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Exploring Systematic Errors in the Inferred Parameters of the Transiting Planets

Presentation #607.15 in the session Population Statistics and Mass-Radius Relations.

Published onApr 03, 2024
Exploring Systematic Errors in the Inferred Parameters of the Transiting Planets

Transiting planet systems offer a unique opportunity to measure precise masses and radii of planets and their host stars. However, relative photometry and radial velocity measurements alone only constrain the host star density, leaving a one-parameter mass-radius degeneracy. We assess the magnitude of systematic errors in the derived system parameters relative to their statistical precision due to different methods of breaking this degeneracy. We first model extant data for the typical hot Jupiter system KELT-15 using EXOFASTv2, considering four methods of breaking the stellar mass-radius degeneracy. We find systematic differences in the inferred physical parameters of the KELT-15 system, including a 6.5% (~1.8 σ) difference in the stellar and planetary radii based the host star mass-radius degeneracy-breaking method employed. We then evaluate the systematic errors for several systems of M-dwarfs transiting FGK host stars. M-dwarfs are the most abundant stars in the galaxy and popular targets for exoplanet searches. However, we only know of dozens of M-dwarfs with fundamental parameters of mass, radius and effective temperature characterized to better than a few percent. Similarly to transiting planets, M-dwarfs in eclipsing binaries can also be robustly characterized. Here we present several targets from the Eclipsing Binary Low Mass (EBLM) survey where we measure M-dwarf masses with precisions better than 5%, radii better than 3% and effective temperatures on order 1%. Using the same methodology employed for KELT-15, we determine that the model uncertainty in the primary star is of similar magnitude to the statistical uncertainty in the model fits of the secondary M-dwarf. Therefore, whilst these can be considered benchmark M-dwarfs, we caution the community to consider model uncertainty when pushing the limits of precise stellar characterization. Finally, we present a homogenous analysis of ~10 hot Jupiter planetary systems with secondary eclipses observed by TESS with consistent systematic uncertainties in their derived properties. Where possible we homogenously estimate albedos, temperatures, and eccentricities of these systems in addition to updated ephemerides. Understanding the eccentricity of these systems is important in understanding the formation of hot Jupiters.

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