Stellar kinematics and metallicities in the Leo I dwarf spheroidal galaxy -- wide field implications for galactic evolution

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dc.creatorKoch, A.
dc.creatorWilkinson, M. I.
dc.creatorKleyna, J. T.
dc.creatorGilmore, G. F.
dc.creatorGrebel, E. K.
dc.creatorMackey, A. D.
dc.creatorEvans, N. W.
dc.creatorWyse, R. F. G.
dc.date2006-11-12
dc.date.accessioned2026-07-07T10:20:46Z
dc.date.available2026-07-07T10:20:46Z
dc.descriptionWe present low-resolution spectroscopy of 120 red giants in the Galactic satellite dwarf spheroidal (dSph) Leo I, obtained with the GeminiN-GMOS and Keck-DEIMOS spectrographs. We find stars with velocities consistent with membership of Leo I out to 1.3 King tidal radii. By measuring accurate radial velocities with a median measurement error of 4.6 km/s we find a mean systemic velocity of 284.2 km/s with a global velocity dispersion of 9.9 km/s. The dispersion profile is consistent with being flat out to the last data point. We show that a marginally-significant rise in the radial dispersion profile at a radius of 3' is not associated with any real localized kinematical substructure. Given its large distance from the Galaxy, tides are not likely to have affected the velocity dispersion, a statement we support from a quantitative kinematical analysis, as we observationally reject the occurrence of a significant apparent rotational signal or an asymmetric velocity distribution. Mass determinations adopting both isotropic stellar velocity dispersions and more general models yield a M/L ratio of 24, which is consistent with the presence of a significant dark halo with a mass of about 3x10^7 M_sun, in which the luminous component is embedded. This suggests that Leo I exhibits dark matter properties similar to those of other dSphs in the Local Group. Our data allowed us also to determine metallicities for 58 of the targets. We find a mildly metal poor mean of -1.31 dex and a full spread covering 1 dex. In contrast to the majority of dSphs, Leo I appears to show no radial gradient in its metallicities, which points to a negligible role of external influences in this galaxy's evolution.
dc.description29 pages, 14 Figures, accepted for publication in the ApJ
dc.identifierhttps://arxiv.org/abs/astro-ph/0611372
dc.identifierhttp://arxiv.org/abs/astro-ph/0611372
dc.identifierAstrophys.J.657:241-261,2007
dc.identifierdoi:10.1086/510879
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/174961
dc.subjectAstrophysics
dc.titleStellar kinematics and metallicities in the Leo I dwarf spheroidal galaxy -- wide field implications for galactic evolution
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