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Transmission spectroscopy of the ultra-hot Jupiter MASCARA-4 b

Zhang, Yapeng and Snellen, Ignas A. G. and Wyttenbach, Aurèlien and Nielsen, Louise D. and Lendl, Monika and Casasayas-Barris, Núria and Chaverot, Guillaume and Kesseli, Aurora Y. and Lovis, Christophe and Pepe, Francesco A. and Psaridi, Angelica and Seidel, Julia V. and Udry, Stéphane and Ulmer-Moll, Solène (2022) Transmission spectroscopy of the ultra-hot Jupiter MASCARA-4 b. Astronomy and Astrophysics, 666 . Art. No. A47. ISSN 0004-6361. doi:10.1051/0004-6361/202244203.

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Context. Ultra-hot Jupiters (UHJs), rendering the hottest planetary atmospheres, offer great opportunities of detailed characterisation with high-resolution spectroscopy. MASCARA-4 b is a recently discovered close-in gas giant belonging to this category. Aims. We aim to characterise MASCARA-4 b, search for chemical species in its atmosphere, and put these in the context of the growing knowledge on the atmospheric properties of UHJs. Methods. In order to refine system and planet parameters, we carried out radial velocity measurements and transit photometry with the CORALIE spectrograph and EulerCam at the Swiss 1.2 m Euler telescope. We observed two transits of MASCARA-4 b with the high-resolution spectrograph ESPRESSO at ESO’s Very Large Telescope. We searched for atomic, ionic, and molecular species via individual absorption lines and cross-correlation techniques. These results are compared to literature studies on UHJs characterised to date. Results. With CORALIE and EulerCam observations, we update the mass of MASCARA-4 b (Mₚ = 1.675 ± 0.241 M_(Jup)) as well as other system and planet parameters. In the transmission spectrum derived from ESPRESSO observations, we resolve excess absorption by Hα, Hβ, NaI D1&D2, CaII H&K, and a few strong lines of MgI, FeI, and FeII. We also present the cross-correlation detection of Mg I, CaI, Cr I, Fe I, and Fe II. The absorption strength of Fe II significantly exceeds the prediction from a hydrostatic atmospheric model, as commonly observed in other UHJs. We attribute this to the presence of Fe II in the exosphere due to hydrodynamic outflows. This is further supported by the positive correlation of absorption strengths of Fe II with the Hα line, which is expected to probe the extended upper atmosphere and the mass loss process. Comparing transmission signatures of various species in the UHJ population allows us to disentangle the hydrostatic regime (as traced via the absorption by Mg I and Fe I) from the exospheres (as probed by Hα and Fe II) of the strongly irradiated atmospheres.

Item Type:Article
Related URLs:
URLURL TypeDescription
Zhang, Yapeng0000-0003-0097-4414
Snellen, Ignas A. G.0000-0003-1624-3667
Wyttenbach, Aurèlien0000-0001-9003-7699
Nielsen, Louise D.0000-0002-5254-2499
Lendl, Monika0000-0001-9699-1459
Casasayas-Barris, Núria0000-0002-2891-8222
Chaverot, Guillaume0000-0003-4711-3099
Kesseli, Aurora Y.0000-0002-3239-5989
Lovis, Christophe0000-0001-7120-5837
Pepe, Francesco A.0000-0002-9815-773X
Psaridi, Angelica0000-0002-4797-2419
Seidel, Julia V.0000-0002-7990-9596
Udry, Stéphane0000-0001-7576-6236
Ulmer-Moll, Solène0000-0003-2417-7006
Additional Information:Based on observations collected at the European Southern Observatory under ESO programme 0104.C-0605. We thank the referee for insightful comments that help improve the manuscript. We thank Aline Vidotto for the discussion on the atmospheric escape of ultra-hot Jupiters. Y.Z. and I.S. acknowledge funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program under grant agreement No. 694513. M.L. acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. The contribution of M.L. and A.P. have been carried out within the framework of the NCCR PlanetS supported by the Swiss National Science Foundation. DACE is a web platform hosted in Geneva and developed by the Swiss National Center of Competence in Research (NCCR) PlanetS.
Funding AgencyGrant Number
European Research Council (ERC)694513
Swiss National Science Foundation (SNSF)PCEFP2_194576
Record Number:CaltechAUTHORS:20221017-12657600.26
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117464
Deposited By: Research Services Depository
Deposited On:20 Oct 2022 16:52
Last Modified:20 Oct 2022 16:52

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