|
Below is a list of the largest known stars by radius. The unit of measurement used is the radius of the Sun (approximately 695,500 kilometers, or 432,450 miles). The exact order of this list is not complete, nor is it perfectly defined: *There are sometimes high uncertainties in derived values and sizes; *The distances to most of these stars are uncertain to differing degrees and this uncertainty affects the size measurements; *All the stars in this list have extended atmospheres, many are embedded in mostly opaque dust shells or disks, and most pulsate, such that their radii are not well defined; *There are theoretical reasons for expecting that no stars in the Milky Way are larger than approximately 1,500 times the Sun, based on evolutionary models and the Hayashi instability zone. The exact limit depends on the metallicity of the star, so for example supergiants in the Magellanic Clouds have slightly different limiting temperature and luminosity. Stars exceeding the limit have been seen to undergo large eruptions and to change their spectral type over just a few months; *A survey of the Magellanic Clouds has catalogued most of the red supergiants and 44 of them are larger than the 700 solar radii cutoff point of this table, with the largest at 1,200–1,300. ==List== 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「List of largest known stars」の詳細全文を読む スポンサード リンク
|