39 Arietis

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39 Arietis
Observation data
Epoch J2000      Equinox J2000
Constellation Aries
Right ascension 02h 47m 54.54142s[1]
Declination +29° 14′ 49.6132″[1]
Apparent magnitude (V) 4.514[2]
Spectral type K1.5 III[3]
U−B color index +1.083[2]
B−V color index +1.118[2]
R−I color index 0.58
Radial velocity (Rv) –15.53 ± 0.14[4] km/s
Proper motion (μ) RA: +149.47 ± 0.25[1] mas/yr
Dec.: –127.05 ± 0.18[1] mas/yr
Parallax (π) 19.01 ± 0.21[1] mas
Distance 172 ± 2 ly
(52.6 ± 0.6 pc)
Mass 1.6[5] M
Radius 11.1 ± 0.8[3] R
Luminosity 56[4] L
Surface gravity (log g) 2.7[4] cgs
Temperature 4,603[4] K
Metallicity [Fe/H] –0.02[4] dex
Rotational velocity (v sin i) 4.5[4] km/s
Other designations
BD+28° 462, HD 17361, HIP 13061, HR 824, SAO 75578.[6]
Database references

39 Arietis (abbreviated 39 Ari) is a star in the northern constellation of Aries. 39 Arietis is the Flamsteed designation. It is visible to the naked eye with an apparent visual magnitude of +4.5.[2] The distance to this star, as determined from an annual parallax shift of 19.01 mas,[1] is approximately 172 light-years (53 parsecs).

This is a giant star with a stellar classification of K1.5 III.[3] It is currently at an evolutionary stage known as a red clump, indicating that it is generating energy through the fusion of helium at its core.[5] 39 Arietis has 1.6[5] times the mass of the Sun, but its outer envelope has expanded to around 11[3] times the Sun's radius. It shines with 56 times the luminosity of the Sun.[4] This energy is being radiated into outer space from its outer atmosphere at an effective temperature of 4,603 K,[4] giving it the cool orange-hued glow of a K-type star.[7]


  1. ^ a b c d e f van Leeuwen, F. (November 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 Oja, T., "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series, 65 (2): 405–4. 
  3. ^ a b c d Nordgren, Tyler E.; et al. (December 1999), "Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer", The Astronomical Journal, 118 (6): 3032–3038, Bibcode:1999AJ....118.3032N, doi:10.1086/301114 
  4. ^ a b c d e f g h Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209. 
  5. ^ a b c Tautvaišienė, G.; et al. (December 2010), "C, N and O abundances in red clump stars of the Milky Way", Monthly Notices of the Royal Astronomical Society, 409 (3): 1213–1219, Bibcode:2010MNRAS.409.1213T, arXiv:1007.4064Freely accessible, doi:10.1111/j.1365-2966.2010.17381.x. 
  6. ^ "NLTT 8982 -- High proper-motion Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-18. 
  7. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 10, 2012, retrieved 2012-01-16 

External links[edit]