Difference: Bestars (2 vs. 3)

AAS233 2019

C.-D. Lee, C.-C. Ngeow, P.-C. Yu and ZTF Collaboration

The hot circumstellar gas in the line-emitting region of Be stars were majorly supplied by the eruptive stellar activity like matter outburst, known as decretion disk. In the outburst event, one can see the photometric fading, since the material was popped up and obscured in the line of sight, along with the spectroscopic brightening in Balmer lines. However, a well-covered spectroscopic follow up was rarely observed, because most of the fadings last more than hundreds days. Now, an enormous amount of Be stars was observed and monitored, after Zwicky Transient Facility (ZTF) survey started. Among them, we have found one Be star in active phase showing several deep fadings up to 2.5 mag. It is HO puppis, also known as a Gamma Cassiopeia type variable, displaying eruptive irregular variation. Even thought the variability type was previously identified in ASAS-SN catalog, the remarkable and repeatable fading events (~30 days) were recorded for the first time. In this work, we present HO puppis light curve with eruptive variability following up by spectroscopic observations using SED machine for witnessing the entire disk decretion process including formation and dissipation.