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Abstract: A survey of Ne, O and Fe coronal abundances culled from the recent literaturefor about 60 late-type stars confirms that the Ne-O ratio of stellar outeratmospheres is about two times the value recently recommended by Asplund et al.The mean Ne-O remains flat from the most active stars down to at leastintermediate activity levels -5L X-L bol<-2, with some evidence for a declinetoward the lowest activity levels sampled. The abundances surveyed are allbased on emission measure distribution analyses and the mean Ne-O is about 0.1dex lower than that found from line ratios in the seminal study of mostlyactive stars by Drake and Testa 2005, but is within the systematicuncertainties of that study. We also confirm a pattern of strongly decreasingFe-O with increasing stellar activity. The observed abundance patterns arereminiscent of the recent finding of a dependence of the solar Ne-O and Fe-Oratios on active region plasma temperature and indicate a universalfractionation process is at work. The firm saturation in stellar Ne-O at higheractivity levels combined with variability in the solar coronal Ne-O leads us tosuggest that Ne is generally depleted in the solar outer atmosphere andphotospheric values are reflected in active stellar coronae. The solution tothe recent solar model problem would then appear to lie in a combination of theAsplund et al O abundance downward revision being too large, and the Neabundance being underestimated for the Sun by about a factor of 2.



Author: D.Garcia-Alvarez 1,2, J.J. Drake 3, P. Testa 3 1 IAC, 2GTC-CALP,3Harvard-Smithsonian CfA

Source: https://arxiv.org/



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