Delta Coronae Borealis

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δ Coronae Borealis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Corona Borealis
Right ascension 15h 49m 35.64682s[1]
Declination +26° 04′ 06.2065″[1]
Apparent magnitude (V) 4.63[2]
Spectral type G3.5III[2]
U−B color index +0.32[3]
B−V color index +0.78[3]
Radial velocity (Rv)−20.11±0.23[2] km/s
Proper motion (μ) RA: -78.83[1] mas/yr
Dec.: -65.28[1] mas/yr
Parallax (π)19.18 ± 0.26[1] mas
Distance170 ± 2 ly
(52.1 ± 0.7 pc)
Absolute magnitude (MV)+1.00[4]
Mass2.4 M
Radius7.4 R
Luminosity34.3 L
Temperature5,180 K
Metallicity [Fe/H]−0.22[4] dex
Rotation17 d
Other designations
δ CrB, 10 Coronae Borealis, BD+26° 2737, HD 141714, HIP 77512, HR 5889, SAO 84019[2]
Database references

Delta Coronae Borealis, Latinized from δ Coronae Borealis, is a star in the constellation Corona Borealis. Its apparent magnitude is 4.60, and it is around 170 light-years distant.[1] It is actually a yellow giant star of spectral type G3.5III that around 2.4 times as massive as the Sun and has swollen to 7.4 times its radius. It has a surface temperature of 5180 K.[6] For most of its existence, Delta Coronae Borealis was a blue-white main sequence star of spectral type B before it ran out of hydrogen fuel in its core. Its luminosity and spectrum suggest it has just crossed the Hertzsprung gap, having finished burning core hydrogen and just begun burning hydrogen in its shell. It is slightly variable, over a period of 59 days, thought to be because of its sunspots. It is a strong source of X-rays due to its hot corona.[7]


  1. ^ a b c d e f van Leeuwen, F. (2007). "Validation of the New Hipparcos Reduction". Astronomy and Astrophysics. 474 (2): 653–64. arXiv:0708.1752Freely accessible. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d "del CrB". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 25 February 2017. 
  3. ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Bibcode:1986EgUBV........0M. 
  4. ^ a b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971Freely accessible, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. 
  5. ^ Gondoin, P. (December 2005), "The relation between X-ray activity and rotation in intermediate-mass G giants", Astronomy and Astrophysics, 444 (2): 531–538, Bibcode:2005A&A...444..531G, doi:10.1051/0004-6361:20053567. 
  6. ^ Gondoin, P. (2005). "The X-ray activity of the slowly rotating G giant δ CrB". Astronomy & Astrophysics. 431: 1027–35. Bibcode:2005A&A...431.1027G. doi:10.1051/0004-6361:20041991. 
  7. ^ Kaler, James B. "Delta Coronae Borealis". Stars. University of Illinois. Retrieved 21 November 2014.