The period change of the Cepheid Polaris suggests enhanced mass loss

TL;DR

This paper investigates the discrepancy between observed and predicted period changes in Polaris, suggesting that enhanced mass loss of about 10^{-6} solar masses per year explains the difference and impacts stellar evolution models.

Contribution

It proposes that pulsation-enhanced mass loss accounts for the period change discrepancy in Polaris, providing new insights into Cepheid mass loss and stellar evolution.

Findings

Polaris is losing mass at approximately 10^{-6} M_sun/yr.

The observed period change rate exceeds model predictions.

Mass loss impacts the understanding of Cepheid evolution and the mass discrepancy.

Abstract

Polaris is one of the most observed stars in the night sky, with recorded observations spanning more than 200 years. From these observations, one can study the real-time evolution of Polaris via the secular rate of change of the pulsation period. However, the measurements of the rate of period change do not agree with predictions from state-of-the-art stellar evolution models. We show that this may imply that Polaris is currently losing mass at a rate of $\dot{M} \approx 10^{-6} M_\odot$ yr$^{-1}$ based on the difference between modeled and observed rates of period change, consistent with pulsation-enhanced Cepheid mass loss. A relation between the rate of period change and mass loss has important implications for understanding stellar evolution and pulsation, and provides insight into the current Cepheid mass discrepancy.