Rho Ophiuchi

From Wikipedia, the free encyclopedia
This article is about the star. For the dark cloud star forming region, see Rho Ophiuchi cloud complex.
ρ Ophiuchi
Ophiuchus constellation map.svg
Red circle.svg
Location of ρ Ophiuchi (circled red)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ophiuchus
Right ascension 16h 25m 35.11766s[1]
Declination −23° 26′ 49.8150″[1]
Apparent magnitude (V) 4.63[2]
Characteristics
ρ Oph AB
Spectral type B2/3V + B2V[3]
U−B color index -0.56[4]
B−V color index +0.24[4]
Astrometry
ρ Oph AB
Radial velocity (Rv)-11.40 ± 3[5] km/s
Proper motion (μ) RA: -5.53[1] mas/yr
Dec.: -21.74[1] mas/yr
Parallax (π)9.03 ± 0.90[1] mas
Distance360 ± 40 ly
(110 ± 10 pc)
Absolute magnitude (MV)-2.5 ± 0.3[6]
Orbit[7]
Primaryρ Oph A
Companionρ Oph B
Period (P)2398 ± 326 yr
Semi-major axis (a)4.25 ± 0.79″
Eccentricity (e)0.675 ± 0.322
Inclination (i)135.3 ± 6.0°
Longitude of the node (Ω)77.5 ± 13.5°
Periastron epoch (T)B 2327 ± 343
Argument of periastron (ω)
(secondary)		226.1 ± 15.3°
Orbit[7]
Primaryρ Oph D
Companionρ Oph E
Period (P)675.5 ± 32.5 yr
Semi-major axis (a)1.01 ± 0.15″
Eccentricity (e)0.707 ± 0.112
Inclination (i)134.8 ± 2.7°
Longitude of the node (Ω)152.7 ± 4.6°
Periastron epoch (T)B 2008.6 ± 34.2
Argument of periastron (ω)
(secondary)		260.4 ± 1.1°
Other designations
ρ Oph A: CD−23° 12861A, HD 147933, HIP 80473A, HR 6112, SAO 184382
ρ Oph B: CD−23° 12861B, HD 147934, HIP 80473, HR 6113, SAO 184381
ρ Oph C: CD−23° 12862, HIP 80474, SAO 184383
ρ Oph D: CD−23° 12860, HD 147888, HIP 80461, SAO 184377
Database references
SIMBADρ Oph
ρ Oph A
ρ Oph B
ρ Oph C
ρ Oph D
Rho Ophiuchi cloud complex (N is up): Antares is the bright star that looks yellow in this image (though in fact Antares is reddish), σ Scorpii is in the red nebula (Sh2-9), and the globular cluster M4 is in between. Rho Ophiuchi is the small group of stars (three prominent) in the blue nebulosity (IC 4604).

Rho Ophiuchi (ρ Ophiuchi) is a multiple star system in the constellation Ophiuchus. The central system has an apparent magnitude of 4.63.[2] Based on the central system's parallax of 9.03 mas,[1] it is located about 360 light-years (110 parsecs) away.[1] The other stars in the system are slightly farther away.[8]

System[]

The central pair is known as Rho Ophiuchi AB. It consists of at least two blue-colored subgiants or main-sequence stars, designated Rho Ophiuchi A and B, respectively.[8] Rho Ophiuchi AB is a visual binary, and the sky-projected distance between the two stars appears to be 3.1″, corresponding to a separation of at least 344 astronomical units (au).[8] However, the actual separation is larger, and the two take about 2,400 years to complete an orbit.[7]

Several other stars are located close to Rho Ophiuchi AB. HD 147932 is located 2.5 arcminutes away (at least 17,000 au), and is known as Rho Ophiuchi C.[8] HD 147888 is located 2.82 arcminutes away (at least 19,000 au), and is known as Rho Ophiuchi DE.[8] Stars C and D are both B-type main-sequence stars,[8] and D itself is another binary with an orbital period of around 680 years.[7]

Cloud complex[]

Main article: Rho Ophiuchi cloud complex

Rho Ophiuchi is the namesake of the Rho Ophiuchi cloud complex. It is a nebula of gas and dust, which the Rho Ophiuchi system is embedded in. It is one of the easiest star forming regions to observe, as it is one of the nearest, and it is visible from both hemispheres.[9]

The interstellar extinction (AV) of Rho Ophiuchi is measured to be 1.45 magnitudes, meaning the dust and gas in front of Rho Ophiuchi absorbs light from the system, making it appear 1.45 magnitudes dimmer than it should be.[10] Additionally, gas and dust also scatters more higher-frequency light, leaving the light appearing more reddish. The interstellar reddening (EB−V) of Rho Ophiuchi has been measured to be 0.47 magnitudes.[6]

References[]

  1. ^ a b c d e f g van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  2. ^ a b Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". VizieR Online Data Catalog. 2237. Bibcode:2002yCat.2237....0D.
  3. ^ Houk, N.; Smith-Moore, M. (1988). "Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4, Declinations −26°.0 to −12°.0". Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume 4. Bibcode:1988mcts.book.....H.
  4. ^ a b Nicolet, B. (1964). "Catalogue of homogeneous data in the UBV photoelectric photometric system". Astronomy and Astrophysics Supplement Series. 34: 1–49. Bibcode:1978A&AS...34....1N.
  5. ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  6. ^ a b Wegner, W. (2003). "The total-to-selective extinction ratio determined from near IR photometry of OB stars". Astronomische Nachrichten. 324 (3): 219–237. Bibcode:2003AN....324..219W. doi:10.1002/asna.200310081.
  7. ^ a b c d Novaković, B. (2007). "Orbits of Five Visual Binary Stars". Baltic Astronomy. 16: 435–442. arXiv:0712.4242. Bibcode:2007BaltA..16..435N.
  8. ^ a b c d e f Cordiner, M. A.; Fossey, S. J.; Smith, A. M.; Sarre, P. J. (2013). "Cordiner, M. A., Fossey, S. J., Smith, A. M. and Sarre, P. J. 2013, ApJ, 764, L10". The Astrophysical Journal Letters. 764 (1): L10. arXiv:1301.6167. Bibcode:2013ApJ...764L..10C. doi:10.1088/2041-8205/764/1/L10. S2CID 119204101.
  9. ^ Wilking, B. A.; Gagné, M.; Allen, L. E. (2008). "Star Formation in the ρ Ophiuchi Molecular Cloud". Handbook of Star Forming Regions. arXiv:0811.0005. Bibcode:2008hsf2.book..351W.
  10. ^ Shatsky, N.; Tokovinin, A. (2002). "The mass ratio distribution of B-type visual binaries in the Sco OB2 association". Astronomy and Astrophysics. 382: 92–103. arXiv:astro-ph/0109456. Bibcode:2002A&A...382...92S. doi:10.1051/0004-6361:20011542. S2CID 16697655.
Retrieved from ""