SIMBAD references

Since the peculiar nature of Lambda Bootis was first noticed in 1943, the Lambda Boo stars have been recognized as a group of peculiar A-type stars. They are Population I dwarfs that show deficiencies of iron-peak elements (up to 2 dex), but have near-solar C, N, O, and S abundances. In a previous paper, we used both observed and synthetic ultraviolet spectra to demonstrate that the C i 1657 A/Al ii 1671 A equivalent width ratio can help distinguish between Lambda Boo stars and other metal-weak stars hotter than 8000 K. In this paper, using observed and synthetic visible (4000-6800 A) spectra, we demonstrate that the C i 5052.17 A/Mg ii 4481 A equivalent width ratio can be used as a quantitative diagnostic for cooler Lambda Boo stars.