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HD 155358 is a low metallicity yellow dwarf star approximately 43 pc away in the constellation Hercules. This star is known to be orbited by two extrasolar planets.〔 The star is 11.9 billion years old and has a mass 0.89 times that of the Sun.〔 At the time of the planets' discoveries, it was notable for being the lowest metallicity planet-bearing star known, with an iron-to-hydrogen ratio 21% of the solar value.〔 == Observation == With a visual magnitude of 7.5, this star can not be observed with the unaided eye. Hence it was discovered only after the introduction of the telescope. In 1859 it was catalogued in the Bonner Durchmusterung by the Prussian astronomer F. W. Argelander, who listed an estimated visual magnitude of 7.2. In 1958 it was identified as a star with a relatively large proper motion by the Nizamiah Observatory, Hyderabad. It was suggested in 1979 that this star may lie within 25 parsecs of the Sun. (Up to that time it had never been catalogued as a nearby star.) Beginning in 2001, this star underwent observation using the High Resolution Spectrograph on the Hobby-Eberly Telescope at McDonald Observatory. Changes were observed in the radial velocity motion of the star, indicating a gravitational influence from orbiting objects. Based on the motion of the star over time, astronomers were able to deduce that there are at least two planets in orbit around HD 155358. 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「HD 155358」の詳細全文を読む スポンサード リンク
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