Three Short Period Jupiters from TESS

Abstract

We report the confirmation and mass determination of three hot Jupiters discovered by the Transiting Exoplanet Survey Satellite (TESS) mission: HIP 65Ab (TOI-129, TIC-201248411) is an ultra-short-period Jupiter orbiting a bright (V=11.1 mag) K4-dwarf every 0.98 days. It is a massive 3.213 ± 0.078 M J planet in a grazing transit configuration with impact parameter b = 1.17 +0.10 −0.08 . As a result the radius is poorly constrained, 2.03 +0.61 −0.49 R J . We perform a full phase-curve analysis of the TESS data and detect both illuminationand ellipsoidal variations as well as Doppler boosting. HIP 65A is part of a binary stellar system, with HIP 65B separated by 269 AU (3.95 arcsec on sky). TOI-157b (TIC 140691463) is a typical hot Jupiter with a mass 1.18 ± 0.13 M J and radius 1.29 ± 0.02 R J . It has a period of 2.08 days, which corresponds to a separation of just 0.03 AU. This makes TOI-157 an interesting system, as the host star is an evolved G9 sub-giant star (V=12.7). TOI-169b (TIC 183120439) is a bloated Jupiter orbiting a V=12.4 G-type star. It has a mass of 0.79 ± 0.06 M J and radius 1.09 +0.08 −0.05 R J . Despite having the longest orbital period (P = 2.26 days) of the three planets, TOI-169b receives the most irradiation and is situated on the edge of the Neptune desert. All three host stars are metal rich with [Fe/H] ranging from 0.18 -0.24.

Systematic Phase Curve Study of Known Transiting Systems from Year One of the TESS Mission

“…The discovery of this system was reported in Nielsen et al (2020). The system, observed by TESS during Sectors 1 and 2, consists of a 3.23 M Jup planet on a grazing 0.98-day orbit around an active 0.79 M K-dwarf.…”

“…Using published system parameters for targets that satisfy the aforementioned brightness and variability constraints, we calculated predicted values for A ellip and A Dopp and selected systems for which one or both of these amplitudes exceed 25 ppm. From this, we obtained three additional systems to include in our analysis -HIP 65A (Nielsen et al 2020), WASP-30 (Anderson et al 2011), andTOI-503 ( Šubjak et al 2019) -for a total of 19 targets.…”

“…Due to the extremely grazing nature of the transit, we placed Gaussian priors on the quadratic limb darkening coefficients. We extrapolated the tabulated coefficient values from Claret (2018) to the effective temperature and surface gravity measurements reported in Nielsen et al (2020) (T eff = 4590 K, log g = 4.611) and set the width of the Gaussian to 0.05 for both coefficients: (u 1 , u 2 ) = (0.50±0.05, 0.16±0.05).…”

“…However, including this term in the joint fit led to a large increase in the BIC and only a slight improvement in the AIC (∆AIC < 3), and therefore, we do not include that amplitude in the results presented in Table 2. Nielsen et al (2020) carried out an independent fit for the phase curve components and obtained the following values: A atm = 57.5 ± 4.7 ppm, A ellip = 33.0 ± 4.7 ppm, and A Dopp = 15.4 ± 4.5 ppm. We note that their approach involved applying a polynomial spline to the light curve prior to fitting to remove long-term trends (without accounting for the momentum dumps and the associated flux ramps) and then phase-folding and binning the light curve, as opposed to our approach of fitting these trends simultaneously with the astrophysical model to the unbinned and unfolded light curve.…”

“…This is the primary reason for the smaller uncertainties on the phase curve amplitudes in their analysis. Furthermore, Nielsen et al (2020) did not remove the two anomalous ramps in the vicinity of momentum dumps that we excised from the light curve prior to fitting (see Appendix). When including both gravitationally induced phase curve terms in the astrophysical model, the fitted values for A ellip and A Dopp from our two analyses agree to well within 1σ.…”