Context. Young stars and multi-planet systems are two types of primary objects that allow us to study, understand, and constrain planetary formation and evolution theories.
Aims: We validate the physical nature of two Neptune-sized planets transiting TOI-942 (TYC 5909-319-1), a previously unacknowledged young star (50-20+30 Myr) observed by the TESS space mission in Sector 5.
Methods: Thanks to a comprehensive stellar characterization, TESS light curve modeling and precise radial-velocity measurements, we validated the planetary nature of the TESS candidate and detected an additional transiting planet in the system on a larger orbit.
Results: From photometric and spectroscopic observations we performed an exhaustive stellar characterization and derived the main stellar parameters. TOI-942 is a relatively active K2.5V star (log R'HK = -4.17 ± 0.01) with rotation period Prot = 3.39 ± 0.01 days, a projected rotation velocity v sin i⋆ = 13.8 ± 0.5 km s-1, and a radius of ~0.9 R⊙. We found that the inner planet, TOI-942 b, has an orbital period Pb = 4.3263 ± 0.0011 days, a radius Rb = 4.242-0.313+0.376 R⊕, and a mass upper limit of 16 M⊕ at 1σ confidence level. The outer planet, TOI-942 c, has an orbital period Pc = 10.1605-0.0053+0.0056 days, a radius Rc = 4.793-0.351+0.410 R⊕, and a mass upper limit of 37 M⊕ at 1σ confidence level.
Astronomy and Astrophysics
- Pub Date:
- January 2021
- planetary systems;
- techniques: photometric;
- techniques: spectroscopic;
- stars: fundamental parameters;
- techniques: radial velocities;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Solar and Stellar Astrophysics