Rho Draconis

Rho Draconis (ρ Draconis) is a solitary[10] star in the northern circumpolar constellation of Draco. It is faintly visible to the naked eye with an apparent visual magnitude is 4.52.[2] Based upon an annual parallax shift of 7.61 mas as measured from Earth,[1] it is located around 429 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.027 due to interstellar dust.[5]

Rho Draconis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Draco
Right ascension  20h 02m 49.07268s[1]
Declination +67° 52′ 24.8294″[1]
Apparent magnitude (V) 4.52[2]
Characteristics
Spectral type K3 III[3]
U−B color index +1.54[2]
B−V color index +1.34[2]
Astrometry
Radial velocity (Rv)−9.80±0.43[4] km/s
Proper motion (μ) RA: +16.44[1] mas/yr
Dec.: +47.31[1] mas/yr
Parallax (π)7.61 ± 0.17[1] mas
Distance429 ± 10 ly
(131 ± 3 pc)
Absolute magnitude (MV)−0.97[5]
Details
Radius28[3] R☉
Luminosity402[6] L☉
Surface gravity (log g)1.90[7] cgs
Temperature4370[7] K
Metallicity [Fe/H]0.03[7] dex
Rotational velocity (v sin i)10[8] km/s
Other designations
ρ Dra, 67 Dra, BD+67° 1222, HD 190940, HIP 98702, HR 7685, SAO 18676[9]
Database references
SIMBADdata

With a stellar classification of K3 III,[3] Rho Draconis is a normal giant star that is past the first dredge-up phase of its post-main sequence evolution.[7] It has the peculiar spectrum of a CN star, showing abnormal line strengths for cyanogen and calcium.[11] The star has expanded to around 28[3] times the Sun's radius and it is radiating 402[6] times the solar luminosity from its photosphere at an effective temperature of 4,370 K.[7]

References
  1. van Leeuwen, F. (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.
  2. Argue, A. N. (1966), "UBV photometry of 550 F, G and K type stars", Monthly Notices of the Royal Astronomical Society, 133: 475–493, Bibcode:1966MNRAS.133..475A, doi:10.1093/mnras/133.4.475.
  3. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (3rd ed.), 367: 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  4. Famaey, B.; et al. (2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430: 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272.
  5. Ryon, Jenna; et al. (August 2009), "Comparing the Ca ii H and K Emission Lines in Red Giant Stars", Publications of the Astronomical Society of the Pacific, 121 (882): 842, arXiv:0907.3346, Bibcode:2009PASP..121..842R, doi:10.1086/605456.
  6. McDonald, I.; et al. (2012), "Fundamental parameters and infrared excesses of Hipparcos stars", Monthly Notices of the Royal Astronomical Society, 427: 343, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  7. Mishenina, T. V.; et al. (October 1995), "Chemical composition of five giants with positive CN-indices.", Astronomy and Astrophysics Supplement, 113: 333, Bibcode:1995A&AS..113..333M.
  8. Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1), Bibcode:1970CoAsi.239....1B.
  9. "rho Dra". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-05-30.
  10. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x.
  11. Mishenina, T. V.; Tsymbal, V. V. (September 1997), "Li and CNO abundances in the atmospheres of nine peculiar giants", Astronomy Letters, 23 (5): 609–614, Bibcode:1997AstL...23..609M.
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