HRT activity monitoring of solar-like stars: The Ca II Infrared triplet

点击翻译按钮获取中文摘要

A relatively little study stellar activity indicator is the Ca II triplet, Iocated in the near infrared, while the Ca II HK lines haven been used for decades as stellar chromospheric activity indicators. Because of instrumental problems few simultaneous data sets of these lines are available, however, with the availability of echelle spectrographs, covering a wide spectral range, it is straightforward to obtain simultaneous coverage of the Ca II H&K and IRT lines. Such simultaneously taken data sets are required to answer the question if Ca II IRT based activity indicators can play the same role as those based on the Ca II H&K lines. These lines are produced by the same ion, however, they are generated in different atmospheric layers and need thus not have the same diagnostic power. Both on CARMENES, a spectroscopic survey for planets around M stars, as well as on GAIA, only the Ca II IRT will be covered as an activity diagnostics, and already for these reasons it is necessary to carry out an activity study of cool stars, which covers both Ca II lines simultaneously, to be able to relate the upcoming Ca II IRT data to the huge body of literature available on the Ca II H&K lines. In the context of the proposed project we want to simultaneously observe and monitor the Ca II H&K and Ca II IRT lines in a larger sample of stars. The required spectral time series can be obtained economically through robotic telescopes. The Hamburg Robotic Telescope can generate the required data and is available to the proposed project.