Asteroseismology of the Nearby SN-II Progenitor: Rigel Part I. The MOST High Precision Photometry and Radial Velocity Monitoring

TL;DR

This study provides detailed photometric and spectroscopic data on Rigel, a nearby blue supergiant and supernova progenitor, revealing nineteen pulsation modes and insights into its internal structure.

Contribution

First comprehensive high-precision photometry and long-term spectroscopic monitoring of Rigel, identifying pulsation modes linked to its internal stellar processes.

Findings

Nineteen significant pulsation modes detected

Variability timescales range from 1.21 to 74.7 days

Correlation between radial velocity and flux variations

Abstract

Rigel (beta Ori, B8 Ia) is a nearby blue supergiant displaying alpha Cyg type variability, and is one of the nearest type-II supernova progenitors. As such it is an excellent test bed to study the internal structure of pre core-collapse stars. In this study, for the first time, we present 28 days of high precision MOST photometry and over 6 years of spectroscopic monitoring. We report nineteen significant pulsation modes of SNR>4.6 from radial velocities, with variability time scales ranging from 1.21 to 74.7 days, which are associated with high order low degree gravity modes. While the radial velocity variations show a degree of correlation with the flux changes, there is no clear interplay between the equivalent widths of different metallic and Halpha lines.