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Utilizing Synthetic UV Spectra to Explore the Physical Basis for the Classification of Lambda Boötis Stars

Cheng, Kwang-Ping; Tarbell, Erik S.; Neff, James E. +6 more

Lambda Boo-type stars are a group of late B to early F-type Population I dwarfs that show mild to extreme deficiencies of iron-peak elements (up to 2 dex), but their C, N, O, and S abundances are near solar. This intriguing stellar class has recently regained the spotlight because of the directly imaged planets around a confirmed Lambda Boo star, …

Ultraviolet Spectroscopy of BL Hyi and EF Eri in High and Intermediate States

Sanad, M. R.; Abdel-Sabour, M. A.

We present the first phase-resolved ultraviolet spectroscopy of two polar systems, BL Hyi and EF Eri, in high and intermediate states from the International Ultraviolet Explorer (IUE) during the periods between 1982-1995 and 1979-1991, respectively. The flux curves for the C IV and He II emission lines for both systems showing variations in their …