Blue-white main-sequence star · Scorpius

Acrab B

Also known as: β² Scorpii (β² Sco), HIP 78821

mag 4.9400 light-years

About

Acrab B (β² Scorpii) is a blue-white main-sequence star of magnitude 4.9 in Scorpius, about 400 light-years away.

Acrab B is in the constellation Scorpius.
Best evenings: around early July it is highest at about 9 pm (10 pm in summer time); a month earlier, two hours later.
Where on Earth: it is seen well, at least 10° up, from south of 60° N.

When it rises and sets tonight, how high it climbs and how much the Moon gets in the way are worked out in your browser for your place.

EyesNeeds a dark sky away from city lights.
Binoculars (10×50)A sharp point; binoculars bring out its colour and the fainter stars around it.
Telescope (6–8 inch)Still a point of light at any magnification — stars are too far away to show a disc. Low in the sky, bright stars twinkle and flash colours.

Stars look the same in any instrument: brighter and sharper, but never bigger.

Proper name	Acrab B
Designation	β² Scorpii (β² Sco)
Hipparcos number	HIP 78821
Type	Blue-white main-sequence star
Spectral type	B2V
Colour	WhiteB−V colour index −0.02
Magnitude	4.9The smaller the number, the brighter.
Distance	400 light-yearsThe light you see left it around 1630.
Proper motion	0.035″ per year across the sky
Constellation	Scorpius
Right ascension (J2000)	16h 05m 26.6s
Declination (J2000)	−19° 48′ 07″