Abstract
Abstract We report the discovery of two short-period massive giant planets from NASA’s Transiting Exoplanet Survey Satellite (TESS). Both systems, TOI-558 (TIC 207110080) and TOI-559 (TIC 209459275), were identified from the 30 minute cadence full-frame images and confirmed using ground-based photometric and spectroscopic follow-up observations from TESS’s follow-up observing program working group. We find that TOI-558 b, which transits an F-dwarf (M * = 1.349 − 0.065 + 0.064 M ⊙, R * = 1.496 − 0.040 + 0.042 R ⊙, T eff = 6466 − 93 + 95 K, age 1.79 − 0.73 + 0.91 Gyr) with an orbital period of 14.574 days, has a mass of 3.61 ± 0.15 M J, a radius of 1.086 − 0.038 + 0.041 R J, and an eccentric (e = 0.300 − 0.020 + 0.022 ) orbit. TOI-559 b transits a G dwarf (M * = 1.026 ± 0.057 M ⊙, R * = 1.233 − 0.026 + 0.028 R ⊙, T eff = 5925 − 76 + 85 K, age 6.8 − 2.0 + 2.5 Gyr) in an eccentric (e = 0.151 ± 0.011) 6.984 days orbit with a mass of 6.01 − 0.23 + 0.24 M J and a radius of 1.091 − 0.025 + 0.028 R J. Our spectroscopic follow up also reveals a long-term radial velocity trend for TOI-559, indicating a long-period companion. The statistically significant orbital eccentricity measured for each system suggests that these planets migrated to their current location through dynamical interactions. Interestingly, both planets are also massive (>3 M J), adding to the population of massive giant planets identified by TESS. Prompted by these new detections of high-mass planets, we analyzed the known mass distribution of hot and warm Jupiters but find no significant evidence for multiple populations. TESS should provide a near magnitude-limited sample of transiting hot Jupiters, allowing for future detailed population studies.
Highlights
The formation and migration of giant planets in close orbits has been debated extensively
After formation, a giant planet could migrate to a close-in orbit through either gentle migration through the gas disk (Goldreich & Tremaine 1980; Lin & Papaloizou 1986; Lin et al 1996) or more dynamical migration caused by interaction with another planet or star (Rasio & Ford 1996; Wu & Murray 2003; Fabrycky & Tremaine 2007; Nagasawa & Ida 2011; Wu & Lithwick 2011), after which the planet’s orbit could be circularized and shrunk by tidal forces (Naoz et al 2011; Beaugé & Nesvorný 2012)
More recent models have suggested that hot Jupiters may form in-situ (Batygin et al 2016) and show that the period-mass distribution and inner boundary of short-period giant planets could be consistent with predictions for in-situ formation (Bailey & Batygin 2018)
Summary
The formation and migration of giant planets in close orbits has been debated extensively. Hot Jupiters (with orbital periods less than 10 days) could theoretically form in a number of ways, with three main formation and migration schemes dominating the literature. More recent models have suggested that hot Jupiters may form in-situ (Batygin et al 2016) and show that the period-mass distribution and inner boundary of short-period giant planets could be consistent with predictions for in-situ formation (Bailey & Batygin 2018). One possible path to determining the dominant mechanism of giant planet migration is to create a complete sample of hot Jupiters with well characterized fundamental parameters (masses and radii, and orbital periods and eccentricities). We examine the existing population of hot Jupiters, studying existing trends in the mass-period distribution and discussing the contribution of TESS discoveries (§4).
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