A SEARCH FOR EVIDENCE OF THE NEON-SODIUM CYCLE IN THE CEPHEID X CYGNI

We have determined abundances of sodium, aluminum, silicon, calcium, and iron from 16 red spectra of 10 Å mm⁻¹ of X Cyg to search for a sodium enhancement that might be expected from partial operation of the neon-sodium hydrogen burning cycle. Such burning is possible if the low oxygen and very high...

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