Der Große Refraktor auf dem Potsdamer Telegrafenberg. Vorträge zu seinem 100jährigen Bestehen [The Great Refractor at the Telegrafenberg in Potsdam. Papers on occasion of its 100th anniversary]
Abstract
This volume contains the opening words and lectures given at the festive celebration. "The venture into the depth of the Universe: 100 years of large telescopes" and "Buildings for science in Prussia" deal with topics closely connected with the erection of the Great Refractor and the architecture of its dome. The three following papers are devoted to the history and the scientific achievements of the telescope and of the Astrophysical Observatory as well, where solar research is represented by a separate contribution. In the appendix, for the first time a report on a study tour is published which had been undertaken by the later director of the Astrophysical Observatory Hermann Carl Vogel to Great Britain in 1875 with regard to erecting the new observatory in Potsdam. All papers in German.
Supplementary resources (2)
An analysis is given of fluxes measured in 1-A bands centered on the Ca
II H and K lines for a sample of 91 main-sequence stars, extending from
about F5 to M2, over time intervals of nine to 11 years. The results are
discussed separately for a set of 18 stars with minimal chromospheric
fluxes used as standards, the program stars of spectral types F7 to G3,
the program stars of types G5 and later, as well as the sun. K/H ratios
are determined and compared for the different groups of stars. It is
tentatively concluded that: (1) no stellar chromospheres are likely to
be constant in time; (2) short-term fluctuations tend to increase in
size with average flux; (3) cyclical variations occur with periods
ranging from about 7 years to probably at least twice as long; (4) the
stellar cycles observed in H and K flux should be regarded as evidence
for analogs of the solar cycle; and (5) the incidence of complete or
probable partial cycles increases toward later spectral types.