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K2-99 revisited: a non-inflated warm Jupiter, and a temperate giant planet on a 522-d orbit around a subgiant

Smith, A. M. S. and Breton, S. N. and Csizmadia, Sz and Dai, F. and Gandolfi, D. and García, R. A. and Howard, A. W. and Isaacson, H. and Korth, J. and Lam, K. W. F. and Mathur, S. and Nowak, G. and Pérez Hernández, F. and Persson, C. M. and Albrecht, S. H. and Barragán, O. and Cabrera, J. and Cochran, W. D. and Deeg, H. J. and Fridlund, M. and Georgieva, I. Y. and Goffo, E. and Guenther, E. W. and Hatzes, A. P. and Kabath, P. and Livingston, J. H. and Luque, R. and Pallé, E. and Redfield, S. and Rodler, F. and Serrano, L. M. and Van Eylen, V. (2022) K2-99 revisited: a non-inflated warm Jupiter, and a temperate giant planet on a 522-d orbit around a subgiant. Monthly Notices of the Royal Astronomical Society, 510 (4). pp. 5035-5049. ISSN 0035-8711. doi:10.1093/mnras/stab3497.

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We report new photometric and spectroscopic observations of the K2-99 planetary system. Asteroseismic analysis of the short-cadence light curve from K2’s Campaign 17 allows us to refine the stellar properties. We find K2-99 to be significantly smaller than previously thought, with R⋆ = 2.55 ± 0.02 R_⊙. The new light curve also contains four transits of K2-99 b, which we use to improve our knowledge of the planetary properties. We find the planet to be a non-inflated warm Jupiter, with R_b = 1.06 ± 0.01 R_(Jup). 60 new radial velocity measurements from HARPS, HARPS-N, and HIRES enable the determination of the orbital parameters of K2-99 c, which were previously poorly constrained. We find that this outer planet has a minimum mass M_csin i_c = 8.4 ± 0.2 M_(Jup)⁠, and an eccentric orbit (e_c = 0.210 ± 0.009) with a period of 522.2 ± 1.4 d. Upcoming TESS observations in 2022 have a good chance of detecting the transit of this planet, if the mutual inclination between the two planetary orbits is small.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemESO archive ItemTNG archive ItemExoFOP-K2 ItemMAST
Smith, A. M. S.0000-0002-2386-4341
Csizmadia, Sz0000-0001-6803-9698
Dai, F.0000-0002-8958-0683
Gandolfi, D.0000-0001-8627-9628
García, R. A.0000-0002-8854-3776
Howard, A. W.0000-0001-8638-0320
Isaacson, H.0000-0002-0531-1073
Korth, J.0000-0002-0076-6239
Lam, K. W. F.0000-0002-9910-6088
Mathur, S.0000-0002-0129-0316
Nowak, G.0000-0002-7031-7754
Barragán, O.0000-0003-0563-0493
Cabrera, J.0000-0001-6653-5487
Cochran, W. D.0000-0001-9662-3496
Deeg, H. J.0000-0003-0047-4241
Fridlund, M.0000-0002-0855-8426
Kabath, P.0000-0002-1623-5352
Livingston, J. H.0000-0002-4881-3620
Luque, R.0000-0002-4671-2957
Pallé, E.0000-0003-0987-1593
Redfield, S.0000-0003-3786-3486
Serrano, L. M.0000-0001-9211-3691
Van Eylen, V.0000-0001-5542-8870
Additional Information:© 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2021 No v ember 26. Received 2021 November 26; in original form 2021 July 29. Published: 02 December 2021. This work is done under the framework of the KESPRINT collaboration ( KESPRINT is an international consortium devoted to the characterization and research of exoplanets discovered with space-based missions. Based on observations made with ESO Telescopes at the La Silla Observatory (Chile) under programmes 097.C-0948(A), 099.C-0491(B), 099.C-0491(A), 0100.C-0808(A), 0101.C-0829(A), 60.A-9700(G), and 1102.C-0923(A), and the TNG telescope at Roque de Los Muchachos Observatory (Spain) under programmes A33TAC_15, A34TAC_10, OPT17A_64, A35TAC_26, OPT17B_59, CAT17B_99, CAT18A_130, OPT18A_44, A37TAC_37, OPT18B_52, and A38TAC_26. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. This research has made use of the Exoplanet Follow-up Observation Program website, and the NASA Exoplanet Archive, which are operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2013-2016) under grant agreement No. 312430 (OPTICON). This research has made use of NASA’s Astrophysics Data System, the SIMBAD data base, operated at CDS, Strasbourg, France, and the Exoplanets Encyclopaedia at We also used ASTROPY, a community-developed core PYTHON package for Astronomy (Astropy Collaboration 2013; Price-Whelan et al. 2018). This work has made use of data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. KWFL, SC, and APH were supported by Deutsche Forschungsgemeinschaft grants HA3279/12-1 and RA714/14-1 within the DFG Schwerpunkt SPP 1992, Exploring the Diversity of Extrasolar Planets. SC is also supported by Deutsche Forschungsgemeinschaft Research Unit 2440: ‘Matter Under Planetary Interior Conditions: High Pressure Planetary and Plasma Physics’. HJD acknowledges support from the Spanish Research Agency of the Ministry of Science and Innovation (AEI-MICINN) under grant PID2019-107061GB-C66, DOI: 10.13039/501100011033. JK gratefully acknowledge the support of the Swedish National Space Agency (SNSA; DNR 2020-00104). SM acknowledges support by the Spanish Ministry of Science and Innovation with the Ramon y Cajal fellowship number RYC-2015-17697 and the grant number PID2019-107187GB-I00. SNB and RAG acknowledge the support of the PLATO CNES grant. LMS and DG gratefully acknowledge financial support from the CRT foundation under Grant No. 2018.2323 ‘Gaseous or rocky? Unveiling the nature of small worlds’. We thank Erik Petigura for his contribution to the collection and analysis of the Keck/HIRES data. Finally, we thank the referee for their careful reading of the manuscript and constructive suggestions, which resulted in improvements to this paper. Data Availability: The data underlying this article are available in the article and at the following public archives. The HARPS spectra can be found at the ESO archive; the HARPS-N spectra at the TNG archive; the HIRES spectra at EXOFOP-K2; and the K2 data at MAST.
Group:Astronomy Department
Funding AgencyGrant Number
European Research Council (ERC)312430
Gaia Multilateral AgreementUNSPECIFIED
Deutsche Forschungsgemeinschaft (DFG)HA3279/12-1
Deutsche Forschungsgemeinschaft (DFG)RA714/14-1
Deutsche Forschungsgemeinschaft (DFG)2440
Ministerio de Ciencia e Innovación (MCINN)PID2019-107061GB-C66
Swedish National Space AgencyDNR 2020-00104
Ramón y Cajal ProgrammeRYC-2015-17697
Ministerio de Ciencia e Innovación (MCINN)PID2019-107187GB-I00
Centre National d'Études Spatiales (CNES)UNSPECIFIED
CRT Foundation2018.2323
Subject Keywords:planetary systems – planets and satellites: detection –planets and satellites: individual: K2-99 b – planets and satellites: individual: K2-99 c
Issue or Number:4
Record Number:CaltechAUTHORS:20220131-699902000
Persistent URL:
Official Citation:A M S Smith, S N Breton, Sz Csizmadia, F Dai, D Gandolfi, R A García, A W Howard, H Isaacson, J Korth, K W F Lam, S Mathur, G Nowak, F Pérez Hernández, C M Persson, S H Albrecht, O Barragán, J Cabrera, W D Cochran, H J Deeg, M Fridlund, I Y Georgieva, E Goffo, E W Guenther, A P Hatzes, P Kabath, J H Livingston, R Luque, E Palle, S Redfield, F Rodler, L M Serrano, V Van Eylen, K2-99 revisited: a non-inflated warm Jupiter, and a temperate giant planet on a 522-d orbit around a subgiant, Monthly Notices of the Royal Astronomical Society, Volume 510, Issue 4, March 2022, Pages 5035–5049,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113176
Deposited By: Tony Diaz
Deposited On:01 Feb 2022 17:29
Last Modified:25 Feb 2022 22:04

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