Artigo Acesso aberto Revisado por pares

Stellar Coronal Abundances. V. Evidence for the First Ionization Potential Effect in α Centauri

1997; IOP Publishing; Volume: 478; Issue: 1 Linguagem: Inglês

10.1086/303755

ISSN

1538-4357

Autores

J. J. Drake, J. M. Laming, K. G. Widing,

Tópico(s)

Astrophysics and Star Formation Studies

Resumo

We present an analysis of the EUV spectrum of the nearby binary α Cen AB (G2 V, K0 V), observed by the Extreme Ultraviolet Explorer satellite (EUVE). Emission measure curves are constructed for elements with high and low first ionization potential (FIP) in order to investigate the coronal composition and determine whether or not a solar-like compositional fractionation mechanism ("FIP effect") is operating in the corona of α Cen. As pointed out in the recent analysis of the α Cen EUVE spectra by Mewe et al., the emission measure distribution is very much like that of the Sun. It peaks at log T ~ 6.3, has a minimum near log T ~ 5.5, and has a slope between these points of approximately 1.75 (EM ∝ T7/4). The emission measure results for the different elements are not consistent with the underlying photospheric composition and indicate that the low-FIP elements are overabundant relative to the high-FIP elements by a factor of about 2. This result represents the first evidence of the FIP effect in solar-like stars with similar activity to that of the Sun.

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