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

A calibration of H-alpha as both a chromospheric diagnostic and an ageindicator is presented, complementing the works previously done on this subject(Herbig 1985, Pasquini & Pallavicini 1991. The chromospheric diagnostic wasbuilt with a statistically significant sample, covering nine years ofobservations, and including 175 solar neighborhood stars. Regarding the ageindicator, the presence of stars for which very accurate ages are determined,such as those belonging to clusters and kinematic groups, lends confidence toour analysis. We also investigate the possibility that stars of the same agemight have gone through different tracks of chromospheric decay, identifying -within the same age range - effects of metallicity and mass. These parameters,however, as well as age, seem to be significant only for dwarf stars, losingtheir meaning when we analyze stars in the subgiant branch. This resultsuggests that, in these evolved stars, the emission mechanism cannot bemagnetohydrodynamical in nature, in agreement with recent models (Fawzy et al.2002c, and references therein). The Sun is found to be a typical star in itsH-alpha chromospheric flux, for its age, mass and metallicity. As a byproductof this work, we developed an automatic method to determine temperatures fromthe wings of H-alpha, which means the suppression of the error inherent to thevisual procedure used in the literature.Comment: 10 pages, 10 figures, accepted for publication in Astronomy &  Astrophysics. Nature of replacement: match astro-ph and ADS title (greek  letter

Fine structure of the chromospheric activity in Solar-type stars – The Hα line