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Correcting Radial Velocities for Long-Term Magnetic Activity Variations.
The Astrophysical Journal
|May 2, 2000
Summary
We found magnetic activity correlates with stellar radial velocities (vr). Correcting for this activity reduces vr dispersion, improving the search for exoplanets around active stars.
Area of Science:
- Stellar Astrophysics
- Exoplanet Detection
Background:
- Stellar magnetic activity influences high-precision radial velocity (vr) measurements.
- Understanding these influences is crucial for accurate exoplanet detection.
Purpose of the Study:
- To investigate correlations between stellar magnetic activity and radial velocities.
- To develop methods for correcting radial velocity data affected by magnetic activity.
Main Methods:
- Analyzing simultaneous measurements of radial velocities and magnetic activity indicators (Ca II S_IR emission index).
- Applying statistical methods to identify and quantify correlations.
- Removing linear trends to assess the impact of activity correction on radial velocity dispersion.
Main Results:
- Significant correlations between magnetic activity and radial velocities were found in approximately 30% of stars studied.
- Correcting for activity reduced radial velocity dispersion by an average of 17%.
- Correction effectiveness varied with stellar type (F stars and less active stars showed better results) and stellar parameters (vsini, Teff).
Conclusions:
- Magnetic activity significantly impacts radial velocity measurements by altering line bisector shapes.
- The developed correction method can improve the precision of radial velocity data.
- This improved precision may enable the detection of smaller planets or planets around younger, more active stars.