Measuring the Rotation Speed of Giant Stars from Gravitational Microlensing
Abstract
During some gravitational lensing events, the lens transits the disk of the star. This event causes a shift in the apparent radial velocity of the star proportional to the star's rotation speed. The magnification of such an event is different from that expected for a point source. By measuring both effects, one can determine the rotation parameter v sin i. The method is especially useful for K-giant stars because these stars have turbulent velocities that are typically large compared with their rotation speed. By making a series of radial velocity measurements, one can typically determine v sin i to the same accuracy as the individual radial velocity measurements. There are approximately 10 microlensing transit events per year that would be suitable for these measurements.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1997
- DOI:
- 10.1086/304244
- arXiv:
- arXiv:astro-ph/9611057
- Bibcode:
- 1997ApJ...483...98G
- Keywords:
-
- Cosmology: Gravitational Lensing;
- Stars: Late-Type;
- Stars: Rotation;
- Astrophysics
- E-Print:
- 11 pages including 1 embedded figure