EUV estimates from CaII H&K activity

DOI

Atmospheric escape is an important factor shaping the exoplanet population and hence drives our understanding of planet formation. Atmospheric escape from giant planets is driven primarily by the stellar X-ray and extreme- ultraviolet (EUV) radiation. Furthermore, EUV and longer wavelength UV radiation power disequilibrium chemistry in the middle and upper atmosphere. Our understanding of atmospheric escape and chemistry, therefore, depends on our knowledge of the stellar UV fluxes. While the far-ultraviolet fluxes can be observed for some stars, most of the EUV range is unobservable due to the lack of a space telescope with EUV capabilities and, for the more distant stars, to interstellar medium absorption. Thus, it becomes essential to have indirect means for inferring EUV fluxes from features observable at other wavelengths. We present here analytic functions for predicting the EUV emission of F, G, K, and M-type stars from the log R'HK activity parameter that is commonly obtained from ground-based optical observations of the Ca II H&K lines. The scaling relations are based on a collection of about 100 nearby stars with published log R'HK and EUV flux values, where the latter are either direct measurements or inferences from high-quality far-ultraviolet (FUV) spectra. The scaling relations presented here return EUV flux values with an accuracy of about three, which is slightly lower than that of other similar methods based on FUV or X-ray measurements.

Cone search capability for table J/A+A/644/A67/table2 (Stellar parameters and EUV fluxes)

Identifier
DOI http://doi.org/10.26093/cds/vizier.36440067
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/A+A/644/A67
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/644/A67
Related Identifier http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/644/A67
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/J/A+A/644/A67
Provenance
Creator Sreejith A. G.; Fossati L.; Youngblood A.; France K.; Ambily S.
Publisher CDS
Publication Year 2020
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Representation
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Interdisciplinary Astronomy; Natural Sciences; Observational Astronomy; Physics; Stellar Astronomy