Researchers in Statistics and Population Studies
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Browsing by Subject "Galaxies: stellar content"
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Item Multivariate comparisons of the period–light-curve shape distributions of Cepheids in five galaxies(Oxford University Press, 2007) Koen, Chris; Siluyele, I.A number of published tests suitable for the comparison of multivariate distributions are described. The results of a small power study, based on realistic Cepheid log period – Fourier coefficient data, are presented. It is found that a statistic due to Henze has good general performance. The tests are applied to Cepheid observations in the Milky Way galaxy, Large Magellanic Cloud, Small Magellanic Cloud, IC 1613 and NGC 6822. The null hypothesis of equal populations is rejected for all pairs compared, except IC 1613 – NGC 6822.Item On the upper limit on stellar masses in the Large Magellanic Cloud cluster R136(Oxford University Press, 2006) Koen, ChrisA truncated power-law distribution is fitted to the 29 largest stellar masses known in R136. Two different statistical techniques are used, with comparable results. An upper limit to the mass distribution of the order of 140–160 M is derived, while the power-law exponent is in the approximate range 0.9–1.7. A power-law distribution with no upper limit on the mass can be rejected with considerable confidence. It is recommended that the calculations be repeated when more reliable mass estimates are available.