLs that were previously not associated with the cluster. Eight RRLs with radial velocities consistent with cluster membership but up to three time the distance from the tidal radius are also reported. These potential extra-tidal RRLs also have exceptionally long periods, which is a curious characteristic of the NGC 6441 RRL population that hosts RRLs with periods longer than seen anywhere else in the Milky Way. As expected of stripped cluster stars, most are inline with the cluster's orbit. Therefore, either the tidal radius of NGC 6441 is underestimated and/or we are seeing dissolving cluster stars stemming from NGC 6441 that are building up the old spheroidal bulge.
Details
- Title: Subtitle
- Radial Velocities of RR Lyrae Stars in and around NGC 6441
- Creators
- Andrea Kunder - Saint Martin's UniversityArthur Mills - Saint Martin's UniversityJoseph Edgecomb - Saint Martin's UniversityMathew Thomas - Saint Martin's UniversityLevi Schilter - Saint Martin's UniversityCraig Boyle - Saint Martin's UniversityStephen Parker - Saint Martin's UniversityGordon Bellevue - Saint Martin's UniversityR. Michael Rich - University of California, Los AngelesAndreas Koch - Heidelberg UniversityChristian I. Johnson - Center for Astrophysics Harvard & SmithsonianDavid M. Nataf - Johns Hopkins University
- Resource Type
- Journal article
- Publication Details
- The Astronomical journal, Vol.155(4), p.171
- Publisher
- The American Astronomical Society
- DOI
- 10.3847/1538-3881/aab42d
- ISSN
- 0004-6256
- eISSN
- 1538-3881
- Number of pages
- 9
- Alternative title
- Radial Velocities of RR Lyrae Stars in and around NGC 6441
- Language
- English
- Date published
- 04/01/2018
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984701730502771
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