Chi Ceti
Triple star in the constellation Cetus
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Chi Ceti is a triple star in the equatorial constellation of Cetus. The name is a Bayer designation that is Latinized from χ Ceti, and abbreviated Chi Cet or χ Cet. They appear to be common proper motion companions, sharing a similar motion through space.[21] 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.[2] 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.
  | |
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Cetus |
| χ Ceti A | |
| Right ascension | 01h 49m 35.10277s[1] |
| Declination | −10° 41′ 11.0719″[1] |
| Apparent magnitude (V) | 4.66[2] |
| χ Ceti Ba | |
| Right ascension | 01h 49m 23.34886s[3] |
| Declination | −10° 42′ 14.0839″[3] |
| Apparent magnitude (V) | 6.75[2] |
| χ Ceti Bb | |
| Right ascension | 01h 49m 23.29444s[4] |
| Declination | −10° 42′ 06.3471″[4] |
| Characteristics | |
| χ Ceti A | |
| Evolutionary stage | main sequence[5] |
| Spectral type | F3 III[6] or F0 V[7] |
| U−B color index | +0.04[2] |
| B−V color index | +0.33[2] |
| χ Ceti Ba | |
| Evolutionary stage | main sequence[3] |
| Spectral type | G3 V[7] |
| U−B color index | +0.12[2] |
| B−V color index | +0.61[2] |
| Variable type | BY Dra[8] |
| Astrometry | |
| χ Ceti A | |
| Radial velocity (Rv) | −1.8[6] km/s |
| Proper motion (μ) | RA: −147.867 mas/yr[1] Dec.: −93.480 mas/yr[1] |
| Parallax (π) | 42.5848±0.1249 mas[1] |
| Distance | 76.6 ± 0.2 ly (23.48 ± 0.07 pc) |
| Absolute magnitude (MV) | +2.83±0.01[9] |
| χ Ceti Ba | |
| Radial velocity (Rv) | −3.89±0.12[10] km/s |
| Proper motion (μ) | RA: −159.846 mas/yr[3] Dec.: −70.666 mas/yr[3] |
| Parallax (π) | 41.8±0.2579 mas[3] |
| Distance | 78.0 ± 0.5 ly (23.9 ± 0.1 pc) |
| Absolute magnitude (MV) | 4.98[11] |
| χ Ceti Bb | |
| Proper motion (μ) | RA: −151.993 mas/yr[4] Dec.: −116.438 mas/yr[4] |
| Parallax (π) | 42.7901±0.0352 mas[4] |
| Distance | 76.22 ± 0.06 ly (23.37 ± 0.02 pc) |
| Details | |
| χ Ceti A | |
| Mass | 1.26[12] M☉ |
| Radius | 1.95[12] R☉ |
| Luminosity | 5.6[12] L☉ |
| Surface gravity (log g) | 3.96[12] cgs |
| Temperature | 6,342[12] K |
| Metallicity [Fe/H] | −0.08[13] dex |
| Rotational velocity (v sin i) | 54.7[13] km/s |
| Age | 1.5[13] Gyr |
| χ Ceti Ba | |
| Mass | 1.03[12] M☉ |
| Radius | 1.00[12] R☉ |
| Luminosity | 0.98[12] L☉ |
| Surface gravity (log g) | 4.53[14] cgs |
| Temperature | 5,804[14] K |
| Metallicity [Fe/H] | −0.09[14] dex |
| Rotation | 10 days[15] |
| Rotational velocity (v sin i) | 2.1[16] km/s |
| Age | 1.1[16] Gyr |
| χ Ceti Bb | |
| Mass | 0.428±0.019[17] M☉ |
| Radius | 0.429±0.017[17] R☉ |
| Luminosity | 0.0090±0.0002[17] L☉ |
| Temperature | 3,332±111[17] K |
| Other designations | |
| χ Cet, GJ 9061, ENG 8 | |
| χ Ceti A: 53 Cet, BD−11°352, FK5 1051, HD 11171, HIP 8497, HR 531, SAO 148036[18] | |
| χ Ceti B (Ba+Bb): EZ Cet, BD−11°351, HD 11131, HIP 8486, SAO 148033, WDS J01494-1042[19] | |
| χ Ceti Bb: TIC 24910400, 2MASS J01492330-1042066[20] | |
| 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.[6] However, Houk and Swift (1999) listed a classification of F0 V,[7] 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.[23]
The secondary, component Ba, shares common proper motion companion with the primary. It is a G-type main sequence star with a classification of G3 V.[7] It is a BY Draconis variable with a periodicity of 8.92 days and a variable-star designation of EZ Ceti.[8]
The tertiary, component Bb, is a proper motion companion to Ba, separated by 6.72" from it.[24] It is much smaller and fainter than either the primary of the secondary.[4][17]