Some misc notes on Ed's picture of NGC891 (Caldwell 23), The Outer Limits Galaxy http://www.utahastronomy.com/album24/NGC891_Mew_1_6x4_150dpi Distance: 31 M l/yr Diameter: 100,000 l/yr - similar to the Milky Way Discovered: Caroline Herschel, 1784 Coordinates: RA 02h22.6m Dec +42h21m S&T Article: Block, Adam. Nov. 2004. Galaxy NGC 891 in Andromeda. S&T 108(5):136. 2004S&T...108e.136B Analogues: Milky Way; NGC4565 in Coma B (Caldwell 38) Ed's picture images a couple of the distinguishing features of this edge-on spiral: vertical chimneys aka galactic fountains. These are dark nebula "sticks" extending perpendicular to NGC's galactic disk. In Ed's picture a prominent one is seen set-off against the galactic bulge. These chimneys are thought to be the result of nova or supernova heating gas and supporting the dark nebula gas tube against galaxy's gravity. In our own Milky Way, these chimneys are identified as low velocity molecular clouds (LVMC) and/or galactic fountains. These chimney clouds continue to rise, cool and slow. Eventually, gravity becomes dominate and then the clouds fall as high-velocity molecular clouds (HVMC). When HVMC's crash back into the gas and dust of the galactic disk, they set off a burst of stellar birth - snr's and novae that create bubbles. Sol is currently transiting the 500-1000 parsec diameter Local Bubble, which is believed to probably be the result of this process (Olano 2000). Sol is also transiting the smaller 50 parsec diameter Local Chimney, a vertical tube of thin hydrogren gas, which is also believed to be the result of a nova remanent of unknown origin. Like most galaxies, we see only a visible fraction of its total extent. The rotational curve of the NGC 891 galaxy implies an enveloping disk of hydrogren gas extending out many times it's visible diameter. A radio-astronomy contour map of HI gas super-imposed on an optical black/white picture of NGC 891 can be seen in Figure 1 of this article: Swaters, R.A. 12/1997. The HI Halo of NGC 891. 1997ApJ...491..140S http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v491n1/36835/36835.p... Because NGC 891 distance is 31 M l/yr, it is foreground to and not part the more distant (200+ M /yr) Perseus-Pisces supercluster at RA 03h19m and the nearly the same declination (see Caldwell 24, NGC1275). NGC 891 is a member of group of galaxies defined by Tully (1988) as the Triangulum Spur. In popular TV culture NGC 891 was the galaxy shown in the opening credits of the original 1960s "Outer Limits" TV series. For a blast from the past, listen to "Outer Limits" intro using the link "Listen to Samples," at: http://www.amazon.com/exec/obidos/tg/detail/-/B000001P19/002-9010935-6813669... - Canopus56 Other sources: O'Meara, S. 2002. The Caldwell Objects. Sky Pub. pp. 96-99. __________________________________ Yahoo! Mail - PC Magazine Editors' Choice 2005 http://mail.yahoo.com