Astronomy:Xi2 Sagittarii
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 18h 57m 43.80s[1] |
| Declination | −21° 06′ 24.0″[1] |
| Apparent magnitude (V) | +3.51[2] |
| Characteristics | |
| Spectral type | G8/K0 II/III[3] |
| U−B color index | +1.13[2] |
| B−V color index | +1.18[2] |
| Astrometry | |
| Radial velocity (Rv) | −20.10[4] km/s |
| Proper motion (μ) | RA: 33.52[1] mas/yr Dec.: -13.552[1] mas/yr |
| Parallax (π) | 8.4092 ± 0.1972[1] mas |
| Distance | 388 ± 9 ly (119 ± 3 pc) |
| Absolute magnitude (MV) | −1.72[5] |
| Details[6] | |
| Mass | 3.627±0.143 M☉ |
| Radius | 26.747±1.97 R☉ |
| Luminosity | 676[4] L☉ |
| Surface gravity (log g) | 2.39±0.19 cgs |
| Temperature | 4,682±75 K |
| Metallicity [Fe/H] | 0±0.5 dex |
| Age | 253±33 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Xi2 Sagittarii, also named Jian,[8] is a star in the zodiac constellation of Sagittarius. Data collected during the Hipparcos mission suggests it is an astrometric binary, although nothing is known about the companion.[9][10] It is visible to the naked eye with a combined apparent visual magnitude of +3.51.[2] Based upon an annual parallax shift of 8.4 mas as seen from Earth,[1] this system is located around 390 light years from the Sun.
The spectrum of Xi2 Sagittarii yields a mixed stellar classification of G8/K0 II/III,[3] showing traits of a G- or K-type giant or bright giant star. It has an estimated 3.6 times the mass of the Sun and about 27 times the Sun's radius. [6] At an age of around 380 million years, it is radiating 676 times the Sun's luminosity from its photosphere at an effective temperature of 4,541 K.[4]
Nomenclature
Xi2 Sagittarii, Latinized from ξ2 Sagittarii, is the star's Bayer designation.
In Chinese astronomy, 建 (Jiàn), meaning Establishment, refers to an asterism consisting of ξ2 Sagittarii, ο Sagittarii, π Sagittarii, 43 Sagittarii, ρ1 Sagittarii, and υ Sagittarii. Consequently, ξ2 Sagittarii itself is known as 建一 (Jiàn yī, English: the First Star of Establishment.)[11] The IAU Working Group on Star Names adopted the name Jian for this star on 13 August 2026, after this Chinese constellation.[8]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 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 Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99): 99, Bibcode: 1966CoLPL...4...99J.
- ↑ 3.0 3.1 Houk, Nancy; Smith-Moore, M. (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode: 1988mcts.book.....H.
- ↑ 4.0 4.1 4.2 Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal 150 (3): 88, doi:10.1088/0004-6256/150/3/88, Bibcode: 2015AJ....150...88L.
- ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 6.0 6.1 Gomes da Silva, J.; Santos, N. C.; Adibekyan, V.; Sousa, S. G.; Campante, T. L.; Figueira, P.; Bossini, D.; Delgado-Mena, E. et al. (2021-02-01). "Stellar chromospheric activity of 1674 FGK stars from the AMBRE-HARPS sample. I. A catalogue of homogeneous chromospheric activity". Astronomy and Astrophysics 646: A77. doi:10.1051/0004-6361/202039765. ISSN 0004-6361. Bibcode: 2021A&A...646A..77G. https://ui.adsabs.harvard.edu/abs/2021A&A...646A..77G. Xi2 Sagittarii's database entry at VizieR.
- ↑ "ksi02 Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=ksi02+Sgr.
- ↑ 8.0 8.1 "IAU Catalog of Star Names". https://exopla.net/star-names/modern-iau-star-names/.
- ↑ Frankowski, A. et al. (March 2007), "Proper-motion binaries in the Hipparcos catalogue. Comparison with radial velocity data", Astronomy and Astrophysics 464 (1): 377–392, doi:10.1051/0004-6361:20065526, Bibcode: 2007A&A...464..377F.
- ↑ Makarov, V. V.; Kaplan, G. H. (May 2005), "Statistical Constraints for Astrometric Binaries with Nonlinear Motion", The Astronomical Journal 129 (5): 2420–2427, doi:10.1086/429590, Bibcode: 2005AJ....129.2420M.
- ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 11 日
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