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| Paper: |
High-Precision Radial-Velocity Measurements of Late-Type Evolved Stars |
| Volume: |
185, Precise Stellar Radial Velocities, IAU Colloquium 170 |
| Page: |
204 |
| Authors: |
Cummings, I. N.; Hearnshaw, J. B.; Kilmartin, P. M.; Gilmore, A. C. |
| Abstract: |
The fibre-fed echelle spectrograph with CCD detector has been used with the 1-m McLellan telescope at Mount John University Observatory to obtain high dispersion spectra for 44 southern evolved stars of spectral type K or M. From these observations relative radial velocities of 50 m/s precision have been obtained by the method of digital cross-correlation. This method of achieving precise relative radial velocities for late-type stars, along with the problems encountered, will be discussed. Using this method, statistically significant radial-velocity variations have been found. As radial-velocity variations could be caused by any one of orbital motion, rotation, star spots, pulsation and time dependent macroturbulence in the star's photosphere, knowledge of a star's light variation as it undergoes its radial-velocity variation is advantageous. To this end 13 of the stars have been observed together with broad-band photometry. For a select group of the observed stars precise radial velocities will be presented and the potential mechanisms of their variation will be examined. |
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