Activity and telluric contamination in HARPS observations of Alpha Centauri B

Abstract

The Alpha Centauri system is the primary target for planet search as it is the closest star system composed of a solar twin Alpha Centauri A, a K-dwarf Alpha Centauri B and an M-dwarf Proxima Centauri, which has a confirmed planet in the temperate zone. Alpha Centauri A & B were monitored intensively with the HARPS spectrograph for over 10 years, providing high-precision radial velocity measurements. In this work we study the available data to better understand the stellar activity and other contaminating signals. We highlight the importance of telluric contamination and its impact on the radial velocity measurements. Our suggested procedures lead to discarding about 5% of HARPS data, providing a dataset with an RMS improved by a factor of 2. We compile and quantify the behaviour of 345 spectral lines with a wide range of line shapes and sensitivity to activity.

References in corpus (27)

• Astropy: A Community Python Package for Astronomy
• The NumPy array: a structure for efficient numerical computation
• No planet for HD 166435
• The HARPS-TERRA project I. Description of the algorithms, performance and new measurements on a few remarkable stars observed by HARPS
• TW Hydrae: evidence of stellar spots instead of a Hot Jupiter
• Long-term magnetic activity of a sample of M-dwarf stars from the HARPS program I. Comparison of activity indices
• High-cadence spectroscopy of M-dwarfs. I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B
• Measuring precise radial velocities on individual spectral lines. I. Validation of the method and application to mitigate stellar activity
• The low-level radial velocity variability in Barnard's star (=GJ 699). Secular acceleration, indications for convective redshift, and planet mass limits
• Ghost in the time series: no planet for Alpha Cen B
• The fundamental definition of 'radial velocity'
• Disentangling stellar activity and planetary signals
• The extreme physical properties of the CoRoT-7b super-Earth
• Radial Velocity Detection of Earth-mass Planets in the Presence of Activity Noise: The Case of Alpha Centauri Bb
• Color difference makes a difference: four planet candidates around tau Ceti
• Do stellar magnetic cycles influence the measurement of precise radial velocities?
• Insights on the Spectral Signatures of Stellar Activity and Planets from PCA
• New Methods for Finding Activity-Sensitive Spectral Lines: Combined Visual Identification and an Automated Pipeline Find a Set of 40 Activity Indicators
• The Impact of Stellar Oscillations on Doppler Velocity Planet Searches
• Telluric-line subtraction in high-accuracy velocimetry: a PCA-based approach
• Impact of micro-telluric lines on precise radial velocities and its correction
• The Changing Face of $\alpha$ Centauri B: Probing plage and stellar activity in K-dwarfs
• Three planets orbiting Wolf 1061
• Planet Detectability in the Alpha Centauri System
• Oscillator Strength Measurements of Atomic Absorption Lines from Stellar Spectra
• High-cadence spectroscopy of M-dwarfs - II. Searching for stellar pulsations with HARPS
• Searching for Earth-mass planets around $\alpha$ Centauri: precise radial velocities from contaminated spectra

Cited by in corpus (13)

• The CARMENES search for exoplanets around M dwarfs. Radial velocities and activity indicators from cross-correlation functions with weighted binary masks
• Automatic model-based telluric correction for the ESPRESSO data reduction software. Model description and application to radial velocity computation
• 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
• Precision Millimeter Astrometry of the $\alpha$ Centauri AB System
• Mitigating stellar activity jitter with different line lists for least-squares deconvolution: analysis of a parametric and a randomised line selection
• PEXO: a global modeling framework for nanosecond timing, microsecond astrometry, and $\mu$m/s radial velocities
• The CARMENES search for exoplanets around M dwarfs. Line-by-line sensitivity to activity in M dwarfs
• The Jiao Tong University Spectroscopic Telescope Project
• Solar photospheric spectrum microvariability II. Observed relations to magnetic activity and radial-velocity modulation
• The Effects of Telluric Contamination in Iodine Calibrated Precise Radial Velocities
• A photospheric and chromospheric activity analysis of the quiescent retrograde-planet host $\nu$ Octantis A
• The CARMENES search for exoplanets around M dwarfs : Understanding the wavelength dependence of radial velocity measurements
• Exploring the robustness of Keplerian signals to the removal of active and telluric features