A full transit of v<SUP>2</SUP> Lupi d and the search for an exomoon in its Hill sphere with CHEOPS

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

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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.

Undetrended and detrended light curves are only available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr ( or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/671/A154