November 9, 2012
NGC 1491, an emission nebula in Perseus
Image Credit & Copyright: Ken Crawford, Rancho Del Sol Observatory (http://www.imagingdeepsky.com)
NGC 1491 (also designated SH2-206 and LBN 704) is a bright emission nebula and HII region, located on the edge of a vast cloud region of neutral gas, about 10,700 light-years away in the Perseus arm of our Milky Way Galaxy in the constellation Perseus.
HII regions are well known for being places where new stars are born, and are created when ultraviolet radiation from hot stars ionizes the surrounding gas, causing it to glow in visible light. The surrounding dust is also heated by this radiation, so we also see it glow in infrared light.
The blue 11.22 magnitude star, BD +50 ° 886, is illuminating the nebula while its strong stellar wind is “blowing” a bubble in the gas that immediately surrounds it. The intense radiation from the star is also eroding the gas clouds surrounding it.
The entire nebula is quite irregular with a subtle bite cut out of the nebulosity from the east side that creates a darker hollow, and a high surface brightness region — as seen in this image — preceding the star. A faint, elongated haze extends from this patch to the northeast past the star giving an elongated appearance.
This narrowband image of the brighter part of NGC 1491 was processed in the standard Hubble palette.