Arcturus
system
Arcturus is the fourth-brightest star in the night sky and the brightest in the northern hemisphere, 36.7 light-years away in Bootes. An ageing orange giant about 25 times the Sun's width and 170 times its light, it belongs to an ancient stream of stars that plunges through the Galactic disk — most likely the remains of a small galaxy the Milky Way swallowed long ago. No planet is known.
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Key facts
Type
Orange giant
Distance
36.7 light-years
Brightness
V −0.05 — 4th-brightest star
Confirmed planets
0
Science
Classification
- Type
- Single red-giant system
- Central star
- Arcturus — K1.5III orange giant (~4286 K, ~25 R☉)
Planets
- Confirmed planets
- None
- Notable
- Member of the Arcturus stellar stream · likely accreted from a disrupted dwarf galaxy
Distance
- Distance
- 36.7 light-years · brightest star of the northern sky
How we know
- Note
- No planet is confirmed around Arcturus, so none is shown. Its light opened the 1933 Chicago World's Fair, and in 1718 Halley used it to prove the stars drift. Map distance is symbolic; the real gap is 36.7 light-years.
Discovery & history
- Method
- Naked-eye star
- Name
- Greek for 'guardian of the bear'; Alpha Bootis, brightest of the Herdsman.
Known since antiquity; in 1718 Halley found it had moved since Greek times, the first proof that the 'fixed' stars drift. No planet is known.
Images
Images from open archives · credit shown per image