Edge on Barred Spiral Galaxy NGC4631
| Object Data | |
| Description | This is an edge view of a
barred spiral, and you are looking nearly straight down the central bar.
The bar is long and thin, and the spiral arms sprouting from each end of
the bar are only about one quarter of a rotation in extent (see image of
M66 for a top view of a barred
spiral). The arm on the far side of the galaxy is largely obscured from view, but it begins just to the left of center and swings gracefully to the right. What you can see of this far arm is its inside portion, which is dominated by bright star forming regions that show up as purple splotches in this image. The purple color is a mixture of red light from clouds of ionized hydrogen gas called HII regions, and blue light from hot young stars embedded within these clouds (see image of NGC2024 and note the color in the lower right corner). The arm on the near side of the galaxy begins just to the right of center and swings off to the left. You are seeing the outside of this arm, which is dominated by cool dark dust clouds that have little or no color and appear mostly gray in this image. These large clouds, common in the outer reaches of spirals, obscure most of the central bar (yellow in color from billions of middle aged stars), and many of the star forming regions on the inside of this arm (purple). The overall shape is distorted somewhat by gravitational effects from nearby galaxy NGC4656, which is well off the lower left of this field of view. The more distant elliptical galaxy is NGC4627. |
| Constellation | Canes Venatici, the two hunting dogs of Bootes: Astarion and Chara. |
| Right Ascension | 12h 42m 17s |
| Declination | +32° 31' 24" |
| Magnitude | 9.7 |
| Angular size | 15.2 arcminutes |
| Distance | 9.7 megaparsecs (31 million light years) |
| Radial Velocity | 606 kilometers per second |
| Image Data | |
| Photographer | Fred Lehman |
| Main Scope | Meade 12" LX200 @ f/5.0 (1525mm) |
| Guide Scope | Orion 120mm refractor @ f/3.75 |
| Guide Camera | SBIG STV |
| Imaging Camera | Starlight Xpress MX7C |
| Resolution | 752 x 580 @ 1.2 arcseconds per pixel |
| Exposure | 15 exposures of two minutes each. Aligned, stacked, and processed with AstroArt. Two luminance frames were discarded due to slight streaking from light puffs of wind. The lower resolution color frames were not affected. |
| Date | April 4, 2003 |
| Location | Sawgrass Recreational Park in Broward County, Florida |