Spinning dust

"Spinning dust" or more formally anomalous microwave dust correlated emission is a new galactic emission mechanism proposed to be generated by very rapidly spinning small dust grains. This was first discovered as a by-product of CMB experiments which make very sensitive measurements of the microwave sky which have to assess comtamination from the galaxy.

It was first seen as a surprising statistical correlation of centimetric wavelength microwave signals in the DMR instrument on board the COBE satellite with far-infrarad data at tenths of a millimeter wavelength of the DIRBE instrument on the same satellite. This signal therefore traced the warm galactic dust emission which was unexpected as extrapolated dust signal at DMR wavelengths should have been orders of magnitude lower than the signal seen. The suggestion at the time was the correlation was due to free-free emission from ionized gas caused by young hot stars which are formed in these dusty regions.