English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Main chromospheric activity indicator is the presence of a distinct emission component in the nuclei of the H and K Caii and hydrogen lines. These emissions, for example, in spectra of Arcturus and some other stars vary periodically, by analogy with the solar cycle. It is assumed that these variations are associated with micro ares, the main source of coronal heating in chromospherically active stars. 61CygAB are BYDra type variables. Longterm X-ray monitoring of 61Cyg binary with XMMNewton was used to investigate possible coronal activity cycles [2]. The X-ray light curves were compared with the long-term monitoring of chromospheric activity, as measured by the Mt. Wilson Caii H+K S-index. Besides variability on short time scales, typical for the RYDra type variables, longterm variations of the X-ray activity were found clearly present. For 61CygA distinct chromospheric activity cycle was found resembling the solar behaviour. The coronal activity of 61CygB also follows the chromospheric variability. 61CygA was the rst star where a persistent coronal activity cycle has been observed [2]. The hydrogen Balmer lines are formed at the middle chromosphere. In active stars they often show lled-in absorption features. They can be used also as a diagnostic tool for the presence of plages and prominences on the stellar surface. The purpose of this work was the detection of rapid variations of spectral lines in sub-second range. Spectra and variations in the spectra at di erent time scales allow us to con rm the presence of rapid variations in the sub-second range for both stellar components of 61Cyg.

Low-resolution spectroscopy of the chromospherically active stars 61 Cyg AB with small telescopes