A Renaissance study of Am stars

I. The mass ratio distribution

ESO, Alonso de Córdova 3107, Casilla 19001, Santiago Chile
e-mail: hboffin@eso.org

Received: 4 August 2010
Accepted: 20 August 2010

Abstract

Aims. Triggered by the study of Carquillat & Prieur (2007, MNRAS, 380, 1064) of Am binaries, I reanalyse their sample of 60 orbits to derive the mass ratio distribution (MRD), assuming as they did a priori functional forms, i.e. a power law or a Gaussian. The sample is then extended using orbits published by several groups and a full analysis of the MRD is made, without any assumption on the functional form.

Methods. I derive the MRD using a Richardson-Lucy inversion method, assuming a fixed mass of the Am primary and randomly distributed orbital inclinations. Using the large sub-sample of double-lined spectroscopic binaries, I show that this methodology is indeed perfectly adequate.

Results. I first derive new parameters of the functional form for the Carquillat & Prieur sample. Using the inversion method, applied to my extended sample of 162 systems, I find that the final MRD can be approximated by a uniform distribution.