The elemental composition of a star's atmosphere is essential to understanding its evolution. Sirius A (Alpha Canis Majoris) is ideal for spectral analysis due to its slow rotation, lack of atmospheri..
The elemental composition of a star's atmosphere is essential to understanding its evolution. Sirius A (Alpha Canis Majoris) is ideal for spectral analysis due to its slow rotation, lack of atmospheric convection. Its parameters, mass, radius, surface gravity, and effective temperature, are all constrained to 1%. Kurucz and Furenlid (1979) published Sample Spectral Atlas for Sirius, however their atlas only covered 354 nm to 440 nm in wavelength. A spectral analysis from 124 nm to 870 nm is necessary to achieve a more accurate abundances using prominent lines of the elements O, Na, Mg, Si, Ca, Cr, Fe, and Zn which lie outside the range covered by Kurucz and Furenlid. To expand the spectral atlas, we used data from the Very Large Telescope Ultraviolet Echelle Spectrograph and the Potsdam Echelle Polarimetric and Spectroscopic Instrument from 305 nm to 805 nm to compare with non-local thermodynamic equilibrium (NLTE) stellar atmosphere models constructed for Sirius. This poster presents the current state of our atlas comparing model spectra to the observed spectra. We found that less than 1.5% of the total modeled spectral lines in the atlas are not well matched to the observed spectra, including 87 LTE lines that are improved in NLTE. Forty NLTE lines poorly match the observed spectra. We show this is likely due to inconsistent atomic data in at least 60% of these cases. Our model’s atomic data will be adjusted to be more consistent with NIST values which will in turn refine the elemental abundances.