학술논문
Characterising TOI-732 b and c: new insights on the M-dwarf radius and density valley
Document Type
Working Paper
Author
Bonfanti, A.; Brady, M.; Wilson, T. G.; Venturini, J.; Egger, J. A.; Brandeker, A.; Sousa, S. G.; Lendl, M.; Simon, A. E.; Queloz, D.; Olofsson, G.; Adibekyan, V.; Alibert, Y.; Fossati, L.; Hooton, M. J.; Kubyshkina, D.; Luque, R.; Murgas, F.; Mustill, A. J.; Santos, N. C.; Van Grootel, V.; Alonso, R.; Asquier, J.; Bandy, T.; Bárczy, T.; Navascues, D. Barrado; Barros, S. C. C.; Baumjohann, W.; Bean, J.; Beck, M.; Beck, T.; Benz, W.; Bergomi, M.; Billot, N.; Borsato, L.; Broeg, C.; Cameron, A. Collier; Csizmadia, Sz.; Cubillos, P. E.; Davies, M. B.; Deleuil, M.; Deline, A.; Delrez, L.; Demangeon, O. D. S.; Demory, B. -O.; Ehrenreich, D.; Erikson, A.; Fortier, A.; Fridlund, M.; Gandolfi, D.; Gillon, M.; Güdel, M.; Günther, M. N.; Heitzmann, A.; Helling, Ch.; Hoyer, S.; Isaak, K. G.; Kasper, D.; Kiss, L. L.; Lam, K. W. F.; Laskar, J.; Etangs, A. Lecavelier des; Magrin, D.; Maxted, P. F. L.; Mordasini, C.; Nascimbeni, V.; Ottensamer, R.; Pagano, I.; Pallé, E.; Peter, G.; Piotto, G.; Pollacco, D.; Ragazzoni, R.; Rando, N.; Rauer, H.; Ribas, I.; Scandariato, G.; Ségransan, D.; Seifahrt, A.; Smith, A. M. S.; Stalport, M.; Stefánsson, G.; Steinberger, M.; Stürmer, J.; Szabó, Gy. M.; Thomas, N.; Udry, S.; Villaver, E.; Walton, N. A.; Westerdorff, K.; Zingales, T.
Source
Subject
Language
Abstract
TOI-732 is an M dwarf hosting two transiting planets, which are located on the two opposite sides of the radius valley. By doubling the number of available space-based observations and increasing the number of radial velocity (RV) measurements, we aim at refining the parameters of TOI-732 b and c. We also aim at using the results to study the slope of both the radius valley and the density valley for a well characterised sample of M dwarf exoplanets. We performed a global MCMC analysis by jointly modelling ground-based light curves, CHEOPS and TESS observations, along with RV time series both taken from the literature and obtained with the MAROON-X spectrograph. The slopes of the M dwarf valleys were quantified via a Support Vector Machine (SVM) procedure. TOI-732 b is an ultra short period planet ($P\sim0.77$ d) with a radius $R_b=1.325_{-0.058}^{+0.057}$ $R_{\oplus}$ and a mass $M_b=2.46\pm0.19$ $M_{\oplus}$ (mean density $\rho_b=5.8_{-0.8}^{+1.0}$ g cm$^{-3}$), while the outer planet at $P\sim12.25$ d has $R_c=2.39_{-0.11}^{+0.10}$ $R_{\oplus}$, $M_c=8.04_{-0.48}^{+0.50}$ $M_{\oplus}$, and thus $\rho_c=3.24_{-0.43}^{+0.55}$ g cm$^{-3}$. Also considering our interior structure calculations TOI-732 b is a super-Earth and TOI-732 c is a mini-Neptune. Following the SVM approach, we quantified $\mathrm{d}\log{R_{p,{\mathrm{valley}}}}/\mathrm{d}\log{P}=-0.065_{-0.013}^{+0.024}$, which is flatter than for Sun-like stars. In line with former analyses, we noted a more filled radius valley for M-planets and we further quantified the density valley slope as $\mathrm{d}\log{\hat{\rho}_{\mathrm{valley}}}/\mathrm{d}\log{P}=-0.02_{-0.04}^{+0.12}$. Compared to FGK stars, the weaker dependence of the position of the radius valley with orbital period might indicate a heavier influence of formation relative to evolution mechanisms in shaping the radius valley around M-dwarfs.
Comment: 28 pages (17 in the main text), 18 figures (9 in the main text), 11 tables (7 in the main text). Accepted for publication in A&A
Comment: 28 pages (17 in the main text), 18 figures (9 in the main text), 11 tables (7 in the main text). Accepted for publication in A&A