Ursa Major
RA: 09 55 52
Dec: +69 40 47
Magnitude 8.4
11.4’ x 4.3’
This remarkable galaxy is better known as Messier 82, and because of that it’s easy to forget it’s also part of the Arp Catalog. It’s one of the brighter objects in Messier’s list, and is often referred to as “Bodes Galaxy” after discoverer Johann Bode, who first came across it in 1774.
What’s most interesting to me though, is that it’s the nearest starburst galaxy at only 11.8 million light years away, and that this activity can be seen when conditions allow.
The most recent starburst activity was probably the result of a close passage to nearby M81 about 100 million years ago, and greatly increased star creation in M82. Previous encounters between the two galaxies had created superclusters of stars concentrated around the core, a couple of which seem to be responsible for the massive polar outflows from either side of M82’s core – this is what Arp, and many other astronomers, considered to be the result of a titanic explosion within the core of M82.
It has since been discovered that supernovae popping off in these super star clusters every 10 years, on average, fuels the polar outflow. They’re easily seen as the dark lanes carving up the core of M82 in relatively small telescopes, but beyond that they’re extremely difficult to see. But not impossible.
During a memorable October 2015 night on Steens Mountain in southeastern Oregon with my 28-inch f/4 scope, the core area of M82 sharpened into a view that was simply astounding.
My notes:
“Holy smokes – all the dark nebulae are lacy when the seeing settled down – amazing sight covering the central half of the galaxy. Never even suspected this before! 408x, 21.47 SQM”
Although I didn’t mention them in my notes, I saw – and sketched - several bright knots near the core, which I later found out to be some of the brighter super star clusters, including the two (A and C) that are responsible for the polar outflows.
M82bOutsidePhotoCropBrightenedand SharpenedStars.jpg M82bOutsidePhotoCropBrightenedand SharpenedStars_INVERT_CROP_rotated.jpg
You can read more about this observation here. Scroll about a third of the way down the page for the details, and you’ll find an annotated version of my sketch that denotes the A and C super star clusters.
I’d observed M82 many times before this revelatory observation, and think the difference was a combination of the high altitude (2260 meters) excellent transparency, and steady seeing coming together. There was significant air glow that night though, so conditions could have been even better, but that will have to wait for another, even luckier night.
Give it go and let us know!
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