Variability of stellar granulation and convective blueshift with spectral type and magnetic activity. I. K and G main sequence stars

Abstract

In solar-type stars, the attenuation of convective blueshift by stellar magnetic activity dominates the RV variations over the low amplitude signal induced by low mass planets. Models of stars that differ from the Sun will require a good knowledge of the attenuation of the convective blueshift to estimate its impact on the variations. It is therefore crucial to precisely determine not only the amplitude of the convective blueshift for different types of stars, but also the dependence of this convective blueshift on magnetic activity, as these are key factors in our model producing the RV. We studied a sample of main sequence stars with spectral types from G0 to K2 and focused on their temporally averaged properties: the activity level and a criterion allowing to characterise the amplitude of the convective blueshift. We find the differential velocity shifts of spectral lines due to convection to depend on the spectral type, the wavelength (this dependence is correlated with the Teff and activity level), and on the activity level. This allows us to quantify the dependence of granulation properties on magnetic activity for stars other than the Sun. The attenuation factor of the convective blueshift appears to be constant over the considered range of spectral types. We derive a convective blueshift which decreases towards lower temperatures, with a trend in close agreement with models for Teff lower than 5800 K, but with a significantly larger global amplitude. We finally compare the observed RV variation amplitudes with those that could be derived from our convective blueshift using a simple law and find a general agreement on the amplitude. Our results are consistent with previous results and provide, for the first time, an estimation of the convective blueshift as a function of Teff, magnetic activity, and wavelength, over a large sample of G and K main sequence stars.

References in corpus (5)

• Spectroscopic parameters for 451 stars in the HARPS GTO planet search program. Stellar [Fe/H] and the frequency of exo-Neptunes
• 'Ultimate' Information Content in Solar and Stellar Spectra: Photospheric line asymmetries and wavelength shifts
• The HARPS search for southern extra-solar planets. IX. Exoplanets orbiting HD 100777, HD 190647, and HD 221287
• Refined Properties of the HD 130322 Planetary System
• Granulation in K-type Dwarf Stars. I. Spectroscopic observations

Cited by in corpus (36)

• Three years of Sun-as-a-star radial-velocity observations on the approach to solar minimum
• Stellar chromospheric activity of 1,674 FGK stars from the AMBRE-HARPS sample I. A catalogue of homogeneous chromospheric activity
• Measuring precise radial velocities on individual spectral lines : II. Dependance of stellar activity signal on line depth
• Color difference makes a difference: four planet candidates around tau Ceti
• Insights on the Spectral Signatures of Stellar Activity and Planets from PCA
• Measuring precise radial velocities on individual spectral lines. III. Dependence of stellar activity signal on line formation temperature
• Variability in stellar granulation and convective blueshift with spectral type and magnetic activity. II. From young to old main-sequence K-G-F stars
• The CARMENES search for exoplanets around M dwarfs. Mapping stellar activity indicators across the M dwarf domain
• Convective blueshift strengths of 810 F to M solar-type stars
• YARARA V2: Reaching sub m/s precision over a decade using PCA on line-by-line RVs
• Black Mirror: The impact of rotational broadening on the search for reflected light from 51 Pegasi b with high resolution spectroscopy
• The Impact of Stellar Surface Magnetoconvection and Oscillations on the Detection of Temperate, Earth-Mass Planets Around Sun-Like Stars
• Target Prioritization and Observing Strategies for the NEID Earth Twin Survey
• Characterisation of stellar activity of M dwarfs. I. Long-timescale variability in a large sample and detection of new cycles
• Activity time series of old stars from late F to early K. I. Simulating radial velocity, astrometry, photometry, and chromospheric emission
• A new method of correcting radial velocity time series for inhomogeneous convection
• Doppler Constraints on Planetary Companions to Nearby Sun-like Stars: An Archival Radial Velocity Survey of Southern Targets for Proposed NASA Direct Imaging Missions
• A comparative study of two X2.2 and X9.3 solar flares observed with HARPS-N: Reconciling Sun-as-a-star spectroscopy and high-spatial resolution solar observations in the context of the solar-stellar connection
• A study of periodograms standardized using training data sets and application to exoplanet detection
• Activity time series of old stars from late F to early K. IV. Limits of the correction of radial velocities using chromospheric emission
• SOAP-GPU: Efficient Spectral Modelling of Stellar Activity Using Graphical Processing Units
• An ablating super-Earth in an eccentric binary from the Dispersed Matter Planet Project
• Rotational modulation of spectroscopic Zeeman signatures in low-mass stars
• Testing the Spectroscopic Extraction of Suppression of Convective Blueshift
• Improving Earth-like planet detection in radial velocity using deep learning
• Simulating Radial Velocity Observations of Trappist-1 with SPIRou
• The CARMENES search for exoplanets around M dwarfs. Line-by-line sensitivity to activity in M dwarfs
• Accounting for stellar activity signals in radial-velocity data by using Change Point Detection techniques
• Solar Photospheric Spectrum Microvariability I. Theoretical searches for proxies of radial-velocity jittering
• Predicting convective blueshift and radial-velocity dispersion due to granulation for FGK stars
• VPNEP: Detailed characterization of TESS targets around the Northern Ecliptic Pole
• DMPP-3: confirmation of short-period S-type planet(s) in a compact eccentric binary star system, and warnings about long-period RV planet detections
• Convective blueshift strengths for 242 evolved stars
• Planetary system architectures with low-mass inner planets: Direct imaging exploration of mature systems beyond 1 au
• Convective Line Shifts in the Spectra of Solar-Type Stars
• Granulation on a quiet K dwarf: HD 166620 I. Spectral signatures as a function of line-formation temperature