2019/06/11 by Sandro Villanova, Lorenzo Monaco, Julia O'Connell +6 · 2 citations
Physics and Astronomy · #Accretion (finance) #Astronomy and Astrophysical Research #Dwarf galaxy #Dwarf spheroidal galaxy #Galaxies: Formation, Evolution, Phenomena #Globular cluster #Metallicity #Milky Way #Orbit (dynamics) #Orbital eccentricity #Stellar, planetary, and galactic studies #Velocity dispersion #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.3847/1538-4357/ab3722
11 pages, 10 figures, submitted to ApJ. arXiv admin note: text overlap with arXiv:1610.01834
arxiv created 2019/06/11 · openalex created_date 2019/06/27 · openalex publication_date 2019/09/10 · arxiv updated 2019/09/25 · openalex updated_date 2026/08/05
Abstract We present detailed chemical abundances, radial velocity, and orbital parameters for FSR 1758, a recently discovered massive cluster in the direction of the Galactic bulge. High-resolution ( R ∼ 42,000) spectra were obtained for nine members using the Magellan /Clay telescope instrumented with the MIKE echelle spectrogragh in the wavelength range of ∼4900–8700 Å. Cluster membership was determined using Gaia DR2 proper motions and confirmed with our radial velocity measurements. We find a metallicity of [Fe/H] = −1.58 ± 0.03, consistent with previous photometric estimates, and no significant iron spread. While other studies have suggested that this massive object could be the remnant of a captured dwarf galaxy, our results are consistent with a globular cluster (GC) nature, given its lack of any intrinsic metallicity spread and the Na–O anticorrelation similar to those of other GC. In addition, the small velocity dispersion of 4.9 ± 1.2 km s −1 we find is that typical of a GC. We also confirm a retrograde orbit that appears to be highly eccentric suggesting it is a halo interloper currently in the bulge. We support the hypothesis that FSR 1758 was part of a disrupted dwarf galaxy named Sequoia.