The GAPS Programme at TNG LXXXI. The puzzle of the HeI absorption signal in the atmosphere of V1298 Tau b with GIARPS@TNG

@misc{guilluy2026gaps,
  title = {{The GAPS Programme at TNG LXXXI. The puzzle of the HeI absorption signal in the atmosphere of V1298 Tau b with GIARPS@TNG}},
  author = {G. Guilluy and J. Orell-Miquel and A. Sozzetti and M. C. D'Arpa and N. Greco and A. F. Lanza and D. Sicilia and A. Caldiroli and R. Spinelli and D. Locci and P. Leonardi and L. Mancini and S. Colombo and M. Rainer and F. Borsa and A. Maggio and A. S. Bonomo and L. Affer and V. Andretta and F. Biassoni and A. Bignamini and W. Boschin and M. Brogi and C. Di Maio and L. Fossati and E. Gallo and F. Haardt and M. López-Puertas and V. Lorenzi and L. Malavolta and J. Maldonaldo and F. Manni and G. Micela and F. Murgas and V. Nascimbeni and E. Palle and J. Sanz-Forcada and G. Scandariato and J. Southworth and J. Tregloan-Reed},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.32815},
  eprint = {2610.32815},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.32815},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - The GAPS Programme at TNG LXXXI. The puzzle of the HeI absorption signal in the atmosphere of V1298 Tau b with GIARPS@TNG
AU  - G. Guilluy
AU  - J. Orell-Miquel
AU  - A. Sozzetti
AU  - M. C. D'Arpa
AU  - N. Greco
AU  - A. F. Lanza
AU  - D. Sicilia
AU  - A. Caldiroli
AU  - R. Spinelli
AU  - D. Locci
AU  - P. Leonardi
AU  - L. Mancini
AU  - S. Colombo
AU  - M. Rainer
AU  - F. Borsa
AU  - A. Maggio
AU  - A. S. Bonomo
AU  - L. Affer
AU  - V. Andretta
AU  - F. Biassoni
AU  - A. Bignamini
AU  - W. Boschin
AU  - M. Brogi
AU  - C. Di Maio
AU  - L. Fossati
AU  - E. Gallo
AU  - F. Haardt
AU  - M. López-Puertas
AU  - V. Lorenzi
AU  - L. Malavolta
AU  - J. Maldonaldo
AU  - F. Manni
AU  - G. Micela
AU  - F. Murgas
AU  - V. Nascimbeni
AU  - E. Palle
AU  - J. Sanz-Forcada
AU  - G. Scandariato
AU  - J. Southworth
AU  - J. Tregloan-Reed
PY  - 2026
DA  - 2026/10/23
PB  - arXiv
DO  - 10.48550/arxiv.2610.32815
UR  - https://arxiv.org/abs/2610.32815
AB  - Atmospheric escape shapes close-in planets mostly in their first tens of Myr. The young V1298Tau system (10-30Myr) is a benchmark for investigating photoevaporation and planetary evolution at early stages. The metastable HeI near-infrared triplet is a key proxy for atmospheric escape. We aim to detect and characterise HeI in the extended atmosphere of V1298Taub. We analysed four transits over a 4-year baseline using GIARPS (GIANO-B + HARPS-N) at the Telescopio Nazionale Galileo. We re-derived the projected spin-orbit angle by modelling the Rossiter-McLaughlin effect. Using simultaneous optical and near-infrared high-resolution transmission spectroscopy of V1298Taub, we monitored the HeI triplet alongside key chromospheric indicators (log R'_HK, Hα, and NaI) to disentangle stellar activity from planetary evaporation. While the stellar spectra show significant night-to-night variability, transmission spectroscopy reveals persistent HeI absorption across all four epochs. This contrasts with Hα and NaI, observed over two nights with simultaneous HARPS-N monitoring, which fluctuate between emission and absorption due to stellar activity. The consistent presence of HeI over 4 years may suggest a planetary origin, despite stellar-driven depth modulation. ATES hydrodynamic simulations show that stellar XUV flux variations modulate the HeI absorption depth and equivalent width. Furthermore, stellar wind fluctuations likely drive the observed night-to-night variability of the exospheric structure. The detection of HeI across all epochs may support planetary evaporation, despite modulation by stellar activity. Our results underscore that disentangling a planetary signal from stellar contamination remains challenging for highly active hosts; securing the planetary nature of the HeI signature requires activity monitoring and full transit coverage to establish a robust baseline.
ER  -