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arXiv · 2002.12656

Let there be more variability in two gamma Cas stars

Yael Naze·Andrzej Pigulski·Gregor Rauw·Myron Smith
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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.

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Yael Naze, Andrzej Pigulski, Gregor Rauw, Myron Smith. 2020-02-28. Let there be more variability in two gamma Cas stars. https://doi.org/10.1093/mnras/staa617

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