2019/01/14 by Fu-Chi Yeh, Giovanni Carraro, Marco Montalto +1 · 2 citations
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.3847/1538-3881/aaff6c
13 pages, 10 figure, in press in the Astronomical Journal
arxiv created 2019/01/14 · arxiv updated 2019/02/20
We employed recent Gaia/DR2 data to investigate the dynamical status of the nearby (300 pc), old (2.5 Gyr) open cluster Ruprecht~147. We found prominent leading and trailing tails of stars along the cluster orbit, which demonstrates that Ruprecht~147 is losing stars at fast pace. Star counts indicate the cluster has a core radius of 33.3 arcmin, and a tidal radius of 137.5 arcmin. The cluster also possesses an extended corona, which cannot be reproduced by a simple King model. We computed the present-day cluster mass using its luminosity and mass function, and derived an estimate of 234±52 M\odot. We also estimated the cluster original mass using available recipes extracted from N-body simulations obtaining a mass at birth of 50000±6500 M\odot. Therefore dynamical mass loss, mostly caused by tidal interaction with the Milky Way, reduced the cluster mass by about 99%. We then conclude that Ruprecht~147 is rapidly dissolving into the general Galactic disc.