Determinations of the {sup 12}C/{sup 13}C Ratio for the Secondary Stars of AE Aquarii, SS Cygni, and RU Pegasi

Journal Article · Mon Jul 10 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA7946· OSTI ID:22663396

Harrison, Thomas E.

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

• OSTI ID: 22663396
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 843; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION SPECTROSCOPY
ABUNDANCE
AUGER ELECTRON SPECTROSCOPY
CARBON 12
CARBON 13
INFRARED SPECTRA
ISOTOPE RATIO
MAGNESIUM
MASS
NOVAE
RESOLUTION
SODIUM
STAR EVOLUTION
STARS