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Starspots are the equivalent of sunspots located on other stars. Spots the size of sunspots are very hard to detect on other stars because they are too small to cause detectable fluctuations in brightness. Observed starspots are in general much larger than those on the Sun: up to about 30% of the stellar surface may be covered, corresponding to starspots 100 times larger than those on the Sun. ==Detection and measurements == To detect and measure the extent of starspots one uses several types of methods. *For rapidly rotating stars – Doppler imaging and Zeeman-Doppler imaging.〔Cameron〕 :With the Zeeman-Doppler imaging technique the direction of the magnetic field on stars can be determined since spectral lines are split according to the Zeeman effect, revealing the direction and magnitude of the field. *For slowly rotating stars – Line Depth Ratio (LDR). :Here one measures two different spectral lines, one sensitive to temperature and one which is not. Since starspots have a lower temperature than their surroundings the temperature-sensitive line changes its depth. From the difference between these two lines the temperature and size of the spot can be calculated, with a temperature accuracy of 10K. *For eclipsing binary stars – Eclipse mapping produces images and maps of spots on both stars.〔Cameron (Eclipse movies ) show spots on two imaged binaries〕 *For stars with transiting extrasolar planets – Light curve variations.〔(Kepler-63b: A Giant Planet in a Polar Orbit around a Young Sun-like Star )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「starspot」の詳細全文を読む スポンサード リンク
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