Let there be more variability in two gamma Cas stars
Abstract
We investigate the short-term optical variability of two gamma Cas analogs, pi Aqr and BZ Cru, thanks to intensive ground-based spectroscopic and space-borne photometric monitorings. For both stars, low-amplitude (mmag) coherent photometric variability is detected. The associated signals display long-term amplitude variations, as in other Be stars. However, these signals appear at high frequencies, especially in pi Aqr, indicating p-modes with a high degree l, a quite unusual feature amongst Be stars. While BZ Cru presents only low-level spectral variability, without clear periodicity, this is not the case of pi Aqr. In this star, the dominant photometric frequencies, near ~12/d, are confirmed spectroscopically in separate monitorings taken during very different disk activity levels ; the spectroscopic analysis suggests a probable tesseral nature for the mode.
Cite
@article{arxiv.2002.12656,
title = {Let there be more variability in two gamma Cas stars},
author = {Yael Naze and Andrzej Pigulski and Gregor Rauw and Myron Smith},
journal= {arXiv preprint arXiv:2002.12656},
year = {2020}
}
Comments
accepted by MNRAS - the arxiv version has some figures in low-resolution