The differential rotation of ǎrepsilon Eri from MOST data
Abstract
From high-precision MOST photometry spanning 35 days the existence of two spots rotating with slightly differing periods is confirmed. From the marginal probability distribution of the derived differential rotation parameter k its expectation value as well as confidence limits are computed directly from the data. The result depends on the assumed range in inclination i, not on the shape of the prior distributions. Two cases have been considered: (a) The priors for angles, inclination i of the star and spot latitudes β1,2, are assumed to be constant over i, β_1, and β_2; (b) the priors are assumed to be constant over cos i, sinβ_1, and sinβ_2. In both cases the full range of inclination is considered: 0o≤i≤90o. Scale-free parameters, i. e. periods and spot areas (in case of small spots) are taken logarithmically. Irrespective of the shape of the prior, k is restricted to 0.03≤k≤0.10 (1 σ limits). The inclination i of the star is photometrically ill-defined.
Based on data from the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies and the University of British Columbia, with the assistance of the University of Vienna.- Publication:
-
Astronomische Nachrichten
- Pub Date:
- December 2007
- DOI:
- 10.1002/asna.200710876
- arXiv:
- arXiv:0711.0806
- Bibcode:
- 2007AN....328.1037F
- Keywords:
-
- methods: data analysis;
- methods: statistical;
- stars: individual (ɛ Eri);
- stars: rotation;
- starspots;
- Astrophysics
- E-Print:
- 3 pages, 4 figures, Astron. Nachr. Vol. 328 (2007), acc