The Rotational Velocity of the Sun

DL Obs 4

SPU-21 Fall 2015

The Doppler Shift of the NaD lines

The doppler shift allows us to measure radial velocity. We will make several spectral measures of the NaD lines (at 5889 and 5896 Angstroms) from the East limb of the Sun and then the West limb of the Sun. Then with the CCD (and attached microscope lens) we take careful measurements of the Doppler shifts of these two lines relative to that of an absorption line in between them, which arises from H2O in the Earth's atmosphere.



We need to derive the most accurate possible minimum positions of the NaD lines vs. the H2O telluric line in order to measure what will be a small Doppler shift.