Chromospheric Emission from Red Giants in the Open Cluster NGC 6940

(2) Harvard-Smithsonian Center for Astrophysics); D. Barrado y Navascues (1) & A.K. Dupree (2) ((1) MEC/Fulbright Fellow at the Smithsonian Astrophysical Observatory; Real Colegio Complutense at Harvard University

arxiv: astro-ph/9710276 · v1 · submitted 1997-10-24 · 🌌 astro-ph

Chromospheric Emission from Red Giants in the Open Cluster NGC 6940

D. Barrado y Navascues (1) & A.K. Dupree (2) ((1) MEC/Fulbright Fellow at the Smithsonian Astrophysical Observatory , Real Colegio Complutense at Harvard University , (2) Harvard-Smithsonian Center for Astrophysics) This is my paper

classification 🌌 astro-ph

keywords emissionlineschromosphericclusterfluxgiantgiantsstars

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The observation of the Ca II H and K lines in red giants in NGC 6940 allows the strength of chromospheres and their behavior to be evaluated in a population whose evolution is well understood. Spectra in the Ca II lines have been obtained for giant stars in this cluster. Emission reversals are present in some objects. The absolute flux in the chromospheric emission is determined as a function of effective temperature for stars on the red giant branch. The stellar surface flux in the Ca II lines decreases smoothly with increasing $(B-V)$ in contradiction to model predictions.

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Chromospheric Emission from Red Giants in the Open Cluster NGC 6940

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