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

Journal article

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 = 6.3980420-0.0000062+ 0.0000067 d) has a mass and radius of 10.2-3.1+ 3.4 M and 2.79 ± 0.10 R, respectively, which 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, which translates to a density of 3.88-0.80+ 0.91g, 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.

Authors: Barragan, O; Armstrong, DJ; Gandolfi, D; Carleo, I; Vidotto, AA

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 514
• Issue: 2
• Pages: 1606-1627
• Publication date: 2022-03-15
• DOI: 10.1093/mnras/stac638
• EISSN: 1365-2966
• ISSN: 0035-8711
• Language: English
• Keywords: planets and satellites: individual: HD 73583 (TOI-560); FFR; techniques: photometric; techniques: radial velocities; stars: activity