Quote:
Originally Posted by skysurfer
EDIT: I had the wrong star, too far east. A little bit west of it is the real nova, indeed orangish, so it is spectral class K.
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Both white dwarfs and novae have their own system of spectral designations. We don't know what type of white dwarf this was before it went nova - at least, we have no observational data, the experts may be able to work it out from its current behaviour.
This one is classed as a "FeII" nova because of the presence of ionised iron emission lines now emerging in its spectrum. My guess as to the pink/orange colour would because of the strong Hydrogen alpha emission lines - ionised hydrogen being blasted into space with the initial explosion. Effectively the same stuff that gives the pinkish colour to M42 and the other emission nebulae, but in is case in an incandescent fireball of expanding gas.
Check out the spectrography forum on IIS for more detail - this nova has the spectrography crowd going nuts. Some amateurs are even able to measure the blue shift of those hydrogen emission lines to estimate the speed of the expanding fireball (about 900 km/s, since you asked ;-) )