Pi Draconis

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Pi Draconis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Draco
Right ascension 19h 20m 40.09333s[1]
Declination +65° 42′ 52.3095″[1]
Apparent magnitude (V) 4.59[2]
Spectral type A2 IIIs[3][4]
U−B color index +0.06[2]
B−V color index +0.02[2]
Proper motion (μ) RA: +15.09[1] mas/yr
Dec.: +41.12[1] mas/yr
Parallax (π) 14.25 ± 0.12[1] mas
Distance 229 ± 2 ly
(70.2 ± 0.6 pc)
Mass 2.70[5] M
Radius 3.2[6] R
Luminosity 60[7] L
Surface gravity (log g) 3.80[8] cgs
Temperature 9,125[8] K
Rotational velocity (v sin i) 26±1[3] km/s
Age 350[5] Myr
Other designations
Dra, 58 Dra, BD+65° 1345, FK5 3547, HD 182564, HIP 95081, HR 7371, SAO 18299[9]
Database references

Pi Draconis (π Dra) is a solitary[5][4] star in the northern circumpolar constellation of Draco. It is visible to the naked eye with an apparent visual magnitude of 4.59.[2] Based upon an annual parallax shift of 14.25 mas as measured from Earth,[1] it is located around 229 light years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.063±0.10 due to interstellar dust.[10]

With an age of 350 million years, this is an A-type star of stellar classification A2 IIIs,[3][4] where the luminosity class of III typically indicates an evolved giant star and the 's' means the spectrum displays sharp absorption lines. It is a candidate Am star,[8] meaning there are some chemical peculiarities. The measured angular size is 0.427±0.062 arc seconds.[10] At the estimated distance of Pi Draconis, this yields a physical size of about 3.2 times the radius of the Sun.[6] It has about 2.70[5] times the mass of the Sun and is radiating 60[7] times the solar luminosity from its photosphere at an effective temperature of 9,125 K.[8]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J. 
  3. ^ a b c Royer, F.; et al. (October 2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393: 897–911, Bibcode:2002A&A...393..897R, arXiv:astro-ph/0205255Freely accessible, doi:10.1051/0004-6361:20020943. 
  4. ^ a b c 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, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x. 
  5. ^ a b c d De Rosa, R. J.; et al. (January 2014), "The VAST Survey - III. The multiplicity of A-type stars within 75 pc", Monthly Notices of the Royal Astronomical Society, 437 (2): 1216–1240, Bibcode:2014MNRAS.437.1216D, arXiv:1311.7141Freely accessible, doi:10.1093/mnras/stt1932. 
  6. ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1.  The radius (R*) is given by:
  7. ^ a b McDonald, I.; et al. (2012), "Fundamental parameters and infrared excesses of Hipparcos stars", Monthly Notices of the Royal Astronomical Society, 427: 343, Bibcode:2012MNRAS.427..343M, arXiv:1208.2037Freely accessible, doi:10.1111/j.1365-2966.2012.21873.x. 
  8. ^ a b c d Yüce, Kutluay; Adelman, Saul J. (April 2014), "Elemental Abundance Analyses with DAO Spectrograms. XXXIV. A Three-Dimensional Graphical Examination of the Elemental Abundances of the Mercury-Manganese and Metallic-Line Stars", Publications of the Astronomical Society of Pacific, 126 (938): 345, Bibcode:2014PASP..126..345Y, doi:10.1086/676335. 
  9. ^ "pi. Dra -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-05-30. 
  10. ^ a b van Belle, Gerard T.; von Braun, Kaspar (2009), "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars", The Astrophysical Journal, 694 (2): 1085–1098, Bibcode:2009ApJ...694.1085V, arXiv:0901.1206Freely accessible, doi:10.1088/0004-637X/694/2/1085.