We have found a young ∼120 Myr, metal-poor [Fe/H] ∼ -1.14, disrupting stellar cluster at a heliocentric distance D ∼ 29 kpc, placing it far into the Milky Way halo, unlike any known young clusters in the Milky Way. At its present Galactocentric position and velocity, the stars are likely associated with the Leading Arm (LA) of the gas stream emanating from the Magellanic cloud system (specifically, LA II). If formed from LA gas, the measured distance to the LA is nearer than simulations of gas stripping and infall from the Clouds would predict. However these models typically do not include ram pressure and gas interactions between Magellanic and Milky Way gas. The orbits of these stars relative to the LA are therefore sensitive to the properties of the hot gaseous halo around the Milky Way. However it formed, the discovery of a young stellar cluster in the Milky Way halo presents an interesting opportunity for study.
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020