by Ann » Sat May 02, 2015 5:59 am
This is a very fine portrait of one of the most photographed galaxies in the sky. Personally I love how it brings out the various stellar populations in NGC 5194, or M51, the Whirlpool galaxy. Note how a fine lattice of dust lanes is crisscrossing the the small bright yellow bulge. Note how faithfully the blue clusters and pink nebulas outline the major spiral arm pattern, although raging fires of hot blue stars have broken the arm symmetry at about one o'clock. Note how the lower left arm seems to flare out at the end, revealing an intermediate to old underlying smooth population.
One of the most amazing background galaxies seen in the direction of a well-known bright galaxy can be seen near the top and slightly to the right in this picture. It looks much like a
blue dumbbell, set inside a blue circle. What is it?
My guess is that the straight blue line of the "dumbbell" is a blue bar.
An old image of NGC 7741 by Adam Block clearly reveals the straight blue bar of that galaxy. The background galaxy in today's APOD likely has a similar bar. So what are the "weights" of the dumbbell, then? I guess they are bar-end enhancements.
A picture of NGC 4151 by Antonio Fernandez clearly reveals the "bar-end enhancements" of that galaxy, even though the bar itself is too weak to be seen. Antonio's image also shows us that the bar-end enhancements of NGC 4151 are really the brightest part of a bluish ring surrounding the yellow bulge. I guess we are seeing such a bluish ring in the background galaxy near M51. What we don't see in that galaxy is a yellow center and spiral arms!
Ann
This is a very fine portrait of one of the most photographed galaxies in the sky. Personally I love how it brings out the various stellar populations in NGC 5194, or M51, the Whirlpool galaxy. Note how a fine lattice of dust lanes is crisscrossing the the small bright yellow bulge. Note how faithfully the blue clusters and pink nebulas outline the major spiral arm pattern, although raging fires of hot blue stars have broken the arm symmetry at about one o'clock. Note how the lower left arm seems to flare out at the end, revealing an intermediate to old underlying smooth population.
One of the most amazing background galaxies seen in the direction of a well-known bright galaxy can be seen near the top and slightly to the right in this picture. It looks much like a [url=http://png-4.findicons.com/files/icons/2472/pretty_office_icon_set_part_7/128/sport_dumbbell.png]blue dumbbell[/url], set inside a blue circle. What is it?
My guess is that the straight blue line of the "dumbbell" is a blue bar. [url=http://www.noao.edu/outreach/aop/observers/n7741block.jpg]An old image of NGC 7741 by Adam Block[/url] clearly reveals the straight blue bar of that galaxy. The background galaxy in today's APOD likely has a similar bar. So what are the "weights" of the dumbbell, then? I guess they are bar-end enhancements. [url=http://asterisk.apod.com/download/file.php?id=17800&mode=view]A picture of NGC 4151 by Antonio Fernandez[/url] clearly reveals the "bar-end enhancements" of that galaxy, even though the bar itself is too weak to be seen. Antonio's image also shows us that the bar-end enhancements of NGC 4151 are really the brightest part of a bluish ring surrounding the yellow bulge. I guess we are seeing such a bluish ring in the background galaxy near M51. What we don't see in that galaxy is a yellow center and spiral arms!
Ann