HIP 41378 observed by CHEOPS: Where is planet d?

Sulis, S.; Borsato, L.; Grouffal, S.; Osborn, H. P.; Santerne, A.; Brandeker, A.; Günther, M. N.; Heitzmann, A.; Lendl, M.; Fridlund, M.; Gandolfi, D.; Alibert, Y.; Alonso, R.; Bárczy, T.; Barrado Navascues, D.; Barros, S. C. C.; Baumjohann, W.; Beck, T.; Benz, W.; Bergomi, M.; Billot, N.; Bonfanti, A.; Broeg, C.; Collier Cameron, A.; Corral van Damme, C.; Correia, A. C. M.; Csizmadia, Sz.; Cubillos, P. E.; Davies, M. B.; Deleuil, M.; Deline, A.; Delrez, L.; Demangeon, O. D. S.; Demory, B.-O.; Derekas, A.; Edwards, B.; Ehrenreich, D.; Erikson, A.; Fortier, A.; Fossati, L.; Gazeas, K.; Gillon, M.; Güdel, M.; Helling, Ch.; Hoyer, S.; Isaak, K. G.; Kiss, L. L.; Korth, J.; Lam, K. W. F.; Laskar, J.; Lecavelier des Etangs, A.; Magrin, D.; Maxted, P. F. L.; Mordasini, C.; Nascimbeni, V.; Olofsson, G.; Ottensamer, R.; Pagano, I.; Pallé, E.; Peter, G.; Piazza, D.; Piotto, G.; Pollacco, D.; Queloz, D.; Ragazzoni, R.; Rando, N.; Rauer, H.; Ribas, I.; Santos, N. C.; Scandariato, G.; Ségransan, D....

Abstract

HIP 41378 d is a long-period planet that has only been observed to transit twice, three years apart, with K2. According to stability considerations and a partial detection of the Rossiter–McLaughlin effect, Pd = 278.36 d has been determined to be the most likely orbital period. We targeted HIP 41378 d with CHEOPS at the predicted transit timing based on Pd = 278.36 d, but the observations show no transit. We find that large (> 22.4 h) transit timing variations (TTVs) could explain this non-detection during the CHEOPS observation window. We also investigated the possibility of an incorrect orbital solution, which would have major implications for our knowledge of this system. If Pd ≠ 278.36 d, the periods that minimize the eccentricity would be 101.22 d and 371.14 d. The shortest orbital period will be tested by TESS, which will observe HIP 41378 in Sector 88 starting in January 2025. Our study shows the importance of a mission like CHEOPS, which today is the only mission able to make long observations (i.e., from space) to track the ephemeris of long-period planets possibly affected by large TTVs.

Citation

Sulis, S., Borsato, L., Grouffal, S., Osborn, H. P., Santerne, A., Brandeker, A., …Zingales, T. (2024). HIP 41378 observed by CHEOPS: Where is planet d?. Astronomy & Astrophysics, 686, Article L18. https://doi.org/10.1051/0004-6361/202449689

• Journal Article Type: Article
• Acceptance Date: May 28, 2024
• Online Publication Date: Jun 21, 2024
• Publication Date: 2024-06
• Deposit Date: Oct 18, 2024
• Journal: Astronomy & Astrophysics
• Print ISSN: 0004-6361
• Electronic ISSN: 1432-0746
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 686
• Article Number: L18
• DOI: https://doi.org/10.1051/0004-6361/202449689
• Keywords: planets and satellites: individual: HIP 41378
• Public URL: https://keele-repository.worktribe.com/output/952121
• Publisher URL: https://www.aanda.org/articles/aa/full_html/2024/06/aa49689-24/aa49689-24.html