Refining the properties of the TOI-178 system with CHEOPS and TESS

Delrez, L.; Leleu, A.; Brandeker, A.; Gillon, M.; Hooton, M. J.; Collier Cameron, A.; Deline, A.; Fortier, A.; Queloz, D.; Bonfanti, A.; Van Grootel, V.; Wilson, T. G.; Egger, J. A.; Alibert, Y.; Alonso, R.; Anglada, G.; Asquier, J.; Bárczy, T.; Barrado y Navascues, D.; Barros, S. C. C.; Baumjohann, W.; Beck, M.; Beck, T.; Benz, W.; Billot, N.; Bonfıls, X.; Borsato, L.; Broeg, C.; Buder, M.; Cabrera, J.; Cessa, V.; Charnoz, S.; Csizmadia, Sz.; Cubillos, P. E.; Davies, M. B.; Deleuil, M.; Demangeon, O. D. S.; Demory, B. -O.; Ehrenreich, D.; Erikson, A.; Fossati, L.; Fridlund, M.; Gandolfi, D.; Güdel, M.; Hasiba, J.; Hoyer, S.; Isaak, K. G.; Jenkins, J. M.; Kiss, L. L.; Laskar, J.; Latham, D. W.; Lecavelier des Etangs, A.; Lendl, M.; Lovis, C.; Luque, R.; Magrin, D.; Maxted, P. F. L.; Mordasini, C.; Nascimbeni, V.; Olofsson, G.; Ottensamer, R.; Pagano, I.; Pallé, E.; Peter, G.; Piotto, G.; Pollacco, D.; Ragazzoni, R.; Rando, N.; Rauer, H.; Ribas, I.; Ricker, G.; Santos, N. C.; Scandariato, G.; Seager, S.; Ségransan, D.; Simon, A. E.; Smith, A. M. S.; Sousa, S. G.; Steller, M.; Szabó, Gy. M.; Thomas, N.; Udry, S.; Vanderspek, R.; Venturini, J.; Viotto, V.; Walton, N. A.; Winn, J. N.
Referencia bibliográfica

Astronomy and Astrophysics

Fecha de publicación:
10
2023
Número de autores
87
Número de autores del IAC
2
Número de citas
6
Número de citas referidas
6
Descripción
Context. The TOI-178 system consists of a nearby late K-dwarf transited by six planets in the super-Earth to mini-Neptune regime, with radii ranging from ~1.1 to 2.9 R⊕ and orbital periods between 1.9 and 20.7 days. All planets but the innermost one form a chain of Laplace resonances. Mass estimates derived from a preliminary radial velocity (RV) dataset suggest that the planetary densities do not decrease in a monotonic way with the orbital distance to the star, contrary to what one would expect based on simple formation and evolution models.
Aims: To improve the characterisation of this key system and prepare for future studies (in particular with JWST), we performed a detailed photometric study based on 40 new CHEOPS visits, one new TESS sector, and previously published CHEOPS, TESS, and NGTS data.
Methods: First we updated the parameters of the host star using the new parallax from Gaia EDR3. We then performed a global analysis of the 100 transits contained in our data to refine the physical and orbital parameters of the six planets and study their transit timing variations (TTVs). We also used our extensive dataset to place constraints on the radii and orbital periods of potential additional transiting planets in the system.
Results: Our analysis significantly refines the transit parameters of the six planets, most notably their radii, for which we now obtain relative precisions of ≲3%, with the exception of the smallest planet, b, for which the precision is 5.1%. Combined with the RV mass estimates, the measured TTVs allow us to constrain the eccentricities of planets c to g, which are found to be all below 0.02, as expected from stability requirements. Taken alone, the TTVs also suggest a higher mass for planet d than that estimated from the RVs, which had been found to yield a surprisingly low density for this planet. However, the masses derived from the current TTV dataset are very prior-dependent, and further observations, over a longer temporal baseline, are needed to deepen our understanding of this iconic planetary system.

The photometric data used in this work are available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/678/A200

Proyectos relacionados
Helio and Asteroseismologia
Sismología Solar y Estelar y Búsqueda de Exoplanetas
Los objetivos genéricos de este Proyecto son: 1) el estudio de la estructura y dinámica del interior solar, 2) la extensión de dicho estudio al caso de otras estrellas, 3) la búsqueda y caracterización de planetas extrasolares por métodos fotométricos (principalmente mediante el método de tránsitos) y espectroscópico (variaciones en la velocidad
Savita
Mathur
Image withthe projects' name
Exoplanetas y Astrobiología
La búsqueda de vida en el Universo se ha visto impulsada por los recientes descubrimientos de planetas alrededor de otras estrellas (los llamados exoplanetas), convirtiéndose en uno de los campos más activos dentro de la Astrofísica moderna. En los últimos años los descubrimientos cada vez más numerosos de nuevos exoplanetas y los últimos avances
Enric
Pallé Bago