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dc.contributor.authorGuthrie, Bruce N. G.en
dc.date.accessioned2019-02-15T14:28:42Z
dc.date.available2019-02-15T14:28:42Z
dc.date.issued1964en
dc.identifier.urihttp://hdl.handle.net/1842/34588
dc.description.abstracten
dc.description.abstractThe effect of rotation on quantities used in classifying B -type stars is discussed. The tendency for stars with high rotational velocities to have weaker Balmer lines for the same (U - B)₀ has been investigated using published data. Abt's explanation of the affect in terms of the change in effective surface gravity due to rotation is confirmed. A correction term in Crawford's method of determining ages of clusters and field stars from Balmer line intensities and UBV photometry is derived. It is shown that errors in age determinations due to rotation are much smaller when the wavelength λ₁ of the Balmer discontinuity is used instead of Balmer line intensities. A colour index sensitive to λ₁ is discussed. Methods of determining the inclinations of the axes of rotation are suggested. It is shown that the "cosmic dispersion" in the relation between Balmer line intensities and absolute magnitudes is largely caused , by rotation. A scheme of two -dimensional spectral classification using measurements of the position and size of the Balmer discontinuity on low dispersion objective prism plates is outlined. Rotational velocities for 18 stars have been derived from slit spectrograms; several lines including five Balmer lines were measured for each star.en
dc.publisherThe University of Edinburghen
dc.relation.isreferencedbyen
dc.subjectAnnexe Thesis Digitisation Project 2019 Block 22en
dc.titleA study of B-type starsen
dc.typeThesis or Dissertationen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnameMSc Master of Scienceen


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