Rho Coronae Borealis

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Not to be confused with R Coronae Borealis. ‹See Tfd›
Rho Coronae Borealis
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Corona Borealis
Right ascension 16h 01m 02.66s [1]
Declination +33° 18′ 12.6″ [1]
Apparent magnitude (V) 5.4
Spectral type G0-2Va
B−V color index 0.61
Variable type None
Radial velocity (Rv) 18.4 km/s
Proper motion (μ) RA: -196.63 ± 0.24 [1] mas/yr
Dec.: -773.02 ± 0.21 [1] mas/yr
Parallax (π) 58.02 ± 0.28[1] mas
Distance 56.2 ± 0.3 ly
(17.24 ± 0.08 pc)
Absolute magnitude (MV) 6.04
Mass 0.95 M
Radius 1.287 ± 0.084 [2] R
Luminosity 1.8 L
Age 6 billion years
Other designations
Database references

Rho Coronae Borealis (ρ CrB, ρ Coronae Borealis) is a Solar twin, yellow dwarf star approximately 57 light-years away in the constellation of Corona Borealis. The star is thought to be similar to the Sun with nearly the same mass, radius, and luminosity. As of 1997, an extrasolar planet has been confirmed to be orbiting the star. It is thought[by whom?] that the star may have a stellar companion, but it may be just an optical companion.[citation needed]

Stellar components[edit]

Rho Coronae Borealis is a Solar twin, yellow dwarf star of the spectral type "G0-2Va". The star is thought to have only 95 percent of the Sun's mass, along with 1.31 times its radius and 1.61 of its luminosity. It may only be 51 to 65 percent as enriched with elements heavier than hydrogen (based on its abundance of iron) and may be somewhat older than the Sun at around six billion years old.

In 2000, preliminary Hipparcos astrometrical satellite data indicated that the orbital inclination of the star's companion was 0.5°, implying that its mass was as much as 115 times Jupiter's. Such a massive body would have to be a dim red dwarf, not a planet. However, this scenario is statistically very improbable, and the claim has not been independently verified.

Planetary system[edit]

The Rho Coronae Borealis system[3]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b >1.093±0.098 MJ 0.229±0.013 39.8449±0.0063 0.057±0.028


The planet, one of the first discovered (on April 24, 1997) is designated as Rho Coronae Borealis b.[4] The planet's distance to the star is only about one fifth Earth's distance from the Sun. The orbit is circular and it takes 40 days to complete one revolution around the star. The planet has a mass about that of Jupiter. However, the inclination of the orbital plane is not known, so the stated value represents a minimum. If the planet orbits in the same plane as the circumstellar disk, the inclination would be about 46°, implying a planetary mass of 1.5 times Jupiter.

Unconfirmed circumstellar disk[edit]

In October 1999, astronomers at the University of Arizona announced the existence of a circumstellar disk that may be similar in composition to the Kuiper Belt of the Solar system. The disk may extend out to 85 astronomical units out from Rho Coronae Borealis (which is beyond the orbital distances of Neptune and Pluto from the Sun). It is inclined at about 46° from Earth's line of sight. However observations with the Spitzer Space Telescope failed to detect any infrared excess at 24 or 70 micrometres wavelengths, which would be expected if a disk were present.[5][6][7]

See also[edit]


  1. ^ a b c d e van Leeuwen, F. (2007). "HIP 78459". Hipparcos, the New Reduction. Retrieved 2009-12-08. 
  2. ^ Gerard T. van Belle and Kaspar von Braun (2009). "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars" (abstract). The Astrophysical Journal 694 (2): 1085–1098. arXiv:0901.1206. Bibcode:2009ApJ...694.1085V. doi:10.1088/0004-637X/694/2/1085. (web Preprint)
  3. ^ Butler et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701. 
  4. ^ Noyes et al. (1997). "A Planet Orbiting the Star ρ Coronae Borealis". The Astrophysical Journal Letters 483 (2): L111–L114. arXiv:astro-ph/9704248. Bibcode:1997ApJ...483L.111N. doi:10.1086/310754. 
  5. ^ Beichman, C. A.; Bryden, G.; Rieke, G. H.; Stansberry, J. A.; Trilling, D. E.; Stapelfeldt, K. R.; Werner, M. W.; Engelbracht, C. W.; Blaylock, M.; Gordon, K. D.; Chen, C. H.; Su, K. Y. L.; Hines, D. C.; Bryden; Rieke; Stansberry; Trilling; Stapelfeldt; Werner; Engelbracht; Blaylock; Gordon; Chen; Su; Hines (2005). "Planets and Infrared Excesses: Preliminary Results from a Spitzer MIPS Survey of Solar-Type Stars". The Astrophysical Journal 622 (2): 1160–1170. arXiv:astro-ph/0412265. Bibcode:2005ApJ...622.1160B. doi:10.1086/428115. 
  6. ^ Bryden, G.; Beichman, C. A.; Carpenter, J. M.; Rieke, G. H.; Stapelfeldt, K. R.; Werner, M. W.; Tanner, A. M.; Lawler, S. M.; Wyatt, M. C.; Trilling, D. E.; Su, K. Y. L.; Blaylock, M.; Stansberry, J. A.; Beichman; Carpenter; Rieke; Stapelfeldt; Werner; Tanner; Lawler; Wyatt; Trilling; Su; Blaylock; Stansberry (2009). "Planets and Debris Disks: Results from a Spitzer/MIPS Search for Infrared Excess". The Astrophysical Journal 705 (2): 1226–1236. Bibcode:2009ApJ...705.1226B. doi:10.1088/0004-637X/705/2/1226. 
  7. ^ Caer McCabe & Carlotta Pham. "Catalog of withdrawn or refuted resolved Disks". Catalog of Resolved Circumstellar Disks. Retrieved 2010-04-03. 

External links[edit]

Coordinates: Sky map 16h 01m 02.6616s, +33° 18′ 12.634″