Flicker as a tool for characterizing planets through Asterodensity Profiling

Abstract

Variability in the time series brightness of a star on a timescale of 8 hours, known as 'flicker', has been previously demonstrated to serve as a proxy for the surface gravity of a star by Bastien et al. (2013). Although surface gravity is crucial for stellar classification, it is the mean stellar density which is most useful when studying transiting exoplanets, due to its direct impact on the transit light curve shape. Indeed, an accurate and independent measure of the stellar density can be leveraged to infer subtle properties of a transiting system, such as the companion's orbital eccentricity via asterodensity profiling. We here calibrate flicker to the mean stellar density of 439 Kepler targets with asteroseismology, allowing us to derive a new empirical relation given by ${\log }_{10}({\rho }_{\star }[\mathrm{kg}{\mathrm{m}}^{-3}])=5.413-1.850{\log }_{10}(F_8[\mathrm{ppm}])$. The calibration is valid for stars with $4500$K$<T_{\mathrm{eff}}<6500$K, $K_P<14$ and flicker estimates corresponding to stars with $3.25<\log g_{\star }<4.43$. Our relation has a model error in the stellar density of 31.7% and so has $\sim 8$ times lower precision than that from asteroseismology but is applicable to a sample $\sim 40$ times greater. Flicker therefore provides an empirical method to enable asterodensity profiling on hundreds of planetary candidates from present and future missions.

6 pages, 3 figures, 1 table. Accepted to ApJ Letters. Code available at https://www.cfa.harvard.edu/~dkipping/flicker.html

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Cited by in corpus (13)

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• The population of long-period transiting exoplanets
• A Granulation "Flicker"-based Measure of Stellar Surface Gravity
• The Eccentricity Distribution of Short-Period Planet Candidates Detected by Kepler in Occultation
• Discovery of a Transiting Planet Near the Snow-Line
• Mitigating flicker noise in high-precision photometry. I -- Characterization of the noise structure, impact on the inferred transit parameters, and predictions for CHEOPS observations
• Systematics-insensitive periodic signal search with K2
• New Suns in the Cosmos III: multifractal signature analysis
• Inference of stellar parameters from brightness variations
• ExELS: an exoplanet legacy science proposal for the ESA Euclid mission. II. Hot exoplanets and sub-stellar systems
• A Refined Model of Convectively-Driven Flicker in Kepler Light Curves
• Stellar activity and transits
• Probabilistic inference of basic stellar parameters: application to flickering stars