Abstract
Aims. We aim at the discovery of new planetary systems by exploiting the transit light-curve results from observations made in TESS orbital observatory Sectors 1 and 2 and validating them with precise Doppler measurements obtained from archival HARPS data. Methods. Taking advantage of the reported TESS transit events around GJ 143 (TOI 186) and HD 23472 (TOI 174), we modeled their HARPS precise Doppler measurements and derived orbital parameters for these two systems. Results. For the GJ 143 system, TESS has reported only a single transit, and thus its period is unconstrained from photometry. Our radial velocity analysis of GJ 143 reveals the full Keplerian solution of the system, which is consistent with an eccentric planet with a mass almost twice that of Neptune and a period of Pb = 35.59−0.1+0.1 days. Our estimates of the GJ 143 b planet are fully consistent with the transit timing from TESS. We confirm the two-planet system around HD 23472, which according to our analysis is composed of two Neptune-mass planets in a possible 5:3 mean motion resonance.
Highlights
The Transiting Exoplanet Survey Satellite (TESS; Ricker et al.2015) has begun its planet hunt
For the GJ 143 system, TESS has reported only a single transit, and its period is unconstrained from photometry
GJ 143 The official TESS Sectors 1 and 2 data release has not provided a transit period of the GJ 143 candidate companion because only one single but significant transit of GJ 143 has been observed between 22 July to 21 September for this target
Summary
To measure the most likely masses of the planetary candidates, we modeled the available HARPS data using a two-planet circular Keplerian model, and used the transit information as a prior. In this case, the only unconstrained parameters in this model are the RV semi-amplitudes Kb,c (related to the planetary masses) because the transit epoch and periods are well established by the photometry. We decided to include the planetary periods and phases in the modeling Our reason for this is the following: Over the ≈14 years of RV measurements, small deviations of the oscillating orbit may accumulate into strong deviations from an unperturbed sine-like curve in some phases where RV data are obtained.
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