Quote:
Originally Posted by Jon
However, in terms of measuring the Doppler shift of the P Cygni profile - which is what we are debating - the is a simple question. What do you measure - the distance between the centre of the absorption line and the blue-ward or red-ward peak of the saddle, or he barycenter of the entire emission line?
|
I'm not sure whether it is best to measure the fitted centre of the emission line or the text book wavelength. I'd be tempted to use the latter, and that is what I have used, because I don't really understand the cause of the asymmetry of the line profiles.
I believe (could well be wrong) that the end of the blue wing of the absorption gives the maximum velocity, which should represent the material that is heading directly towards us and hence the ejecta velocity.
Due to my general lack of knowledge of the details I'm treating all of my measurements with a high level of uncertainty.