Alpha Ophiuchi

Ras Alhague ( from Arabic. رأس الحية ra ʾ s al - Hayya " head of the snake "), even Rasalhague or α Ophiuchi ( Alpha Ophiuchi ) is a star in the constellation Ophiuchus with an apparent visual magnitude of 2.1 mag. The star forms the northern tip of the constellation, and is about 5 ° to the southeast of the star Ras Algethi ( α Herculis ).

Ras Alhague is a double star system, whose main star is a giant star of spectral type A5, which has a mass of about 2.8 solar masses. The companion was discovered by variations in the proper motion and has a mass of about 0.8 solar masses and is a main sequence star of spectral type K 5 The orbital period of the system is 8.7 years, the distance between the components of about 7 AU. The system is about 47 light-years away from Earth. There are indications that the system is a member of the major stream causes. However, the current evidence does not allow any decision on this issue.