Refining Parameters for RV-Amenable TESS Planet Candidates

The Transiting Exoplanet Survey Satellite (TESS) is finding thousands of planet candidates, many of which are amenable to further characterization via radial velocity (RV) follow-up. It is not feasible to observe every planet candidate, so we must identify the most promising targets to guide follow-up efforts. However, we must first have precise measurements of host star parameters to obtain an accurate prediction of planet parameters. This would inform the decision of whether to invest competitive resources in following up a planet, since we must prioritize planets that would be the most likely to produce successful mass measurements. Our original dataset consisted of 34,140 RV-amenable stars that were observed during TESS Cycle 3, 155 of which were identified as TESS Objects of Interest (TOIs). After removing false positives, we characterized a sample of 115 TOIs by using the Python package AstroARIADNE to fit TOI spectral energy distributions (SEDs) to stellar atmospheric models. The SEDs were constructed using published broadband photometry from the UV, visible, and infrared regimes. AstroARIADNE estimated stellar parameters for 99 out of 115 TOIs, with similar but more precise values than those found in the TESS Input Catalog (TIC v8.1). The distances to these stars were updated using Gaia DR2 parallaxes and the latest Stilism reddening maps. The median fractional radius error decreased from 4.3% to 1.2%, and the median fractional Teff error decreased from 2.7% to 0.6%. We used these updated parameters to recalculate the radius, predicted mass, and predicted RV semi-amplitude for 125 planet candidates. The updated values were then uploaded to the TESS Exoplanet Follow-Up Observing Program (ExoFOP).