The HD 93963 A transiting system: A 1.04 d super-Earth and a 3.65 d sub-Neptune discovered by TESS and CHEOPS

Creators: Serrano, L. M.; Gandolfi, D.; Hoyer, S.; Brandeker, A.; Hooton, M. J.; Sousa, S.; Murgas, F.; Ciardi, D. R.; Howell, S. B.; Benz, W.; Billot, N.; Florén, H.-G.; Bekkelien, A.; Bonfanti, A.; Krenn, A.; Mustill, A. J.; Wilson, T. G.; Osborn, H.; Parviainen, H.; Heidari, N.; Pallé, E.; Fridlund, M.; Adibekyan, V.; Fossati, L.; Deleuil, M.; Knudstrup, E.; Collins, K. A.; Lam, K. W. F.; Grziwa, S.; Salmon, S.; Albrecht, S.; Alibert, Y.; Alonso, R.; Anglada-Escudé, G.; Bárczy, T.; Barrado y Navascues, D.; Barros, S. C. C.; Baumjohann, W.; Beck, M.; Beck, T.; Bieryla, A.; Bonfils, X.; Boyd, P. T.; Broeg, C.; Cabrera, J.; Charnoz, S.; Chazelas, B.; Christiansen, J. L.; Collier Cameron, A.; Cortés-Zuleta, P.; Csizmadia, Szilárd; Davies, M. B.; Deline, A.; Delrez, L.; Demangeon, O. D. S.; Demory, B.-O.; Dunlavey, A.; Ehrenreich, D.; Erikson, A.; Fortier, A.; Fukui, A.; Garai, Z.; Gillon, M.; Güdel, M.; Hébrard, G.; Heng, Kevin; Huang, C. X.; Isaak, K. G.; Jenkins, J. M.; Kiss, L. L.; Laskar, J.; Latham, D. W.; Lecavelier des Etangs, A.; Lendl, M.; Levine, A. M.; Lovis, C.; Lund, M. B.; Magrin, D.; Maxted, P. F. L.; Narita, N.; Nascimbeni, V.; Olofsson, G.; Ottensamer, R.; Pagano, I.; Pessanha, A. C. S. V.; Peter, G.; Piotto, G.; Pollacco, D.; Queloz, D.; Ragazzoni, R.; Rando, N.; Ratti, F.; Rauer, H.; Ribas, I.; Ricker, G.; Rowden, P.; Santos, N. C.; Scandariato, G.; Seager, S.; Ségransan, D.; Simon, A. E.; Smith, A. M. S.; Steller, M.; Szabó, Gy. M.; Thomas, N.; Twicken, J. D.; Udry, S.; Ulmer, B.; Van Grootel, V.; Vanderspek, R.; Viotto, V.; Walton, N.

Abstract

We present the discovery of two small planets transiting HD 93963A (TOI-1797), a GOV star (M_* = 1.109 ± 0.043M_⊙, R_* = 1.043 ± 0.009 R_⊙) in a visual binary system. We combined TESS and CHEOPS space-borne photometry with MuSCAT 2 ground-based photometry, 'Alopeke and PHARO high-resolution imaging, TRES and FIES reconnaissance spectroscopy, and SOPHIE radial velocity measurements. We validated and spectroscopically confirmed the outer transiting planet HD 93963 A c, a sub-Neptune with an orbital period of P_c ≈ 3.65 d that was reported to be a TESS object of interest (TOI) shortly after the release of Sector 22 data. HD 93963 A c has amass of M_c = 19.2 ± 4.1 M_⊕ and a radius of R_c = 3.228 ± 0.059 R_⊕, implying a mean density of ρ_c = 3.1 ± 0.7 g cm^(-3). The inner object, HD 93963 A b, is a validated 1.04 d ultra-short period (USP) transiting super-Earth that we discovered in the TESS light curve and that was not listed as a TOI, owing to the low significance of its signal (TESS signal-to-noise ratio ≈6.7, TESS + CHEOPS combined transit depth D_b = 141.5_(−8.3)^(+8.5) ppm). We intensively monitored the star with CHEOPS by performing nine transit observations to confirm the presence of the inner planet and validate the system. HD 93963 A b is the first small (R_b = 1.35 ± 0.042 R_⊕) USP planet discovered and validated by TESS and CHEOPS. Unlike planet c, HD 93963 Ab is not significantly detected in our radial velocities (M_b = 7.8 ± 3.2 M_⊕). The two planets are on either side of the radius valley, implying that they could have undergone completely different evolution processes. We also discovered a linear trend in our Doppler measurements, suggesting the possible presence of a long-period outer planet. With a V-band magnitude of 9.2, HD 93963 A is among the brightest stars known to host a USP planet, making it one of the most favourable targets for precise mass measurement via Doppler spectroscopy and an important laboratory to test formation, evolution, and migration models of planetary systems hosting ultra-short period planets.

Additional Information

CHEOPS is an ESA mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden, and the United Kingdom. The CHEOPS Consortium would like to gratefully acknowledge the support received by all the agencies, offices, universities, and industries involved. Their flexibility and willingness to explore new approaches were essential to the success of this mission. We acknowledge the use of public TESS data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center for the production of the SPOC data products. This research has made use of the NASA Exoplanet Archive, of the Exoplanet Follow-up Observation Program website, which are operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. L.M.S. and D.G. gratefully acknowledges financial support from the CRT foundation under Grant No. 2018.2323 "Gaseous or rocky? Unveiling the nature of small worlds". S.H. gratefully acknowledges CNES funding through the grant 837319. ABr was supported by the SNSA. S.G.S. acknowledge support from FCT through FCT contract nr. CEECIND/00826/2018 and POPH/FSE (EC). Some of the observations in the paper made use of the High-Resolution Imaging instrument 'Alopeke obtained under Gemini LLP Proposal Number: GN/S-2021A-LP-105. 'Alopeke was funded by the NASA Exoplanet Exploration Program and built at the NASA Ames Research Center by Steve B. Howell, Nic Scott, Elliott P. Horch, and Emmett Quigley. Alopeke was mounted on the Gemini North (and/or South) telescope of the international Gemini Observatory, a programme of NSF's OIR Lab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. on behalf of the Gemini partnership: the National Science Foundation (United States), National Research Council (Canada), Agencia Nacional de Investigación y Desarrollo (Chile), Ministerio de Ciencia, Tecnologia e Innovación (Argentina), Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brazil), and Korea Astronomy and Space Science Institute (Republic of Korea). A.C.C. and T.W. acknowledge support from STFC consolidated grant number ST/M001296/1. M.F. and C.M.P. gratefully acknowledge the support of the Swedish National Space Agency (DNR 65/19, 174/18). This project was supported by the CNES. unding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (Grant agreement no.: DNRF106). This work makes use of observations from the LCOGT network. LCOGT telescope time was granted by NOIRLab through the Mid-Scale Innovations Program (MSIP). MSIP is funded by NSF. Y.A. and M.J.H. acknowledge the support of the Swiss National Fund under grant 200020_172746. We acknowledge support from the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grants ESP2016-80435-C2-1-R, ESP2016-80435-C2-2-R, PGC2018-098153-B-C33, PGC2018-098153-B-C31, ESP2017-87676-C5-1-R, MDM-2017-0737 Unidad de Excelencia Maria de Maeztu-Centro de Astrobiología (INTA-CSIC), as well as the support of the Generalitat de Catalunya/CERCA programme. The MOC activities have been supported by the ESA contract no. 4000124370. S.C.C.B. acknowledges support from FCT through FCT contracts nr. IF/01312/2014/CP1215/CT0004. X.B., S.C., D.G., M.F. and J.L. acknowledge their role as ESA-appointed CHEOPS science team members. P.C. thanks the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining Grant Number 1829740, the Brinson Foundation, and the Moore Foundation. Her participation in the programme has benefited this work. A.De. acknowledges support from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (project FOUR ACES, grant agreement no. 724427), and from the National Centre for Competence in Research "PlanetS" supported by the Swiss National Science Foundation (SNSF). The Belgian participation to CHEOPS has been supported by the Belgian Federal Science Policy Office (BELSPO) in the framework of the PRODEX Program, and by the University of Liège through an ARC grant for Concerted Research Actions financed by the Wallonia-Brussels Federation. L.D. is an F.R.S.-FNRS Postdoctoral Researcher. This work was supported by FCT – Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020 – Programa Operacional Competitividade e Internacionalizacão by these grants: UID/FIS/04434/2019, UIDB/04434/2020, UIDP/04434/2020, PTDC/FIS-AST/32113/2017 & POCI-01-0145-FEDER-032113, PTDC/FIS-AST/28953/2017 & POCI-01-0145-FEDER-028953, PTDC/FIS-AST/28987/2017 & POCI-01-0145-FEDER-028987, O.D.S.D. is supported in the form of work contract (DL 57/2016/CP1364/CT0004) funded by national funds through FCT. B.-O.D. acknowledges support from the Swiss National Science Foundation (PP00P2-190080). This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (project FOUR ACES grant agreement No 724427). ZG was supported by the VEGA grant of the Slovak Academy of Sciences number 2/0031/22, and by the Slovak Research and Development Agency - the contract no. APVV-20-0148. M.G. is an F.R.S.-FNRS Senior Research Associate. C.X.H.'s work was funded by the Australian Government through the Australian Research Council. K.G.I. is the ESA CHEOPS Project Scientist and is responsible for the ESA CHEOPS Guest Observers Programme. She does not participate in, or contribute to, the definition of the Guaranteed Time Programme of the CHEOPS mission through which observations described in this paper have been taken, nor to any aspect of target selection for the programme. This work was granted access to the HPC resources of MesoPSL financed by the Region Ile de France and the project Equip@Meso (reference ANR-10-EQPX-29-01) of the programme Investissements d'Avenir supervised by the Agence Nationale pour la Recherche. M.L. acknowledges support of the Swiss National Science Foundation under grant number PCEFP2_194576. P.M. acknowledges support from STFC research grant number ST/M001040/1. This work is partly supported by JSPS KAKENHI Grant Number JP17H04574, JP18H05439, JST CREST Grant Number JPMJCR1761, the Astrobiology Center of National Institutes of Natural Sciences (NINS) (Grant Number AB031010). This article is based on observations made with the MuSCAT2 instrument, developed by ABC, at Telescopio Carlos Sanchez operated on the island of Tenerife by the IAC in the Spanish Observatorio del Teide. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127). Acknowledges support from the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grant PGC2018-098153-B-C33, as well as the support of the Generalitat de Catalunya/CERCA programme. Gy.M.Sz. and Z.G. acknowledges the support of the Hungarian National Research, Development and Innovation Office (NKFIH) grant K-125015, a PRODEX Institute Agreement between the ELTE Eötvös Lorand University and the European Space Agency (ESA-D/SCI-LE-2021-0025), the Lendület LP2018-7/2021 grant of the Hungarian Academy of Science and the support of the city of Szombathely. V.V.G. is an F.R.S.-FNRS Research Associate.

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The HD 93963 A transiting system: A 1.04 d super-Earth and a 3.65 d sub-Neptune discovered by TESS and CHEOPS

Abstract

Additional Information

Additional details