Classical Stellar Chromospheres and Dependence on Teff, and Chemical Abundances
Abstract
I would like to continue to observe stars which appear in the HR diagram close to the dividing line between the convective and non-convective stars. Since convection is supposed to be a necessary condition for the formation of chromospheres we should be able to determine the boundary line for convection from the boundary line for the existence of classical chromospheres. I would like to continue to investigate whether the phenomenon of metallic line stars can in any way be related to the onset of convection and thereby to the presence or absence of chromospheres. We also want to observe a few manganese stars in order to check if any effects of the surface convection zone due to He ionization could be detected in the UV spectrum of Mn stars. I would like to extend the study of the onset of convection to the region of the He rich hot white dwarfs for which convection is expected for temperatures up to 30,000 K. Of special interest would be the observation of some dwarf novae. I would like to study chromospheres and transition layers of Pop II stars, red giants and subdwarfs and compare those to Pop I stars. Knowing the chromospheric spectra of field Pop II stars, I would like to analyse the integrated spectra of globular clusters and their center to limb variation. One might hope to be able to determine the population and perhaps the break off of the lower main sequence which appears to depend on the metal abundance of the cluster. The study of the globular clusters will also reveal the presence or absence of hot blue objects and their distribution in the cluster. If the lambda 2200 absorption could be detected this may give some information about the presence of interstellar dust and gas in the clusters, which is expected to be there but has not yet been found.
- Publication:
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IUE Proposal
- Pub Date:
- 1979
- Bibcode:
- 1979iue..prop..171B