Potential Hydrosphere Stability of TESS Objects of Interest 700, 256, and 203

The presence of liquid water is one of the most essential ingredients for life as we know it. Indeed, many studies of exoplanet habitability have tied the definition of habitability to the existence of liquid water. In this study, we firstly characterize the stars of the TOI systems through empirical relations based on public 2MASS and Gaia data. Following this, we re-fit the TESS observations to obtain more accurate parameters for use in the simulations. Finally, we apply the VPlanet simulation software to the resultant MCMC trace to yield statistically significant metrics for hydrosphere stability. Initial characterization of the observable stellar characteristics is done through the standard methods for M-dwarf stars using publically available 2MASS and Gaia measurements. We then use the lightkurve module in Python to extract and detrend the lightcurves from the TESS target pixel files. After correcting and de-trending the light curves, a transit model is constructed using exoplanet and sample the posterior distributions using the No U-turn Sampler as part of PyMC3. Finally, we estimate the mass distribution using a non-parametric mass-radius relationship within the Python implementation mrexo. Simulations of long-term hydrodynamic stability linked with rotational and orbital evolution are done using VPlanet. In order to preserve a connection to the observed data, we create a simulation for each step of the MCMC trace created previously. In each simulation, the planet is given an initial inventory of 10 Earth oceans of water as in the Luger & Barnes (2015) simulation of Venus. Each simulation is run for the age of the star if known or 1Gyr if not. After the simulation finishes, we use several metrics to analyze the potential hydrosphere stability of the planet: 1) the percentage of cases of total desiccation compares to the number of simulations; 2) a comparison of the final water inventory to the initial 10 Earth oceans; and 3) the desiccation rate 1Myr from the stop time of the simulation. We will present these metrics, along with an overall assessment of the hydrosphere stability of TOIs 700, 256, and 203.