M101 is a relatively large galaxy compared to the Milky Way. With a diameter of 170,000 light-years it is seventy percent larger than the Milky Way. It has a disk mass on the order of 100 billion solar masses, along with a small central bulge of about 3 billion solar masses.[10]

M101 is noted for its high population of H II regions, many of which are very large and bright. H II regions usually accompany the enormous clouds of high density molecular hydrogen gas contracting under their own gravitational force where stars form. H II regions are ionized by large numbers of extremely bright and hot young stars; those in M101 are capable of creating hot superbubbles.[11] In a 1990 study, 1264 H II regions were cataloged in the galaxy.[12] Three are prominent enough to receive New General Catalogue numbers - NGC 5461, NGC 5462, and NGC 5471.[13]

M101 is asymmetrical due to the tidal forces from interactions with its companion galaxies. These gravitational interactions compress interstellar hydrogen gas, which then triggers strong star formation activity in M101's spiral arms that can be detected in ultraviolet images.[14]

In 2001, the x-ray source P98, located in M101, was identified as an ultra-luminous X-ray source - a source more powerful than any single star but less powerful than a whole galaxy - using the Chandra X-ray Observatory. It received the designation M101 ULX-1. In 2005, Hubble and XMM-Newton observations showed the presence of an optical counterpart, strongly indicating that M101 ULX-1 is an x-ray binary.[15] Further observations showed that the system deviated from expected models - the black hole is just 20 to 30 solar masses, and consumes material (including captured stellar wind) at a higher rate than theory suggests.[16]

The above references are from Wikiopedia

I find this particular framed image from my data very interesting in that the galaxies referenced in Wikeopedia are the same as the photons gathered during my image session. I was very pleased that the image depicts the Ha and HII regions rather nicely.

This was my first ever long imaging session of M101 and will try to gather another 2 hours of data on the next clear night.

I will also post M101 on Astrobin from this data cropped and possibly enlarged to show the Ha regions more clearly.

Click on this image and you will see a much larger full resolution of my M101 data.