The Orbit and Mass of the Cepheid AW Per

TL;DR

This study determines the orbit and masses of the Cepheid AW Per using interferometry, spectroscopy, and Gaia data, revealing its binary nature and providing precise mass estimates for the components.

Contribution

The paper presents the first detailed orbit and mass measurements of AW Per, including its binary companion, using combined interferometric, spectroscopic, and Gaia data.

Findings

The long period orbit of AW Per is well characterized.

The Cepheid's mass is estimated at 6.79 ± 0.85 solar masses.

The secondary's combined mass is 8.79 ± 0.50 solar masses.

Abstract

The Cepheid AW Per is a component in a multiple system with a long period orbit. The radial velocities of Griffin (2016) cover the 38 year orbit well. An extensive program of interferometry with the CHARA array is reported here, from which the long period orbit is determined. In addition, a {\it Hubble Space Telescope} high resolution spectrum in the ultraviolet demonstrates that the companion is itself a binary with nearly equal mass components. These data combined with a distance from {\it Gaia} provide a mass of the Cepheid (primary) of M$_1$ = 6.79 $\pm$ 0.85 $M_\odot$. The combined mass of the secondary is M$_S$ = 8.79 $\pm$ 0.50 $M_\odot$. The accuracy of the mass will be improved after the fourth Gaia data release expected in approximately two years.