[seminar] Seminar FO, Morel

[hbuljan at phy.hr]

Poštovani kolege,

idući utorak s početkom u 14:15 sati predavanje naslovljeno
"Neon to the rescue of the solar interior models?
Insights from the analysis of nearby B stars" održati će nam
Dr. T. Morel iz Liegea. Predavanje će se održati
na Fizičkom odsjeku u predavaonici F08. Sažetak se nalazi
u nastavku poruke.

Srdačan pozdrav,
Hrvoje Buljan

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KOLOKVIJ FIZIČKOG ODSJEKA
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Vrijeme:   utorak, 20. 05. 2008., 14:15 sati (točno)
Mjesto:    Fizički odsjek, Bijenička c. 32, predavaonica F08

   Neon to the rescue of the solar interior models?
     Insights from the analysis of nearby B stars

                 Dr. Thierry Morel
             Liege University, Liege, Belgium

The recent downward revision of the abundances of most metals in the Sun
leads to large discrepancies between the theoretical predictions for the
internal structure of the Sun and the helioseismic data (sound speed and
density profiles in the interior, properties of the convective zone).
Changes in the input physics of the standard solar models (opacity tables,
treatment of diffusion, etc.) have so far failed to restore the past
agreement.

Neon is an important contributor to the opacities in the solar radiative
zone and it has been proposed that this problem arises from a severe
underestimation of the abundance of this element. It is unfortunately
difficult to test the validity of this hypothesis, as the Ne abundance can
only be indirectly estimated from observations of the solar corona and is
therefore highly uncertain.

However, an alternative approach to constrain the Ne content of the Sun is
offered by nearby hot stars, as they are the only stellar objects whose
neon abundance can be estimated from the direct analysis of photospheric
lines. After a description of the problems posed by the new solar
abundances and a brief review of the solutions proposed to solve them, I
will present a project aimed at determining the neon abundance in a sample
of B stars in the solar neighbourhood. The relevance of neon as a solution
to the solar problem will be discussed in the light of our results.

			Voditelj seminara i kolokvija FO
			Hrvoje Buljan, hbuljan at phy.hr
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