Mitigating stellar activity jitter with different line lists for least-squares deconvolution: analysis of a parametric and a randomised line selection

Abstract

Stellar activity limits the radial velocity search and characterisation of exoplanets, as it introduces spurious jitter in the data sets and prevents the correct retrieval of a planetary signal. This is key for M dwarfs, considering that they manifest high activity levels and are primary targets for present and future searches of habitable Earth-like planets. Effective filtering of activity is crucial to achieve the sensitivity required for small planet detections. Here, we analyse the impact of selecting different line lists for least-squares deconvolution on the dispersion in our RV data sets, to identify the line list that most effectively reduces the jitter. We employ optical observations of the active M dwarf EV Lac collected with ESPaDOnS and NARVAL, and study two line selection approaches: a parametric one based on line properties and a randomised algorithm that samples the line combination space. We test the latter further to find the line list that singles out the activity signal from other sources of noise, and on AD Leo and DS Leo to examine its consistency at mitigating jitter for different activity levels. The analysis is complemented with planetary injection tests. The parametric selection yields a RV RMS reduction of less than 10%, while the randomised selection a systematic >50% improvement, regardless of the activity level of the star examined. Furthermore, if activity is the dominant source of noise, this approach allows the construction of lists containing mainly activity-sensitive lines, which could be used to enhance the rotational modulation of the resulting data sets and determine the stellar rotation period more robustly. Finally, the output line lists allow the recovery of a synthetic planet (0.3-0.6 MJup on a 10 d orbit) in the presence of both moderate (20 m/s semi-amplitude) and high (200 m/s) activity levels, without affecting the planet signal substantially.

17 pages, 16 figures, 4 tables

References in corpus (19)

• The NumPy array: a structure for efficient numerical computation
• The Transiting Exoplanet Survey Satellite
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The James Webb Space Telescope
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Constraining the Age-Activity Relation for Cool Stars: The SDSS DR5 Low-Mass Star Spectroscopic Sample
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• Stellar activity of planetary host star HD 189733
• Measuring precise radial velocities on individual spectral lines : II. Dependance of stellar activity signal on line depth
• Spectropolarimetric observations of the transiting planetary system of the K dwarf HD 189733
• Magnetic fields in M dwarfs from the CARMENES survey
• Investigating the young AU~Mic system with SPIRou: large-scale stellar magnetic field and close-in planet mass
• The HARPS search for southern extra-solar planets XXXV. Planetary systems and stellar activity of the M dwarfs GJ 3293, GJ 3341, and GJ 3543
• YARARA: Significant improvement of RV precision through post-processing of spectral time-series
• Insights on the Spectral Signatures of Stellar Activity and Planets from PCA
• A new method of correcting radial velocity time series for inhomogeneous convection
• Activity and telluric contamination in HARPS observations of Alpha Centauri B
• Stellar variability in radial velocity

Cited by in corpus (13)

• Line-by-line velocity measurements, an outlier-resistant method for precision velocimetry
• Constraining atmospheric parameters and surface magnetic fields with $\text{ZeeTurbo}$: an application to SPIRou spectra
• Monitoring the large-scale magnetic field of AD~Leo with SPIRou, ESPaDOnS and Narval. Toward a magnetic polarity reversal?
• The CARMENES search for exoplanets around M dwarfs: Benchmarking the impact of activity in high-precision radial velocity measurements
• Impact of stellar flares on the chemical composition and transmission spectra of gaseous exoplanets orbiting M dwarfs
• Optical and near-infrared stellar activity characterization of the early M dwarf Gl~205 with SOPHIE and SPIRou
• The space weather around the exoplanet GJ 436b
• The CARMENES search for exoplanets around M dwarfs. Line-by-line sensitivity to activity in M dwarfs
• Correlations between laboratory line lists for FeH, CrH, and NiH and M-star spectra collected with ESPaDOnS and SPIRou
• Chromaticity of stellar activity in radial velocities : Anti-correlated families of lines on the M dwarf EV Lac with SPIRou and SOPHIE
• Using Doppler Imaging to model stellar activity and search for planets around Sun-like stars
• The CARMENES search for exoplanets around M dwarfs : Understanding the wavelength dependence of radial velocity measurements
• An Hα Transit of HD 189733b to Assess Stellar Activity Across the Transit Chord Close to JWST Observations