Publication details
Gaia21bty: An EXor light curve exhibiting a FUor spectrum
| Authors | |
|---|---|
| Year of publication | 2023 |
| Type | Article in Periodical |
| Magazine / Source | Monthly Notices of the Royal Astronomical Society |
| MU Faculty or unit | |
| Citation | |
| web | |
| Doi | http://dx.doi.org/10.1093/mnras/stad2135 |
| Keywords | accretion; accretion discs; stars: formation; stars: pre-main-sequence; stars: variables: T Tauri; Herbig Ae/Be |
| Description | Gaia21bty, a pre-main-sequence star that previously had shown aperiodic dips in its light curve, underwent a considerable Delta G approximate to 2.9 mag brightening that occurred over a few months between 2020 October and 2021 February. The Gaia light curve shows that the star remained near maximum brightness for about 4-6 months, and then started slowly fading over the next 2 yr, with at least three superimposed similar to 1 mag sudden rebrightening events. Whereas the amplitude and duration of the maximum is typical for EX Lupi-type stars, optical and near-infrared spectra obtained at the maximum are dominated by features which are typical for FU Ori-type stars (FUors). Modelling of the accretion disc at the maximum indicates that the disc bolometric luminosity is 43 L-circle dot and the mass accretion rate is 2.5 x 10(-5) M-circle dot yr(-1), which are typical values for FUors even considering the large uncertainty in the distance (1.7(-0.4)(+0.8) kpc). Further monitoring is necessary to understand the cause of the quick brightness decline, the rebrightening, and the other post-outburst light changes, as our multicolour photometric data suggest that they could be caused by a long and discontinuous obscuration event. We speculate that the outburst might have induced large-scale inhomogeneous dust condensations in the line of sight leading to such phenomena, whilst the FUor outburst continues behind the opaque screen. |