Could Segue 1 be a destroyed star cluster? - a dynamical perspective
  We attempt to find a progenitor for the ultra-faint object Segue 1 under the assumption that it formed as a dark matter free star cluster in the past. We look for orbits, using the elongation of Segue 1 on the sky as a tracer of its path. Those orbits are followed backwards in time to find the starting points of our N-body simulations. The successful orbit, with which we can reproduce Segue 1 has a proper motion of mu_alpha = -0.19 mas/yr and mu_delta = -1.9 mas/yr, placing Segue 1 near its apo-galacticon today. Our best fitting model has an initial mass of 6224 Msun and an initial scale-length of 5.75 pc. 
Raul Dominguez (1), Michael Fellhauer (1), Matias Bla\~na (2),   Juan-Pablo Farias (1,4), J\"org Dabringhausen (1), Graeme N...
astro-ph.GA