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| Cigar Galaxy (M82), May 12, 2023 |
One Eyed Wonder
The young man had only one good eye, yet he saw things no one had seen before.
It was New Year’s eve, the year 1774. In the port city of Hamburg in what would become present day Germany, the 27 year old astronomer was observing the night sky, about to make a discovery that would bear his name.
Using his telescope he scanned the area near the head of Ursa Major, the Great Bear when a pair of wispy nebulous patches caught his eye. In his journal he scribbled these notes:
“I found through the seven-foot telescope, closely above the head of UMa, east near the star d at its ear, two small nebulous patches separated by about 0.75 degrees, .... The patch Alpha (M81) appears mostly round and has a dense nucleus in the middle. The other, Beta, on the other hand, is very pale and of elongated shape. ... Beta was too faint and disappeared from my eyes as soon as I shifted apart the halves of the objective glass.” The man was Joahann Elert Bode, a home-schooled son of a businessman, who showed great promise early in life in mathematics, and despite having only one good eye, in astronomy. On that New Year's eve, he had just discovered a pair of galaxies, which he then thought to be nebulae. These would be eventually known as Bode's galaxy and the Cigar galaxy and a few years later make it to the catalog of French comet hunter Charles Messier as M81 and M82.
The above image is of M82, the Cigar galaxy, the fainter of the pair as photographed from my backyard in New Jersey, about 248 years after Bode's discovery, and nearly that many years after America as we know it came to exist.
A Smoking Cigar
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M82 composite with HST data in red and Chandra X-ray data
in blue. Source: Nasa |
M82, also known as the Cigar galaxy for its unique shape, is both a Seyfert and a "starburst" galaxy. The
Seyfert class is about 10% of all galaxies with very bright quasar like cores. Unlike quasars, the whole galaxy is visible possibly since they are much closer to us (millions instead of billions of light years). M82, is thought to be a spiral galaxy seen edge on at about 12 million light years. Filaments of red plumes of gas are seen to be pouring out of its center and unusual dark lanes form a web around its core. This is best visible in infrared and X-Rays. It is believed that the gases at its core are collapsing under gravity and as a result forming stars at a rate 10 times faster than typical galaxies. This type of galaxy is called a "Starburst" galaxy. The starburst activity is believed to have started hundreds of million of years ago and expected to last tens of millions of years, gradually depleting the galaxy of its star forming matter.
Close Encounters
While the smoking gun points to an unusual event in the life of the galaxy, the culprit is still at large. In one possible scenario, astronomers believe it had a close encounter with a nearby galaxy which brushed past it, stirring up the gases in its center. As a result, these core gases are now seen collapsing upon themselves and causing a furious rate of star formation like the grand finale of a cosmic fireworks show.
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| Source: NASA |
The interacting galaxy in question may have been Bode's galaxy (M81) or nearby NGC 3077. It may also be that NGC 3077 was not involved in the crime but was born when M81 and M82 interacted. A third possibility is a galaxy that is invisible since it got swallowed by M82 in the interaction.
So what really happened at M82 that ignited the firestorm? We may never find out for sure in the absence of a reliable witness. Unless, we get a hint from the most famous bear of all.
Reference
Photography
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Celestron 127 SLT OTA with 0.6x focal reducer
Celestron AVX mount, ZWO ASI294MC Pro cooled camera, guided
20x180s light frames with calibration frames
Capture Software: CPWI, NINA, PHD
Processing Software: DeepSkyStacker, GIMP, TopazDeNoise AI
Further Reading
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