Chi Ceti

Chi Ceti (χ Ceti), is the Bayer designation for a double star in the equatorial constellation of Cetus. They appear to be common proper motion companions, sharing a similar motion through space.^[15] The brighter component, HD 11171, is visible to the naked eye with an apparent visual magnitude of 4.66, while the fainter companion, HD 11131, is magnitude 6.75.^[3] Both lie at roughly the same distance, with the brighter component lying at an estimated distance of 76.6 light years from the Sun based upon an annual parallax shift of 42.58 mas.

Chi Ceti

A light curve for EZ Ceti, plotted from TESS data[1]
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Cetus
HD 11171
Right ascension	01h 49m 35.10277s[2]
Declination	−10° 41′ 11.0719″[2]
Apparent magnitude (V)	4.66[3]
HD 11131
Right ascension	01h 49m 23.34886s[4]
Declination	−10° 42′ 14.0839″[4]
Apparent magnitude (V)	6.75[3]
Characteristics
HD 11171
Spectral type	F3 III[5] or F0 V[6]
U−B color index	+0.04[3]
B−V color index	+0.33[3]
HD 11131
Spectral type	G3 V[6]
U−B color index	+0.12[3]
B−V color index	+0.61[3]
Variable type	BY Dra[7]
Astrometry
HD 11171
Radial velocity (Rv)	−1.8[5] km/s
Proper motion (μ)	RA: −147.867[2] mas/yr Dec.: −93.480[2] mas/yr
Parallax (π)	42.5848±0.1249 mas[2]
Distance	76.6 ± 0.2 ly (23.48 ± 0.07 pc)
Absolute magnitude (MV)	+2.83±0.01[8]
HD 11131
Radial velocity (Rv)	−3.89±0.12[9] km/s
Proper motion (μ)	RA: −159.846[4] mas/yr Dec.: −70.666[4] mas/yr
Parallax (π)	41.8±0.2579 mas[4]
Distance	78.0 ± 0.5 ly (23.9 ± 0.1 pc)
Absolute magnitude (MV)	4.98[10]
Details
HD 11171
Mass	1.36[5] M☉
Luminosity	5.6[5] L☉
Temperature	6,746±258[5] K
Metallicity [Fe/H]	0.14[8] dex
Age	1.2[5] Gyr
HD 11131
Surface gravity (log g)	4.53[11] cgs
Temperature	5,804[11] K
Metallicity [Fe/H]	−0.09[11] dex
Rotational velocity (v sin i)	3.34[12] km/s
Other designations
χ Cet, Gj 9061, ENG 8
χ Ceti A: 53 Cet, HD 11171, BD−11°352, FK5 1051, HIP 8497, HR 531, SAO 148036[13]
χ Ceti B: EZ Cet, HD 11131, BD−11°351, HIP 8486, SAO 148033[14]
Database references
SIMBAD	χ Ceti
	χ Ceti A
	χ Ceti B

The primary, component A, is an evolved K-type giant star with a stellar classification of F3 III.^[5] However, Houk and Swift (1999) listed a classification of F0 V,^[6] which would match an F-type main sequence star. It displays an infrared excess at a wavelength of 70 μm and thus is a candidate host of an orbiting debris disk.^[16]

The common proper motion companion, component B, is a G-type main sequence star with a classification of G3 V.^[6] It is a BY Draconis variable with a periodicity of 8.92 days and a variable star designation of EZ Cet.^[7]