Rotational Doppler beaming in eclipsing binaries

TL;DR

This paper introduces the concept of rotational Doppler beaming in eclipsing binaries, highlighting its significance for accurate stellar parameter determination and potential for measuring stellar obliquities and rotational velocities.

Contribution

It presents the theoretical framework and example light curves demonstrating rotational Doppler beaming effects in eclipsing binaries, emphasizing its importance in stellar parameter analysis.

Findings

Rotational Doppler beaming can surpass orbital effects in fast-spinning binaries.

Including this effect is essential for accurate stellar parameter estimation.

The method can help measure stellar obliquities and rotational velocities.

Abstract

In eclipsing binaries the stellar rotation of the two components will cause a rotational Doppler beaming during eclipse ingress and egress when only part of the eclipsed component is covered. For eclipsing binaries with fast spinning components this photometric analogue of the well-known spectroscopic Rossiter-McLaughlin effect can exceed the strength of the orbital effect. Example light curves are shown for a detached double white dwarf binary, a massive O-star binary and a transiting exoplanet case, similar to WASP-33b. Inclusion of the rotational Doppler beaming in eclipsing systems is a prerequisite for deriving the correct stellar parameters from fitting high quality photometric light curves and can be used to determine stellar obliquities as well as e.g. an independent measure of the rotational velocity in those systems that may be expected to be fully synchronized.