Rho Ophiuchi

This article is about the star. For the dark cloud star forming region, see 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
Distance360 (ρ Oph AB)[2] ly
(111 (ρ Oph AB) pc)
Absolute magnitude (MV)-0.70
Orbit
Period (P)2,000 yr
Semi-major axis (a)344 AU[7]
Details
Mass9 / 8 M☉
Luminosity4,900 / 2,100 L☉
Temperature27,200 K
Rotation+300
Other designations
Rho Ophiuchi, Rho Oph, ρ Ophiuchi, ρ Oph, 5 Ophiuchi, 5 Oph, HIP 80473, 2MASS J16253509-2326486

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, 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]

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 "rho Oph, SIMAD".
  2. 1 2 3 4 5 "van Leeuwen, F. 2007, Hipparcos, the New Reduction of the Raw Data".
  3. 1 2 3 4 5 6 7 8 9 "Ducati, J. R. 2002, CDS/ADC Collection of Electronic Catalogues".
  4. ↑ "rho Oph A, SIMBAD".
  5. ↑ "rho Oph B, SIMBAD".
  6. ↑ "Houk, N. and Smith-Moore, M. 1988, Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Declinations -26°.0 to -12°.0.".
  7. 1 2 3 "Cordiner, M. A., Fossey, S. J., Smith, A. M. and Sarre, P. J. 2013, ApJ, 764, L10".


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