About five years ago there was a brief flurry of posts about a mysterious faint band of emission roughly three degrees wide and thirty degrees long stretching from the base of the LMC all the way to Triangulum Australe. At the time only eight observers had ever reported it, over a period from 2005 to 2018. There was no info about it at all in the professional literature. The observers were all experienced enthusiasts who kept records of their observations. Could it be eight observers with solid reputations had been seized with a decade-long case of delusions of glimmer?
Timo Karhula, who observes from Geraldton, was one of those observers. Dave Riddle and Chris Beere were two others. I logged the emission several times between 2013 and 2018. The tricky bit is that the luminosity is so feeble that it can be seen only in Bortle 1 skies on ultra-clear nights where there are no human-originated lights anywhere. This limits observing locales to the Chilean Andes, Namibia, the Karoo aridlands in South Africa, and the w-a-a-y outback in Australia.
Since there was no mention of this emission in the professional literature, I had to work backwards from the observations to likely causes. After two years of research in the professional papers, the emission has turned out to be several faint clumps of Galactic dust clouds 240 parsecs high in the Milky Way thin disc whose sole illumination is the combined light of the entire Milky Way. Most galactic dust clouds emit only a feeble gray-mauve coloured light well below the 25 MPSAS seeing limit of the dark-adapted human eye. The Magellan's Ghost emission reaches a barely-visible 24.5 MPSAS only because the local magnetic fields surrounding a series of dust clumps in the Milky Way's spiral inter-arm have been deformed by the shock waves of a series of supernovae in the Vela Shock Zone. The Vela Shock Zone is a slowly-dissipating ancient Giant Molecular Cloud that has spawned at least 12 supernovae and 10 star clusters over the last two million years. The dust clouds are magnetically sensitive because about half the dust particles are based on silica and sulphur compounds, which have a dipole structure that responds by lining up with magnetic fields. In Magellan's Ghost they form into a planar structure that polarizes light instead of diffusing it. We just happen to be in the line of sight of those reflections.
Magellan's Ghost is a singular case of amateur astronomers spotting something the professionals have not, and then going to the trouble of figuring out what they see and presenting the results with the same rigour as the professionals.
A new report from my just-begun online publication "Sky Candy" tells the complicated story of how the physics of Magellan's Ghost was finally tracked down. It is a bit of a chewy read, but the pictures make it all easy to grasp. It is freely downloadable at
https://issuu.com/douglasbullis/docs...st_150dpi_14mb . Enjoy the read. =Doug Bullis in South Afric
