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arXiv · 2110.13069

The young HD 73583 (TOI-560) planetary system: Two 10-M$_\oplus$ mini-Neptunes transiting a 500-Myr-old, bright, and active K dwarf

Abstract

We present the discovery and characterisation of two transiting planets observed by \textit{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 characterise the system. We found that HD73583 is a young ($\sim 500$~Myr) active star with a rotational period of $12.08 \pm 0.11 $\,d, and a mass and radius of $ 0.73 \pm 0.02 M_\odot$ and $0.65 \pm 0.02 R_\odot$, respectively. HD73583 b ($P_b=6.3980420 _{ - 0.0000062 }^{+0.0000067}$ d) has a mass and radius of $10.2 _{-3.1}^{+3.4} M_\oplus$ and$2.79 \pm 0.10 R_\oplus$, respectively, that gives a density of $2.58 _{-0.81}^{ 0.95} {\rm g\,cm^{-3}}$. HD73583 c ($P_c= 18.87974 _{-0.00074 }^{+0.00086}$) has a mass and radius of $9.7_{-1.7} ^ {+1.8} M_\oplus$ and $2.39_{-0.09}^{+0.10} R_\oplus$, respectively, this translates to a density of $3.88 _{-0.80}^{+0.91} {\rm g\,cm^{-3}}$. 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.

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O. Barragán, D. J. Armstrong, D. Gandolfi, I. Carleo, A. A. Vidotto, C. Villarreal D'Angelo, A. Oklopčić, H. Isaacson, D. Oddo, K. Collins, M. Fridlund, S. G. Sousa, C. M. Persson, C. Hellier, S. Howell, A. Howard, S. Redfield, N. Eisner, I. Y. Georgieva, D. Dragomir, D. Bayliss, L. D. Nielsen, B. Klein, S. Aigrain, M. Zhang, J. Teske, J D. Twicken, J. Jenkins, M. Esposito, V. Van Eylen, F. Rodler, V. Adibekyan, J. Alarcon, D. R. Anderson, J. M. Akana Murphy, D. Barrado, S. C. C. Barros, B. Benneke, F. Bouchy, E. M. Bryant, P. Butler, J. Burt, J. Cabrera, S. Casewell, P. Chaturvedi, R. Cloutier, W. D. Cochran, J. Crane, I. Crossfield, N. Crouzet, K. I. Collins, F. Dai, H. J. Deeg, A. Deline, O. D. S. Demangeon, X. Dumusque, P. Figueira, E. Furlan, C. Gnilka, M. R. Goad, E. Goffo, F. Gutiérrez-Canales, A. Hadjigeorghiou, Z. Hartman, A. P. 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, M. Raimbault, G. R. Ricker, R A. Rubenzahl, C. Stockdale, N. C. Santos, N. Scott, R. P. Schwarz, S. Shectman, S. Seager, D. Ségransan, L. M. Serrano, M. Skarka, A. M. S. Smith, J. Šubjak, T. G. Tan, S. Udry, C. Watson. 2021-10-25. The young HD 73583 (TOI-560) planetary system: Two 10-M$_\oplus$ mini-Neptunes transiting a 500-Myr-old, bright, and active K dwarf. https://doi.org/10.1093/mnras/stac638

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