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3 Equulei is a single[3] star located in the small northern constellation of Equuleus. It is faintly visible to the naked eye at an apparent visual magnitude of 5.6.[2] Based upon an annual parallax shift of 2.7 mas, 3 Equulei is roughly 1,220 light-years (370 parsecs) distant from Earth, give or take a 40 light-year margin of error. At that distance, the apparent brightness of the star is diminished by 0.15 in visual magnitude because of extinction from interstellar gas and dust.[4]

3 Equulei has been referred to in some sources as ζ (Zeta) Equulei, although it was not given that designation by Bayer.[9]

Properties

3 Equulei is an evolved giant star with a stellar classification of K5 III.[3] The measured angular diameter of this star, after correction for limb darkening, is 2.44±0.03 mas.[10] At the estimated distance of 1,220 light-years, this yields a physical size of about 100 times the radius of the Sun.[11] It is radiating an estimated 2,581 times the luminosity of the Sun[1] from this expanded outer envelope at an effective temperature of 4,029 K.[6] At this temperature, it shines with the orange-hued glow of a K-type star.[12]

References

  1. ^ a b c d e f g h i j Vallenari, A.; et al. (Gaia collaboration) (2023). “Gaia Data Release 3. Summary of the content and survey properties”. Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A…674A…1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c d Cousins, A. W. J. (1984). “Standardization of Broadband Photometry of Equatorial Standards”. South African Astronomical Observatory Circulars. 8: 59. Bibcode:1984SAAOC…8…59C.
  3. ^ 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. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
  4. ^ a b Famaey, B.; et al. (January 2005). “Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters”. Astronomy and Astrophysics. 430 (1): 165–186. arXiv:astro-ph/0409579. Bibcode:2005A&A…430..165F. doi:10.1051/0004-6361:20041272. S2CID 17804304.
  5. ^ Ryon, Jenna; Shetrone, Matthew D.; Smith, Graeme H. (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): 842–856. arXiv:0907.3346. Bibcode:2009PASP..121..842R. doi:10.1086/605456. S2CID 17821279.
  6. ^ a b c Stassun, Keivan G.; et al. (2019). “The Revised TESS Input Catalog and Candidate Target List”. The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ….158..138S. doi:10.3847/1538-3881/ab3467.
  7. ^ Henry, Gregory W.; et al. (September 2000). “Photometric Variability in a Sample of 187 G and K Giants”. The Astrophysical Journal Supplement Series. 130 (1): 201–225. Bibcode:2000ApJS..130..201H. CiteSeerX 10.1.1.40.8526. doi:10.1086/317346. S2CID 17160805.
  8. ^ “* 3 Equ”. SIMBAD. Centre de données astronomiques de Strasbourg.
  9. ^ Hoffleit, D.; Warren, W. H. (1995). “VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)”. VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS….C……0H. 5050. Bibcode:1995yCat.5050….0H.
  10. ^ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005). “CHARM2: An updated Catalog of High Angular Resolution Measurements”. Astronomy and Astrophysics. 431 (2): 773–777. Bibcode:2005A&A…431..773R. doi:10.1051/0004-6361:20042039.
  11. ^ Lang, Kenneth R. (2006). Astrophysical formulae. Astronomy and astrophysics library. Vol. 1 (3 ed.). Birkhäuser. ISBN 3-540-29692-1.. The radius (R*) is given by:
  12. ^ “The Colour of Stars”. Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. Archived from the original on March 18, 2012. Retrieved 2012-07-21.