Astronomy:3 Equulei
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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[1] mas |
| 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 | |
| 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
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
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 Cousins, A. W. J. (1984). "Standardization of Broadband Photometry of Equatorial Standards". South African Astronomical Observatory Circulars 8: 59. Bibcode: 1984SAAOC...8...59C.
- ↑ 3.0 3.1 3.2 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. doi:10.1111/j.1365-2966.2008.13596.x. Bibcode: 2008MNRAS.389..869E.
- ↑ 4.0 4.1 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. doi:10.1051/0004-6361:20041272. Bibcode: 2005A&A...430..165F.
- ↑ 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. doi:10.1086/605456. Bibcode: 2009PASP..121..842R.
- ↑ 6.0 6.1 6.2 Stassun, Keivan G. et al. (2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. Bibcode: 2019AJ....158..138S.
- ↑ 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. doi:10.1086/317346. Bibcode: 2000ApJS..130..201H.
- ↑ "* 3 Equ". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+3+Equ.
- ↑ 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. doi:10.1051/0004-6361:20042039. Bibcode: 2005A&A...431..773R.
- ↑ Lang, Kenneth R. (2006). Astrophysical formulae. Astronomy and astrophysics library. 1 (3 ed.). Birkhäuser. ISBN 3-540-29692-1. https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41.. The radius (R*) is given by:
- ↑ "The Colour of Stars". Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html.
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