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AT Microscopii is a binary star system located at a distance of from the Sun in the constellation of Microscopium.〔 Both members are flare stars,〔 meaning they are red dwarf stars that undergo random eruptions that increase their brightness. This pair lies physically near the red dwarf star AU Microscopii, which may mean they form a wide triple star system.〔 ==Observational history== In 1926, Dutch-American astronomer Willem Jacob Luyten reported that the lines in the spectrum of this star underwent variation. A photographic plate taken in June 23, 1895 showed bright lines of hydrogen that were much weaker on a plate taken June 29, 1895. A photograph taken on July 1, 1903 showed no such lines. The net variation in brightness of the star was small, not exceeding 0.5 in magnitude. Luyten noted that the star has a large proper motion, changing its position by 0.43 seconds of arc between 1899 and 1923.〔 By 1927, the object was found to be a pair of stars with an angular separation of 2.95 arcseconds. Both were shown to be of 'dwarf Me' type, indicating they are red dwarfs with emission lines in their spectrum. This was the first such pair of matching dwarf Me stars to be discovered. The first parallax measurements of the pair showed an annual shift of about 0.1 arcseconds, while their radial velocity was measured to be +5 km/s away from the Sun. A nearby star HD 197981, later named AU Microscopii, was shown to have a similar radial velocity of +10 km/s. For this reason it was suggested that the three stars are physically associated.〔 Following the discovery in 1949 that certain types of variable stars are characterized by rapid but brief changes in brightness, accompanied by emission lines in their spectrum,〔 in 1954 both HD 196982 A and B were listed as suspected flare stars by Czech solar physicist Zdeněk Švestka.〔 With the introduction of photometric instruments to astronomy, the variability of stars could now be monitored over intervals of time. Measurements of HD 196982 during 1969 showed them to be the most active flare stars known at that time: over a period of 16.31 hours, 54 flares were observed. The flares increased the combined magnitude of the pair by more than 0.05 for more than half of this observation period.〔 By 1972, the pair had received the variable star designation AT Microscopii.〔 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「AT Microscopii」の詳細全文を読む スポンサード リンク
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