Measuring star temperature
Posted 14 November 2013 - 05:59 PM
I am sharing it here in case anyone would like to use it, improve on it or critique it.
Posted 16 November 2013 - 08:06 AM
I would recommend extracting the continuum from the spectrum first(ie use the spectrum with the lines removed) so that the absorption lines do not skew the fit. This is particularly important for cooler stars where the absorption lines will dominate the spectrum (and unfortunately also make it difficult to determine the continuum shape with any accuracy in low resolution spectra - try to fit the curve to the high spots in the spectrum rather than through the mean) Also be sure to limit the fit to wavelengths above the Balmer jump at 3646A
Do not be surprised though if your results deviate significantly from the text book values for Teff. Despite what some books say, star spectra are not in general particularly good fits to black body curves.
Incidentally, the 2 column dat files produced by RSpec are not unique to RSpec but can also generated and read by other spectral processing software such as Visual Spec and ISIS, IRAF,MIDAS etc. For maximum compatibility though it is a good idea to export dat files from RSpec with the constant bin size option selected. (This is not the default, I believe)
Posted 16 November 2013 - 11:28 PM
Great point about deleting the absorption lines. That's next on my list!
Posted 17 November 2013 - 09:58 AM
There is an interesting article here on using the Star Analyser to estimate temperature from the spectrum using Visual Spec software
Here they use an empirical correction factor to compensate for the effect of the star not being a perfect black body.