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Characterisation of the TOI-421 planetary system using CHEOPS, TESS, and archival radial velocity data

Fuente: arXiv

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Hauptverfasser:	Krenn, A. F., Kubyshkina, D., Fossati, L., Egger, J. A., Bonfanti, A., Deline, A., Ehrenreich, D., Beck, M., Benz, W., Cabrera, J., Wilson, T. G., Leleu, A., Sousa, S. G., Adibekyan, V., Correira, A. C. M., Alibert, Y., Delrez, L., Lendl, M., Patel, J. A., Venturini, J., Alonso, R., Anglada, G., Asquier, J., Bárczy, T., Navascues, D. Barrado, Barros, S. C. C., Baumjohann, W., Beck, T., Billot, N., Bonfils, X., Borsato, L., Brandeker, A., Broeg, C., Charnoz, S., Cameron, A. Collier, Csizmadia, Sz., Cubillos, P. E., Davies, M. B., Deleuil, M., Demangeon, O. D. S., Demory, B. -O., Erikson, A., Fortier, A., Fridlund, M., Gandolfi, D., Gillon, M., Güdel, M., Günther, M. N., Hasiba, J., Heitzmann, A., Helling, C., Hoyer, S., Isaak, K. G., Kiss, L. L., Lam, K. W. F., Laskar, J., Etangs, A. Lecavelier des, Lovis, C., Magrin, D., Maxted, P. F. L., Mordasini, C., Nascimbeni, V., Olofsson, G., Ottensamer, R., Pagano, I., Pallé, E., Peter, G., Piotto, G., Pollacco, D., Queloz, D., Ragazzoni, R., Rando, N., Rauer, H., Ribas, I., Rieder, M., Santos, N. C., Scandariato, G., Ségransan, D., Simon, A. E., Smith, A. M. S., Stalport, M., Steller, M., Szabó, Gy. M., Thomas, N., Udry, S., Ulmer, B., Van Grootel, V., Villaver, E., Viotto, V., Walton, N. A., Zingales, T.
Format:	Preprint
Veröffentlicht:	2024
Schlagworte:	Earth and Planetary Astrophysics
Online-Zugang:	Acceder al recurso
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author	Krenn, A. F. Kubyshkina, D. Fossati, L. Egger, J. A. Bonfanti, A. Deline, A. Ehrenreich, D. Beck, M. Benz, W. Cabrera, J. Wilson, T. G. Leleu, A. Sousa, S. G. Adibekyan, V. Correira, A. C. M. Alibert, Y. Delrez, L. Lendl, M. Patel, J. A. Venturini, J. Alonso, R. Anglada, G. Asquier, J. Bárczy, T. Navascues, D. Barrado Barros, S. C. C. Baumjohann, W. Beck, T. Billot, N. Bonfils, X. Borsato, L. Brandeker, A. Broeg, C. Charnoz, S. Cameron, A. Collier Csizmadia, Sz. Cubillos, P. E. Davies, M. B. Deleuil, M. Demangeon, O. D. S. Demory, B. -O. Erikson, A. Fortier, A. Fridlund, M. Gandolfi, D. Gillon, M. Güdel, M. Günther, M. N. Hasiba, J. Heitzmann, A. Helling, C. Hoyer, S. Isaak, K. G. Kiss, L. L. Lam, K. W. F. Laskar, J. Etangs, A. Lecavelier des Lovis, C. Magrin, D. Maxted, P. F. L. Mordasini, C. Nascimbeni, V. Olofsson, G. Ottensamer, R. Pagano, I. Pallé, E. Peter, G. Piotto, G. Pollacco, D. Queloz, D. Ragazzoni, R. Rando, N. Rauer, H. Ribas, I. Rieder, M. Santos, N. C. Scandariato, G. Ségransan, D. Simon, A. E. Smith, A. M. S. Stalport, M. Steller, M. Szabó, Gy. M. Thomas, N. Udry, S. Ulmer, B. Van Grootel, V. Villaver, E. Viotto, V. Walton, N. A. Zingales, T.
author_facet	Krenn, A. F. Kubyshkina, D. Fossati, L. Egger, J. A. Bonfanti, A. Deline, A. Ehrenreich, D. Beck, M. Benz, W. Cabrera, J. Wilson, T. G. Leleu, A. Sousa, S. G. Adibekyan, V. Correira, A. C. M. Alibert, Y. Delrez, L. Lendl, M. Patel, J. A. Venturini, J. Alonso, R. Anglada, G. Asquier, J. Bárczy, T. Navascues, D. Barrado Barros, S. C. C. Baumjohann, W. Beck, T. Billot, N. Bonfils, X. Borsato, L. Brandeker, A. Broeg, C. Charnoz, S. Cameron, A. Collier Csizmadia, Sz. Cubillos, P. E. Davies, M. B. Deleuil, M. Demangeon, O. D. S. Demory, B. -O. Erikson, A. Fortier, A. Fridlund, M. Gandolfi, D. Gillon, M. Güdel, M. Günther, M. N. Hasiba, J. Heitzmann, A. Helling, C. Hoyer, S. Isaak, K. G. Kiss, L. L. Lam, K. W. F. Laskar, J. Etangs, A. Lecavelier des Lovis, C. Magrin, D. Maxted, P. F. L. Mordasini, C. Nascimbeni, V. Olofsson, G. Ottensamer, R. Pagano, I. Pallé, E. Peter, G. Piotto, G. Pollacco, D. Queloz, D. Ragazzoni, R. Rando, N. Rauer, H. Ribas, I. Rieder, M. Santos, N. C. Scandariato, G. Ségransan, D. Simon, A. E. Smith, A. M. S. Stalport, M. Steller, M. Szabó, Gy. M. Thomas, N. Udry, S. Ulmer, B. Van Grootel, V. Villaver, E. Viotto, V. Walton, N. A. Zingales, T.
contents	The TOI-421 planetary system contains two sub-Neptune-type planets and is a prime target to study the formation and evolution of planets and their atmospheres. The inner planet is especially interesting as the existence of a hydrogen-dominated atmosphere at its orbital separation cannot be explained by current formation models without previous orbital migration. We jointly analysed photometric data of three TESS sectors and six CHEOPS visits as well as 156 radial velocity data points to retrieve improved planetary parameters. We also searched for TTVs and modelled the interior structure of the planets. Finally, we simulated the evolution of the primordial H-He atmospheres of the planets using two different modelling frameworks. We determine the planetary radii and masses of TOI-421 b and c to be $R_{\rm b} = 2.64 \pm 0.08 \, R_{\oplus}$, $M_{\rm b} = 6.7 \pm 0.6 \, M_{\oplus}$, $R_{\rm c} = 5.09 \pm 0.07 \, R_{\oplus}$, and $M_{\rm c} = 14.1 \pm 1.4 \, M_{\oplus}$. We do not detect any statistically significant TTV signals. Assuming the presence of a hydrogen-dominated atmosphere, the interior structure modelling results in both planets having extensive envelopes. While the modelling of the atmospheric evolution predicts for TOI-421 b to have lost any primordial atmosphere that it could have accreted at its current orbital position, TOI-421 c could have started out with an initial atmospheric mass fraction somewhere between 10 and 35%. We conclude that the low observed mean density of TOI-421 b can only be explained by either a bias in the measured planetary parameters (e.g. driven by high-altitude clouds) and/or in the context of orbital migration. We also find that the results of atmospheric evolution models are strongly dependent on the employed planetary structure model.
format	Preprint
id	arxiv_https___arxiv_org_abs_2404_11074
institution	arXiv
publishDate	2024
record_format	arxiv
spellingShingle	Characterisation of the TOI-421 planetary system using CHEOPS, TESS, and archival radial velocity data Krenn, A. F. Kubyshkina, D. Fossati, L. Egger, J. A. Bonfanti, A. Deline, A. Ehrenreich, D. Beck, M. Benz, W. Cabrera, J. Wilson, T. G. Leleu, A. Sousa, S. G. Adibekyan, V. Correira, A. C. M. Alibert, Y. Delrez, L. Lendl, M. Patel, J. A. Venturini, J. Alonso, R. Anglada, G. Asquier, J. Bárczy, T. Navascues, D. Barrado Barros, S. C. C. Baumjohann, W. Beck, T. Billot, N. Bonfils, X. Borsato, L. Brandeker, A. Broeg, C. Charnoz, S. Cameron, A. Collier Csizmadia, Sz. Cubillos, P. E. Davies, M. B. Deleuil, M. Demangeon, O. D. S. Demory, B. -O. Erikson, A. Fortier, A. Fridlund, M. Gandolfi, D. Gillon, M. Güdel, M. Günther, M. N. Hasiba, J. Heitzmann, A. Helling, C. Hoyer, S. Isaak, K. G. Kiss, L. L. Lam, K. W. F. Laskar, J. Etangs, A. Lecavelier des Lovis, C. Magrin, D. Maxted, P. F. L. Mordasini, C. Nascimbeni, V. Olofsson, G. Ottensamer, R. Pagano, I. Pallé, E. Peter, G. Piotto, G. Pollacco, D. Queloz, D. Ragazzoni, R. Rando, N. Rauer, H. Ribas, I. Rieder, M. Santos, N. C. Scandariato, G. Ségransan, D. Simon, A. E. Smith, A. M. S. Stalport, M. Steller, M. Szabó, Gy. M. Thomas, N. Udry, S. Ulmer, B. Van Grootel, V. Villaver, E. Viotto, V. Walton, N. A. Zingales, T. Earth and Planetary Astrophysics The TOI-421 planetary system contains two sub-Neptune-type planets and is a prime target to study the formation and evolution of planets and their atmospheres. The inner planet is especially interesting as the existence of a hydrogen-dominated atmosphere at its orbital separation cannot be explained by current formation models without previous orbital migration. We jointly analysed photometric data of three TESS sectors and six CHEOPS visits as well as 156 radial velocity data points to retrieve improved planetary parameters. We also searched for TTVs and modelled the interior structure of the planets. Finally, we simulated the evolution of the primordial H-He atmospheres of the planets using two different modelling frameworks. We determine the planetary radii and masses of TOI-421 b and c to be $R_{\rm b} = 2.64 \pm 0.08 \, R_{\oplus}$, $M_{\rm b} = 6.7 \pm 0.6 \, M_{\oplus}$, $R_{\rm c} = 5.09 \pm 0.07 \, R_{\oplus}$, and $M_{\rm c} = 14.1 \pm 1.4 \, M_{\oplus}$. We do not detect any statistically significant TTV signals. Assuming the presence of a hydrogen-dominated atmosphere, the interior structure modelling results in both planets having extensive envelopes. While the modelling of the atmospheric evolution predicts for TOI-421 b to have lost any primordial atmosphere that it could have accreted at its current orbital position, TOI-421 c could have started out with an initial atmospheric mass fraction somewhere between 10 and 35%. We conclude that the low observed mean density of TOI-421 b can only be explained by either a bias in the measured planetary parameters (e.g. driven by high-altitude clouds) and/or in the context of orbital migration. We also find that the results of atmospheric evolution models are strongly dependent on the employed planetary structure model.
title	Characterisation of the TOI-421 planetary system using CHEOPS, TESS, and archival radial velocity data
topic	Earth and Planetary Astrophysics
url	https://arxiv.org/abs/2404.11074