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The young HD 73583 (TOI-560) planetary system: two 10-M⊕ mini-Neptunes transiting a 500-Myr-old, bright, and active K dwarf

O. Barragán, D. J. Armstrong, D. Gandolfi, I. Carleo, A. A. Vidotto, C. Villarreal D'Angelo, A. Oklopčić, H. Isaacson, D. Oddo, K. A. Collins, M. Fridlund, S. G. Sousa, C. M. Persson, C. Hellier, S. B. Howell, A. W. Howard, S. Redfield, N. Eisner, I. Georgieva, D. Dragomir, D. Bayliss, L. D. Nielsen, B. Klein, S. Aigrain, M. Zhang, J. Teske, J. D. Twicken, J. M. Jenkins, M. Esposito, V. Van Eylen, F. Rodler, V. Zh. Adibekyan, J. Alarcon, D. R. Anderson, Joseph M. A. Murphy, D. Barrado, S. C. C. Barros, B. Benneke, F. Bouchy, E. M. Bryant, R. P. Butler, J. A. Burt, J. Cabrera, S. Casewell, P. Chaturvedi, R. Cloutier, W. D. Cochran, J. D. Crane, I. J. M. Crossfield, N. Crouzet, K. I. Collins, F. Dai, H. J. Deeg, A. Deline, O. Demangeon, X. Dumusque, P. Figueira, E. Furlan, C. L. Gnilka, M. R. Goad, E. Goffo, F. Gutiérrez-Canales, A. Hadjigeorghiou, Z. Hartman, A. Hatzes, M. Harris, B. Henderson, T. Hirano, S. Hojjatpanah, S. Hoyer, P. Kabáth, J. Korth, J. Lillo-Box, R. Luque, M. Marmier, T. Močnik, A. Muresan, F. Murgas, E. Nagel, H. L. M. Osborne, A. Osborn, H. P. Osborn, E. Palle, G. R. Ricker, R. A. Rubenzahl, C. Stockdale, N. C. Santos, N. J. Scott, R. P. Schwarz, S. A. Shectman, M. Raimbault, M. Raimbault, S. Seager, D. Ségransan, L. M. Serrano, M. Skarka, A. M. S. Smith, J. ¦ubjak, T. G. Tan, S. Udry, C. A. Watson, P. J. Wheatley, R. G. West, J. N. Winn, S. X. Wang, A. Wolfgang, C. Ziegler

We present the discovery and characterization of two transiting planets observed by TESS in the light curves of the young and bright (V = 9.67) star HD73583 (TOI-560). We perform an intensive spectroscopic and photometric space- and ground-based follow-up in order to confirm and characterize the system. We found that HD73583 is a young (∼500 Myr) active star with a rotational period of 12.08 ± 0.11  d, and a mass and radius of 0.73 ± 0.02 M and 0.65 ± 0.02 R, respectively. HD 73583 b (Pb = 6.3980420+0.0000067−0.0000062 d) has a mass and radius of 10.2+3.4−3.1 M and 2.79 ± 0.10 R, respectively, which gives a density of 2.58+0.95−0.81 gcm−3⁠. HD 73583 c (Pc = 18.87974+0.00086−0.00074 d) has a mass and radius of 9.7+1.8−1.7 M and 2.39+0.10−0.09 R, respectively, which translates to a density of 3.88+0.91−0.80 gcm−3⁠. Both planets are consistent with worlds made of a solid core surrounded by a volatile envelope. Because of their youth and host star brightness, they both are excellent candidates to perform transmission spectroscopy studies. We expect ongoing atmospheric mass-loss for both planets caused by stellar irradiation. We estimate that the detection of evaporating signatures on H and He would be challenging, but doable with present and future instruments.

techniques: photometric, techniques: radial velocities, planets and satellites: individual: HD 73583 (TOI-560), stars: activity

Monthly Notices of the Royal Astronomical Society
Volume 514, Issue 2, Page 1606
2022 August

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Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia