Improving transit characterisation with Gaussian process modelling of stellar variability

Abstract

New photometric space missions to detect and characterise transiting exoplanets are focusing on bright stars to obtain high cadence, high signal-to-noise light curves. Since these missions will be sensitive to stellar oscillations and granulation even for dwarf stars, they will be limited by stellar variability. We tested the performance of Gaussian process (GP) regression on the characterisation of transiting planets, and in particular to determine how many components of variability are necessary to describe high cadence, high signal-to-noise light curves expected from CHEOPS and PLATO. We found that the best GP stellar variability model contains four to five variability components: one stellar oscillation component, two to four granulation components, and/or one rotational modulation component. This high number of components is in contrast with the one-component GP model (1GP) commonly used in the literature for transit characterisation. Therefore, we compared the performance of the best multi-component GP model with the 1GP model in the derivation of transit parameters of simulated transits. We found that for Jupiter- and Neptune-size planets the best multi-component GP model is slightly better than the 1GP model, and much better than the non-GP model that gives biased results. For Earth-size planets, the 1GP model fails to retrieve the transit because it is a poor description of stellar activity. The non-GP model gives some biased results and the best multi-component GP is capable of retrieving the correct transit model parameters. We conclude that when characterising transiting exoplanets with high signal-to-noise ratios and high cadence light curves, we need models that couple the description of stellar variability with the transits analysis, like GPs. Moreover, for Earth-like exoplanets a better description of stellar variability improves the planetary characterisation.

13 pages, 5 figures, 11 tables accepted for publication in A&A

References in corpus (32)

• emcee: The MCMC Hammer
• The Transiting Exoplanet Survey Satellite
• The PLATO 2.0 Mission
• batman: BAsic Transit Model cAlculatioN in Python
• Fast and scalable Gaussian process modeling with applications to astronomical time series
• The CoRoT satellite in flight : description and performance
• Transiting exoplanets from the CoRoT space mission VIII. CoRoT-7b: the first Super-Earth with measured radius
• A Gaussian process framework for modelling instrumental systematics: application to transmission spectroscopy
• The connection between stellar granulation and oscillation as seen by the Kepler mission
• Kepler Mission Stellar and Instrument Noise Properties
• PASTIS: Bayesian extrasolar planet validation. I. General framework, models, and performance
• Granulation in Red Giants: observations by the Kepler mission and 3D convection simulations
• How stellar activity affects the size estimates of extrasolar planets
• Using the Sun to estimate Earth-like planets detection capabilities.I. Impact of cold spots
• Precise time-series photometry for the Kepler-2.0 mission
• Transit timing variations in WASP-10b induced by stellar activity?
• Large eccentricity, low mutual inclination: the three-dimensional architecture of a hierarchical system of giant planets
• Uncovering the planets and stellar activity of CoRoT-7 using only radial velocities
• Accurate p-mode measurements of the G0V metal-rich CoRoT target HD 52265
• Bayesian peak bagging analysis of 19 low-mass low-luminosity red giants observed with Kepler
• On the use of marginal posteriors in marginal likelihood estimation via importance-sampling
• A fresh look at the seismic spectrum of HD49933: analysis of 180 days of CoRoT photometry
• WASP-10b: a 3M_J, gas-giant planet transiting a late-type K star
• Radial Velocity Observations and Light Curve Noise Modeling Confirm That Kepler-91b is a Giant Planet Orbiting a Giant Star
• K2-97b: A (Re-?)Inflated Planet Orbiting a Red Giant Star
• Revisiting the transits of CoRoT-7b at a lower activity level
• Stellar Granulation as the Source of High-Frequency Flicker in Kepler Light Curves
• Transit timing variation and activity in the WASP-10 planetary system
• Gaussian Process modelling of granulation and oscillations in red-giant stars
• The Sun-like activity of the solar twin 18 Scorpii
• Distinguishing the albedo of exoplanets from stellar activity
• Seismic analysis of HD43587Aa, a solar-like oscillator in a multiple system

Cited by in corpus (33)

• Warm terrestrial planet with half the mass of Venus transiting a nearby star
• Transit detection of the long-period volatile-rich super-Earth ${\nu }^2$ Lupi d with $CHEOPS$
• Detection of the tidal deformation of WASP-103b at $3\sigma$ with CHEOPS
• The GAPS Programme with HARPS-N at TNG. XXXVII. A precise density measurement of the young ultra-short period planet TOI-1807 b
• HD 23472: A multi-planetary system with three super-Earths and two potential super-Mercuries
• A Fast, 2D Gaussian Process Method Based on Celerite: Applications to Transiting Exoplanet Discovery and Characterization
• Broadband transmission spectroscopy of HD209458b with ESPRESSO: Evidence for Na, TiO, or both
• Planetary system around LTT 1445A unveiled by ESPRESSO: Multiple planets in a triple M-dwarf system
• 55 Cancri e's occultation captured with CHEOPS
• Multi-band transit follow up observations of five hot-Jupiters with critical noise treatments: Improved physical properties
• The young mini-Neptune HD 207496b that is either a naked core or on the verge of becoming one
• A hot mini-Neptune in the radius valley orbiting solar analogue HD 110113
• A warm super-Neptune around the G-dwarf star TOI-1710 revealed with TESS, SOPHIE and HARPS-N
• Is the orbit of the exoplanet WASP-43b really decaying? TESS and MuSCAT2 observations confirm no detection
• EXPRES. II. Searching for Planets Around Active Stars: A Case Study of HD 101501
• Far beyond the Sun: II. Probing the stellar magnetism of the young Sun ι Horologii from the photosphere to its corona
• TOI-1442 b and TOI-2445 b: two potentially rocky ultra-short period planets around M dwarfs
• Precise Transit Photometry Using TESS II: Revisiting 28 Additional Transiting Systems With Updated Physical Properties
• Enabling Robust Exoplanet Atmospheric Retrievals with Gaussian Processes
• Detection of photometric variability in the very low-mass binary VHS J1256-1257AB using TESS and Spitzer
• A hot mini-Neptune and a temperate, highly eccentric sub-Saturn around the bright K-dwarf TOI-2134
• Precise Transit Photometry Using TESS: Updated Physical Properties for 28 Exoplanets Around Bright Stars
• SOAPv4: A new step toward modeling stellar signatures in exoplanet research
• Rapidly rotating stars and their transiting planets: KELT-17b, KELT-19Ab, and KELT-21b in the CHEOPS and TESS era
• Is binning always sinning? The impact of time-averaging for exoplanet phase curves
• Understanding and predicting cadence effects in the characterization of exoplanet transits
• The CHEOPS view of HD 95338b: refined transit parameters, and a search for exomoons
• gallifrey: JAX-based Gaussian process structure learning for astronomical time series
• Detection of a peculiar noise type in the TESS "fast" light curves
• FINKER: Frequency Identification through Nonparametric KErnel Regression in astronomical time series
• Disentangling auroral, cloud and magnetic spot driven variability in three early L-dwarfs with HST/WFC3
• Revisiting the secondary eclipses of KELT-1b using TESS observations
• Scaling relations of convective granulation noise across the HR diagram from 3D stellar atmosphere models