Theta Tauri
Binary star in the constellation Taurus
From Wikipedia, the free encyclopedia
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 34.49209s[1] |
| Declination | +15° 57′ 44.2832″[2] |
| Apparent magnitude (V) | +3.84 |
| θ2 Tauri | |
| Right ascension | 04h 28m 39.74455s[1] |
| Declination | +15° 52′ 15.1226″[2] |
| Apparent magnitude (V) | +3.35 - 3.42[3] |
| Characteristics | |
| θ1 Tauri | |
| Spectral type | G9 III Fe-0.5[4] |
| θ2 Tauri | |
| Spectral type | A7 III[5] |
| Variable type | δ Scuti[3] |
| Astrometry | |
| θ1 Tauri | |
| Parallax (π) | 21.4183±0.3731 mas[1] |
| Distance | 152 ± 3 ly (46.7 ± 0.8 pc) |
| Absolute magnitude (MV) | +0.416[6] |
| θ2 Tauri | |
| Parallax (π) | 20.8354±0.3731 mas[2] |
| Distance | 157 ± 3 ly (48.0 ± 0.9 pc) |
| Absolute magnitude (MV) | +0.08[7] |
| Orbit[8] | |
| Primary | A |
| Name | B |
| Period (P) | 5,997 days |
| Eccentricity (e) | 0.64 |
| Semi-amplitude (K1) (primary) | 8.39 km/s |
| Orbit[9] | |
| Primary | Aa |
| Name | 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[10] M☉ |
| Radius | 4.4[10] R☉ |
| Luminosity | 59[9] L☉ |
| Surface gravity (log g) | 3.6[10] cgs |
| Temperature | 7,800[10] K |
| Rotational velocity (v sin i) | 68.4[9] km/s |
| Ab | |
| Mass | 2.16[10] M☉ |
| Radius | 2.7[10] R☉ |
| Luminosity | 21[9] L☉ |
| Temperature | 7,800[9] K |
| Rotational velocity (v sin i) | 113[9] km/s |
| Age | 650[9] Myr |
| θ1 Tauri | |
| Mass | 2.67[11] M☉ |
| Radius | 9.42±0.22[12] R☉ |
| Luminosity | 47.7±2.3[12] L☉ |
| Surface gravity (log g) | 3.21[11] cgs |
| Temperature | 4,940±55[12] K |
| Metallicity [Fe/H] | +0.14[11] dex |
| Rotational velocity (v sin i) | 1.40[11] km/s |
| Age | 510[11] 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.
Nomenclature
θ Tauri (Latinised to Theta Tauri) is the double star's Bayer designation;[citation needed] θ1 Tauri and θ2 Tauri those of its two constituents. The designations of the two constituents as Theta Tauri A and B, and those of the four components - Theta Tauri Aa, Ab, Ba and Bb - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[13]
In the mythology of the Maya peoples, Theta Tauri is known as Chamukuy, meaning a small bird in the Yucatec Maya language.[14] In 2016, the IAU organized a Working Group on Star Names (WGSN)[15] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[16] It approved the name Chamukuy for the component Theta Tauri Aa on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[17]
In Chinese, 畢宿 (Bì Xiù), meaning Net, refers to an asterism consisting of Theta² Tauri, Epsilon Tauri (named Ain), Delta³ Tauri, Delta¹ Tauri, Gamma Tauri, Alpha Tauri (Aldebaran), 71 Tauri and Lambda Tauri.[18] Consequently, the Chinese name for Theta² Tauri itself is 畢宿六 (Bì Xiù liù), "the Sixth Star of Net".[19]
Properties
Theta Tauri A has a mean apparent magnitude of +3.40. It is classified as a Delta Scuti type variable star and its brightness varies from magnitude +3.35 to +3.42 with a period of 1.82 hours.[21] Its primary component, Theta Tauri Aa, is a white A-type giant. The secondary, Theta Tauri Ab, is of the 6th magnitude and is 0.005 arcseconds, or at least 2 AU, distant. It completes an orbit once every 141 days.
Theta Tauri B is the dimmer constituent. Its primary component, Theta Tauri Ba, is an orange K-type giant with an apparent magnitude of +3.84. The secondary, Theta Tauri Bb, is of the 7th-magnitude. It has a mass of 1.31 M☉ and orbits the primary every 16.26 years on a fairly eccentric (at 0.570) orbit.[22]