3 Equulei
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Equuleus |
| Right ascension | 21h 04m 34.65162s[1] |
| Declination | +05° 30′ 10.3117″[1] |
| Apparent magnitude (V) | 5.593[2] |
| Characteristics | |
| Evolutionary stage | red giant branch[1] |
| Spectral type | K5 III[3] |
| U−B color index | +1.934[2] |
| B−V color index | +1.651[2] |
| Astrometry | |
| Radial velocity (Rv) | −15.26±0.2[4] km/s |
| Proper motion (μ) | RA: +13.115[1] mas/yr Dec.: +0.752[1] mas/yr |
| Parallax (π) | 2.6635±0.0940 mas[1] |
| Distance | 1,220 ± 40 ly (380 ± 10 pc) |
| Absolute magnitude (MV) | −1.02[5] |
| Details | |
| Mass | 7.2[1] M☉ |
| Radius | 116[6] R☉ |
| Luminosity | 2,581[1] L☉ |
| Surface gravity (log g) | 1.06[1] cgs |
| Temperature | 4,029[6] K |
| Rotational velocity (v sin i) | 4.6[7] km/s |
| Other designations | |
| ζ Equ, 3 Equ, BD+04°4606, HD 200644, HIP 104031, HR 8066, SAO 126518[8] | |
| Database references | |
| SIMBAD | data |
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
[edit]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
[edit]- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ "* 3 Equ". SIMBAD. Centre de données astronomiques de Strasbourg.
- ^ 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.
- ^ 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.
- ^ 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:
- ^ "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.
