Radial Velocities from VLT-KMOS Spectra of Giant Stars in the Globular Cluster NGC 6388

Journal
Date Issued
2015
Author(s)
Lapenna, E.
•
•
Mucciarelli, A.
•
Lanzoni, B.
•
Ferraro, F. R.
•
•
Valenti, E.
•
Cirasuolo, M.
DOI
Description
This research is part of the project Cosmic-Lab ( http://www.cosmic-lab.eu ) funded by the European Research Council (under contract ERC-2010-AdG-267675). E.V. acknowledges ESO DGDF (SL) 14/51/E. NSO/Kitt Peak FTS data used here were produced by NSF/NOAO. We warmly thank the anonymous referee for suggestions that improved the paper.
Abstract
We present new radial velocity measurements for 82 stars, members of the Galactic globular cluster (GC) NGC 6388, obtained from ESO-VLT K-band Multi Object Spectrograph (KMOS) spectra acquired during the instrument Science Verification. The accuracy of the wavelength calibration is discussed and a number of tests of the KMOS response are presented. The cluster systemic velocity obtained (81.3 ± 1.5 km s-1) is in very good agreement with previous determinations. While a hint of ordered rotation is found between 9'' and 20'' from the cluster center, where the distribution of radial velocities is clearly bimodal, more data are needed before drawing any firm conclusions. The acquired sample of radial velocities has also been used to determine the cluster velocity dispersion (VD) profile between ~9'' and 70'', supplementing previous measurements at r < 2'' and r > 60'' obtained with ESO-SINFONI and ESO-FLAMES spectroscopy, respectively. The new portion of the VD profile nicely matches the previous ones, better defining the knee of the distribution. The present work clearly shows the effectiveness of a deployable integral field unit in measuring the radial velocities of individual stars for determining the VD profile of Galactic GCs. It represents the pilot project for an ongoing large program with KMOS and FLAMES at the ESO-VLT, aimed at determining the next generation of VD and rotation profiles for a representative sample of GCs.

Based on observations collected at the ESO-VLT (Cerro Paranal, Chile) under program 60.A-9448(A).

Volume
798
Issue
1
Start page
23
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2015ApJ...798...23L
Rights
open.access
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