The Orbit of the New Milky Way Globular Cluster FSR1716=VVV-GC05

Author(s):Show less -

Contreras Ramos, Rodrigo ^{[1, 2]} ; Minniti, Dante ^{[1, 3, 4]} ; Fernandez-Trincado, Jose G. ^{[5, 6]} ; Alonso-Garcia, Javier ^{[1, 7]} ; Catelan, Marcio ^{[1, 2]} ; Gran, Felipe ^{[1, 2]} ; Hajdu, Gergely ^{[1, 2, 8]} ; Hanke, Michael ^[8] ; Hempel, Maren ^{[1, 2]} ; Moreno Diaz, Edmundo ^[9] ; Perez-Villegas, Angeles ^[10] ; Rojas-Arriagada, Alvaro ^{[1, 2]} ; Zoccali, Manuela ^{[1, 2]}

Affiliation

^[1] Inst Milenio Astrofis, Santiago - Chile

^[2] Pontificia Univ Catolica Chile, Inst Astrofis, Ave Vicuna Mackenna 4860, Santiago 7820436 - Chile

^[3] Univ Andres Bello, Dept Ciencias Fis, Fac Ciencias Exactas, Ave Fernandez Concha 700, Santiago - Chile

^[4] Vatican Observ, I-V00120 Vatican City - Vatican

^[5] Univ Concepcion, Dept Astron, Casilla 160-C, Concepcion - Chile

^[6] Univ Bourgogne Franche Comte, Inst Utinam, CNRS UMR 6213, OSU THETA Franche Comte, Observ Besancon, BP 1615, F-25010 Besancon - France

^[7] Univ Antofagasta, Unidad Astron, Fac Cs Basicas, Avda Univ Antofagasta 02800, Antofagasta - Chile

^[8] Heidelberg Univ, Astron Rechen Inst, Zentrum Astron, Monchhofstr 12-14, D-69120 Heidelberg - Germany

^[9] Univ Nacl Autonoma Mexico, Inst Astron, Apdo Postal 70264, Mexico City 04510, DF - Mexico

^[10] Univ Sao Paulo, IAG, Rua Matao 1226, Cidade Univ, BR-05508900 Sao Paulo - Brazil

• Document type: Journal article
• Source: ASTROPHYSICAL JOURNAL; v. 863, n. 1 AUG 10 2018.
• Web of Science Citations: 2

Abstract

We use deep, multi-epoch near-IR images of the VISTA Variables in the Via Lactea (VVV) Survey to measure proper motions (PMs) of stars in the Milky Way globular cluster (GC) FSR1716 = VVV-GC05. The color-magnitude diagram of this object, made by using PM-selected members, shows an extended horizontal branch, nine confirmed RR Lyrae (RRL) members in the instability strip, and possibly several hotter stars extending to the blue. Based on the fundamental-mode (ab-type) RRL stars that move coherently with the cluster, we confirmed that FSR1716 is an Oosterhoff I GC with a mean period P-ab = 0.574 days. Intriguingly, we detect tidal extensions to both sides of this cluster in the spatial distribution of PM-selected member stars. Also, one of the confirmed RRabs is located similar to 11 arcmin in projection from the cluster center, suggesting that FSR1716 may be losing stars due to the gravitational interaction with the Galaxy. We also measure radial velocities (RVs) for five cluster red giants selected using the PMs. The combination of RVs and PMs allow us to compute for the first time the orbit of this GC, using an updated Galactic potential. The orbit results to be confined within vertical bar Z(max)vertical bar < 2.0 kpc, and has eccentricity 0.4 < e < 0.6, with perigalactic distance 1.5 < R-peri (kpc) < 2.3, and apogalactic distance 5.3 < R-apo (kpc) < 6.4. We conclude that, in agreement with its relatively low metallicity ({[}Fe/H] = -1.4 dex), this is an inner-halo GC plunging into the disk of the Galaxy. As such, this is a unique object with which to test the dynamical processes that contribute to the disruption of Galactic GCs. (AU)

• FAPESP's process: 17/15893-1 - Globular cluster orbits of bulge: the formation and evolution of the Milky Way
• Grantee: Maria de Los Angeles Perez Villegas
• Support Opportunities: Scholarships in Brazil - Post-Doctoral