On the derivation of radial velocities of SB2 components: a "CCF vs TODCOR" comparison

Jean-Louis Halbwachs, Flavien Kiefer, Frédéric Arenou, Benoît Famaey, Patrick Guillout, Rodrigo Ibata, Tsevi Mazeh, Dimitri Pourbaix

Published 2017-10-06Version 1

The radial velocity (RV) of a single star is easily obtained from cross-correlation of the spectrum with a template, but the treatment of double-lined spectroscopic binaries (SB2s) is more difficult. Two different approaches were applied to a set of SB2s: the fit of the cross-correlation function with two normal distributions, and the cross-correlation with two templates, derived with the TODCOR code. It appears that the minimum masses obtained through the two methods are sometimes rather different, although their estimated uncertainties are roughly equal. Moreover, both methods induce a shift in the zero point of the secondary RVs, but it is less pronounced for TODCOR. All-in-all the comparison between the two methods is in favour of TODCOR.