HIP 41378 observed by CHEOPS: Where is planet d?

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

Publications: Contribution to journalArticlePeer Reviewed

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.

Original languageEnglish
Article numberL18
Number of pages6
JournalAstronomy and Astrophysics
Volume686
DOIs
Publication statusPublished - 1 Jun 2024

Austrian Fields of Science 2012

  • 103003 Astronomy
  • 103004 Astrophysics
  • 103038 Space exploration

Keywords

  • HIP 41378
  • individual
  • Planets and satellites

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