Zeta Herculis

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Zeta Herculis A/B
Observation data
Epoch J2000
Constellation
(pronunciation)
Hercules
Right ascension 16h 41m 17.16s
Declination +31° 36′ 09.8″
Apparent magnitude (V) 2.89
Characteristics
Spectral type G0 IV/K0 V
U-B color index 0.21
B-V color index 0.64
Variable type Suspected
Astrometry
Radial velocity (Rv) -69.9 km/s
Proper motion (μ) RA: -462.64 mas/yr
Dec.: 345.08 mas/yr
Parallax (π) 92.64 ± 0.60 mas
Distance 35.2 ± 0.2 ly
(10.79 ± 0.07 pc)
Absolute magnitude (MV) 2.72
Details
Mass 1.5/0.85 M
Radius 2.5/0.92 R
Luminosity 6/0.65 L
Temperature 5780/5420 K
Metallicity ? % Sun
Rotation <10 km/s.
Age 3.8 × 109 years
Other designations
ζ Her, 40 Her, 40 Herculis, GJ 635, HR 6212, BD +31°2884, HD 150680, LHS 3234, LTT 14952, GCTP 3799.00, SAO 65485, NSV 07915, WDS 16413+3136, HIP 81693.

Zeta Herculis (ζ Her, ζ Herculis) is a binary star system in the constellation Hercules. The primary star is a sub-giant that is somewhat larger than the Sun and has just begun to evolve away from the main sequence. It is orbited by a smaller and fainter star that is separated from the primary by just over 1 arcsec. The stars orbit each other with a period of 34.5 years and a semi-major axis of 1.36". Stars A & B are separated each other by an average separation of 14.65 AUs and swing as close as 8 AUs and as far away as 21.3 AUs.

This system forms part of the Zeta Herculis moving group of stars. This group includes: δ Trianguli, φ2 Pavonis, ζ Reticuli, 1 Hydrae, Gl 456, Gl 678, and Gl 9079.[1]

[edit] References

  1. ^ G. F. Porto de Mello, L. da Silva (1991). "On the physical existence of the Zeta HER moving group - A detailed analysis of Phi exp 2 Pavonis". Astronomical Journal 102: 1816–1825. doi:10.1086/116006. 

[edit] External links