http://arxiv.org/abs/2209.14301
It has long been understood that the light curve of a transiting planet constrains the density of its host star. That fact is routinely used to improve measurements of the stellar surface gravity, and has been argued to be an independent check on the stellar mass. Here we show how the stellar density can also provide meaningful constraints on the radius and effective temperature of the star. This additional constraint is especially significant when we properly account for the 4.2% radius and 2.4% temperature systematic errors inherent in the stellar evolutionary and atmospheric models. In the typical case, we can measure stellar radii to 3% and temperatures to 1.75%. In the best real-world cases, we can infer radii to 1.7% and temperatures to 1.2% — well below the systematic floors from stellar models alone — which can improve the precision in the planetary parameters by a factor of two. We explain in detail the mechanism that makes it possible and show a demonstration of the technique for a near-ideal system, WASP-4.
We also show that both the statistical and systematic uncertainties in the parallax from Gaia DR3 are often a significant component of the uncertainty in $L_*$ and must be treated carefully. Taking advantage of our technique requires simultaneous models of the stellar evolution, bolometric flux (e.g., a stellar spectral energy distribution), and the planetary transit, while accounting for the systematic errors in each, as is done in EXOFASTv2.
J. Eastman, H. Diamond-Lowe and J. Tayar
Fri, 30 Sep 22
42/71
Comments: 16 pages, 10 figures, 5 tables, submitted to AAS journals
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