Beta Sagittarii

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β¹ Sagittarii

Observation data Epoch J2000.0
Constellation (pronunciation)	Sagittarius
Right ascension	19h 22m 38.3s
Declination	-44° 27' 32"
Apparent magnitude (V)	+3.96
Distance	378 ± 42 ly (116 ± 13 pc)
Spectral type	B9V
Other designations
Arkab Prior, HR 7337, HD 181454, SAO 229646, HIP 95241, CCDM 19226-4428

The Bayer designation Beta Sagittarii (β Sgr / β Sagittarii) is shared by two star systems, β¹ Sagittarii and β² Sagittarii, in the constellation Sagittarius. The two stars are separated by 0.36° on the sky. Beta Sagittarii also has the traditional name Arkab, from the Arabic عرقوب ^carqūb meaning hamstring.

[edit] β¹ Sagittarii

Beta-1 Sagittarii, also called Arkab Prior since it leads β² across the sky, is a binary star lying 378 light years from Earth. Arkab Prior A is a spectral type B9 main sequence dwarf which has an apparent magnitude of +3.96. Arkab Prior B is a type A3 dwarf with an apparent magnitude of +7.4. The two stars have a separation on the sky of 28 arcseconds, which puts them at least 3300 Astronomical Units apart.

[edit] β² Sagittarii

β² Sagittarii

Observation data Epoch J2000.0
Constellation (pronunciation)	Sagittarius
Right ascension	19h 23m 13.2s
Declination	-44° 47' 59"
Apparent magnitude (V)	+4.27
Distance	139 ± 5 ly (43 ± 2 pc)
Spectral type	F2III
Other designations
Arkab Posterior, HR 7343, HD 181623, SAO 229654, HIP 95294

Beta-2 Sagittarii, also called Arkab Posterior since it trails β¹ across the sky, is a spectral type F2 giant which has an apparent magnitude of +4.27. It is 137 light years from Earth.