Rho Ophiuchi

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Not to be confused with Rho Ophiuchi cloud complex.
Rho Ophiuchi
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ophiuchus
Right ascension 16h 25m 35.118s[1][2]
Declination −23° 26′ 49.81″
Apparent magnitude (V) 4.63[1][3]
Characteristics
Spectral type B2/B3V (ρ Oph A);[4] B2 V (ρ Oph B)[5][6]
Apparent magnitude (U) 4.30[1][3]
Apparent magnitude (B) 4.85[1][3]
Apparent magnitude (V) 4.63[1][3]
Apparent magnitude (R) 4.27[1][3]
Apparent magnitude (I) 3.96[1][3]
Apparent magnitude (J) 3.74[1][3]
Apparent magnitude (H) 3.56[1][3]
Apparent magnitude (K) 3.51[1][3]
U−B color index -0.55
B−V color index +0.23
Variable type ??
Astrometry
Proper motion (μ) RA: -5.53[1][2] mas/yr
Dec.: -21.74 mas/yr
Parallax (π) 9.03[1][2] ± 0.90 mas
Distance 360 (ρ Oph AB)[2] ly
(111 (ρ Oph AB) pc)
Absolute magnitude (MV) -0.70
Orbit
Period (P) 2,000[citation needed] yr
Semi-major axis (a) 344 AU[7]
Details
Mass 9 / 8[citation needed] M
Luminosity 4,900 / 2,100[citation needed] L
Temperature 27,200[citation needed] K
Rotation +300[citation needed]
Other designations

Rho Ophiuchi (ρ Ophiuchi) is a multiple star system in the constellation Ophiuchus.[1] It consists of at least two blue subgiants, ρ Oph A and ρ Oph B, both of which are of class B.[7] ρ Oph AB is a visual binary, and the sky-projected distance between ρ Oph A and ρ Oph B is 3.1" (or 344 AU at the 111 pc distance of ρ Oph AB).[7] Two to three other blue subgiants, ρ Oph C and ρ Oph DE, are found to be related to the star system, with sky-projected distances to ρ Oph AB of ~ 17,000 and ~ 19,000 AU, respectively. ρ Oph C and ρ Oph D are also of class B. The apparent brightness of the star system has been dimmed by about 2 magnitudes[citation needed], as a result of interstellar extinction, due to its location within the Ophiuchus cloud. The star system, ρ Oph AB, is located about 360 light years away.[2]

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