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Article Dans Une Revue Monthly Notices of the Royal Astronomical Society Année : 2019

Detailed study of the Milky Way globular cluster Laevens 3

Nicolas F. Martin
Rodrigo Ibata
Michelle Collins
Eric Bell
  • Fonction : Auteur
Dougal Mackey
  • Fonction : Auteur

Résumé

We present a photometric and spectroscopic study of the Milky Way satellite Laevens 3. Using MegaCam/Canada-France-Hawaii Telescope 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 (M V = −2.8 +0.2 −0.3 mag) and compact (r h = 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 * α , μ δ) = (0.51 ± 0.28, −0.83 ± 0.27) mas yr −1 , which, combined with the system's radial velocity (v r = −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 that strengthens our conclusion that Laevens 3 is a globular cluster.
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Dates et versions

hal-03095279 , version 1 (04-01-2021)

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Nicolas Longeard, Nicolas F. Martin, Rodrigo Ibata, Michelle Collins, Benjamin Laevens, et al.. Detailed study of the Milky Way globular cluster Laevens 3. Monthly Notices of the Royal Astronomical Society, 2019, 490 (2), pp.1498-1508. ⟨10.1093/mnras/stz2592⟩. ⟨hal-03095279⟩
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