.. SPDX-FileCopyrightText: 1992-2026 NWO-I/SRON Space Research Organisation Netherlands .. .. SPDX-License-Identifier: CC-BY-4.0 .. _sec:abundance: Abundance: standard abundances ============================== Overview ~~~~~~~~ For the plasma models, a default set of abundances is used. All abundances are calculated relative to those standard values. The current default abundance set 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 (`see the Table below <#tab:standabu>`__) can be used in SPEX: .. table:: 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 `Lodders `_ solar Lodders Solar photospheric `Lodders `_ =========== ============================================================ 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 the table below, we show the values of the standard abundances. They are expressed in logarithmic units, with hydrogen by definition 12.0. .. table:: Abundances for the standard sets == ==== ======= ===== ============== ===== ======== ===== ======= ===== Z elem Default AG Allen RA Grevesse GS Lodders solar == ==== ======= ===== ============== ===== ======== ===== ======= ===== 1 H 12.000 12.00 12.00 12.00 12.00 12.00 12.00 12.00 2 He 10.987 10.99 10.93 10.80 10.97 10.99 10.98 10.90 3 Li 3.331 1.16 0.70 1.00 1.16 3.31 3.35 3.28 4 Be 1.373 1.15 1.10 1.15 1.15 1.42 1.48 1.41 5 B 2.860 2.6 <3.0 2.11 2.6 2.79 2.85 2.78 6 C 8.443 8.56 8.52 8.62 8.55 8.52 8.46 8.39 7 N 7.912 8.05 7.96 7.94 7.97 7.92 7.90 7.83 8 O 8.782 8.93 8.82 8.84 8.87 8.83 8.76 8.69 9 F 4.491 4.56 4.60 4.56 4.56 4.48 4.53 4.46 10 Ne 8.103 8.09 7.92 7.47 8.08 8.08 7.95 7.87 11 Na 6.347 6.33 6.25 6.28 6.33 6.32 6.37 6.30 12 Mg 7.599 7.58 7.42 7.59 7.58 7.58 7.62 7.55 13 Al 6.513 6.47 6.39 6.52 6.47 6.49 6.54 6.46 14 Si 7.586 7.55 7.52 7.65 7.55 7.56 7.61 7.54 15 P 5.505 5.45 5.52 5.50 5.45 5.56 5.54 5.46 16 S 7.210 7.21 7.20 7.20 7.21 7.20 7.26 7.19 17 Cl 5.299 5.5 5.60 5.50 5.5 5.28 5.33 5.26 18 Ar 6.553 6.56 6.90 6.01 6.52 6.40 6.62 6.55 19 K 5.161 5.12 4.95 5.16 5.12 5.13 5.18 5.11 20 Ca 6.367 6.36 6.30 6.35 6.36 6.35 6.41 6.34 21 Sc 3.123 1.10 1.22 1.04 3.20 3.10 3.15 3.07 22 Ti 4.979 4.99 5.13 5.05 5.02 4.94 5.00 4.92 23 V 4.042 4.00 4.40 4.02 4.00 4.02 4.07 4.00 24 Cr 5.703 5.67 5.85 5.71 5.67 5.69 5.72 5.65 25 Mn 5.551 5.39 5.40 5.42 5.39 5.53 5.58 5.50 26 Fe 7.514 7.67 7.60 7.50 7.51 7.50 7.54 7.47 27 Co 4.957 4.92 5.10 4.90 4.92 4.91 4.98 4.91 28 Ni 6.276 6.25 6.30 6.28 6.25 6.25 6.29 6.22 29 Cu 4.319 4.21 4.50 4.06 4.21 4.29 4.34 4.26 30 Zn 4.700 4.60 4.20 4.45 4.60 4.67 4.70 4.63 == ==== ======= ===== ============== ===== ======== ===== ======= ===== .. warning:: For `Allen (1973) `_ the value for boron is just an upper limit. The current active solar abundance table can be shown using the command ``abundance show``. Interfaces ~~~~~~~~~~ - Python interface: :ref:`pyapi-abun`. - Fortran interface: :ref:`spexapi_abun`. Syntax ~~~~~~ The following syntax rules apply: | ``abundance #a`` : Set the standard abundances to the values of reference #a in the table above. | ``abundance show`` : Show the currently active abundance table. Examples ~~~~~~~~ | ``abundance gs`` : change the standard abundances to the set of `Grevesse & Sauval (1998) `_ | ``abundance reset`` : reset the abundances to the standard set | ``abundance show`` : show the currently active abundance table