On the nature of the neutron exposure event of U Aquarii.
Abstract
With regard to the search for an explanation on the origin of the peculiar cool R CrB star U Aquarii, it is important to determine whether the observed heavy element enhancements are due to a single neutron exposure as previously suggested, or to a series of exponentially weighted exposures. High-dispersion spectra of U Aquarii were obtained in order to investigate this. The Sr and Y enhancements are found to be lower than previously believed. Zr is found to be slightly overabundant, but no significant enhancement of Ba is detected. It is shown that a weak exponentially weighted distribution of neutron exposures characterized by τ0 ≡ 0.1 mb-1 can, within the observational uncertainties, represent these enhancements. The implications of these results to theories regarding the origin of U Aquarii and other R CrB stars is discussed.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- October 1985
- DOI:
- 10.1093/mnras/216.3.743
- Bibcode:
- 1985MNRAS.216..743M
- Keywords:
-
- Cool Stars;
- Heavy Elements;
- Neutrons;
- Peculiar Stars;
- Stellar Composition;
- Stellar Evolution;
- Abundance;
- Exponential Functions;
- High Dispersion Spectrographs;
- Nuclear Fusion;
- Nuclear Reactions;
- Spectral Line Width;
- Stellar Spectra;
- Variable Stars;
- Astrophysics