Modelling the photosphere of active stars for planet detection and characterization

Abstract

Stellar activity patterns are responsible for jitter effects that are observed at different timescales and amplitudes. These effects are currently in the focus of many exoplanet search projects, since the lack of a well-defined characterization and correction strategy hampers the detection of the signals associated with small exoplanets. Accurate simulations of the stellar photosphere can provide synthetic time series data. These may help to investigate the relation between activity jitter and stellar parameters when considering different active region patterns. Moreover, jitters can be analysed at different wavelength scales in order to design strategies to remove or minimize them. In this work we present the StarSim tool, which is based on a model for a spotted rotating photosphere built from the integration of the spectral contribution of a fine grid of surface elements. The model includes all significant effects affecting the flux intensities and the wavelength of spectral features produced by active regions and planets. A specific application for the characterization and modelling of the spectral signature of active regions is considered, showing that the chromatic effects of faculae are dominant for low temperature contrasts of spots. Synthetic time series are modelled for HD 189733. Our algorithm reproduces both the photometry and the RVs to good precision, generally better than the studies published to date. We evaluate the RV signature of the activity in HD 189733 by exploring a grid of solutions from the photometry. We find that the use of RV data in the inverse problem could break degeneracies and allow for a better determination of some stellar and activity parameters. In addition, the effects of spots are studied for a set of simulated transit photometry, showing that these can introduce variations which are very similar to the signal of an atmosphere dominated by dust.

arXiv comment19 pages, 13 figures

References in corpus (61)

• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• Solar Chemical Abundances Determined with a CO5BOLD 3D Model Atmosphere
• No planet for HD 166435
• Transiting exoplanets from the CoRoT space mission VIII. CoRoT-7b: the first Super-Earth with measured radius
• The CORALIE survey for southern extra-solar planets VII. Two short-period Saturnian companions to HD108147 and HD168746
• Chromospheric CaII Emission in Nearby F, G, K, and M stars
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• Detection of atmospheric haze on an extrasolar planet: The 0.55 - 1.05 micron transmission spectrum of HD189733b with the Hubble Space Telescope
• ELODIE metallicity-biased search for transiting Hot Jupiters II. A very hot Jupiter transiting the bright K star HD189733
• The prevalence of dust on the exoplanet HD 189733b from Hubble and Spitzer observations
• Hubble Space Telescope Transmission Spectroscopy of the Exoplanet HD 189733b: High-altitude atmospheric haze in the optical and near-UV with STIS
• Eclipsing binaries in open clusters. II. V453 Cyg in NGC 6871
• Water Vapor in the Spectrum of the Extrasolar Planet HD 189733b: 1. the Transit
• A simple method to estimate radial velocity variations due to stellar activity using photometry
• Using the Sun to estimate Earth-like planets detection capabilities II. Impact of plages
• Planetary detection limits taking into account stellar noise. I. Observational strategies to reduce stellar oscillation and granulation effects
• SOAP 2.0: A tool to estimate the photometric and radial velocity variations induced by stellar spots and plages
• Starspots, spin-orbit misalignment, and active latitudes in the HAT-P-11 exoplanetary system
• Hubble Space Telescope times-series photometry of the planetary transit of HD189733: no moon, no rings, starspots
• Stellar activity of planetary host star HD 189733
• Search for exoplanets with the radial-velocity technique: quantitative diagnostics of stellar activity
• Searching for Star-Planet interactions within the magnetosphere of HD 189733
• The Rossiter-McLaughlin effect of CoRoT-3b & HD189733b
• The Transit Light Curve Project. V. System Parameters and Stellar Rotation Period of HD 189733
• Characterizing the Variability of Stars with Early-Release Kepler Data
• SOAP. A tool for the fast computation of photometry and radial velocity induced by stellar spots
• Effect of stellar spots on high-precision transit light-curve
• Using the Sun to estimate Earth-like planets detection capabilities.I. Impact of cold spots
• Measurement of the Spin-Orbit Alignment in the Exoplanetary System HD 189733
• Making Sense of Sunspot Decay I: Parabolic Decay Law and Gnevyshev-Waldmeier Relation
• The HARPS search for southern extra-solar planets I. HD330075 b: a new 'hot Jupiter'
• Impact of occultations of stellar active regions on transmission spectra: Can occultation of a plage mimic the signature of a blue sky?
• A homogeneous database of sunspot areas covering more than 130 years
• Transit timing variations in WASP-10b induced by stellar activity?
• On the intensity contrast of solar photospheric faculae and network elements
• Planetary detection limits taking into account stellar noise. II. Effect of stellar spot groups on radial-velocities
• The solar magnetic field since 1700: I. Characteristics of sunspot group emergence and reconstruction of the butterfly diagram
• Spectropolarimetric observations of the transiting planetary system of the K dwarf HD 189733
• The Rotation Period of the Planet-Hosting Star HD 189733
• Properties of starspots on CoRoT-2
• Line-profile variations in radial-velocity measurements: Two alternative indicators for planetary searches
• Disentangling Planets and Stellar Activity for Gliese 667C
• Reconstructing the solar integrated radial velocity using MDI/SOHO
• Photospheric activity, rotation, and radial velocity variations of the planet-hosting star CoRoT-7
• Solar irradiance variability: A six-year comparison between SORCE observations and the SATIRE model
• SOAP-T: A tool to study the light-curve and radial velocity of a system with a transiting planet and a rotating spotted star
• On the relationship between the size and surface coverage of starspots on magnetically active low-mass stars
• Statistics of Stellar Variability from Kepler - I: Revisiting Quarter 1 with an Astrophysically Robust Systematics Correction
• Butterfly Diagram and Activity Cycles in HR 1099
• MOST Spacebased Photometry of the Transiting Exoplanet System HD 189733: Precise Timing Measurements for Transits Across an Active Star
• An Analytic Model for Rotational Modulations in the Photometry of Spotted Stars
• Photospheric activity and rotation of the planet-hosting star CoRoT-Exo-4a
• On the Age of Stars Harboring Transiting Planets
• Spot Sizes on Sun-like Stars
• Deriving the radial-velocity variations induced by stellar activity from high-precision photometry - Test on HD189733 with simultaneous MOST/SOPHIE data
• Looking for Super-Earths in the HD 189733 System: A Search for Transits in Most Space-Based Photometry
• Finding Exoplanets Orbiting Young Active Stars. I. Technique
• Photospheric activity, rotation, and star-planet interaction of the planet-hosting star CoRoT-6
• Making Sense of Sunspot Decay II: Deviations from the Mean Law and Plage Effects
• Deriving stellar inclination of slow rotators using stellar activity
• Bisectors of the HARPS Cross-Correlation-Function. The dependence on stellar atmospheric parameters

Cited by in corpus (52)

• The Transit Light Source Effect II: The Impact of Stellar Heterogeneity on Transmission Spectra of Planets Orbiting Broadly Sun-like Stars
• Filtering solar-like oscillations for exoplanet detection in radial velocity observations
• Radial Velocity Planet Detection Biases at the Stellar Rotational Period
• The CARMENES search for exoplanets around M dwarfs: Radial-velocity variations of active stars in visual-channel spectra
• The full spectral radiative properties of Proxima Centauri
• A decade of H$\alpha$ transits for HD 189733 b: stellar activity versus absorption in the extended atmosphere
• The effects of stellar activity on optical high-resolution exoplanet transmission spectra
• Stellar surface inhomogeneities as a potential source of the atmospheric signal detected in the K2-18 b transmission spectrum
• GJ1214: Rotation period, starspots, and uncertainty on the optical slope of the transmission spectrum
• The HADES RV Programme with HARPS-N@TNG II. Data treatment and simulations
• The HADES RV Programme with HARPS-N@TNG. III. Flux-flux and activity-rotation relationships of early-M dwarfs
• The CARMENES search for exoplanets around M dwarfs. Mapping stellar activity indicators across the M dwarf domain
• The CARMENES search for exoplanets around M dwarfs: Convective shift and starspot constraints from chromatic radial velocities
• Spectral variability of photospheric radiation due to faculae I: The Sun and Sun-like stars
• Stellar signal components seen in HARPS and HARPS-N solar radial velocities
• Multi-band high resolution spectroscopy rules out the hot Jupiter BD+20 1790b - First data from the GIARPS Commissioning
• The Impact of Stellar Surface Magnetoconvection and Oscillations on the Detection of Temperate, Earth-Mass Planets Around Sun-Like Stars
• The CARMENES search for exoplanets around M dwarfs: Stable radial-velocity variations at the rotation period of AD~Leonis -- A test case study of current limitations to treating stellar activity
• Activity time series of old stars from late F to early K. I. Simulating radial velocity, astrometry, photometry, and chromospheric emission
• $\text{PyTranSpot}$ - A tool for multiband light curve modeling of planetary transits and stellar spots
• Auto-correlation functions of astrophysical processes, and their relation to Gaussian processes; Application to radial velocities of different starspot configurations
• Spatially resolved spectroscopy across stellar surfaces. I. Using exoplanet transits to analyze 3-D stellar atmospheres
• Evidence for abnormal H$\alpha$ variability during near-transit observations of HD 189733 b
• Activity time series of old stars from late F to early K. II. Radial velocity jitter and exoplanet detectability
• Stellar Magnetic Activity and "Butterfly Diagram" of Kepler-63
• SOAP-GPU: Efficient Spectral Modelling of Stellar Activity Using Graphical Processing Units
• A transmission spectrum of the sub-Earth planet L98-59~b in 1.1-1.7 $\mu$m
• Forward modelling of Kepler-band variability due to faculae and spots
• The effects of granulation and supergranulation on Earth-mass planet detectability in the habitable zone around F6-K4 stars
• Measuring precise radial velocities and cross-correlation function line-profile variations using a Skew Normal density
• Gaussian processes for radial velocity modeling Better rotation periods and planetary parameters with the quasi-periodic kernel and constrained priors
• HADES RV Programme with HARPS-N at TNG VI. GJ 3942 b behind dominant activity signals
• A Machine Learning approach for correcting radial velocities using physical observables
• SAGE: A tool to constrain impacts of stellar activity on transmission spectroscopy
• Spatially resolved spectroscopy across stellar surfaces. V. Observational prospects: Toward Earth-like exoplanet detection
• Near-UV transit photometry of HAT-P-32 b with the LBT: Silicate aerosols in the planetary atmosphere
• $\text{GRASS}$: Distinguishing Planet-induced Doppler Signatures from Granulation with a Synthetic Spectra Generator
• Estimating Magnetic Filling Factors From Simultaneous Spectroscopy and Photometry: Disentangling Spots, Plage, and Network
• Evidence for stellar contamination in the transmission spectra of HAT-P-12b
• Testing the solar activity paradigm in the context of exoplanet transits
• The widest broadband transmission spectrum (0.38-1.71 $\mu$m) of HD 189733b from ground-based chromatic Rossiter-McLaughlin observations
• Stellar activity consequence on the retrieved transmission spectra through chromatic Rossiter-McLaughlin observations
• Simulations of starspot anomalies within TESS exoplanetary transit light curves -- I. The detection limits of starspot anomalies in TESS light curves
• SOAPv4: A new step toward modeling stellar signatures in exoplanet research
• Noise Sources in Photometry and Radial Velocities
• Simulations of starspot anomalies within TESS exoplanetary transit light curves -- II
• The CARMENES search for exoplanets around M dwarfs. The impact of rotation and magnetic fields on the radial velocity jitter in cool stars
• 3D Radiative MHD Simulations of Starspots II: Large-scale Structure
• Quantifying the Effect of Short-timescale Stellar Activity Upon Transit Detection in M Dwarfs
• Where does the simplified Stellar Contamination Model fail in Exoplanet Transmission Spectroscopy?
• Measuring masses of transiting Earth-like planets: first insights from the PLATO RV data challenge
• PAStar: a model for stellar surface from the Sun to active stars