The Search for Super-saturation in Chromospheric Emission

Damian J. Christian*, Mihalis Mathioudakis, Tersi Arias, Moira Jardine, David B. Jess

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


We investigate if the super-saturation phenomenon observed at X-ray wavelengths for the corona exists in the chromosphere for rapidly rotating late-type stars. Moderate resolution optical spectra of fast-rotating EUV- and X-ray-selected late-type stars were obtained. Stars in α Per were observed in the northern hemisphere with the Isaac Newton 2.5 m telescope and Intermediate Dispersion Spectrograph. Selected objects from IC 2391 and IC 2602 were observed in the southern hemisphere with the Blanco 4 m telescope and R-C spectrograph at CTIO. Ca II H and K fluxes were measured for all stars in our sample. We find the saturation level for Ca II K at log (L CaK/L bol) = -4.08. The Ca II K flux does not show a decrease as a function of increased rotational velocity or smaller Rossby number as observed in the X-ray. This lack of "super-saturation" supports the idea of coronal stripping as the cause of saturation and super-saturation in stellar chromospheres and coronae, but the detailed underlying mechanism is still under investigation.
Original languageEnglish
Article number164
Number of pages7
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 10 Sept 2011


  • open clusters and associations: individual: α Per IC 2391 IC 2602
  • stars: activity
  • stars: chromospheres
  • stars: late-type
  • stars: rotation


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