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Epoch J2000 Equinox J2000
|Right ascension||18h 07m 32.55073s|
|Declination||+28° 45′ 44.9679″|
|Apparent magnitude (V)||3.83|
|Spectral type||B9.5 V|
|U−B color index||–0.07|
|B−V color index||–0.02|
|Variable type||γ Cas|
|Radial velocity (Rv)||–29.5 km/s|
|Proper motion (μ)||RA: –0.02 mas/yr
Dec.: +8.55 mas/yr
|Parallax (π)||9.65 ± 0.16 mas|
|Distance||338 ± 6 ly
(104 ± 2 pc)
|Rotational velocity (v sin i)||194 km/s|
Omicron Herculis is a B9.5V star approximately 106 pc from the Earth. It has an apparent magnitude of 3.83, and an absolute magnitude of -1.29. The star burns bluish-white, and has a luminosity approximately 180x as bright as the Sun. Omicron Herculis is 3.32 solar masses.
Omicron Herculis is an eruptive variable of the Gamma Cassiopeia class, which are rapidly rotating B-class stars with mass outflow.
Omicron Herculis is both a spectroscopic and an interferometric binary star with a separation of 0.1 arcsec.
Omicron Hercules is notable for residing close to the coordinates of the solar apex, the direction towards which the Sun is moving. This was first noticed by William Herschel in 1783, although in his first calculation he identified this point with Lambda Herculis. It will eventually become the brightest star in the sky in approximately 3 million years from today, at -0.4, slightly less bright than Canopus today.
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