Solar rotation inferred from radial velocities of the sun-as-a-star during the 2012 May 21 eclipse
arXiv:1411.1481 · doi:10.1093/pasj/psu139
Abstract
With an aim to examine how much information of solar rotation can be obtained purely spectroscopically by observing the sun-as-a-star during the 2012 May 21 eclipse at Okayama Astrophysical Observatory, we studied the variation of radial velocities (V_r), which were derived by using the iodine-cell technique based on a set of 184 high-dispersion spectra consecutively obtained over the time span of ~4 hours. The resulting V_r(t) was confirmed to show the characteristic variation (Rossiter-McLaughlin effect) caused by time-varying visibility of the solar disk. By comparing the observed V_r(t) curve with the theoretical ones, which were simulated with the latitude (psi) dependent solar rotation law omega(psi) = A + B sin^2(psi) (deg/day), we found that the relation B = -5.5 A + 77 gives the best fit, though separate determinations of A and B were not possible. Since this relationship is consistent with the real values known for the sun (A = 14.5, B = -2.8), we may state that our analysis yielded satisfactory results. This consequence may provide a prospect of getting useful information on stellar rotation of eclipsing binaries from radial-velocity studies during eclipse, if many spectra of sufficiently high time-resolution are available.
arXiv comment7 text pages and 11 figures, with ancillary material (electronic table) in "anc" directory, acceptd for publication in Publ. Astron. Soc. Japan
References in corpus (3)
- The Rossiter-McLaughlin effect and analytic radial velocity curves for transiting extrasolar planetary systems
- New measurements of rotation and differential rotation in A-F stars: Are there two populations of differentially rotating stars?
- Doin' the twist: Secular changes in the surface differential rotation on AB Doradus