Astronomy:Rho Ophiuchi
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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) | −14.6±1.5[5] km/s |
| Proper motion (μ) | RA: −5.53[1] mas/yr Dec.: −21.74[1] mas/yr |
| Parallax (π) | 7.19 ± 0.13[6] mas |
| Distance | 451±12 ly (138.2±3.6 pc) |
| Absolute magnitude (MV) | −2.5±0.3[7] |
| Orbit[5] | |
| Primary | ρ Oph Aa |
| Companion | ρ Oph Ab |
| Period (P) | 87.831±0.010 days |
| Semi-major axis (a) | 0.995±0.026 astronomical unit|AU |
| Eccentricity (e) | 0.17931±0.00017 |
| Inclination (i) | 71.348±0.020° |
| Longitude of the node (Ω) | 303.385±0.034° |
| Periastron epoch (T) | 60101.11 RJD |
| Argument of periastron (ω) (secondary) | 4.80±0.24° |
| Semi-amplitude (K1) (primary) | 55.5±3.6 km/s |
| Semi-amplitude (K2) (secondary) | 65.7±3.6 km/s |
| Orbit[8] | |
| Primary | ρ Oph A |
| Companion | ρ Oph B |
| Period (P) | 2,398±326 years |
| 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[8] | |
| Primary | ρ Oph D |
| Companion | ρ Oph E |
| Period (P) | 675.5±32.5 years |
| 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° |
| Details[6] | |
| ρ Oph Aa | |
| Mass | 9.21±0.79[5] M☉ |
| Radius | 4.2±0.3 R☉ |
| Luminosity | 4,270+980 −800 L☉ |
| Surface gravity (log g) | 4.25±0.25 cgs |
| Temperature | 23,000±1,000 K |
| Rotation | 1.205[9] days |
| Rotational velocity (v sin i) | 206±5 km/s |
| Age | 15±6 Myr |
| ρ Oph Ab | |
| Mass | 7.79±0.70[5] M☉ |
| Radius | 3.1±0.2 R☉ |
| Luminosity | 1,000+400 −290 L☉ |
| Surface gravity (log g) | 4.25±0.25 cgs |
| Temperature | 19,000±1,000 K |
| Rotational velocity (v sin i) | 227±5 km/s |
| Age | 15±6 Myr |
| ρ Oph B | |
| Mass | 4.507+0.059 −0.060[10] M☉ |
| Radius | 6.78+0.69 −0.22[10] R☉ |
| Luminosity | 8,046+600 −400[10] L☉ |
| Surface gravity (log g) | 3.41+0.96 −0.23[10] cgs |
| Temperature | 11,568+980 −501[10] K |
| Metallicity [Fe/H] | 0.35+0.78 −0.25[10] dex |
| Rotational velocity (v sin i) | 233±11[11] km/s |
| ρ Oph C | |
| ρ Oph D | |
| Mass | 3.06[8] M☉ |
| ρ Oph E | |
| Mass | 1.97[8] M☉ |
| Other designations | |
| ρ Oph AB: CD−23°12861, HIP 80473 | |
| ρ Oph A: HD 147933, HR 6112, SAO 184382 | |
| ρ Oph B: HD 147934, HR 6113, SAO 184381 | |
| ρ Oph C: CD−23°12862, HIP 80474, SAO 184383 | |
| Database references | |
| SIMBAD | ρ Oph |
| ρ Oph A | |
| ρ Oph B | |
| ρ Oph C | |
| ρ Oph D/E | |
Rho Ophiuchi (ρ Ophiuchi) is a multiple star system in the constellation Ophiuchus. The central triple system has an apparent magnitude of 4.63.[2] Based on the central system's parallax, it is located about 450 light-years distant.[5] The other three stars in the system appear to be slightly farther away.[12]
System
| D | |||||||||||||||||
| P = 675.5 yr | |||||||||||||||||
| E | |||||||||||||||||
| 2.82' separation | |||||||||||||||||
| Aa | |||||||||||||||||
| P = 87.8 d | |||||||||||||||||
| Ab | |||||||||||||||||
| P = 2,398 yr | |||||||||||||||||
| B | |||||||||||||||||
| 2.5' separation | |||||||||||||||||
| C | |||||||||||||||||
Hierarchy of orbits in the system
The central system is known as Rho Ophiuchi AB. It consists of three blue-colored subgiants or main-sequence stars, designated Rho Ophiuchi Aa, Ab and B, respectively.[12] Rho Ophiuchi A is a spectroscopic binary with an orbital period of 88 days and an orbital separation of 1.1 astronomical units.[6] Farther away is the B companion, a visual binary whose sky-projected distance from the inner pair appears to be 3.1″, corresponding to a separation of at least 344 AU.[12] However, the actual separation is larger, and the two take about 2,400 years to complete an orbit.[8] The two stars dominate the radiation field around the Rho Ophiuchi cloud complex.[9]
Rho Ophiuchi A emits weak X-rays due to the strong magnetic field of the secondary companion, Rho Ophiuchi Ab, whose dipole strength is 4 kG.[6][13] Rho Ophiuchi B also emits X-rays at an intensity much higher than the expected for a B2V-type star, and appear to show flares on its light curve and spectrum, suggesting it may be an Algol-type system with a K-type companion.[13]
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.[12] HD 147888 is located 2.82 arcminutes away (at least 19,000 AU), and is known as Rho Ophiuchi DE.[12] Stars C and D are both B-type main-sequence stars,[12] and D itself is another binary with an orbital period of around 680 years.[8]
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.[14]
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 would be if there were no dust or gas.[15] 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.[7]
References
- ↑ 1.0 1.1 1.2 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 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.
- ↑ 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. Bibcode: 1988mcts.book.....H.
- ↑ 4.0 4.1 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.
- ↑ 5.0 5.1 5.2 5.3 5.4 Klement, R.; Shultz, M. E.; Rivinius, Th (2025-06-01). "Spatially resolved centrifugal magnetosphere caught in motion around the secondary component of ρ Oph A" (in en). Astronomy & Astrophysics 699: A37. doi:10.1051/0004-6361/202554689. ISSN 0004-6361.
- ↑ 6.0 6.1 6.2 6.3 Shultz, M. E.; Berry, I.; Bohlender, D.; Catanzaro, G.; Giarrusso, M.; Klement, R.; Labadie-Bartz, J.; Leone, F. et al. (2025-08-01). "Discovery of the binary nature of the magnetospheric B-type star ρ Oph A" (in en). Astronomy & Astrophysics 700: A14. doi:10.1051/0004-6361/202554023. ISSN 0004-6361.
- ↑ 7.0 7.1 Wegner, W. (2003). "The total-to-selective extinction ratio determined from near IR photometry of OB stars". Astronomische Nachrichten 324 (3): 219–237. doi:10.1002/asna.200310081. Bibcode: 2003AN....324..219W.
- ↑ 8.0 8.1 8.2 8.3 8.4 8.5 Novaković, B. (2007). "Orbits of Five Visual Binary Stars". Baltic Astronomy 16: 435–442. Bibcode: 2007BaltA..16..435N.
- ↑ 9.0 9.1 Hubrig, S.; Schöller, M.; Järvinen, S. P.; Küker, M.; Kholtygin, A. F.; Steinbrunner, P. (2018). "Detection of a centrifugal magnetosphere in one of the most massive stars in the ρ Oph star-forming cloud". Astronomische Nachrichten 339 (1): 72–77. doi:10.1002/asna.201713457. Bibcode: 2018AN....339...72H.
- ↑ 10.0 10.1 10.2 10.3 10.4 10.5 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ Glebocki, R.; Gnacinski, P. (2005). "VizieR Online Data Catalog: Catalog of Stellar Rotational Velocities (Glebocki+ 2005)". VizieR On-line Data Catalog. Bibcode: 2005yCat.3244....0G.
- ↑ 12.0 12.1 12.2 12.3 12.4 12.5 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. doi:10.1088/2041-8205/764/1/L10. Bibcode: 2013ApJ...764L..10C. https://zenodo.org/record/897951.
- ↑ 13.0 13.1 Gunderson, Sean J.; Codd, Jackson; Golay, Walter W.; Huenemoerder, David P.; Cannon, John M.; Fluegel, J. Alex; Griffin, Philip E.; Haurberg, Nathalie C. et al. (2025). "A Multiwavelength View of ρ Oph. I. Resolving the X-Ray Source between A and B". The Astrophysical Journal 995: 13. doi:10.3847/1538-4357/ae0d7e.
- ↑ Wilking, B. A.; Gagné, M.; Allen, L. E. (2008). "Star Formation in the ρ Ophiuchi Molecular Cloud". Handbook of Star Forming Regions. Bibcode: 2008hsf2.book..351W.
- ↑ 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. doi:10.1051/0004-6361:20011542. Bibcode: 2002A&A...382...92S.
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