The giant HII region NGC 3576 is ionised by a large star cluster visible in the infrared and at least 10 times brighter than the Orion nebula. Curiously for such a prominent HII region, no very hot O-stars have yet been identified in the central cluster. A 2002 paper finds the brightest star to be the B1 V
FBDC 48. (Although the paper says that the data might allow for this to be a late (cool) O-star as well.)
Avedisova identifies 4 nearby stars that may help to ionise the nebula, including three B-class stars and the O7.5 III giant
HD 97319 (SIMBAD gives an O9.5 Ib class for this star). She places NGC 3576 in the star formation region
SFR 291.30-0.69 with 23 components, including 3 masers and the smaller HII regions
NGC 3576 IRS 1 and
NGC 3581.
You can see a
good visual image of NGC 3576 here and see the
MSX 8μ infrared false-colour image here.
Ionised by a large star cluster visible in the infrared.[
1]
NGC 3576 is one of the brightest HII regions in the galaxy and is at least 10 times brighter than the Orion nebula. The hottest star identified is the B1 V
FBDC 48. (Although the paper says that this might be a cool (late) O-star.[
2]
Notes
1. ^ Persi, P., Roth, M., Tapia, M., et al. (1994). "The young stellar
population associated with the HII region NGC 3576", Astronomy and
Astrophysics, Vol. 282, 474-484. [1994A&A...282..474P]
2. ^ Figuerêdo, E., Blum, R. D., Damineli, A., et al. (2002). "The Stellar
Content of Obscured Galactic Giant H II Regions. IV. NGC 3576", The
Astronomical Journal, Vol. 124, 2739-2748. [2002AJ....124.2739F]