MOST photometry of the enigmatic PMS pulsator HD 142666

TL;DR

This study uses high-quality MOST satellite photometry to identify multiple pulsation frequencies in the Herbig Ae star HD 142666, revealing complexities in its pulsation behavior and challenging existing stellar models.

Contribution

First detailed multi-periodic pulsation analysis of HD 142666 using MOST data, highlighting discrepancies with current stellar models and suggesting the need for revised parameters or additional physics.

Findings

Identified 12 pulsation frequencies in HD 142666.

Model fits suggest the star's luminosity may be overestimated.

Additional physics like mass accretion might be necessary in models.

Abstract

We present precise photometry of the pulsating Herbig Ae star HD 142666 obtained in two consecutive years with the MOST (Microvariability & Oscilations of STars) satellite. Previously, only a single pulsation period was known for HD 142666. The MOST photometry reveals that HD 142666 is multi-periodic. However, the unique identification of pulsation frequencies is complicated by the presence of irregular variability caused by the star's circumstellar dust disk. The two light curves obtained with MOST in 2006 and 2007 provided data of unprecedented quality to study the pulsations in HD 142666 and also to monitor the circumstellar variability. We attribute 12 frequencies to pulsation. Model fits to the three frequencies with the highest amplitudes lie well outside the uncertainty box for the star's position in the HR diagram based on published values. The models suggest that either (1) the published estimate of the luminosity of HD 142666, based on a relation between circumstellar disk radius and stellar luminosity, is too high and/or (2) additional physics such as mass accretion may be needed in our models to accurately fit both the observed frequencies and HD 142666's position in the HR diagram.