Rho Coronae Borealis

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Not to be confused with R Coronae Borealis.
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 G0V[2]
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
Temperature 5823 K
Metallicity -0.24 (± 0.08)
Age 9.0 (± 1.7) 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. In 1997, an extrasolar planet was announced on the basis of radial velocity measurements. This detection method gives only a minimum mass on the planet. Follow-up studies with the Hipparcos satellite indicate that the companion is actually low-mass star in a nearly face-on orbit.[3]

Stellar components[edit]

Rho Coronae Borealis is a solar analog, 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.

A companion, initially thought to be an extrasolar planet in a 39.6-day orbit was discovered in 1997 by observing the star's radial velocity variations.[4] This detection method only gives a lower limit on the true mass of the companion. In 2001, preliminary Hipparcos astrometrical satellite data indicated that the orbital inclination of the star's companion was 0.5°, nearly face-on, implying that its mass was as much as 115 times Jupiter's.[5] This was confirmed in 2011 using a new reduction of the astrometric data, with an updated mass value of 169.7 times Jupiter, with a 3σ confidence region 100.1 to 199.6 Jupiter masses.[3] Such a massive body would be a dim red dwarf star, not a planet.

Sun comparison[edit]

This chart compares the sun to Rho Coronae Borealis

Identifier J2000 Coordinates Distance
Right ascension Declination
Sun 0.00 G2V 5,778 +0.00 4.6 [6]
Rho Coronae Borealis [7] 16h 01m 02.66s +33° 18′ 12.6″ 56.8 G0V 5755 -0.24 9

Searches for circumstellar material[edit]

In October 1999, astronomers at the University of Arizona announced the existence of a circumstellar disk around the star.[8] Follow-up observations with the Spitzer Space Telescope failed to confirm this detect any infrared excess at 24 or 70 micrometres wavelengths, which would be expected if a disk were present.[9][10][11] No evidence for a disc was detected in observations with the Herschel Space Observatory either.[12]

See also[edit]


  1. ^ a b c d e van Leeuwen, F. (2007). "HIP 78459". Hipparcos, the New Reduction. Retrieved 2009-12-08. 
  2. ^ a b Gerard T. van Belle & Kaspar von Braun (2009). "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars" (abstract). The Astrophysical Journal. 694 (2): 1085–1098. arXiv:0901.1206free to read. Bibcode:2009ApJ...694.1085V. doi:10.1088/0004-637X/694/2/1085. (web Preprint)
  3. ^ a b Reffert, S.; Quirrenbach, A. (2011). "Mass constraints on substellar companion candidates from the re-reduced Hipparcos intermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs". Astronomy & Astrophysics. 527. id.A140. arXiv:1101.2227free to read. Bibcode:2011A&A...527A.140R. doi:10.1051/0004-6361/201015861. 
  4. ^ Noyes, Robert W.; Jha, Saurabh; Korzennik, Sylvain G.; Krockenberger, Martin; Nisenson, Peter; Brown, Timothy M.; Kennelly, Edward J.; Horner, Scott D. (1997). "A Planet Orbiting the Star ρ Coronae Borealis". The Astrophysical Journal. 483 (2): L111–L114. arXiv:astro-ph/9704248free to read. Bibcode:1997ApJ...483L.111N. doi:10.1086/310754. 
  5. ^ Han, Inwoo; Black, David C.; Gatewood, George (2001). "Preliminary Astrometric Masses for Proposed Extrasolar Planetary Companions". The Astrophysical Journal. 548 (1): L57–L60. Bibcode:2001ApJ...548L..57H. doi:10.1086/318927. 
  6. ^ Williams, D.R. (2004). "Sun Fact Sheet". NASA. Retrieved 2009-06-23. 
  7. ^ Rho Coronae Borealis at SIMBAD - Ids - Bibliography - Image.
  8. ^ Trilling, D. E.; Brown, R. H.; Rivkin, A. S. (2000). "Circumstellar Dust Disks around Stars with Known Planetary Companions". The Astrophysical Journal. 529 (1): 499–505. Bibcode:2000ApJ...529..499T. doi:10.1086/308280. 
  9. ^ Beichman, C. A.; Bryden, G.; Rieke, G. H.; Stansberry, J. A.; Trilling, D. E.; Stapelfeldt, K. R.; Werner, M. W.; Engelbracht, C. W.; et al. (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/0412265free to read. Bibcode:2005ApJ...622.1160B. doi:10.1086/428115. 
  10. ^ Bryden, G.; Beichman, C. A.; Carpenter, J. M.; Rieke, G. H.; Stapelfeldt, K. R.; Werner, M. W.; Tanner, A. M.; Lawler, S. M.; et al. (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. 
  11. ^ Caer McCabe & Carlotta Pham. "Catalog of withdrawn or refuted resolved Disks". Catalog of Resolved Circumstellar Disks. Retrieved 2010-04-03. 
  12. ^ Marshall, J. P.; Moro-Martín, A.; Eiroa, C.; Kennedy, G.; Mora, A.; Sibthorpe, B.; Lestrade, J.-F.; Maldonado, J.; et al. (2014). "Correlations between the stellar, planetary, and debris components of exoplanet systems observed by Herschel". Astronomy & Astrophysics. 565. id.A15. arXiv:1403.6186free to read. Bibcode:2014A&A...565A..15M. doi:10.1051/0004-6361/201323058. 

External links[edit]

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