About the Subject

Bode's Galaxy, the bright spiral galaxy just to the left of center in this image, is a "grand design spiral" meaning it has prominent, well defined spiral arms which extend around the entire galaxy. It is one of the nearest spiral galaxies to our own Milky Way at a distance of roughly 12 million light years. Because of its proximity and relative brightness it is a favorite target for amateurs and professionals alike. The galaxy was first discovered by Johann Elert Bode in 1774 and was first cataloged as "Bode's Nebula" before galaxies were known to be separate island universes rather than nebulous regions within our own galaxy. 

The Cigar Galaxy, on the right side of the image, is a starburst galaxy that is undergoing a wave of new star formation, likely caused by a recent gravitational interaction with Bode's Galaxy (M81) when the two passed near each other. The Cigar (M82) is the nearest starburst galaxy to the Milky Way and is considered the prototype for this class of object. Until 2005 it was thought to be an irregular galaxy, but recent observations of spiral arms have caused it to be re-classified as an edge on spiral. The bipolar outflow ("superwind") streaming from the core of M82 is where there are four bright cores of star formation that include strong x-ray sources. Periodic supernovae within the clumps are thought to be the source of the outflow.

You will notice that the background regions around these two galaxies appear to be filled with luminous dust and gas. This material is called the "integrated flux nebula" or "galactic cirrus". It is thought to be interstellar dust and gas located well above or below the plane of the Milky Way that is lit up by the integrated light of the entire galaxy rather than by a single star or cluster of stars. This Integrated Flux (IFN) was possibly observed visually as long ago as the 1780's by William Herschel, but Herschel's descriptions were limited to a couple sentences in his notes, and the IFN was quickly forgotten. Though there have been periodic mentions of high galactic latitude nebulosity, the IFN wasn't truly rediscovered until 2005 by California amateur astronomer, Steve Mandel, using sensitive CCD cameras and a wide field telescope. Imaging the IFN requires very dark skies with minimal light pollution as well as good technique and plenty of integration time.