# The young HD 73583 (TOI-560) planetary system: Two 10-M⊕ 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 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 (~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 =$6.3980420 _{ - 0.0000062 } ^ { + 0.0000067 }$ d) has a mass and radius of $10.2 _{ - 3.1 } ^ { + 3.4 }$ M and 2.79 ± 0.10 R, respectively, that gives a density of $2.58 _{ - 0.81 } ^ { + 0.95 }$ g cm-3. HD 73583 c (Pc=$18.87974 _{ - 0.00074 } ^ { + 0.00086 }$ d) has a mass and radius of $9.7 _{ - 1.7 } ^ { + 1.8 }$ M and $2.39 _{ - 0.09 } ^ { + 0.10 }$ R, respectively, this translates to a density of $3.88 _{ - 0.80 } ^ { + 0.91 }$ 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 on-going 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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Submitted on : Friday, May 13, 2022 - 1:53:29 PM
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### Citation

O. Barragán, D. J. Armstrong, D. Gandolfi, I. Carleo, A. A. Vidotto, et al.. The young HD 73583 (TOI-560) planetary system: Two 10-M mini-Neptunes transiting a 500-Myr-old, bright, and active K dwarf. Monthly Notices of the Royal Astronomical Society, 2022, ⟨10.1093/mnras/stac638⟩. ⟨insu-03667449⟩

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