The impact of unresolved magnetic spots on high precision radial velocity measurements

Abstract

The Doppler method of exoplanet detection has been extremely successful, but suffers from contaminating noise from stellar activity. In this work a model of a rotating star with a magnetic field based on the geometry of the K2 star Epsilon Eridani is presented and used to estimate its effect on simulated radial velocity measurements. A number of different distributions of unresolved magnetic spots were simulated on top of the observed large-scale magnetic maps obtained from eight years of spectropolarimetric observations. The radial velocity signals due to the magnetic spots have amplitudes of up to 10 m s${}^{-1}$, high enough to prevent the detection of planets under 20 Earth masses in temperate zones of solar type stars. We show that the radial velocity depends heavily on spot distribution. Our results emphasize that understanding stellar magnetic activity and spot distribution is crucial for detection of Earth analogues.

Main text: 7 pages, 3 figures. Appendix: 6 pages, 6 figures. Author name typo corrected. Accepted for publication in MNRAS

References in corpus (13)

• The NumPy array: a structure for efficient numerical computation
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• Toroidal versus poloidal magnetic fields in Sun-like stars: a rotation threshold
• Magnetic Activity Cycles in the Exoplanet Host Star epsilon Eridani
• Magnetic fields in M dwarfs from the CARMENES survey
• The hot Jupiter of the magnetically-active weak-line T Tauri star V830 Tau
• 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 relation between stellar magnetic field geometry and chromospheric activity cycles I: The highly variable field of Epsilon Eridani at activity minimum
• A HARPS RV search for planets around young nearby stars
• Sunspot Sizes and The Solar Cycle: Analysis Using Kodaikanal White-light Digitized Data
• A combined spectroscopic and photometric stellar activity study of Epsilon Eridani
• Recovering planet radial velocity signals in the presence of starspot activity in fully convective stars
• Surface magnetic activity of the fast-rotating G5-giant IN Comae, central star of the faint planetary nebula LoTr 5

Cited by in corpus (2)

• Magnetism, rotation, and nonthermal emission in cool stars -- Average magnetic field measurements in 292 M dwarfs
• Spatially resolved spectroscopy across stellar surfaces. V. Observational prospects: Toward Earth-like exoplanet detection