  | |
| Observation data EpochJ2000 EquinoxJ2000 | |
|---|---|
| Constellation | Taurus |
| χ Tau A | |
| Right ascension | 04h 22m 34.944s[1] |
| Declination | +25° 37′ 45.53″[1] |
| Apparent magnitude (V) | 5.378[2] |
| χ Tau B | |
| Right ascension | 04h 22m 35.550s[3] |
| Declination | +25° 38′ 03.22″[3] |
| Apparent magnitude (V) | 8.423[4] |
| Characteristics | |
| χ Tau A | |
| Spectral type | B9V[4] |
| U−Bcolor index | -0.12[5] |
| B−Vcolor index | -0.04[5] |
| χ Tau B | |
| Spectral type | F8 + G6 + K4 + K4[4] |
| U−Bcolor index | +0.10[5] |
| B−Vcolor index | +0.63[5] |
| Astrometry | |
| χ Tau A | |
| Radial velocity (Rv) | +15.3 ± 3.4[4] km/s |
| Proper motion (μ) | RA: 20.953[1]mas/yr Dec.: -16.495[1]mas/yr |
| Parallax (π) | 11.0472±0.1599 mas[1] |
| Distance | 295 ± 4 ly (91 ± 1 pc) |
| Absolute magnitude (MV) | 0.82 ± 0.18[4] |
| χ Tau B | |
| Radial velocity (Rv) | +14.694 ± 0.081[4] km/s |
| Proper motion (μ) | RA: 15.766[3] mas/yr Dec.: −20.396[3] mas/yr |
| Parallax (π) | 11.5348 ± 0.0857 mas[3] |
| Distance | 283 ± 2 ly (86.7 ± 0.6 pc) |
| Absolute magnitude (MV) | 3.85 ± 0.18 (total) 4.20 ± 0.18 (Ba) 5.27 ± 0.18 (Bb) 7.87 / 7.87 (Bc)[4] |
| Orbit[4] | |
| Primary | χ Tau Ba |
| Companion | χ Tau Bb |
| Period (P) | 17.602309 ± 0.000036 d |
| Eccentricity (e) | 0.2938 ± 0.0013 |
| Inclination (i) | 53.3 ± 0.5° |
| Periastronepoch (T) | 2,448,891.649 ± 0.014 |
| Argument of periastron (ω) (secondary) | 249.43 ± 0.33° |
| Semi-amplitude (K1) (primary) | 41.287 ± 0.080 km/s |
| Semi-amplitude (K2) (secondary) | 48.133 ± 0.080 km/s |
| Orbit[4] | |
| Primary | χ Tau Bab |
| Companion | χ Tau Bc |
| Period (P) | 3,450.6 ± 6.1 d |
| Eccentricity (e) | 0.3560 ± 0.0068 |
| Inclination (i) | 73 ± 6° |
| Periastronepoch (T) | 2,447,546.5 ± 9.7 |
| Argument of periastron (ω) (secondary) | 250.3 ± 1.5° |
| Semi-amplitude (K1) (primary) | 8.625 ± 0.067 km/s |
| Details | |
| Age | 200 ± 50[4] Myr |
| χ Tau A | |
| Mass | 2.60 ± 0.05[4] M☉ |
| Radius | 2.15[6] R☉ |
| Surface gravity (log g) | 4.15 ± 0.14[7] cgs |
| Temperature | 10,300 ± 300[4] K |
| Rotational velocity (v sin i) | 263[7] km/s |
| χ Tau Ba | |
| Mass | 1.19[4] M☉ |
| Surface gravity (log g) | 4.5[4] cgs |
| Temperature | 6,180 ± 150[4] K |
| Rotational velocity (v sin i) | 1 ± 3[4] km/s |
| χ Tau Bb | |
| Mass | 1.02[4] M☉ |
| Surface gravity (log g) | 4.5[4] cgs |
| Temperature | 5,620 ± 150[4] K |
| Rotational velocity (v sin i) | 1 ± 3[4] km/s |
| χ Tau Bc | |
| Mass | ~0.70 / 0.70[4] M☉ |
| Other designations | |
| χ Tau,59 Tau,BD+25° 707,HD 27638,HIP 20430,HR 1369,SAO 76573,ADS 3161 AB,CCDM J04226+2538AB | |
| Database references | |
| SIMBAD | χ Tau A |
| χ Tau B | |
Chi Tauri,Latinised fromχ Tauri, is astar system in theconstellation ofTaurus.Parallax measurements made by theHipparcos spacecraft put it at a distance of about 291light-years (89parsecs) fromEarth. The primary component has anapparent magnitude of about 5.4,[2] meaning it is visible with thenaked eye.
The main component of the system is Chi Tauri A. It is aB-type main-sequence star. Its mass is 2.6 times that of theSun and its surface glows with aneffective temperature of10,300 K. It may be abinary star itself, as suggested fromastrometric data fromHipparcos, although no orbit could be derived.[4]
The secondary component of the system is Chi Tauri B, separated about 19″[4] from Chi Tauri A. It was thought to be a post-T Tauri star from its unusual spectrum,[8] but later studies ruled this out.[4] It is a double-linedspectroscopic binary—the two stars are not resolved but their spectra have periodicDoppler shifts indicating orbital motion. The two stars are anF-type star and aG-type star, respectively, and are designated Ba and Bb.[4]
Theradial velocity of Chi Tauri B has a slow drift indicating the presence of another star in the system. Designated Chi Tauri Bc, this massive object is too dim to be detected, but it appears in Chi Tauri B's spectrum as aninfrared excess. Because of this infrared excess, this unseen component is thought to be a pair ofK-type main-sequence stars both with masses 70% ofthe Sun's. The stars within the system appear to be dynamically interacting.[4]
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