Determinations of the 12C/13C Ratio for the Secondary Stars of AE Aquarii, SS Cygni, and RU Pegasi*
作者： Thomas E. Harrison , Rachel E. Marra
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摘要: We present new moderate-resolution near-infrared spectroscopy of three CVs obtained using GNIRS on Gemini-North. These spectra covered 13CO bandheads found in the K-band, allowing us to derive isotopic abundance ratios for carbon. find small 12C/13C all donor stars. In addition, these objects show carbon deficits, with AE Aqr being most extreme ([C/Fe] = −1.4). This result confirms conjecture that stars some long-period have undergone considerable nuclear evolution prior becoming semi-contact binaries. addition results carbon, we sodium is enhanced objects, and secondary both RU Peg SS Cyg suffer magnesium deficits. Explaining such anomalies appears require higher mass progenitors than commonly assumed CVs.
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