Line Bisector Variability in Active Dwarfs and its Relationship to Radial Velocity Variations
Abstract
We study absorption line bisectors as diagnostics of the non-uniform spatial and temporal properties of active, cool dwarf stars. We analyze high resolution (lambda /Delta lambda ~ 125,000), high signal-to-noise (200 <= S/N <= 500) line profiles observed with the stellar echelle spectrograph of the McMath-Pierce Solar telescope. We find that various measures of the bisector shape can vary on timescales of days, implying significant spatial non-uniformity of the surface convective and brightness (starspot) patterns. Observations at fixed rotational phase show the bisectors can evolve on timescales of a few rotations, suggesting rapid rearrangement of the stellar surface structures. We also detect some evidence for correlations between changes in bisector parameters and changes in high precision radial velocities. The results are discussed in the context of stellar surfaces and their effect on radial velocity searches for extrasolar planets.
- Publication:
-
American Astronomical Society Meeting Abstracts #194
- Pub Date:
- September 1999
- Bibcode:
- 1999AAS...19410502S