Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics
Scientific paper
2010-02-18
Astronomy and Astrophysics
Astrophysics
Galaxy Astrophysics
21 figures, submitted to AJ
Scientific paper
We have probed the tidal tails of the Sagittarius dwarf spheroidal galaxy using an as yet unmeasured sample, stars in the Red Clump. While contamination from the disk of our Galaxy is a primary concern and a possible reason for ignoring this population of stars until this point, we have developed a method to systematically eliminate this background using the stellar parameters of our program stars. We present this procedure for selecting Red Clump stars. Using this method, we measure the mean of the metallicity distribution of the streams in two areas to be [Fe/H] = -0.4 and -0.2 which agree well with previous measurements of the core of the dwarf galaxy. We also find the kinematics of one sample to have a velocity of -120 +/- 20 km/s which is in good agreement with an M giant measurement in the same area. Finally, we find that the density of Red Clump stars varies as a function of distance from the Sagittarius dwarf galaxy. Densities of rho = 3.0 +/- 0.3 RC stars/kpc^3 and rho <= 1.3 +/- 0.3 RC stars/kpc^3 in areas at different distances from the core of the dwarf galaxy were found. This factor of two difference is likely the result of the Red Clump stars being preferentially stripped during the most recent peri-galacticon passage. This suggests that the Red Clump stars may have been more centrally located in the Sagittarius dwarf galaxy than their Population II counterparts. Observations were carried out at Kitt Peak National Observatory using the WIYN telescope.
Carrell Kenneth
Wilhelm Ronald
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