MOST photometry of the enigmatic PMS pulsator HD?142666

摘要

Context. Modeling of pre-main sequence (PMS) stars through asteroseismology of PMS p-mode pulsators has only recently become possible, and spacebased photometry is one of the important sources of data for these efforts. We present precise photometry of the pulsating Herbig Ae star HD142666obtained in two consecutive years with the MOST (Microvariability & Oscilations of STars) satellite. Aims. Previously, only a single pulsation period was known for HD142666. The MOST photometry reveals that HD142666is 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 2007provided data of unprecedented quality to study the pulsations in HD142666and also to monitor the circumstellar variability. Methods. Frequency analysis was performed using the routine SIGSPECand the results from the 2006 and 2007 campaigns were then compared to each other with the software CINDERELLAto identify frequencies common to both light curves. The correlated frequencies were then submitted to an asteroseismic analysis. Results. We attribute 12frequencies 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. Some of the frequencies appear to be rotationally split modes. Conclusions. The models suggest that either (1) the published estimate of the luminosity of HD142666, 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 HD142666's position in the HR diagram. Key words: stars: pre-main sequence - stars: variables: Sct - stars: individual: HD142666 - techniques: photometric