A Renaissance study of Am stars. I. The mass ratio distribution

TL;DR

This study reanalyzes the mass ratio distribution of Am star binaries using an inversion method, revealing a nearly uniform distribution without assuming a specific functional form, based on an extended sample of 162 systems.

Contribution

It introduces a non-parametric inversion approach to determine the MRD of Am binaries, extending previous analyses and challenging prior assumptions about the distribution shape.

Findings

The MRD of Am binaries is approximately uniform.

The inversion method is validated with double-lined spectroscopic binaries.

Extended sample analysis improves the robustness of the MRD estimate.

Abstract

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. 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. 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.