HeI 5876 & 10830{AA} EWs of solar-type stars Virtual Observatory Resource

Authors
  1. Andretta V.
  2. Giampapa M.S.
  3. Covino E.
  4. Reiners A.
  5. Beeck B.
  6. Published by
    CDS
Abstract

Simultaneous, high-quality measurements of the neutral helium triplet features at 5876{AA} and 10830{AA} in a sample of solar-type stars are presented. The observations were made with ESO telescopes at the La Silla Paranal Observatory under program ID 088.D-0028(A) and MPG Utility Run for Fiber Extended-range Optical Spectrograph 088.A-9029(A). The equivalent widths of these features combined with chromospheric models are utilized to infer the fractional area coverage, or filling factor, of magnetic regions outside of spots. We find that the majority of the sample is characterized by filling factors less than unity. However, discrepancies occur among the coolest K-type and the warmest and most rapidly rotating F-type dwarf stars. We discuss these apparently anomalous results and find that in the case of K-type stars, they are an artifact of the application of chromospheric models best suited to the Sun than to stars with significantly lower Teff. The case of the F-type rapid rotators can be explained by the measurement uncertainties of the equivalent widths, but they may also be due to a non-magnetic heating component in their atmospheres. With the exceptions noted above, preliminary results suggest that the average heating rates in the active regions are the same from one star to the other, differing in the spatially integrated, observed level of activity due to the area coverage. Hence, differences in activity in this sample are mainly due to the filling factor of active regions.

Keywords
  1. g-stars
  2. line-intensities
Bibliographic source Bibcode
2017ApJ...839...97A
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/839/97
IVOA Identifier IVOID
ivo://CDS.VizieR/J/ApJ/839/97
Document Object Identifer DOI
doi:10.26093/cds/vizier.18390097

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http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/839/97
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http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/839/97/ews?

History

2018-01-12T13:04:40Z
Resource record created
2018-01-12T13:04:40Z
Created
2018-03-12T09:11:08Z
Updated

Contact

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CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr