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Detailed study of the Milky Way globular cluster Laevens 3

Longeard, Nicolas, Martin, Nicolas, Ibata, Rodrigo A., Collins, Michelle L. M., Laevens, Benjamin P. M., Bell, Eric and Mackey, Dougal (2019) Detailed study of the Milky Way globular cluster Laevens 3 Monthly Notices of the Royal Astronomical Society.

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We present a photometric and spectroscopic study of the Milky Way satellite Laevens 3. Using MegaCam/CFHT g and i photometry and Keck II/DEIMOS multi-object spectroscopy, we refine the structural and stellar properties of the system. The Laevens 3 colour-magnitude diagram shows that it is quite metal-poor, old (13.0 ± 1.0 Gyr), and at a distance of 61.4 ± 1.0 kpc, partly based on two RR Lyrae stars. The system is faint (⁠MV=−2.8+0.2−0.3 mag) and compact (rh = 11.4 ± 1.0 pc). From the spectroscopy, we constrain the systemic metallicity ([Fe/H]spectro = −1.8 ± 0.1 dex) but the metallicity and velocity dispersions are both unresolved. Using Gaia DR2, we infer a mean proper motion of (μ∗αδ)=(0.51±0.28,−0.83±0.27) mas yr−1, which, combined with the system’s radial velocity (˂vr˃ = −70.2 ± 0.5 km s−1), translates into a halo orbit with a pericenter and apocenter of 40.7+5.6−14.7 and 85.6+17.2−5.9 kpc, respectively. Overall, Laevens 3 shares the typical properties of the Milky Way's outer halo globular clusters. Furthermore, we find that this system shows signs of mass-segregation which strengthens our conclusion that Laevens 3 is a globular cluster.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
Longeard, Nicolas
Martin, Nicolas
Ibata, Rodrigo A.
Collins, Michelle L.
Laevens, Benjamin P. M.
Bell, Eric
Mackey, Dougal
Date : 2019
DOI : 10.1093/mnras/stz2592
Copyright Disclaimer : © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (
Uncontrolled Keywords : Cluster: Globular. Local Group. Object : Laevens 3.
Depositing User : Clive Harris
Date Deposited : 26 Sep 2019 07:49
Last Modified : 26 Sep 2019 07:50

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