Stellar Velocity Dispersion of the Leo A Dwarf Galaxy
Warren R. Brown, Margaret J. Geller, Scott J. Kenyon, and Michael J., Kurtz (Smithsonian Astrophysical Observatory)
TL;DR
This paper reports the first measurement of stellar velocity dispersion in Leo A dwarf galaxy, revealing it is predominantly dark matter with a high mass-to-light ratio based on radial velocity data.
Contribution
It provides the first velocity dispersion measurement for Leo A and estimates its mass and dark matter content using stellar and HII region velocities.
Findings
Velocity dispersion of 9.3 km/s measured.
Mass within 2 arcmin is approximately 8 x 10^7 solar masses.
Dark matter constitutes at least 80% of Leo A's mass.
Abstract
We measure the first stellar velocity dispersion of the Leo A dwarf galaxy, \sigma = 9.3 +- 1.3 km/s. We derive the velocity dispersion from the radial velocities of ten young B supergiants and two HII regions in the central region of Leo A. We estimate a projected mass of 8 +- 2.7 x10^7 solar masses within a radius of 2 arcmin, and a mass to light ratio of at least 20 +- 6 M_sun/L_sun. These results imply Leo A is at least ~80% dark matter by mass.
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