39 Arietis

39 Arietis (abbreviated 39 Ari), officially named Lilii Borea /ˈlɪliaɪ ˈbɔːriə/,[7] is a star in the northern constellation of Aries. 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).

39 Arietis

39 Arietis in optical light
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]
Characteristics
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
Astrometry
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
Distance172 ± 2 ly
(52.6 ± 0.6 pc)
Details
Mass1.6[5] M☉
Radius11.1 ± 0.8[3] R☉
Luminosity56[4] L☉
Surface gravity (log g)2.7[4] cgs
Temperature4,603[4] K
Metallicity [Fe/H]–0.02[4] dex
Rotational velocity (v sin i)4.5[4] km/s
Other designations
Lilii Borea, BD+28° 462, HD 17361, HIP 13061, HR 824, SAO 75578.[6]
Database references
SIMBADdata

Nomenclature

39 Arietis is the star's Flamsteed designation.

This star was described as Lilii Borea by Nicolas-Louis de Lacaille in 1757,[8][9] as a star of the now-defunct constellation of Lilium (the Lilly), the words are simply the Latin phrase Līliī Boreā 'in the north of Lilium'. Līliī Austrīnā /ɔːˈstraɪnə/ 'in the south of Lilium' was 41 Arietis.

In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[10] to catalog and standardize proper names for stars. The WGSN approved the name Lilii Borea for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[7]

In Chinese, 胃宿 (Wèi Su), meaning Stomach, refers to an asterism consisting of 39 Arietis, 35 Arietis and 41 Arietis.[11] Consequently, the Chinese name for 39 Arietis itself is 胃宿二 (Wèi Su èr, English: the Second Star of Stomach).[12]

Properties

39 Arietis is a giant star with a stellar classification of K1.5 III.[3] It is currently at an evolutionary stage known as the red clump, indicating that it is generating energy through the fusion of helium at its core.[5] It 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.[13]

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References
  1. van Leeuwen, F. (November 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. Oja, T., "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series, 65 (2): 405–4.
  3. 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. 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. 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, arXiv:1007.4064, Bibcode:2010MNRAS.409.1213T, doi:10.1111/j.1365-2966.2010.17381.x.
  6. "* 39 Ari". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-18.
  7. "Naming Stars". IAU.org. Retrieved 16 December 2017.
  8. de Lacaille, Nicolas-Louis (1757). Astronomiae fundamenta novissimis solis et stellarum observationibus stabilita, Lutetiae in Collegio mazarineo et in Africa ad caput Bonae Spei peractis a Nicolao Ludovico de La Caille. J.-J.-St. Collombat. pp. 227, 233.
  9. Bailey, Francis (1833). La Caille's Catalogue of 398 principal Stars, Memoirs of the Royal Astronomical Society, Vol 5. Priestley and Weale. pp. 110, 121.
  10. "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  11. (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  12. (in Chinese) 白羊座
  13. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on February 22, 2012, retrieved 2012-01-16
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