Perseus OB1

Perseus OB1 is an OB association in the Northern Celestial Hemisphere in the constellation Perseus. It is centered around the double cluster (NGC 869 and NGC 884),^[6] and has lent its name to the Perseus Arm of the Milky Way.^[8] The brightest member of the association is the blue supergiant 9 Persei.^[4]

Perseus OB1
Double cluster at the heart of Per OB1 Credit: Chrisguidry
Observation data (J2000 epoch)
Constellation	Perseus
Right ascension	02h 21m [1][2]
Declination	+57.6°[1][2]
Mean distance	6.0 kly (1.83 kpc)[3]
Span	1,000 × 750 light years[4]
Radial velocity	−43.4[5] km/s
Physical characteristics
Members	149[6]
OB stars	≥65[7]
Other designations	Per OB1[1]
See also: Stellar association, Moving groups