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Metallicities and radial velocities of five open clusters including a new candidate member of the Monoceros stream

journal contribution
posted on 2023-05-16, 23:29 authored by Warren, SR, Andrew ColeAndrew Cole
Near-infrared spectra of 133 red giant stars from 10 Galactic open clusters and two Galactic globular clusters spanning 2.2dex in metallicity and 11Gyr in age are presented. We combine this sample with 10 clusters from Cole and collaborators to investigate the CaII triplet line strengths and their relation to cluster metallicity and position along the red giant branch. We show that characterizing the stellar surface gravity using Ks-band photometry (relative to the horizontal branch) taken from the Two Micron All-Sky Survey allows for metallicity measurements at least as precise as those derived using V- or I-band data. This has the great advantage that uniform photometry and reliable astrometry are available for a large number of clusters. Using Ks-band photometry also reduces the effect of differential reddening within a given cluster. We find no significant evidence for age or metallicity effects to the linear CaII triplet-metallicity relationship over the small range in magnitudes studied when homogeneous reference metallicities are used. We derive the first spectroscopic metallicity and new radial velocity estimates for five open clusters: Berkeley81, Berkeley99, IC1311, King2 and NGC7044. King2 has an anomalous radial velocity compared with the local disc population. We discuss the possibility that it is part of the Monoceros tidal stream.

History

Publication title

Monthly Notices of the Royal Astronomical Society

Volume

393

Pagination

272-296

ISSN

0035-8711

Department/School

School of Natural Sciences

Publisher

Blackwell Publishing

Place of publication

Oxford, UK

Rights statement

The definitive published version is available online at: http://interscience.wiley.com

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the physical sciences

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