A model atmosphere analysis of the Ap star kappa Cancri.
A detailed model atmosphere analysis is presented for the peculiar A star ;c Cancri based on high dispersion spectrograms secured at the coud6 focus of the Lick 120-inch telescope and a published energy distribution. The observed energy distribution and hydrogen-line profiles indicate that the atmosphere can be represented by a model with 0 = .36 at log T8000 = 0.0 and with log g = 3.6. The metal-line equivalent widths, half widths, and central line depths served to determine the stellar abundances and to further verify the model. A micro- turbulent velocity of 5 km/s was established from the shapes of the metal-line profiles, from the abundance- equivalent width correlations and from the shape of the curve of growth. The analysis shows that phosphorus is overabundant by a factor of 300, manganese by a factor of 200, gallium by a factor of 2000, and mercury and xenon by factors of 108 or more. Helium is underabundant by a factor of 2, magnesium by a factor of 6 and calcium by a factor of 30. Among the iron-peak elements titanium and scandium are overabundant, iron is marginally overabundant and chromium and nickel are marginally underabundant. The composition of Cancri is similar to that of 3 Cen A and other manganese stars. The extent of the manganese overabundance in each manganese star may be correlated with its effective temperature. Key words: model atmosphere - abundances - Ap star
Astronomy and Astrophysics
- Pub Date:
- May 1970