Xi1 Ceti

For other stars with this Bayer designation, see ξ Ceti.
Xi1 Ceti
Location of ξ1 Ceti (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cetus
Right ascension 02h 12m 59.99769s[1]
Declination +08° 50′ 48.2023″[1]
Apparent magnitude (V) +4.36[2] [combined]
Characteristics
Spectral type G7III Ba0.4 Fe-1[3] + DA4[4]
B−V color index 0.878±0.024[2]
Astrometry
Radial velocity (Rv)−3.93±0.09[2] km/s
Proper motion (μ) RA: −24.498[1] mas/yr
Dec.: −5.952[1] mas/yr
Parallax (π)9.5451 ± 0.3275 mas[1]
Distance340 ± 10 ly
(105 ± 4 pc)
Absolute magnitude (MV)–0.99[5]
Orbit[6]
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
Mass3.80[5] M☉
Radius18.2+1.0
−2.4[1] R☉
Luminosity209.9±8.2[1] L☉
Surface gravity (log g)2.60[1] cgs
Temperature5,184±50[5] K
Metallicity [Fe/H]−0.01[5] dex
Age100[7] Myr
B
Mass0.8[5] M☉
Surface gravity (log g)8.4[8] cgs
Other designations
ξ1 Cet, ksi01 Cet, 65 Ceti, NSV 749, BD+08° 345, HD 13611, HIP 10324, HR 649, SAO 110408, WDS 02130+0851, WD 02130+0851[9]
Database references
SIMBADdata
Exoplanet Archivedata

Xi1 Ceti , Latinized from ξ1 Ceti, is a binary star[10] system located in the equatorial constellation of Cetus. It is visible to the naked eye with a combined apparent visual magnitude of +4.36.[2] The distance to this system is approximately 340 light years based on parallax measurements, and it is drifting closer to the Sun with a radial velocity of −4 km/s.[2] The proximity of the star to the ecliptic means it is subject to lunar occultations.[11]

The spectroscopic binary nature of Xi1 Ceti was discovered in 1901 by William Wallace Campbell using the Mills spectrograph at the Lick Observatory.[12][6] The pair have a circular orbit with a period of 4.5 years and a separation of 3.8 AU.[5] It is a suspected eclipsing binary with an amplitude of 0.03 in magnitude, which would suggest the orbital plane has a high inclination.[13]

The primary, designated component A, is a mild barium[14] giant star with a stellar classification of G7III Ba0.4 Fe-1.[3] Morgan and Keenan in 1973 had classified it as a bright giant star with an anomalous underabundance of the CN molecule.[15] Evidence has been found for an overabundance of s-process elements,[5] although this is disputed.[7] The star has 3.8[5] times the mass and 18[1] 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.[4] It was detected in 1985 by its ultraviolet emission.[8]

In Chinese, 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.[16]

  1. ^ a b c d e f g h i Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d e Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Keenan_McNeil_1989 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference McCook_Sion_1999 was invoked but never defined (see the help page).
  5. ^ a b c d e f g h Cite error: The named reference Kong_et_al_2018 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Griffin1981 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Smiljanic_et_al_2007 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Böhm-Vitense_Johnson_1985 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Schmidtke_Africano_1984 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Campbell1901 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Hoffleit1996 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Pinsonneault1984 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Morgan_Keenan_1973 was invoked but never defined (see the help page).
  16. ^ (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