Young stars raining through the Galactic Halo: the nature and orbit of
  Price-Whelan 1
  We present radial velocities for five member stars of the recently discovered
young (age= 100-150 Myr) stellar system Price-Whelan 1 (PW 1), that is located
far away in the Galactic Halo (D~ 29 kpc, Z~ 15 kpc), and that is probably
associated to the Leading Arm (LA) of the Magellanic Stream. We measure the
systemic radial velocity of PW 1, V_r=275 +/- 10 km/s, significantly larger
than the velocity of the LA gas in the same direction. We re-discuss the main
properties and the origin of this system in the light of these new
observations, computing the orbit of the system and comparing its velocity with
that of the HI in its surroundings. We show that the bulk of the gas at the
velocity of the stars is more than 10 deg (5~kpc) away from PW 1 and the
velocity difference between the gas and the stars become larger as gas closer
to the stars is considered. We discuss the possibilities that (a) the parent
gas cloud was dissolved by the interaction with the Galactic gas, and (b) that
the parent cloud is the high velocity cloud HVC287.5+22.5+240, lagging behind
the stellar system by ~25 km/s and ~10 deg.
