8-12 July 2013
Africa/Johannesburg timezone
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Astereoseismology of Beta Cepheid Stars using multicolor photometry: Mode Identi cation.

Presented by Mr. LLOYD KEELEY on 10 Jul 2013 from 17:40 to 18:40
Type: Poster Presentation
Session: Poster2
Track: Track D1 - Astrophysics


The thesis involves the study of young population B type Cepheid variable stars using seismic waves to study their oscillation modes. The goal is to identify the modes associated with the frequencies over the ranges of the quantum numbers n and l so that deductions can be made about the internal structure and composition of the star. For the Cepheids there are two types of pulsation modes p, or pressure modes, and g, or gravity modes, each of which penetrate to di erent depths in the star thus probe conditions in the outer and inner parts of the star. Time series data collected from observations at Sutherland will be Fourier analyzed and modes identi ed from the frequency peaks in the spectrum. In the theoretical model, the amplitude ratios are calculated for di er- ent values of the degree l of the spherical harmonic and wavelength  and the computed values then compared with amplitude ratios obtained from observational measurements at the same wavelengths. The theoret- ical model includes information about metallicity, temperature, density, pressure and the known atmospheric parameters with regards to the hy- pothetical Cepheid star. Once the theoretical amplitudes are matched with the observational amplitudes, within a certain error bar, then the mode l can be identi ed. My goals will be to analyze the observed pulsa- tions in certain Cepheid stars to obtain information about their physical parameters such as size and evolutionary state.






Professor Medupe



Primary authors