Detailed Images of Spiral Galaxy M81

Hubble's high-resolution images of distinct regions contained within M81 illustrate various structures contained within the spiral galaxy. [Left] The inner bulge and nucleus of M81 are relatively structure free, except for fine dust lanes that wind into the center. Several whitish-colored concentrations of stars, known as globular clusters are easily visible. [Middle] A string of star-forming regions show along a spiral arm, their glowing hydrogen gas appears green in color. A denser concentration of dust is visible along the arms. [Right] Interspersed within the active spiral arms are areas of new star formation. Here, associations of hot blue stars have formed. These massive stars' lifetimes are relatively short compared to the overall age of the galaxy. Their existance and inevitable death will help to enrich the surrounding area with heavier elements which will in turn make more robust, longer-living stars.

About the colours

This image is a composite of many separate exposures made by the ACS instrument on the Hubble Space Telescope. Three filters were used to sample light from broad wavelengths. The color results from assigning different hues (colors) to each monochromatic image. In this case, the assigned colors are: Blue: F435W (B) Green: F606W (V) Red: F814W (I)

About the data

The ACS data was from the HST proposal 10584 : A. Zezas, G. Fabbiano, A. Prestwich, and M. Garcia (Harvard-Smithsonian Center for Astrophysics), J. Gallagher (University of Wisconsin, Madison), J. Miller (University of Michigan), P. Kaaret (University of Iowa), V. Kalogera (Northwestern University), M. Ward (University of Durham), and A. King (University of Leicester); and proposal 10250: J. Huchra, P. Barmby, and B. Mcleod (Harvard-Smithsonian Center for Astrophysics) and J. Brodie and J. Strader (University of California, Santa Cruz).