HD 20644
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Aries |
| Right ascension | 03h 20m 20.36111s[1] |
| Declination | +29° 02′ 54.4451″[1] |
| Apparent magnitude (V) | 4.47[2] |
| Characteristics | |
| Spectral type | K3IIIa Ba0.5[3] |
| B−V color index | 1.555±0.020[2] |
| Astrometry | |
| Radial velocity (Rv) | −3.09±0.28[2] km/s |
| Proper motion (μ) | RA: −7.71[1] mas/yr Dec.: −16.91[1] mas/yr |
| Parallax (π) | 6.01 ± 0.25 mas[1] |
| Distance | 540 ± 20 ly (166 ± 7 pc) |
| Absolute magnitude (MV) | −1.63[2] |
| Details | |
| Mass | 3.07±0.39[4] M☉ |
| Radius | 75.32+3.30 −7.57[5] R☉ |
| Luminosity | 1,292±89[5] L☉ |
| Surface gravity (log g) | 2.00[4] cgs |
| Temperature | 3,987+217 −85[5] K |
| Metallicity [Fe/H] | −0.27±0.04[2] dex |
| Rotational velocity (v sin i) | 1.4[6] km/s |
| Age | 350±140[4] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 20644 is a suspected binary star[6] system in the constellation Aries. It has an orange hue and is visible to the naked eye with an apparent visual magnitude of 4.47.[2] The system is located at a distance of approximately 540 light years from the Sun based on parallax,[1] but is drifting closer with a radial velocity of −3 km/s.[2]
The visible component is an aging giant star with a stellar classification of K3IIIa Ba0.5,[3] where the suffix notation indicates this is a mild barium star. The atmosphere of this star is enriched with s-process elements that are posited to have been transferred from what is now a white dwarf companion when it evolved along the asymptotic giant branch (AGB).[8] Alternatively, this star may itself be on the AGB.[9]
HD 20644 is about 350[4] million years old with three[4] times the mass of the Sun and is spinning with a projected rotational velocity of 1.4 km/s.[6] With the supply of hydrogen at its core exhausted, it has expanded to 75[5] times the Sun's radius. It is radiating 1,292[5] times the luminosity of the Sun from its photosphere at an effective temperature of 3,987 K.[5]
References
- ^ a b c d e f van Leeuwen, F. (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.
- ^ a b c d e f g Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
- ^ a b Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
- ^ a b c d e Baines, Ellyn K.; et al. (2018), "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer", The Astronomical Journal, 155, 30, arXiv:1712.08109, Bibcode:2018AJ....155...30B, doi:10.3847/1538-3881/aa9d8b.
{{citation}}: CS1 maint: unflagged free DOI (link) - ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ a b c Lèbre, A.; et al. (May 2006), "Lithium abundances and rotational behavior for bright giant stars", Astronomy and Astrophysics, 450 (3): 1173–1179, Bibcode:2006A&A...450.1173L, doi:10.1051/0004-6361:20053485.
{{citation}}: CS1 maint: multiple names: authors list (link) - ^ "HD 20644". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-12-22.
- ^ Yang, Guo-Chao; et al. (January 2016), "Chemical abundance analysis of 19 barium stars", Research in Astronomy and Astrophysics, 16 (1), arXiv:1602.08704, Bibcode:2016RAA....16...19Y, doi:10.1088/1674-4527/16/1/019, 19.
- ^ Mennessier, M. O.; et al. (October 1997), "Barium stars, galactic populations and evolution", Astronomy and Astrophysics, 326: 722–730, Bibcode:1997A&A...326..722M.
