Variable nebula

Japanese: 変光星雲 - へんこうせいうん（英語表記）variable nebula

A type of diffuse nebula, in which the brightness of the entire nebula changes due to the variation in the light of the star that illuminates it. Most are caused by T Tauri type variable stars, which are new stars that were born from the surrounding interstellar material that changes their light irregularly. Examples include the Hind Nebula (NGC1555), which is illuminated by T Tauri, the Hubble Nebula (NGC2261), which is illuminated by R Monoceros, and the Schmidt Nebula (NGC6729), which is illuminated by R Corona Austrinus. The light of all of these nebulae is similar to the spectrum of the illuminating star, and appears bluer, so it is thought that the reflected component is dominant.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

散光星雲の一種で，星雲を照らす星が変光するため星雲全体の明るさが変化するもの。多くはおうし座T星型変光星によるもので，この星は，不規則な変光を繰り返す周囲の星間物質から生まれてまもない恒星である。例えば，おうし座T星に照らされるヒンド星雲(NGC1555)，いっかくじゅう座R星に照らされるハッブル星雲(NGC2261)，みなみのかんむり座R星に照らされるシュミット星雲(NGC6729)がある。いずれも星雲の光は照明星のスペクトルと類似しており，より青く見えるので反射成分が優勢と考えられる。

出典　株式会社平凡社世界大百科事典第２版について　情報

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