Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Kinematic subpopulations in dwarf spheroidal galaxies
AU - Ural, Uğur
AU - Wilkinson, Mark I.
AU - Koch, Andreas
AU - Gilmore, Gerard
AU - Beers, Timothy C.
AU - Belokurov, V.
AU - Wyn Evans, N.
AU - Grebel, E.K.
AU - Vidrih, Simon
AU - Zucker, D. B.
PY - 2009/12/18
Y1 - 2009/12/18
N2 - We present new spectroscopic data for 26 stars in the recently discovered Canes Venatici I (CVn I) dwarf spheroidal galaxy, obtained with the Gemini Multi-Object Spectrograph North (GMOS-N) on the Gemini North telescope. We use these data to investigate the recent claim of the presence of two dynamically inconsistent stellar populations in this system. While we find no evidence for kinematically distinct subpopulations in our sample, we also show that the available kinematic data set in CVnI is likely too small to draw robust conclusions about its subpopulations. We are, however, able to obtain a mass estimate for CVn I that is consistent with all available data, including previously published data. We discuss possible differences between our sample and the earlier data set, and study the general detectability of subpopulations in small kinematic samples. We conclude that, in the absence of additional supporting observational evidence (e.g. metallicity gradients), subpopulations in small kinematic samples (typically fewer than 100 stars) should be treated with caution, as their identification depends on multiple parameters and rarely produces a signal at a high confidence level. It is therefore essential to explicitly determine the statistical significance of any suggested subpopulation.
AB - We present new spectroscopic data for 26 stars in the recently discovered Canes Venatici I (CVn I) dwarf spheroidal galaxy, obtained with the Gemini Multi-Object Spectrograph North (GMOS-N) on the Gemini North telescope. We use these data to investigate the recent claim of the presence of two dynamically inconsistent stellar populations in this system. While we find no evidence for kinematically distinct subpopulations in our sample, we also show that the available kinematic data set in CVnI is likely too small to draw robust conclusions about its subpopulations. We are, however, able to obtain a mass estimate for CVn I that is consistent with all available data, including previously published data. We discuss possible differences between our sample and the earlier data set, and study the general detectability of subpopulations in small kinematic samples. We conclude that, in the absence of additional supporting observational evidence (e.g. metallicity gradients), subpopulations in small kinematic samples (typically fewer than 100 stars) should be treated with caution, as their identification depends on multiple parameters and rarely produces a signal at a high confidence level. It is therefore essential to explicitly determine the statistical significance of any suggested subpopulation.
U2 - 10.1111/j.1365-2966.2009.15975.x
DO - 10.1111/j.1365-2966.2009.15975.x
M3 - Journal article
VL - 402
SP - 1357
EP - 1368
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 2
ER -