M81 in True-Color

This true-color composite CCD image shows the familiar appearance of M81 (NGC 3031). The central bulge has the yellowish color of an old stellar population, fading to the blue tints of star-forming regions in the outer spiral arms. This is a "grand-design" spiral, perhaps due to an encounter with neighboring M82 outside the field to the north (top). Dust lanes also marking the spiral pattern are especially visible where they block the background light of the bulge (which they give a reddish hue, blocking blue light more effectively than red).

This image was taken with a focal-reducer camera on the 1.3-meter (50-inch) telescope on McGraw-Hill Observatory on Kitt Peak, Arizona, and was provided by Greg Bothun (University of Oregon). The field shown is 8.7 by 12.3 arcminutes in size. The relay optics needed to image such a nearby galaxy all at once produced reflections of the brighter stars, visible as red or blue patches around the image edge; the black centers of bright star images are due to digital overflow in the camera electronics.

M81 multiwavelength data | Messier gallery | Galaxies | Image gallery | UA Astronomy | Bill Keel's home page

Last changes: 5/2001      © 2001