SPEX Reference manual (PDF) - SRON

Chapter 2
Syntax overview
2.1 Abundance: standard abundances
Overview
For the plasma models, a default set of abundances is used. All abundances are calculated relative
to those standard values. Thecurrent default abundanceset are the proto-Solar abundances
of Lodders et al. ([2009]). Note that in older versions of SPEX, Anders & Grevesse ([1989]) was
the default. In particular, we recommend to use the proto-Solar (= Solar system) abundances
for most applications, as the Solar photospheric abundance has been affected by nucleosynthesis
(burning of H to He) and settlement in the Sun during its lifetime. The following abundances
(Table 2.1) can be used in SPEX:
Table 2.1: Standard abundance sets
Abbrevation Reference
reset default (=Lodders et al. 2009)
ag Anders & Grevesse ([1989])
allen Allen ([1973])
ra Ross & Aller ([1976])
grevesse Grevesse et al. ([1992])
gs Grevesse & Sauval ([1998])
lodders Lodders proto-Solar ([2003])
solar Lodders Solar photospheric ([2003])
For the case of Grevesse & Sauval (1998) we adopted their meteoritic values (in general more
accurate than the photospheric values, but in most cases consistent), except for He (slightly
enhanced in the solar photosphere due to element migration at the bottom of the convection
zone), C, N and O (largely escaped from meteorites) Ne and Ar (noble gases).
In Table 2.2 we show the values of the standard abundances. They are expressed in logarithmic
units, with hydrogen by definition 12.0. For Allen ([1973]) the value for boron is just an upper
limit.
Warning: For Allen ([1973]) the value for boron is just an upper limit.
Syntax
The following syntax rules apply: