VVV-WIT-13: An eruptive young star with cool molecular features
| dc.contributor.author | Lynas-Gray, Anthony Eugene | |
| dc.contributor.author | Guo, Zhen | |
| dc.contributor.author | Lucas, Philip | |
| dc.date.accessioned | 2025-12-11T07:35:23Z | |
| dc.date.available | 2025-12-11T07:35:23Z | |
| dc.date.issued | 2025 | |
| dc.description.abstract | Context. Outburst phenomena are observed at different stages of stellar evolution, due to the enhancement of the mass accretion rate on protostars or even stellar merger events. In the case of a young stellar object (YSO), the episodic mass accretion event plays an important role in the pre-main-sequence stellar mass assembly. Here we investigate an infrared eruptive source (RA = 16:53:44.38; Dec = − 43:28:19.47), identified from the decade-long VISTA Variables in the Vía Láctea survey (VVV). We named this target after a group of variable sources discovered by VVV, as VVV-WIT-13, where WIT stands for ‘What is this?’, due to its unique photometric variation behaviour and the mysterious origin of the outburst. This target exhibited an outburst with a 5.7 mag amplitude in the K s -band, remained on its brightness plateau for 3.5 years, and then rapidly faded to its pre-eruptive brightness afterwards. Aims. Our aim is to reveal the variable nature and outburst origin of VVV-WIT-13 by presenting our follow-up photometric and spectroscopic observations along with theoretical models. Methods. We gathered photometric time series in both near- and mid-infrared wavelengths. We obtained near-infrared spectra during the outburst and decaying stages on XSHOOTER/VLT and FIRE/Magellan, and then fitted the detected molecular absorption features using models from ExoMol. We applied 2D numerical simulations to re-create the observables of the eruptive phenomenon. Results. We observe deep AlO absorption bands in the infrared spectra of VVV-WIT-13, during the outburst stage, along with other more common absorption bands (e.g. CO). Our best-fit model suggests a 600 K temperature of the AlO absorption band. In the decaying stage, the AlO bands disappeared, whilst broad blue-shifted H2 lines arose, a common indicator of stellar wind and outflow. The observational evidence suggests that the CO and TiO features originate from an outflow or a wind environment. Conclusions. We find that VVV-WIT-13 is an eruptive young star with instability occurring in the accretion disk. One favoured theoretical explanation of this event is a disrupted gas clump at a distance of 3 au from the source. If confirmed, this would be the first such event observed in real time. | |
| dc.identifier.citation | Guo, Z., Lucas, P., Yurchenko, S.N., Kaminski, T., Montesinos, M., Nayakshin, S., Elbakyan, V., Osses, J., o Garatti, A.C., Zhao, H. and Kurtev, R., 2025. VVV-WIT-13: An eruptive young star with cool molecular features. Astronomy & Astrophysics, 703, p.A141. | |
| dc.identifier.uri | https://doi.org/10.1051/0004-6361/202556048 | |
| dc.identifier.uri | https://hdl.handle.net/10566/21570 | |
| dc.language.iso | en | |
| dc.publisher | EDP Sciences | |
| dc.subject | Herbig Ae/Be | |
| dc.subject | stars: formation | |
| dc.subject | stars: protostars | |
| dc.subject | stars: variables: T Tauri | |
| dc.subject | VVV-WIT-13 infrared outburst | |
| dc.title | VVV-WIT-13: An eruptive young star with cool molecular features | |
| dc.type | Article |