We present the first high resolution spectroscopic observations of one red giant star in the ultra-faint dwarf galaxy Segue 2 , which has the lowest total mass ( including dark matter ) estimated for any known galaxy .
These observations were made using the MIKE spectrograph on the Magellan II Telescope at Las Campanas Observatory .
We perform a standard abundance analysis of this star , SDSS J021933.13 + 200830.2 , and present abundances of 21 species of 18 elements as well as upper limits for 25 additional species .
We derive [ Fe/H ] = - 2.9 , in excellent agreement with previous estimates from medium resolution spectroscopy .
Our main result is that this star bears the chemical signatures commonly found in field stars of similar metallicity .
The heavy elements produced by neutron-capture reactions are present , but they are deficient at levels characteristic of stars in other ultra-faint dwarf galaxies and a few luminous dwarf galaxies .
The otherwise normal abundance patterns suggest that the gas from which this star formed was enriched by metals from multiple Type II supernovae reflecting a relatively well-sampled IMF .
This adds to the growing body of evidence indicating that Segue 2 may have been substantially more massive in the past .