Theta Tauri

From Wikipedia, the free encyclopedia
Jump to: navigation, search
θ¹ Tauri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Taurus
Right ascension 04h 28m 34.49603s[1]
Declination +15° 57′ 43.8494″[1]
Apparent magnitude (V) +3.84
Absolute magnitude (V) +0.416[2]
Distance 154 ± 2[1] ly
(47.3 ± 0.6 pc)
Spectral type K0 IIIb Fe-0.5
Other designations
77 Tau, BD+15 631, HD 28307, HIP 20885, HR 1411, SAO 93955.
θ² Tauri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Taurus
Right ascension 04h 28m 39.74070s[1]
Declination +15° 52′ 15.1745″[1]
Apparent magnitude (V) +3.40
Distance 150 ± 3[1] ly
(46.1 ± 1.0 pc)
Spectral type A7 III
Other designations
Phaesula, 78 Tau, BD+15 632, HD 28319, HIP 20894, HR 1412, SAO 93957.

Theta Tauri (θ Tau, θ Tauri) is a double star in the constellation Taurus and a member of the Hyades open cluster. It dominated by two 3rd magnitude stars, θ¹ Tauri and θ² Tauri, which are separated by 5.62 arcminutes (0.094°) on the sky. Based upon parallax measurements, the first component, θ¹ Tauri, is located at a distance of 154.4 ly (47.3 pc), while the second component, θ² Tauri is at a distance of 150.4 light-years (46.1 parsecs).[1] If these estimates are correct, then the two components are separated by about four light years and hence are unlikely to form a binary star system.

θ¹ Tauri is the dimmer star, an orange K-type giant with an apparent magnitude of +3.84. θ² Tauri is a white A-type giant with a mean apparent magnitude of +3.40. θ² Tauri 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.

Both bright stars are spectroscopic binaries and have at least one closer companion. θ¹ Tauri has a 7th magnitude companion 0.082 arcseconds, or at least 4 astronomical units (AU), away from the primary. θ² has a 6th magnitude companion 0.005 arcseconds, or at least 2 AU, distant. It completes an orbit once every 141 days.

Culture signification[edit]

The Yucatec Maya say that this star is chakumuy, the name of small bird.[3]


  1. ^ a b c d e f g van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 
  2. ^ Böhm-Vitense, Erika; et al. (December 2000), "Ultraviolet Emission Lines in BA and Non-BA Giants", The Astrophysical Journal, 545 (2): 992−999, Bibcode:2000ApJ...545..992B, doi:10.1086/317850. 
  3. ^ p. 253, Star gods of the Maya: astronomy in art, folklore, and calendars, Susan Milbrath, Texas, University of Texas, 1999.

External links[edit]