The GAPS programme at TNG LXXVIII. Phase-resolved detection of multiple atomic species in the atmosphere of KELT-20b/MASCARA-2b

@misc{biassoni2026gaps,
  title = {{The GAPS programme at TNG LXXVIII. Phase-resolved detection of multiple atomic species in the atmosphere of KELT-20b/MASCARA-2b}},
  author = {F. Biassoni and F. Borsa and L. Fossati and M. C. D'Arpa and A. S. Bonomo and G. Guilluy and T. Zingales and D. Sicilia and A. Sozzetti and M. Rainer and M. Basilicata and I. Carleo and R. Cosentino and R. Claudi and P. Giacobbe and A. Harutyunyan and L. Malavolta and L. Mancini},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.09278},
  eprint = {2609.09278},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.09278},
}

TY  - UNPB
TI  - The GAPS programme at TNG LXXVIII. Phase-resolved detection of multiple atomic species in the atmosphere of KELT-20b/MASCARA-2b
AU  - F. Biassoni
AU  - F. Borsa
AU  - L. Fossati
AU  - M. C. D'Arpa
AU  - A. S. Bonomo
AU  - G. Guilluy
AU  - T. Zingales
AU  - D. Sicilia
AU  - A. Sozzetti
AU  - M. Rainer
AU  - M. Basilicata
AU  - I. Carleo
AU  - R. Cosentino
AU  - R. Claudi
AU  - P. Giacobbe
AU  - A. Harutyunyan
AU  - L. Malavolta
AU  - L. Mancini
PY  - 2026
DA  - 2026/09/08
PB  - arXiv
DO  - 10.48550/arxiv.2609.09278
UR  - https://arxiv.org/abs/2609.09278
AB  - Among the different classes of exoplanets, ultra-hot Jupiters represent prime laboratories for atmospheric characterisation. With an equilibrium temperature of ~2300 K, KELT-20b/MASCARA-2b (HD 185603 b) is a well-studied ultra-hot Jupiter, for which several atomic species have already been detected in both transmission and emission spectroscopy. Nevertheless, important open questions remain regarding the completeness of the chemical inventory and the interpretation of spurious aliasing signals that may mimic genuine atmospheric signatures. In addition, asymmetries in the detected signals across transits can encode valuable information on the spatial structure and dynamics of the planetary atmosphere. In this work, we analyse seven transits of KELT-20b/MASCARA-2b observed with the high-resolution spectrograph HARPS-N at the Telescopio Nazionale Galileo. We apply the cross-correlation function technique to a large set of atomic and ionic species, accounting for aliasing effects that can lead to false detections. We confirm previous detections of HI, NaI, MgI, CrI, FeI, and FeII, and tentatively detect CrII. We further report new detections of KI, CaI, VI, MnI, and BaII, and a tentative detection of PrI in the planetary atmosphere. By performing a phase-resolved analysis and splitting the transit into pre- and post-mid-transit phases, we investigate longitudinal variations in the detected signals. For several species, we observe a double-peaked structure in the Kp-Vsys maps, notably in CaI, VI, CrI, and FeI, consistent with absorption arising from two distinct atmospheric limbs of the planet.
ER  -