NGC 5474

Click on image for larger version.

NGC 5474 is an asymmetric spiral galaxy and it it is being dramatically disturbed by its much larger neighbor M101. With respect to this image, M101 is several fields away towards the upper left direction. At first glance, it might appear that M101 is somehow gravitationally dragging the nucleus right out of NGC 5474. However, astronomers that model these kinds of galactic interactions on a computer find a slightly different story. When using tens (if not hundreds) of thousands of point masses for stars, astronomers found that the asymmetry displayed in NGC 5474 is probably relatively short lived. We just happen to be looking at this galaxy in a state of "sloshed" agitation. As NGC 5474 orbits M101, the amount of asymmetry depends of the relationship between the direction of orbital revolution about M101 and the sense of rotation for NGC 5474's disk. If the revolution is opposite that of disk rotation, as it is in the case of NGC 5474, then the lopsided state can survive for many galactic rotations after an initial (strong) tidal perturbation.

Note that the seemingly grainy appearence of this galaxy is due to partially resolving some of the brighter stars in the disk (v=20-21). A healthy sprinkling of pink starforming regions, and blue (young) stellar associations can also be seen along the spiral structure of the galaxy.


20in RC Optical Systems telescope Operating at f/8.4
Paramount ME Robotic Telescope Mount
SBIG ST10XME CCD camera with color filter wheel

L R G B color production was used to create this image.

Luminance = 90 minutes binned 1x1
Red = 20 minutes binned 2x2
Green = 20 minutes binned 2x2
Blue = 20 minutes binned 2x2

  • Digital Development (DDP) via Maxim/DL was also used in order to display the the very dim and very bright details of the image simultaneously.

  • Minimum credit line: Adam Block/NOAO/AURA/NSF

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    Updated: 5/20/2004