A full transit of vLupi d and the search for an exomoon in its Hill sphere with CHEOPS

D. Ehrenreich*, L. Delrez, B. Akinsanmi, T.G. Wilson, A. Bonfanti, M. Beck, W. Benz, S. Hoyer, D. Queloz, Y. Alibert, S. Charnoz, A. Collier Cameron, A. Deline, M. Hooton, M. Lendl, G. Olofsson, S.G. Sousa, V. Adibekyan, R. Alonso, G. AngladaD. Barrado, S.C.C. Barros, W. Baumjohann, T. Beck, A. Bekkelien, M. Bergomi, N. Billot, X. Bonfils, A. Brandeker, C. Broeg, T. Bárczy, Z.K. Berta-Thompson, J. Cabrera, C. Corral Van Damme, S. Csizmadia, M.B. Davies, M. Deleuil, O. Demangeon, B.-O. Demory, J.P. Doty, A. Erikson, M.M. Fausnaugh, H.-G. Florén, A. Fortier, L. Fossati, M. Fridlund, D. Futyan, D. Gandolfi, M. Gillon, P. Guterman, M. Güdel, K. Heng, K.G. Isaak, A. Jäckel, J.M. Jenkins, L.L. Kiss, J. Laskar, D.W. Latham, A. Lecavelier Des Etangs, A.M. Levine, C. Lovis, D. Magrin, P.F.L. Maxted, E.H. Morgan, V. Nascimbeni, H.P. Osborn, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, G. Piotto, D. Pollacco, R. Ragazzoni, N. Rando, H. Rauer, I. Ribas, G.R. Ricker, S. Salmon, N.C. Santos, G. Scandariato, A.E. Simon, A.M.S. Smith, M. Steinberger, M. Steller, G.M. Szabó, D. Ségransan, A. Shporer, N. Thomas, M. Tschentscher, S. Udry, R. Vanderspek, V. Van Grootel, N.A. Walton

*Corresponding author for this work

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The planetary system around the naked-eye star v2 Lupi (HD 136352; TOI-2011) is composed of three exoplanets with masses of 4.7, 11.2, and 8.6 Earth masses (M). The TESS and CHEOPS missions revealed that all three planets are transiting and have radii straddling the radius gap separating volatile-rich and volatile-poor super-earths. Only a partial transit of planet d had been covered so we re-observed an inferior conjunction of the long-period 8.6 M exoplanet v2 Lup d with the CHEOPS space telescope. We confirmed its transiting nature by covering its whole 9.1 h transit for the first time. We refined the planet transit ephemeris to P = 107.1361-0.0022+0.0019 days and Tc = 2459009.7759-0.0096+0.0101 BJDTDB, improving by ~40 times on the previously reported transit timing uncertainty. This refined ephemeris will enable further follow-up of this outstanding long-period transiting planet to search for atmospheric signatures or explore the planet's Hill sphere in search for an exomoon. In fact, the CHEOPS observations also cover the transit of a large fraction of the planet's Hill sphere, which is as large as the Earth's, opening the tantalising possibility of catching transiting exomoons. We conducted a search for exomoon signals in this single-epoch light curve but found no conclusive photometric signature of additional transiting bodies larger than Mars. Yet, only a sustained follow-up of v2 Lup d transits will warrant a comprehensive search for a moon around this outstanding exoplanet.
Original languageEnglish
Article numberA154
Number of pages16
JournalAstronomy and Astrophysics
Publication statusPublished - 20 Mar 2023


  • Planets and satellites: detection
  • Planets and satellites: general
  • Planets and satellites: individual: HD 136352


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