From the Companion Mass Ratio Distribution to the Planetary Mass Function: Using Multiple Systems to Constrain Models of Star and Planet Formation

Abstract

We present new results regarding the companion mass ratio distribution (CMRD) of stars, and sub-stellar objects. Considering the new survey of multiples for solar type field stars (Raghavan et al. ApJS 190:1, 2010) and M dwarfs (Janson et al. ApJ 754(1):26, 2012), we test the universality of the CMRD derived in Reggiani and Meyer (ApJ 738:60, 2011). Whereas we do not find significant differences in the CMRD for M dwarfs compared to previous results, the solar type CMRD appears to inconsistent with the previously derived CMRD from Reggiani and Meyer (ApJ 738:60, 2011). Despite the fact that this survey spans a wider range of angular separations than the previously studied samples, there is no evidence for variations in the CMRD as a function of orbital separation. Assuming that we can extrapolate both the stellar CMRD into the BD regime and the radial velocity planetary Companion Mass Function (Cumming et al. PASP 120:531, 2008) to larger separations, we can run MC simulations to test in which mass range we expect the planet population to become more important than BDs as companions to stars. This tool can be useful to predict the outcome of future surveys for very low mass companions or to analyze already existing datasets.