KINEMATICS AND CHEMISTRY OF RECENTLY DISCOVERED RETICULUM 2 AND HOROLOGIUM 1 DWARF GALAXIES

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dc.contributor.authorKoposov, Sergey E.
dc.contributor.authorCasey, Andrew R.
dc.contributor.authorBelokurov, Vasily
dc.contributor.authorLewis, James R.
dc.contributor.authorGilmore, Gerard
dc.contributor.authorWorley, Clare
dc.contributor.authorHourihane, Anna
dc.contributor.authorRandich, S.
dc.contributor.authorBensby, T.
dc.contributor.authorBragaglia, A.
dc.contributor.authorBergemann, M.
dc.contributor.authorCarraro, G.
dc.contributor.authorCostado, M. T.
dc.contributor.authorFlaccomio, E.
dc.contributor.authorFrancois, P.
dc.contributor.authorHeiter, U.
dc.contributor.authorHill, V.
dc.contributor.authorJofre, P.
dc.contributor.authorLando, C.
dc.contributor.authorLanzafame, A. C.
dc.contributor.authorde Laverny, P.
dc.contributor.authorMonaco, L.
dc.contributor.authorMorbidelli, L.
dc.contributor.authorSbordone, L.
dc.contributor.authorMikolaitis, S.
dc.contributor.authorRyde, N.
dc.date.accessioned2025-01-23T21:34:10Z
dc.date.available2025-01-23T21:34:10Z
dc.date.issued2015
dc.description.abstractWe report on VLT/GIRAFFE spectra of stars in two recently discovered ultra-faint satellites, Reticulum 2 and Horologium 1, obtained as part of the Gaia-ESO Survey. We identify 18 members in Reticulum 2 and five in Horologium 1. We find Reticulum 2 to have a velocity dispersion of 3.22(-0.49)(+1.64) km s(-1) , implying a mass-to-light ratio (M/L) of similar to 500. The mean metallicity of Reticulum 2 is [Fe/H] = -2.46, with an intrinsic dispersion of similar to 0.3 dex and alpha-enhancement of similar to 0.4 dex. We conclude that Reticulum 2 is a dwarf galaxy. We also report on the serendipitous discovery of four stars in a previously unknown stellar substructure near Reticulum 2 with [Fe/H] similar to -2 and V-hel similar to 220 km s(-1), far from the systemic velocity of Reticulum 2. For Horologium 1 we infer a velocity dispersion of sigma (V) = 4.9(-0.9)(+2.8) km s(-1) and a M/L ratio of similar to 600, leading us to conclude that Horologium 1 is also a dwarf galaxy. Horologium 1 is slightly more metal-poor than Reticulum 2 ([Fe/H] = -2.76) and is similarly alpha-enhanced: [alpha/Fe] similar to 0.3 dex with a significant spread of metallicities of 0.17 dex. The line-of-sight velocity of Reticulum 2 is offset by 100 km s(-1) from the prediction of the orbital velocity of the Large Magellanic Cloud (LMC), thus making its association with the Cloud uncertain. However, at the location of Horologium 1, both the backward-integrated orbit of the LMC and its halo are predicted to have radial velocities similar to that of the dwarf. Therefore, it is possible that Horologium 1 is or once was a member of the Magellanic family.
dc.fuente.origenWOS
dc.identifier.doi10.1088/0004-637X/811/1/62
dc.identifier.eissn1538-4357
dc.identifier.issn0004-637X
dc.identifier.urihttps://doi.org/10.1088/0004-637X/811/1/62
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/101530
dc.identifier.wosidWOS:000363471600063
dc.issue.numero1
dc.language.isoen
dc.revistaAstrophysical journal
dc.rightsacceso restringido
dc.subjectgalaxies: abundances
dc.subjectgalaxies: dwarf
dc.subjectgalaxies: kinematics and dynamics
dc.subjectGalaxy: halo
dc.subjectglobular clusters: general
dc.subjectstars: abundances
dc.titleKINEMATICS AND CHEMISTRY OF RECENTLY DISCOVERED RETICULUM 2 AND HOROLOGIUM 1 DWARF GALAXIES
dc.typeartículo
dc.volumen811
sipa.indexWOS
sipa.trazabilidadWOS;2025-01-12
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