Measuring precise radial velocities on individual spectral lines. III. Dependence of stellar activity signal on line formation temperature

Abstract

Context. To enable radial velocity (RV) precision on the order of ~0.1 m/s required for the detection of Earth-like exoplanets orbiting solar-type stars, the main obstacle lies in mitigating the impact of stellar activity. Aims. This study investigates the dependence of derived RVs with respect to the formation temperature of spectral line segments. Methods. Using spectral synthesis, we compute for each observed wavelength point of unblended spectral lines the stellar temperature below which 50% of the emergent flux originates. We can then construct RV time series for different temperature ranges, using template matching. Results. With HARPS-N solar data and HARPS $\alpha$ Cen B measurements, we demonstrate on time intervals of prominent stellar activity that the activity-induced RV signal has different amplitude and periodicity depending on the temperature range considered. We compare the solar measurements with simulated contributions from active surface regions seen in simultaneous images, and find that the suppression of convective motion is the dominant effect. Conclusions. From a carefully selected set of spectral lines, we are able to measure the RV impact of stellar activity at various stellar temperatures ranges. We are able to strongly correlate the effect of convective suppression with spectral line segments formed in hotter temperature ranges. At cooler temperatures, the derived RVs exhibit oppositely directed variations compared to the average RV time series and stronger anti-correlations with chromospheric emission.

arXiv commentAccepted for publication in A&A

References in corpus (21)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Spectroscopy Made Easy: Evolution
• 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
• Measuring precise radial velocities on individual spectral lines. I. Validation of the method and application to mitigate stellar activity
• The Sun as a planet-host star: Proxies from SDO images for HARPS radial-velocity variations
• A multi-site campaign to measure solar-like oscillations in Procyon. I. Observations, Data Reduction and Slow Variations
• Constraining the difference in convective blueshift between the components of alpha Cen with precise radial velocities
• Measuring precise radial velocities on individual spectral lines : II. Dependance of stellar activity signal on line depth
• The IAG solar flux atlas: Accurate wavelengths and absolute convective blueshift in standard solar spectra
• The origin of the reversed granulation in the solar photosphere
• YARARA: Significant improvement of RV precision through post-processing of spectral time-series
• Variability of stellar granulation and convective blueshift with spectral type and magnetic activity. I. K and G main sequence stars
• RASSINE: Interactive tool for normalising stellar spectra I. Description and performance of the code
• The EXPRES Stellar Signals Project II. State of the Field in Disentangling Photospheric Velocities
• Convective blueshift strengths of 810 F to M solar-type stars
• A new method of correcting radial velocity time series for inhomogeneous convection
• Deriving stellar inclination of slow rotators using stellar activity
• The chemical composition of $\alpha$ Cen AB revisited

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• The CARMENES search for exoplanets around M dwarfs. Line-by-line sensitivity to activity in M dwarfs
• GRASS II: Simulations of Potential Granulation Noise Mitigation Methods
• Solar Photospheric Spectrum Microvariability I. Theoretical searches for proxies of radial-velocity jittering
• Quiet Please: Detrending Radial Velocity Variations from Stellar Activity with a Physically Motivated Spot Model
• Chromaticity of stellar activity in radial velocities : Anti-correlated families of lines on the M dwarf EV Lac with SPIRou and SOPHIE
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• Searching for Low-Mass Exoplanets Amid Stellar Variability with a Fixed Effects Linear Model of Line-by-Line Shape Changes
• TILARA: Template-Independent Line-by-line Algorithm for Radial velocity Analysis. I. Description of the code and application on a Sun-like star
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• Solar photospheric spectrum microvariability III. Radial velocities and line profiles in magnetic active-region granulation
• Granulation on a quiet K dwarf: HD 166620 I. Spectral signatures as a function of line-formation temperature
• Measuring masses of transiting Earth-like planets: first insights from the PLATO RV data challenge