Spectroscopic Observations of Obscured Populations in the Inner Galaxy: 2MASS-GC02, Terzan 4, and the 200 km/s stellar peak
arXiv:2106.02647 · doi:10.3847/1538-3881/ac0888
Abstract
The interpretation of potentially new and already known stellar structures located at low-latitudes is hindered by the presence of dense gas and dust, as observations toward these sight-lines are limited. We have identified APOGEE stars belonging to the low-latitude globular clusters 2MASS-GC02 and Terzan 4, presenting the first chemical element abundances of stars residing in these poorly studied clusters. As expected, the signature of multiple populations co-existing in these metal-rich clusters is evident. We redetermine the radial velocity of 2MASS-GC02 to be -87 +- 7 km/s, finding that this cluster's heliocentric radial velocity is offset by more than 150 km/s from the literature value. We investigate a potentially new low-latitude stellar structure, a kiloparsec-scale nuclear disk (or ring) which has been put forward to explain a high-velocity (V_{GSR} ~200 km/s) peak reported in several Galactic bulge fields based on the APOGEE commissioning observations. New radial velocities of field stars at (l,b)=(-6,0) are presented and combined with the APOGEE observations at negative longitudes to carry out this search. Unfortunately no prominent -200 km/s peak at negative longitudes along the plane of the Milky Way is apparent, as predicted for the signature of a nuclear feature. The distances and Gaia EDR3 proper motions of the high-V_{GSR} stars do not support the current models of stars on bar-supporting orbits as an explanation of the +200 km/s peak.
accepted to AJ
References in corpus (27)
- The 2.5 m Telescope of the Sloan Digital Sky Survey
- Gaia EDR3 view on Galactic globular clusters
- Target Selection for the SDSS-IV APOGEE-2 Survey
- Made-to-Measure models of the Galactic Box/Peanut bulge: stellar and total mass in the bulge region
- VIRAC: The VVV Infrared Astrometric Catalogue
- The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XIX. A Chemical Tagging of the Multiple Stellar Populations Over the Chromosome Maps
- The Chemical Compositions of Accreted and {\it in situ} Galactic Globular Clusters According to SDSS/APOGEE
- The formation of stellar nuclear discs in bar-induced gas inflows
- Comparing CN and CH Line Strengths in a Homogeneous Spectroscopic Sample of 8 Galactic Globular Clusters
- Proper motions and kinematics of selected bulge globular clusters
- Variable stars in the VVV globular clusters. I. 2MASS-GC02 and Terzan10
- The Bulge Radial Velocity Assay for RR Lyrae stars (BRAVA-RR) DR2: a Bimodal Bulge?
- The Relationship Between Globular Cluster Mass, Metallicity, and Light Element Abundance Variations
- Two Groups of Red Giants with Distinct Chemical Abundances in the Bulge Globular Cluster NGC 6553 Through the Eyes of APOGEE
- Globular clusters in the inner Galaxy classified from dynamical orbital criteria
- Aluminum Enhanced Metal-Poor Stars buried in the Inner Galaxy
- Kinematics in the Galactic Bulge with APOGEE: II. High-Order Kinematical Moments and Comparison to Extragalactic Bar Diagnostics
- Insights into the chemical composition of the metal-poor Milky Way halo globular cluster NGC 6426
- The enigmatic globular cluster UKS~1 obscured by the bulge: \textit{H}-band discovery of nitrogen-enhanced stars
- Effects of the selection function on metallicity trends in spectroscopic surveys of the Milky Way
- The Blanco DECam Bulge Survey. I. The Survey Description and Early Results
- Predicted Stellar Kinematics of a Kiloparsec-Scale Nuclear Disc (or Ring) in the Milky Way
- Chemical abundances and ages of the bulge stars in APOGEE high-velocity peaks
- Chemical Abundances of the Highly Obscured Galactic Globular Clusters 2MASS GC02 and Mercer 5
- Understanding the velocity distribution of the Galactic Bulge with APOGEE and Gaia
- Spectroscopic analysis of the bulge Globular Cluster ESO~456-SC38
- Models of Bars with Exponential Density Profiles