Bootes II ReBooted: An MMT/MegaCam Study of An Ultra-Faint Milky Way Satellite

Understand

[abridged] We present MMT/Megacam imaging in Sloan $g$ and $r$ of the extremely low luminosity Bo\"otes II Milky Way companion.

• We use a bootstrap approach to perform robust measurements of, and uncertainties on, Bo\"otes II's distance, luminosity, size, and morphology.
• We show that Bo\"otes II's stellar population is old and metal-poor ([Fe/H] $\lta$ -2).
• Assuming a stellar population like that of M92, Bo\"otes II is at a distance of 42 $\pm$ 2 kpc, closer than the initial published estimate of 60 $\pm$ 10 kpc.