학술논문
A compact multi-planet system transiting HIP 29442 (TOI-469) discovered by TESS and ESPRESSO. Radial velocities lead to the detection of transits with low signal-to-noise ratio
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Working Paper
Author
Damasso, M.; Rodrigues, J.; Castro-González, A.; Lavie, B.; Davoult, J.; Osorio, M. R. Zapatero; Dou, J.; Sousa, S. G.; Owen, J. E.; Sossi, P.; Adibekyan, V.; Osborn, H.; Leinhardt, Z.; Alibert, Y.; Lovis, C.; Mena, E. Delgado; Sozzetti, A.; Barros, S. C. C.; Bossini, D.; Ziegler, C.; Ciardi, D. R.; Matthews, E. C.; Carter, P. J.; Lillo-Box, J.; Mascareño, A. Suárez; Cristiani, S.; Pepe, F.; Rebolo, R.; Santos, N. C.; Prieto, C. Allende; Benatti, S.; Bouchy, F.; Briceño, C.; Di Marcantonio, P.; D'Odorico, V.; Dumusque, X.; Egger, J. A.; Ehrenreich, D.; Faria, J.; Figueira, P.; Santos, R. Génova; Gonzales, E. J.; Hernández, J. I. González; Law, N.; Curto, G. Lo; Mann, A. W.; Martins, C. J. A. P.; Mehner, A.; Micela, G.; Molaro, P.; Nunes, N. J.; Palle, E.; Poretti, E.; Schlieder, J. E.; Udry, S.
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Subject
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Abstract
We followed-up with ESPRESSO the K0V star HIP 29442 (TOI-469), already known to host a validated sub-Neptune companion TOI-469.01. We aim to verify the planetary nature of TOI-469.01. We modelled radial velocity and photometric time series to measure the dynamical mass, radius, and ephemeris, and to characterise the internal structure and composition of TOI-469.01. We confirmed the planetary nature of TOI-469.01. Thanks to ESPRESSO we discovered two additional close-in companions. We also detected their low signal-to-noise transit signals in the TESS light curve. HIP 29442 is a compact multi-planet system, and the three planets have orbital periods $P_{\rm orb, b}=13.63083\pm0.00003$, $P_{\rm orb, c}=3.53796\pm0.00003$, and $P_{\rm orb, d}=6.42975^{+0.00009}_{-0.00010}$ days, and we measured their masses with high precision: $m_{\rm p, b}=9.6\pm0.8~M_{\oplus}$, $m_{\rm p, c}=4.5\pm0.3~M_{\oplus}$, and $m_{\rm p, d}=5.1\pm0.4~M_{\oplus}$. We measured radii and bulk densities of all the planets (the 3$\sigma$ confidence intervals are shown in parenthesis): $R_{\rm p, b}=3.48^{+0.07 (+0.19)}_{-0.08 (-0.28)} ~R_{\oplus}$ and $\rho_{\rm p, b}=1.3\pm0.2 (0.3) g~cm^{-3}$; $R_{\rm p, c}=1.58^{+0.10 (+0.30)}_{-0.11 (-0.34)}~R_{\oplus}$ and $\rho_{\rm p, c}=6.3^{+1.7 (+6.0)}_{-1.3 (-2.7)} g~cm^{-3}$; $R_{\rm p, d}=1.37\pm0.11^{(+0.32)}_{(-0.43)}~R_{\oplus}$ and $\rho_{\rm p, d}=11.0^{+3.4 (+21.0)}_{-2.4 (-6.3)} g~cm^{-3}$. We used the more conservative 3$\sigma$ confidence intervals for the radii as input to the interior structure modelling. We find that HIP 29442 $b$ appears as a typical sub-Neptune, likely surrounded by a gas layer of pure H-He with a mass of $0.27^{+0.24}_{-0.17} M_{\oplus}$ and a thickness of $1.4\pm0.5 R_{\oplus}$. For the innermost companions HIP 29442 $c$ HIP 29442 $d$, the model supports an Earth-like composition.
Comment: Accepted for publication on A&A
Comment: Accepted for publication on A&A