Research Projects
A trio of month-long flares in the nova-like variable V704 And
We discovered an unusual set of flares in the nova-like variable V704 And using data from AAVSO, ASAS-SN, and ZTF. The events last for roughly a month, and exhibit the unusual shape of a slow rise and faster decay. As the disk of V704 is expected to already be in the high-viscosity and high-accretion rate state, we conclude that the driver of the variations must be changes in the mass transfer rate from the companion star.
Accretion variability of the multiple system VW Cha
VW Cha is a multiple T Tauri system, of which we took spectra in both fainter and brighter photometric states. We found that the photometric brightening event can be explained by increased accretion. In addition, our spectroscopic data also suggest that the primary component of VW Cha is a spectroscopic binary.
Accretion variability from minute to decade timescales in the classical T Tauri star CR Cha
We combined high-resolution spectroscopic monitoring observations with high-cadence and multifilter photometric measurements in order to study the variability of the the T Tauri system CR Cha. These revealed periodic brightness changes due stellar rotation, and also more stochastic accretion-related variations. We were also able to study the accretion process on timescales from hours to a decade by including earlier data from the AAT/UCLES and the HARPS instruments. These show that the accretion variations increase on timescales from hours to days/weeks, after which it saturates, and the overall accretion variability is within the factor of ~3 on timescales of a decade.
The Weakening Outburst of the Young Eruptive Star V582 Aur
We studied an FU Orionis type object, V582 Aur, which is currently in an outbursting state but shows photometric variations due to an orbiting dust clump. Long-term photometric data revealed the absolute fading of the system, and we speculate that the source will return to quiescence in ~80 yr. The long-term decreasing trend in the accretion rate is also consistent with this conclusion.
ADS link: Zsidi, G; Ábrahám, P; Acosta-Pulido, J. A; Kóspál, Á; et al (2019)