YARARA V2: Reaching sub m/s precision over a decade using PCA on line-by-line RVs

Abstract

Context. The detection of Earth-like planets with the radial-velocity (RV) method is extremely challenging today due to the presence of non-Doppler signatures such as stellar activity and instrumental signals that mimic and hide the signals of exoplanets. In a previous paper, we presented the YARARA pipeline, which implements corrections for telluric absorption, stellar activity and instrumental systematics at the spectral level, then extracts line-by-line (LBL) RVs with significantly better precision than standard pipelines. Aims. In this paper, we demonstrate that further gains in RVs precision can be achieved by performing Principal Component Analysis (PCA) decomposition on the LBL RVs. Methods. The mean-insensitive nature of PCA means that it is unaffected by true Doppler shifts, and thus can be used to isolate and correct nuisance signals other than planets. Results. We analysed the data of 20 intensively observed HARPS targets by applying our PCA approach on the LBL RVs obtained by YARARA. The first principal components show similarities across most of the stars and correspond to newly identified instrumental systematics, which we can now correct for. For several targets, this results in an unprecedented RV root-mean-square of around 90 cm/s over the full lifetime of HARPS. We use the corrected RVs to confirm a previously published 120-day signal around 61Vir, and to detect a Super-Earth candidate (K = 60 +/- 6 cm/s, m sin i = 6.6 +/- 0.7 Earth mass) around the G6V star HD20794, which spends part of its 600-day orbit within the habitable zone of the host star. Conclusions. This study highlights the potential of LBL PCA to identify and correct hitherto unknown, long-term instrumental effects and thereby extend the sensitivity of existing and future instruments towards the Earth analogue regime.

arXiv comment22 pages, 19 figures

References in corpus (43)

• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Habitable Zones Around Main-Sequence Stars: New Estimates
• Spectroscopic parameters for 451 stars in the HARPS GTO planet search program. Stellar [Fe/H] and the frequency of exo-Neptunes
• ESPRESSO@VLT -- On-sky performance and first results
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• Assessing statistical significance of periodogram peaks
• The HARPS search for Earth-like planets in the habitable zone: I -- Very low-mass planets around HD20794, HD85512 and HD192310
• Oxygen Abundances in Nearby FGK Stars and the Galactic Chemical Evolution of the Local Disk and Halo
• PASTIS: Bayesian extrasolar planet validation. I. General framework, models, and performance
• Measuring precise radial velocities on individual spectral lines. I. Validation of the method and application to mitigate stellar activity
• A public HARPS radial velocity database corrected for systematic errors
• Herschel imaging of 61 Vir: implications for the prevalence of debris in low-mass planetary systems
• The HARPS search for southern extra-solar planets. XXXVIII. Bayesian re-analysis of three systems. New super-Earths, unconfirmed signals, and magnetic cycles
• Three Years of HARPS-N High-Resolution Spectroscopy and Precise Radial Velocity Data for the Sun
• A Super-Earth and two Neptunes Orbiting the Nearby Sun-like star 61 Virginis
• HARPS-N observes the Sun as a star
• The Precision of Mass Measurements Required for Robust Atmospheric Characterization of Transiting Exoplanets
• Revisiting Proxima with ESPRESSO
• 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
• Radial Velocity Data Analysis with Compressed Sensing Techniques
• Using the Sun to estimate Earth-like planets detection capabilities. V. Parameterizing the impact of solar activity components on radial velocities
• 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
• Radial Velocity Fitting Challenge. I. Simulating the data set including realistic stellar radial-velocity signals
• On the Feasibility of Intense Radial Velocity Surveys for Earth-twin Discoveries
• Characterization of a spurious one-year signal in HARPS data
• 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
• Bias and robustness of eccentricity estimates from radial velocity data
• Analytical determination of orbital elements using Fourier analysis. I. The radial velocity case
• Observing the Sun as a star: Design and early results from the NEID solar feed
• A new wavelength calibration for echelle spectrographs using Fabry-Perot etalons
• Stellar activity correction using PCA decomposition of shells
• Efficient modeling of correlated noise I. Statistical significance of periodogram peaks
• EXPRES I. HD~3651 an Ideal RV Benchmark
• Stellar signal components seen in HARPS and HARPS-N solar radial velocities
• Target Prioritization and Observing Strategies for the NEID Earth Twin Survey
• Doppler Constraints on Planetary Companions to Nearby Sun-like Stars: An Archival Radial Velocity Survey of Southern Targets for Proposed NASA Direct Imaging Missions
• New wavelength calibration of the HARPS spectrograph
• Testing whether a signal is strictly periodic. Application to disentangling planets and stellar activity in radial velocities
• The effects of granulation and supergranulation on Earth-mass planet detectability in the habitable zone around F6-K4 stars
• $\text{Wapiti}$: a data-driven approach to correct for systematics in RV data -- Application to SPIRou data of the planet-hosting M dwarf GJ 251

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• Fishing for Planets: A Comparative Analysis of EPRV Survey Performance in the Presence of Correlated Noise
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• Revisiting the multi-planetary system of the nearby star HD 20794: Confirmation of a low-mass planet in the habitable zone of a nearby G-dwarf
• Gl 725A b: a potential super-Earth detected with SOPHIE and SPIRou in an M dwarf binary system at 3.5 pc
• Using Doppler Imaging to model stellar activity and search for planets around Sun-like stars
• TOI-2322: two transiting rocky planets close to the stellar rotation period and its first harmonic
• Characterizing planetary systems with SPIRou: Detection of a sub-Neptune in a 6-day period orbit around the M dwarf Gl 410
• The SPIRou Legacy Survey: near-infrared and optical radial velocity analysis of Gl 480 and Gl 382 using SPIRou, HARPS and CARMENES spectrographs
• Solar Flux Atlases: The new HARPS-N Quiet Sun Benchmark and Ca II H & K Lines Continuum Normalisation
• Studying the variability of the He triplet to understand the detection limits of evaporating exoplanet atmospheres
• The RoPES project with HARPS and HARPS-N II. A third planet in the multi-planet system HD 176986
• The SPIRou Legacy Survey: Detection of a nearby world orbiting in the habitable zone of Gl725B achieved by correcting strong telluric contamination in near-infrared radial velocities with WAPITI
• SPORES-HWO. II. Companion Mass Limits and Updated Planet Properties for 120 Future Exoplanet Imaging Targets from 35 yr of Precise Doppler Monitoring
• Modelling solar radial velocities and photometric variability with SOAPv4
• Measuring masses of transiting Earth-like planets: first insights from the PLATO RV data challenge
• Discovery of a multi-planetary system orbiting the aged Sun-like star HD 224018
• Granulation on a quiet K dwarf: HD 166620 I. Spectral signatures as a function of line-formation temperature
• A Theoretical Study of the Structure and Elemental Abundances of HD 20794