In researching the Danish language, I've read about a series of stops [b̥ d̥ ɡ̊]. What are those? Apparently they are different from the commonplace voiced stops [b d ɡ] and the voiceless stops [p t k] because analysts have gone to the effort of using a voiced letter with a voiceless diacritic. What phenomenon does this represent; some sort of partial voicing?
Danish also has a contrasting series of stops, which at least one source analyzes as [b̥ʰ ɡ̊ʰ] (I'm leaving out the third member because it's different and out of the scope of this question). What are those? How can a partially voiced stop be aspirated? I thought only voiceless stops could be aspirated.
Note: This is not a question about the behavior of Danish stop phonemes. This question is from a purely phonetic standpoint. I'm trying to figure out what sounds these symbols represent, in general and/or specifically in Danish: [b̥ d̥ ɡ̊ b̥ʰ ɡ̊ʰ]