|
WR 142 is a Wolf-Rayet star in the constellation Cygnus, an extremely rare star on the WO oxygen sequence. ==Features== WR 142 is usually assumed to be a member of the open cluster Berkeley 87, whose distance from the Sun is not very well known but thought to be around 1.23 kiloparsecs (4,000 light-years). As with its home cluster its light is very reddened and extinguished by interstellar dust.〔 〕 This star, of spectral classification WO2, is one of the very few known oxygen-sequence Wolf-Rayet stars, just four in the Milky Way galaxy and five in external galaxies. It is also one of the hottest known with a surface temperature of 200,000 K.〔 Modelling the atmosphere gives a luminosity around , while calculations from brightness and distance give luminosities of or more. It is a very small dense star, with a radius 40% of the solar one but 20 times more massive. Very strong stellar winds, with a terminal velocity of 5,000 kilometers per second are causing WR 142 to lose /year.〔 For comparison, the Sun loses (2-3) x 10−14 solar masses per year due to its solar wind, several hundred million times less than WR 142. Hard X-Ray emission has been detected from this star with the help of the Chandra space telescope, that has been suggested to be caused by the presence of a companion, a B-type main sequence star located at a distance of 1 AU from WR 142. There is no other indication of a companion and other reasons for the x-ray luminosity are considered more likely.〔 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「WR 142」の詳細全文を読む スポンサード リンク
|