VVV-WIT-13: An eruptive young star with cool molecular features
Bibliographic record
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 H 2 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.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".