HATS-34b and HATS-46b: Re-characterization using TESS and Gaia

We present a revised characterization of the previously discovered transiting planet systems HATS-34 and HATS-46. We make use of the newly available space-based light curves from the NASA TESS mission and high-precision parallax and absolute photometry measurements from the ESA Gaia mission to determine the mass and radius of the planets and host stars with dramatically increased precision and accuracy compared to published values, with the uncertainties in some parameters reduced by as much as a factor of 7. Using an isochrone-based fit, for HATS-34 we measure a revised host star mass and radius of $0.952_{-0.020}^{+0.040}$ $\, \mathrm{M}_\odot$ and 0.9381 ± 0.0080 $\, \mathrm{R}_\odot$, respectively, and a revised mass and radius for the transiting planet of 0.951 ± 0.050 MJ and 1.282 ± 0.064 RJ, respectively. Similarly, for HATS-46 we measure a revised mass and radius for the host star of 0.869 ± 0.023 $\, \mathrm{M}_\odot$ and 0.894 ± 0.010 $\, \mathrm{R}_\odot$, respectively, and a revised mass and radius for the planet of 0.158 ± 0.042 MJ and 0.951 ± 0.029 RJ, respectively. The uncertainties that we determine on the stellar and planetary masses and radii are also substantially lower than re-determinations that incorporate the Gaia results without performing a full re-analysis of the light curves and other observational data. We argue that, in light of Gaia and TESS, a full re-analysis of previously discovered transiting planets is warranted.