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Measurement of the limb darkening coefficient of stars |
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| Authors: | Zhao Ding-feng Hang Heng-rong |
| Institution: | 1 Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China 2 Zhejiang Normal University, Jinhua 321004, China |
| Abstract: | This paper introduces a new method of describing the limb darkening phenomenon of stellar atmospheres in the 1st and 2nd order approximations. The limb darkening coefficients are given by direct measurements of relevant physical quantities or measurements of flux and a supplementary quantity, namely, the star's surface temperature. The comparison either with solar observations or with the method of numerical simulation of the atmosphere shows that the new method can very accurately describe the star's limb darkening and determine its relevant coefficients. The accuracy of the new direct method is assessed using 176 observational data points of the Sun, and the mean fractional differences is found to be 0.38% for the 1st-, and 0.26% for the 2nd-order approximations. The mean differences of the indirect method are close to, and slightly larger than these values. When compared with numerical models of the atmosphere, the differences are in the range from under 1% to under 3%. |
| Keywords: | stellar atmosphere limb darkening coefficient |
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