[sjastro]

TZ Mensae is an Algol type spectroscopic binary with an orbital period of 8.569 days.

The components are of spectral classes A1III and B9V.
The ideal scenario would have been to image the star when each component was in transit but I had no information on this.
Instead the two set of spectral images were taken five days apart.
I would have preferred to have taken the images at half the orbital period but the weather didn't cooperate.

As I am still a beginner at this, I am rapidly learning of the limitations of low resolution spectroscopy.
Since eclipsing binaries are in the line of sight of the observer, the conditions for Doppler shift are at their most favourable.
Even though the attachment shows a "shift" between the spectra, the magnitude of the shift is only around 1 nm which probably reflects a calibration error than any Doppler effect.
At a dispersion of 1.1 nm/pixel, I suppose a minimum shift of 5 nm at 500 nm based on optics and seeing conditions is required to be confident that the shift is real.

The difference in the spectra is the more dominant hydrogen absorption lines
in the 23/03 image perhaps indicating the A1 star was near transit.
What is puzzling however is the Planck curves for blackbody temperature looks remarkably the same for both spectra.
I'd be interested in hearing comments on this apparent discrepancy.

Steven