HD144548: A young triply eclipsing system in the Upper Scorpius OB association

TL;DR

HD144548 is a young, triply eclipsing star system in Upper Scorpius, where detailed analysis combining photometry and radial velocities revealed the masses and radii of all three stellar components, marking a first in such measurements.

Contribution

This study provides the first measurement of radial velocities for all components in a triply eclipsing system, enabling precise determination of stellar parameters.

Findings

System composed of a 1.44 M_sun star and a close binary of two 0.96 M_sun stars.

Eccentric orbit with period of 33.945 days for the third star.

First triply eclipsing system with all component radial velocities measured.

Abstract

The star HD144548 (=HIP~78977; TYP~6212-1273-1) has been known as a detached eclipsing binary and a bona-fide member of the Upper Scorpius OB association. Continuous photometry from the K2 mission on Campaign Two has revealed the presence of additional eclipses due to the presence of a third star in the system. These are explained by a system composed of the two previously known members of the eclipsing system (Ba and Bb) with a period of 1.63 d, orbiting around an F7-F8V star with a period of 33.945 +/- 0.002 d in an eccentric orbit (e_A = 0.2652 +/- 0.0003). The timing of the eclipses of Ba and Bb reveals the same 33.9 d periodicity, which we interpret as the combination of a light time effect combined with dynamical perturbations on the close system. Here we combine radial velocities and analytical approximations for the timing of the eclipses to derive masses and radii for the three components of the system. We obtain a mass of 1.44 +/- 0.04 M_sun and radius of 2.41 +/- 0.03 R_sun for the A component, and almost identical masses and radii of about 0.96 M_sun and 1.33 R_sun for each of the two components of the close binary. HD144548 is the first triply eclipsing system for which radial velocities of all components could be measured.