Xi1 Ceti

Xi1 Ceti
Location of ξ1 Ceti (circled)
Observation data
Epoch J2000.0      Equinox ICRS
Constellation Cetus
Right ascension 02h 12m 00.000s
Declination +08° 50′ 48.128″
Apparent magnitude (V) +4.36 [combined]
Characteristics
Spectral type G7III Ba0.4 Fe-1 + DA4
B−V color index 0.878±0.024
Astrometry
Radial velocity (Rv)−3.93±0.09 km/s
Proper motion (μ) RA: −26.965 mas/yr
Dec.: −1.154 mas/yr
Parallax (π)10.4184±0.3462 mas
Distance310 ± 10 ly
(96 ± 3 pc)
Absolute magnitude (MV)–0.99
Orbit
Period (P)1,642.1±1.3
Semi-major axis (a)≥ 0.896 ± 0.020 AU (134 ± 3 Gm)
Eccentricity (e)0 (fixed)
Periastron epoch (T)34,985±5 MJD
Semi-amplitude (K1)
(primary)		5.91±0.14 km/s
Details
A
Mass3.40+0.21
−0.11 M☉
3.80 M☉
Radius16.8±0.6 R☉
Luminosity169.7+10.7
−10.4 L☉
Surface gravity (log g)2.74+1.46
−0.56 cgs
Temperature5,138+662
−1,131 K
Metallicity [Fe/H]−0.01 dex
Age100 Myr
271+34
−46 Myr
B
Mass0.8 M☉
Surface gravity (log g)8.4 cgs
Other designations
Bawy, ξ1 Cet, 65 Ceti, NSV 749, BD+08°345, HD 13611, HIP 10324, HR 649, SAO 110408, WDS 02130+0851, WD 02130+0851
Database references
SIMBADdata

Xi1 Ceti, also named Bawy, is a binary star system located in the equatorial constellation of Cetus. This system is visible to the naked eye with a combined apparent visual magnitude of +4.36. The distance to this system is approximately 310 light years based on parallax measurements, and it is drifting closer to the Sun with a radial velocity of −4 km/s. The proximity of the star to the ecliptic means it is subject to lunar occultations.

Nomenclature

Xi1 Ceti is a Bayer designation that is Latinized from ξ1 Ceti, and is abbreviated Xi1 Cet or ξ1 Cet.

In Chinese astronomy, 天囷 (Tiān Qūn), meaning Circular Celestial Granary, refers to an asterism consisting of α Ceti, κ1 Ceti, λ Ceti, μ Ceti, ξ1 Ceti, ξ2 Ceti, ν Ceti, γ Ceti, δ Ceti, 75 Ceti, 70 Ceti, 63 Ceti and 66 Ceti. Consequently, the Chinese name for Xi1 Ceti itself is "the Fifth Star of Circular Celestial Granary", Tiān Qūn Wu.

Bawy (bȝwy), the dual form of Ba 'the Soul', is an ancient Egyptian decan which is not precisely identified, but likely corresponds to a pair of stars in Cetus – perhaps Xi1 and Xi2 Ceti. The IAU Working Group on Star Names adopted the name Bawy for Xi1 Ceti A on 15 October 2026.

Properties

The spectroscopic binary nature of Xi1 Ceti was discovered in 1901 by William Wallace Campbell using the Mills spectrograph at the Lick Observatory. The pair have a circular orbit with a period of 4.5 years and a separation of 3.8 AU. It is a suspected eclipsing binary with an amplitude of 0.03 in magnitude, which would suggest the orbital plane has a high inclination.

The primary, designated component A, is a mild barium giant star with a stellar classification of G7III Ba0.4 Fe-1. Morgan and Keenan in 1973 had classified it as a bright giant star with an anomalous underabundance of the CN molecule. Evidence has been found for an overabundance of s-process elements, although this is disputed. The star has 3.4 times the mass and 16.8 times the radius of the Sun. The companion, component B, is a small white dwarf companion with 80% of the mass of the Sun and a class of DA4. It was detected in 1985 by its ultraviolet emission.

References

  1. 1 2 3 4 5 6 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. XHIP record for this object at VizieR.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 Vallenari, A.; Brown, A. G. A.; Prusti, T.; De Bruijne, J. H. J.; 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.{{cite journal}}: CS1 maint: overridden setting (link) Gaia DR3 record for this source at VizieR.
  3. 1 2 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.
  4. 1 2 McCook, G. P.; Sion, E. M. (1999). "A Catalogue of Spectroscopically Identified White Dwarfs". The Astrophysical Journal Supplement Series. 121 (1): 1–130. Bibcode:1999ApJS..121....1M. doi:10.1086/313186.
  5. 1 2 3 4 5 6 Kong, X. M.; Zhao, G.; Zhao, J. K.; Shi, J. R.; et al. (May 2018). "Chemical abundances of primary stars in the Sirius-like binary systems". Monthly Notices of the Royal Astronomical Society. 476 (1): 724–740. arXiv:1801.10284. Bibcode:2018MNRAS.476..724K. doi:10.1093/mnras/sty280.
  6. 1 2 Griffin, R. F.; Herbig, G. H. (1981). "Spectroscopic Orbits of Xi Piscium 60 Andromedae and ξ1 Ceti". Monthly Notices of the Royal Astronomical Society. 196: 33–43. Bibcode:1981MNRAS.196...33G. doi:10.1093/mnras/196.1.33.
  7. 1 2 Smiljanic, R.; Porto de Mello, G. F.; da Silva, L. (June 2007). "Abundance analysis of barium and mild barium stars". Astronomy and Astrophysics. 468 (2): 679–693. arXiv:astro-ph/0702421. Bibcode:2007A&A...468..679S. doi:10.1051/0004-6361:20065867. S2CID 5863942.
  8. 1 2 Böhm-Vitense, E.; Johnson, H. R. (June 1985). "Detection of a compact companion of the mild barium star ksi1 Ceti". Astrophysical Journal. 293: 288–293. Bibcode:1985ApJ...293..288B. doi:10.1086/163236.
  9. ↑ "ksi01 Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-07-02.
  10. 1 2 "IAU Catalog of Star Names". Archived from the original on 11 February 2025. Retrieved 18 October 2026.
  11. ↑ 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.
  12. ↑ Schmidtke, P. C.; Africano, J. L. (September 1984). "KPNO lunar occultation summary. I". Astronomical Journal. 89: 1371–1378. Bibcode:1984AJ.....89.1371S. doi:10.1086/113637.
  13. ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 11 日 Archived 2012-02-04 at the Wayback Machine
  14. ↑ Hoffmann, Susanne M; Belmonte Avilés, Juan Antonio. "Bawy". All Skies Encyclopaedia. IAU Working Group on Star Names. Retrieved 18 October 2026.
  15. ↑ Campbell, William Wallace (1901). "Some recent results secured with the Mills spectrograph". Lick Observatory Bulletin. 1 (4): 22–25. Bibcode:1901LicOB...1...22C. doi:10.5479/ADS/bib/1901LicOB.1.22C.
  16. ↑ Hoffleit, Dorrit (1996). "A Catalogue of Correlations Between Eclipsing Binaries and Other Categories of Double Stars". The Journal of the American Association of Variable Star Observers. 24 (2): 105–116. Bibcode:1996JAVSO..24..105H.
  17. ↑ Pinsonneault, M. H.; Sneden, C.; Smith, V. V. (March 1984). "Lithium in the barium stars". Publications of the Astronomical Society of the Pacific. 96: 239–246. Bibcode:1984PASP...96..239P. doi:10.1086/131327. S2CID 120248035.
  18. ↑ Morgan, W. W.; Keenan, P. C. (1973). "Spectral Classification". Annual Review of Astronomy and Astrophysics. 11: 29. Bibcode:1973ARA&A..11...29M. doi:10.1146/annurev.aa.11.090173.000333.