Evidence of a small velocity dispersion for the Carina dwarf spheroidal?
Open Access
- 1 November 1987
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 229 (1) , 7P-13P
- https://doi.org/10.1093/mnras/229.1.7p
Abstract
Three independent determinations of the velocity dispersion of the Carina dwarf spheroidal give σc = 6±3, 6±2, 8±4 km s−1 which appear to be in good agreement. However, star by star comparison shows no correlation between the observers as to which stars move more slowly or faster than the mean. After intercomparison we conclude that all the observers have overestimated their accuracy by a factor of 2 in km s−1 and that the true velocity dispersion of Carina is unknown with best estimates in the range 1.1–3.2 km s−1. This would give this low mass dwarf spheroidal a stellar M/L ratio. In dwarf spheroidals and other systems velocity dispersions close to the observational errors should only be believed when the offsets of stellar velocities from the mean as measured by different observing systems show clear correlation. It is not yet clear that the high M/L ratios found in dwarf spheroidals are real.Keywords
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