NGC 2170 is a dusty reflection nebula and stellar nursery that formed about 6 to 10 million years ago, located at the edge of the elliptically shaped, giant star-forming molecular cloud Monoceros, some 2,700 light-years away in the constellation of Monoceros.

NGC 2170 is specifically, the blue nebula in the bottom right quadrant of this image, this region ia approximately 15 light-years across and displays a mix of nebula types. The bluish section are reflection nebulae. The dust particle size in these areas reflects blue light. The reddish areas are emission nebulae, ultraviolet light from nearby stars lights the hydrogen and other gases in the nebula, which then emit light of their own in specific colors. Finally, what looks a bit like black ink spilled across the image are dark absorption nebulae, and are only seen because of the light that they block. In other words, the dark nebula is seen in silhouette.

Copyright: Albert Barr

NGC 1365 taken at Martin Pugh Astrophotography in Australia.

NGC 1365 is barred spiral galaxy in the Fornax cluster. Within the larger long bar stretching across the center of the galaxy appears to be a smaller bar that comprises the core, with an apparent size of about 50″ × 40″.

This second bar is more prominent in infrared images of the central region of the galaxy, and likely arises from a combination of dynamical instabilities of stellar orbits in the region, along with gravity, density waves, and the overall rotation of the disc. The inner bar structure likely rotates as a whole more rapidly than the larger long bar, creating the diagonal shape seen in images. The spiral arms extend in a wide curve north and south from the ends of the east-west bar and form an almost ring like Z-shaped halo.

Astronomers think NGC 1365's prominent bar plays a crucial role in the galaxy's evolution, drawing gas and dust into a star-forming maelstrom and ultimately feeding material into the central black hole.

NGC 1365, including its two outer spiral arms, spreads over around 200,000 light-years. Different parts of the galaxy take different times to make a full rotation around the core of the galaxy, with the outer parts of the bar completing one circuit in about 350 million years. NGC 1365 and other galaxies of its type have come to more prominence in recent years with new observations indicating that the Milky Way could also be a barred spiral galaxy. Such galaxies are quite common — two thirds of spiral galaxies are barred according to recent estimates, and studying others can help astronomers understand our own galactic home.

Copyright: Albert Barr