Revisiting the atmosphere of the exoplanet 51 Eridani b with VLT/SPHERE - Sorbonne Université Access content directly
Journal Articles Astronomy and Astrophysics - A&A Year : 2023

Revisiting the atmosphere of the exoplanet 51 Eridani b with VLT/SPHERE

S. Brown-Sevilla
  • Function : Author
P. Mollière
  • Function : Author
R. Gratton
  • Function : Author
V. d'Orazi
  • Function : Author
M. Langlois
  • Function : Author
D. Mesa
  • Function : Author
M. Meyer
  • Function : Author
A. Pavlov
  • Function : Author
C. Petit
  • Function : Author
D. Rouan
  • Function : Author
T. Schmidt
  • Function : Author
A. Vigan
  • Function : Author
L. Weber
  • Function : Author


Aims. We aim to better constrain the atmospheric properties of the directly imaged exoplanet 51 Eri b using a retrieval approach with data of higher signal-to-noise ratio (S/N) than previously reported. In this context, we also compare the results from an atmospheric retrieval to using a self-consistent model to fit atmospheric parameters. Methods. We applied the radiative transfer code petitRADTRANS to our near-infrared SPHERE observations of 51 Eri b in order to retrieve its atmospheric parameters. Additionally, we attempted to reproduce previous results with the retrieval approach and compared the results to self-consistent models using the best-fit parameters from the retrieval as priors. Results. We present a higher S/N YH spectrum of the planet and revised K1K 2 photometry ( M K 1 = 15.11 ± 0.04 mag, M K 2 = 17.11 ± 0.38 mag). The best-fit parameters obtained using an atmospheric retrieval differ from previous results using self-consistent models. In general, we find that our solutions tend towards cloud-free atmospheres (e.g. log τ clouds = −5.20 ± 1.44). For our 'nominal' model with new data, we find a lower metallicity ([Fe/H] = 0.26 ± 0.30 dex) and C/O ratio (0.38 ± 0.09), and a slightly higher effective temperature ( T eff = 807 ± 45 K) than previous studies. The surface gravity (log g = 4.05 ± 0.37) is in agreement with the reported values in the literature within uncertainties. We estimate the mass of the planet to be between 2 and 4 M Jup . When comparing with self-consistent models, we encounter a known correlation between the presence of clouds and the shape of the P – T profiles. Conclusions. Our findings support the idea that results from atmospheric retrievals should not be discussed in isolation, but rather along with self-consistent temperature structures obtained using the best-fit parameters of the retrieval. This, along with observations at longer wavelengths, might help to better characterise the atmospheres and determine their degree of cloudiness.
Fichier principal
Vignette du fichier
aa44826-22.pdf (2.95 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

hal-04208505 , version 1 (18-09-2023)



S. Brown-Sevilla, A.-L. Maire, P. Mollière, M. Samland, M. Feldt, et al.. Revisiting the atmosphere of the exoplanet 51 Eridani b with VLT/SPHERE. Astronomy and Astrophysics - A&A, 2023, 673, pp.A98. ⟨10.1051/0004-6361/202244826⟩. ⟨hal-04208505⟩
0 View
0 Download



Gmail Facebook Twitter LinkedIn More