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Titanium chemistry of WASP-121 b with ESPRESSO in 4-UT mode

Prinoth, B. LU orcid ; Seidel, J. V. ; Hoeijmakers, H. J. LU orcid ; Morris, B. M. ; Baratella, M. ; Borsato, N. W. LU orcid ; Damasceno, Y. C. ; Parmentier, V. ; Kitzmann, D. and Sedaghati, E. , et al. (2025) In Astronomy and Astrophysics 694.
Abstract

Transit spectroscopy usually relies on the integration of one or several transits to achieve the signal-to-noise ratio (S/N) necessary to resolve spectral features. Consequently, high-S/N observations of exoplanet atmospheres, where we can forgo integration, are essential for disentangling the complex chemistry and dynamics beyond global trends. In this study, we combined two partial 4-UT transits of the ultrahot Jupiter WASP-121 b, observed with the ESPRESSO at the European Southern Observatory’s Very Large Telescope in order to revisit its titanium chemistry. Through cross-correlation analysis, we achieved detections of H I, Li I, Na I, K I, Mg I, Ca I, Ti I, V I, Cr I, Mn I, Fe I, Fe II, Co I, Ni I, Ba II, Sr I, and Sr II.... (More)

Transit spectroscopy usually relies on the integration of one or several transits to achieve the signal-to-noise ratio (S/N) necessary to resolve spectral features. Consequently, high-S/N observations of exoplanet atmospheres, where we can forgo integration, are essential for disentangling the complex chemistry and dynamics beyond global trends. In this study, we combined two partial 4-UT transits of the ultrahot Jupiter WASP-121 b, observed with the ESPRESSO at the European Southern Observatory’s Very Large Telescope in order to revisit its titanium chemistry. Through cross-correlation analysis, we achieved detections of H I, Li I, Na I, K I, Mg I, Ca I, Ti I, V I, Cr I, Mn I, Fe I, Fe II, Co I, Ni I, Ba II, Sr I, and Sr II. Additionally, narrow-band spectroscopy allowed us to resolve strong single lines, resulting in significant detections of H α, H β, H γ, Li I, Na I, K I, Mg I, Ca II, Sr I, Sr II, and Mn I. Our most notable finding is the high-significance detection of Ti I (∼5σ per spectrum, and ∼19σ stacked in the planetary rest frame). Comparison with atmospheric models reveals that Ti I is indeed depleted compared to V I. We also resolve the planetary velocity traces of both Ti I and V I, with Ti I exhibiting a significant blueshift toward the end of the transit. This suggests that Ti I primarily originates from low-latitude regions within the super-rotating jet observed in WASP-121 b. Our observations suggest limited mixing between the equatorial jet and the mid-latitudes, in contrast with model predictions from General Circulation Models. We also report the non-detection of TiO, which we attribute to inaccuracies in the line list that could hinder its detection, even if present. Thus, the final determination of the presence of TiO must await space-based observations. We conclude that the 4-UT mode of ESPRESSO is an excellent testbed for achieving high S/N on relatively faint targets, paving the way for future observations with the Extremely Large Telescope.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
planets, planets and satellites: atmospheres, planets and satellites: gaseous planets, satellites: individual: WASP-121 b, techniques: spectroscopic
in
Astronomy and Astrophysics
volume
694
article number
A284
publisher
EDP Sciences
external identifiers
  • scopus:85218414995
ISSN
0004-6361
DOI
10.1051/0004-6361/202452405
language
English
LU publication?
yes
additional info
Publisher Copyright: © The Authors 2025.
id
38d909ea-47a4-48ca-b48c-02febdda22c5
date added to LUP
2025-03-25 15:14:38
date last changed
2025-05-20 18:09:06
@article{38d909ea-47a4-48ca-b48c-02febdda22c5,
  abstract     = {{<p>Transit spectroscopy usually relies on the integration of one or several transits to achieve the signal-to-noise ratio (S/N) necessary to resolve spectral features. Consequently, high-S/N observations of exoplanet atmospheres, where we can forgo integration, are essential for disentangling the complex chemistry and dynamics beyond global trends. In this study, we combined two partial 4-UT transits of the ultrahot Jupiter WASP-121 b, observed with the ESPRESSO at the European Southern Observatory’s Very Large Telescope in order to revisit its titanium chemistry. Through cross-correlation analysis, we achieved detections of H I, Li I, Na I, K I, Mg I, Ca I, Ti I, V I, Cr I, Mn I, Fe I, Fe II, Co I, Ni I, Ba II, Sr I, and Sr II. Additionally, narrow-band spectroscopy allowed us to resolve strong single lines, resulting in significant detections of H α, H β, H γ, Li I, Na I, K I, Mg I, Ca II, Sr I, Sr II, and Mn I. Our most notable finding is the high-significance detection of Ti I (∼5σ per spectrum, and ∼19σ stacked in the planetary rest frame). Comparison with atmospheric models reveals that Ti I is indeed depleted compared to V I. We also resolve the planetary velocity traces of both Ti I and V I, with Ti I exhibiting a significant blueshift toward the end of the transit. This suggests that Ti I primarily originates from low-latitude regions within the super-rotating jet observed in WASP-121 b. Our observations suggest limited mixing between the equatorial jet and the mid-latitudes, in contrast with model predictions from General Circulation Models. We also report the non-detection of TiO, which we attribute to inaccuracies in the line list that could hinder its detection, even if present. Thus, the final determination of the presence of TiO must await space-based observations. We conclude that the 4-UT mode of ESPRESSO is an excellent testbed for achieving high S/N on relatively faint targets, paving the way for future observations with the Extremely Large Telescope.</p>}},
  author       = {{Prinoth, B. and Seidel, J. V. and Hoeijmakers, H. J. and Morris, B. M. and Baratella, M. and Borsato, N. W. and Damasceno, Y. C. and Parmentier, V. and Kitzmann, D. and Sedaghati, E. and Pino, L. and Borsa, F. and Allart, R. and Santos, N. and Steiner, M. and Mascareño, A. Suárez and Tabernero, H. and Osorio, M. R.Zapatero}},
  issn         = {{0004-6361}},
  keywords     = {{planets; planets and satellites: atmospheres; planets and satellites: gaseous planets; satellites: individual: WASP-121 b; techniques: spectroscopic}},
  language     = {{eng}},
  month        = {{02}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{Titanium chemistry of WASP-121 b with ESPRESSO in 4-UT mode}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/202452405}},
  doi          = {{10.1051/0004-6361/202452405}},
  volume       = {{694}},
  year         = {{2025}},
}