Theta Tauri
Theta Tauri (θ Tauri, abbreviated Theta Tau, θ Tau) is a wide double star in the constellation of Taurus and a member of the Hyades open cluster.
Hyades showing θ Tauri | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Taurus |
| θ1 Tauri | |
| Right ascension | 04h 28m 34.49603s |
| Declination | +15° 57′ 43.8494″ |
| Apparent magnitude (V) | +3.84 |
| θ2 Tauri | |
| Right ascension | 04h 28m 39.74070s |
| Declination | +15° 52′ 15.1745″ |
| Apparent magnitude (V) | +3.35 - 3.42 |
| Characteristics | |
| θ1 Tauri | |
| Spectral type | G9 III Fe-0.5 |
| θ2 Tauri | |
| Spectral type | A7 III |
| Variable type | δ Scuti |
| Astrometry | |
| θ1 Tauri | |
| Parallax (π) | 21.4183 ± 0.3731 mas |
| Distance | 152 ± 3 ly (46.7 ± 0.8 pc) |
| Absolute magnitude (MV) | +0.416 |
| θ2 Tauri | |
| Parallax (π) | 20.8354 ± 0.3731 mas |
| Distance | 157 ± 3 ly (48.0 ± 0.9 pc) |
| Absolute magnitude (MV) | +0.30/+1.44 |
| Orbit | |
| Primary | A |
| Companion | B |
| Period (P) | 5,997 days |
| Eccentricity (e) | 0.64 |
| Semi-amplitude (K1) (primary) | 8.39 km/s |
| Orbit | |
| Primary | Aa |
| Companion | Ab |
| Period (P) | 140.7302 days |
| Semi-major axis (a) | 18.91″ |
| Eccentricity (e) | 0.7360 |
| Inclination (i) | 47.8° |
| Semi-amplitude (K1) (primary) | 32.95 km/s |
| Semi-amplitude (K2) (secondary) | 43.68 km/s |
| Details | |
| Aa | |
| Mass | 2.86 M☉ |
| Radius | 4.4 R☉ |
| Luminosity | 59 L☉ |
| Surface gravity (log g) | 3.6 cgs |
| Temperature | 7,800 K |
| Rotational velocity (v sin i) | 68.4 km/s |
| Ab | |
| Mass | 2.16 M☉ |
| Radius | 2.7 R☉ |
| Luminosity | 21 L☉ |
| Temperature | 7,800 K |
| Rotational velocity (v sin i) | 113 km/s |
| Age | 650 Myr |
| θ1 Tauri | |
| Mass | 2.67 M☉ |
| Radius | 10.55 R☉ |
| Luminosity | 71 L☉ |
| Surface gravity (log g) | 3.21 cgs |
| Temperature | 5,080 K |
| Metallicity [Fe/H] | +0.14 dex |
| Rotational velocity (v sin i) | 1.40 km/s |
| Age | 510 Myr |
| Other designations | |
θ Tauri | |
| θ1 Tauri: 77 Tauri, BD+15 631, HD 28307, HIP 20885, HR 1411, SAO 93955 | |
| θ2 Tauri: Chamukuy, 78 Tauri, BD+15 632, HD 28319, HIP 20894, HR 1412, SAO 93957 | |
| Database references | |
| SIMBAD | θ1 Tauri |
| θ2 Tauri | |
θ Tauri is composed of two 3rd magnitude stars, designated Theta1 Tauri (Theta Tauri B) and Theta2 Tauri (Theta Tauri A). Theta² is brighter, hence the pair are sometimes referred to as Theta Tauri B and A, respectively. They are separated by 5.62 arcminutes (0.094°) on the sky. Based upon parallax measurements, Theta¹ Tauri is located at a distance of 152 ly (47 pc), while Theta² Tauri is at a distance of 157 light-years (48 parsecs). θ Tauri A and B are both spectroscopic binaries; the four components are designated Theta Tauri Aa (formally named Chamukuy /ˈtʃɑːmuːkuːi/), Ab, Ba, and Bb.
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