Atlas of the Ultraviolet Spectrum of Procyon

A preliminary step in the spectral study of a stellar objects is the identification of its spectral lines. The line identification is performed by checking those ions expected to be present in the photosphere of the object of interest. This is done by using synthetic spectra generated with a set of previously estimated physical parameters (effective temperature, surface gravity and metal abundance). Different techniques, like the fitting of the ultraviolet spectral energy distribution, have been developed to determine these fundamental parameters.

Procyon (Alpha CMi, HD 61421, HR 2943) is the brightest and most extensively studied middle F star widely used for photometric and spectroscopic reference.  The study of Procyon in the ultraviolet range, in addition to expand the spectral  tracings published for the visual region,  is of special importance for the stellar structure and evolution theories  since the UV range contains many more lines of the less common elements and lines of species not observable in the visual range whose analysis is of critical importance for theories like the microscopic diffusion hypothesis (Faraggiana et al., 1986).

Line identification was done with a synthetic spectrum generated using the fully blanketed atmosphere models ATLAS9. For the computation of the synthetic model the following parameters Teff: 6500 K, log g: 4.0 and [M/H] = 0.0 have been adopted. Spectral lines with a central line depth less than 0.8 were rejected.

An IUE high resolution spectrum of Procyon in the range 2100-2150 Angstroms is shown below. Click on the desired wavelength to generate a zoom plot of 2 Angstroms region with line identification. Red crosses in the IUE spectra indicate bad-quality points. Yb I 2127.41 and Te I 2143.49 Angstroms are examples of species not observable in the visible but present in the ultraviolet range.

2100_2102 2102_2104 2104_2106 2106_2108 2108_2110 2110_2112 2112_2114 2114_2116 2116_2118 2118_2120 2120_2122 2122_2124 2124_2126 2126_2128 2128_2130 2130_2132 2132_2134 2134_2136 2136_2138 2138_2140 2140_2142 2142_2144 2144_2146 2146_2148 2148_2150


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