Kornephoros (Beta Herculis)
Kornephoros (Beta Herculis) is a star in the constellation Hercules, magnitude 2.8.
The club bearer — Hercules’ brightest star, a giant with a hidden partner.
Kornephoros is Greek for “the club bearer”, a fitting name for the brightest star of Hercules. In July 1899 the American astronomer W. W. Campbell noticed that its speed along our line of sight kept changing, and concluded that an unseen companion was tugging on it. In 1977 Antoine Labeyrie and colleagues finally resolved the pair, using speckle interferometry on the Hale Telescope at Palomar.
The two stars circle each other about every 410 days on a stretched orbit. The main star is a yellow giant of nearly three times the Sun’s mass, swollen to 16 times its width; its partner is a little lighter than the Sun.
Kornephoros was once a hot B-type star much like Zubeneschamali in Libra. Now about 420 million years old, it probably fuses helium in its core. It is not heavy enough to explode, so it will end as a white dwarf, like Sirius B but less massive.
Kornephoros (Beta Herculis) is 140 light-years away: the light we see from it set off around 1885, 7 years after Edison lit his first practical light bulb — the start of light pollution.
Did you know?
- The armpit. Its other old name, Rutilicus, is a corruption of the Latin titillicus, “armpit”. The US Navy gave that name to a cargo ship, USS Rutilicus (AK-113).
- In the river. In Chinese astronomy it is the first star of the Right Wall of the Heavenly Market Enclosure, representing Hézhōng — which R. H. Allen rendered as Ho Chung, “in the river”.
- Capella’s warmer cousin. Astronomers compare it with the main star of Capella: a similar giant, but warmer and brighter.
A yellow star of magnitude 2.8, the brightest in Hercules. Find the Keystone, then drop about 10 degrees south from Zeta Herculis, its south-western corner. It looks single in any amateur telescope.
When and where to see it
It is best placed in the evening sky around June, when it crosses the meridian at about 10 pm local time (around midnight in May). It can be seen from everywhere north of 69°S and never sets north of 69°N.
At its highest it stands 61° up from 50°N, 76° up from 35°N, 69° up from the equator, 34° up from 35°S.
Facts
- Type
- Star
- Constellation
- Hercules
- Designations
- Beta Herculis, β Her, 27 Her, HR 6148, HD 148856, HIP 80816
- Magnitude
- 2.8
- Position
- RA 16h 30.2m, Dec +21° 29′ (J2000)
- Spectral type
- G7IIIaFe-0.5
- Colour
- orange (B−V 0.93)
- Distance
- 140 light-years
- Discovered
- Known since antiquity; W. W. Campbell found its companion from its spectrum in 1899
Open AstroPilot to see when Kornephoros (Beta Herculis) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view.