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The First Near-infrared Transmission Spectrum of HIP 41378 f, A Low-mass Temperate Jovian World in a Multiplanet System

Alam, Munazza K. and Kirk, James and Dressing, Courtney D. and López-Morales, Mercedes and Ohno, Kazumasa and Gao, Peter and Akinsanmi, Babatunde and Santerne, Alexandre and Grouffal, Salomé and Adibekyan, Vardan and Barros, Susana C. C. and Buchhave, Lars A. and Crossfield, Ian J. M. and Dai, Fei and Deleuil, Magali and Giacalone, Steven and Lillo-Box, Jorge and Marley, Mark and Mayo, Andrew W. and Mortier, Annelies and Santos, Nuno C. and Sousa, Sérgio G. and Turtelboom, Emma V. and Wheatley, Peter J. and Vanderburg, Andrew M. (2022) The First Near-infrared Transmission Spectrum of HIP 41378 f, A Low-mass Temperate Jovian World in a Multiplanet System. Astrophysical Journal Letters, 927 (1). Art. No. L5. ISSN 2041-8205. doi:10.3847/2041-8213/ac559d.

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We present a near-infrared transmission spectrum of the long-period (P = 542 days), temperate (T_(eq) = 294 K) giant planet HIP 41378 f obtained with the Wide-Field Camera 3 instrument aboard the Hubble Space Telescope (HST). With a measured mass of 12 ± 3 M_⊕ and a radius of 9.2 ± 0.1 R_⊕, HIP 41378 f has an extremely low bulk density (0.09 ± 0.02 g cm⁻³). We measure the transit depth with a median precision of 84 ppm in 30 spectrophotometric channels with uniformly sized widths of 0.018 μm. Within this level of precision, the spectrum shows no evidence of absorption from gaseous molecular features between 1.1 and 1.7 μm. Comparing the observed transmission spectrum to a suite of 1D radiative-convective-thermochemical-equilibrium forward models, we rule out clear, low-metallicity atmospheres and find that the data prefer high-metallicity atmospheres or models with an additional opacity source, such as high-altitude hazes and/or circumplanetary rings. We explore the ringed scenario for HIP 41378 f further by jointly fitting the K2 and HST light curves to constrain the properties of putative rings. We also assess the possibility of distinguishing between hazy, ringed, and high-metallicity scenarios at longer wavelengths with the James Webb Space Telescope. HIP 41378 f provides a rare opportunity to probe the atmospheric composition of a cool giant planet spanning the gap in temperature, orbital separation, and stellar irradiation between the solar system giants, directly imaged planets, and the highly irradiated hot Jupiters traditionally studied via transit spectroscopy.

Item Type:Article
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URLURL TypeDescription Paper
Alam, Munazza K.0000-0003-4157-832X
Kirk, James0000-0002-4207-6615
Dressing, Courtney D.0000-0001-8189-0233
López-Morales, Mercedes0000-0003-3204-8183
Ohno, Kazumasa0000-0003-3290-6758
Gao, Peter0000-0002-8518-9601
Akinsanmi, Babatunde0000-0001-6519-1598
Santerne, Alexandre0000-0002-3586-1316
Grouffal, Salomé0000-0002-2805-5869
Adibekyan, Vardan0000-0002-0601-6199
Barros, Susana C. C.0000-0003-2434-3625
Buchhave, Lars A.0000-0003-1605-5666
Crossfield, Ian J. M.0000-0002-1835-1891
Dai, Fei0000-0002-8958-0683
Deleuil, Magali0000-0001-6036-0225
Giacalone, Steven0000-0002-8965-3969
Lillo-Box, Jorge0000-0003-3742-1987
Marley, Mark0000-0002-5251-2943
Mayo, Andrew W.0000-0002-7216-2135
Mortier, Annelies0000-0001-7254-4363
Santos, Nuno C.0000-0003-4422-2919
Sousa, Sérgio G.0000-0001-9047-2965
Turtelboom, Emma V.0000-0002-1845-2617
Wheatley, Peter J.0000-0003-1452-2240
Vanderburg, Andrew M.0000-0001-7246-5438
Alternate Title:The First Near-Infrared Transmission Spectrum of HIP 41378 f, a Low-Mass Temperate Jovian World in a Multi-Planet System
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2022 January 7; revised 2022 February 9; accepted 2022 February 15; published 2022 March 1. We thank the anonymous referee for their insightful comments. We appreciate the painstaking work of the HST technical staff including Patrica Royle and Nikolay Nikolov in scheduling this long sequence of observations. This paper makes use of observations from the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. These observations are associated with HST-GO program 16267 (PI: Dressing), and the analysis was supported by grant HST-GO-16267. M.K.A. is grateful to Johanna Teske and Anjali Piette for useful discussions. C.D.D. gratefully acknowledges additional support from the David & Lucile Packard Foundation (grant No. 2019–69648) and helpful conversations with Christina Hedges. K.O. was supported by JSPS Overseas Research Fellowship. N.S., S.B., and B.A. acknowledge the support by FCT (Fundaçao para a Ciência e a Tecnologia) through national funds and by FEDER through COMPETE2020—Programa Operacional Competitividade e Internacionalização by these grants: UID/FIS/04434/2019; UIDB/04434/2020; UIDP/04434/2020; PTDC/FISAST/32113/2017 & POCI-01-0145-FEDER-032113; PTDC/FISAST/28953/2017 & POCI-01-0145-FEDER-028953. V.A. acknowledges the support from FCT through Investigador contract nr. IF/00650/2015/CP1273/CT0001. J.L.-B. acknowledges financial support received from "la Caixa" Foundation (ID 100010434) and from the European Unions Horizon 2020 research and innovation program under the Marie Slodowska-Curie grant agreement No. 847648, with fellowship code LCF/BQ/PI20/11760023. This research has also been partly funded by the Spanish State Research Agency (AEI) Project No. ESP2017-87676-C5-1-R and No. MDM-2017-0737 Unidad de Excelencia "María de Maeztu"- Centro de Astrobiología (INTA-CSIC). Facility: HST(WFC3). -
Funding AgencyGrant Number
NASANAS 5-26555
David and Lucile Packard Foundation2019-69648
Japan Society for the Promotion of Science (JSPS)UNSPECIFIED
Fundação para a Ciência e a Tecnologia (FCT)UID/FIS/04434/2019
Fundação para a Ciência e a Tecnologia (FCT)UIDB/04434/2020
Fundação para a Ciência e a Tecnologia (FCT)UIDP/04434/2020
Fundação para a Ciência e a Tecnologia (FCT)PTDC/FIS-AST/32113/2017
Fundação para a Ciência e a Tecnologia (FCT)POCI-01-0145-FEDER-032113
Fundação para a Ciência e a Tecnologia (FCT)PTDC/FISAST/28953/2017
Fundação para a Ciência e a Tecnologia (FCT)POCI-01-0145-FEDER-028953
Fundação para a Ciência e a Tecnologia (FCT)IF/00650/2015/CP1273/CT0001
European Regional Development FundUNSPECIFIED
La Caixa Foundation100010434
Marie Curie Fellowship847648
Marie Curie FellowshipLCF/BQ/PI20/11760023
Agencia Estatal de InvestigaciónESP2017-87676-C5-1-R
Agencia Estatal de InvestigaciónMDM-2017-0737
Subject Keywords:Exoplanet atmospheres; Exoplanets
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Exoplanet atmospheres (487); Exoplanets (498)
Record Number:CaltechAUTHORS:20220228-183326182
Persistent URL:
Official Citation:Munazza K. Alam et al 2022 ApJL 927 L5
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113655
Deposited By: George Porter
Deposited On:01 Mar 2022 18:40
Last Modified:09 Mar 2022 18:24

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