13 Ceti

13 Ceti

A light curve for BU Ceti, plotted from TESS data
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cetus
Right ascension 00h 35m 14.87968s[1]
Declination −03° 35′ 34.2367″[1]
Apparent magnitude (V) 5.20[2] (5.61 + 6.90)[3]
Characteristics
Evolutionary stage Main sequence
Spectral type F6 V + G4 V + K3.5 V[4][5]
B−V color index 0.567±0.008[2]
Variable type RS CVn[6]
Astrometry
Radial velocity (Rv)+10.37±0.40[7] km/s
Proper motion (μ) RA: +408.34[1] mas/yr
Dec.: −35.22[1] mas/yr
Parallax (π)47.05 ± 0.67 mas[1]
Distance69.3 ± 1.0 ly
(21.3 ± 0.3 pc)
Absolute magnitude (MV)3.56[2]
Orbit[8]
PrimaryA
CompanionB
Period (P)2,516.6163±2.7808 d
Eccentricity (e)0.77300
Periastron epoch (T)56,935.2034 MJD
Argument of periastron (ω)
(secondary)		283.8°°
Orbit[9]
PrimaryAa
CompanionAb
Period (P)2.081891±0.000005 d
Semi-major axis (a)≥1.260±0.010 Mm
Eccentricity (e)0.0 (fixed)
Periastron epoch (T)2,443,400.4573±0.0032 HJD
Argument of periastron (ω)
(secondary)		0.0°
Semi-amplitude (K1)
(primary)		43.98±0.39 km/s
Details
Aa
Mass1.18±0.09[5] M☉
Luminosity2.63[8] L☉
Temperature6,457[8] K
Age3.8+1.8
−0.3[2] Gyr
B
Mass0.90±0.09[5] M☉
Luminosity0.83[8] L☉
Temperature5,754[8] K
Age2.5[8] Gyr
Other designations
HO 212, 13 Cet, BU Cet, NSV 212, BD−04°62, GC 696, GJ 23, HD 3196, HIP 2762, HR 142, SAO 128839, WDS 00352-0336[10]
Database references
SIMBADdata

13 Ceti is a triple star system[5] in the equatorial constellation of Cetus. It is dimly visible to the naked eye with a combined apparent visual magnitude of 5.20.[2] The system is located at a distance of approximately 69 light years from the Sun based on stellar parallax, and is drifting further away with a radial velocity of +10.4 km/s.[7] It shares a common motion with the Hyades moving group,[5] although it is too old to be a member.[11]

This star was identified as a visual binary system by G. W. Hough in 1844 and given the identifier HO 212.[12] The pair have an orbital period of 6.9 years and an eccentricity of 0.77.[8] The brighter member, designated component A, is an F-type main-sequence star with a stellar classification of F6 V[4] and a visual magnitude of 5.61.[3] It appears to have an active chromosphere and is classified as an RS Canum Venaticorum variable with a variable star designation of BU Cet.[6] The star was detected as a source of soft X-ray emission by EXOSAT.[13] It has 18%[5] more mass than the Sun and is estimated to be about four[2] billion years old.

In 1907, E. B. Frost discovered the primary is a spectroscopic binary, making this a triple star system. This is a double-lined spectroscopic binary with a period of 2.1 days and a circularized orbit. The companion signature was confirmed using the separated fringe packet technique with the CHARA array.[14] It is most likely a K-type main-sequence star with a class of K3.5 V and 70% of the mass of the Sun.[5]

The secondary member of the visual binary, designated component B, is a G-type main-sequence star with a class of G4 V.[4] It has 90%[5] of the Sun's mass and a visual magnitude of 6.90.[3] A distant visual companion to this system was detected by S. W. Burnham in 1877. Designated component C, this star is a background object[15] of magnitude 12.50. As of 1999, it was located at an angular separation of 24.0″ from the primary along a position angle of 322°.[3]

  1. ^ a b c d e Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference WDSC2014 was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference Strassmeier1993 was invoked but never defined (see the help page).
  5. ^ a b c d e f g h Cite error: The named reference Andrade2019 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Fernandez-Figueroa1994 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference karatas2004 was invoked but never defined (see the help page).
  8. ^ a b c d e f g Cite error: The named reference Piccotti2020 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Duquennoy1991 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Montes2001 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Bauer1944 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Bedford1985 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Raghavan2012 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Pogo1928 was invoked but never defined (see the help page).