3.1.1. Abundance: standard abundances

3.1.1.1. 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) can be used in SPEX:

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.

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.

3.1.1.2. 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.

3.1.1.3. 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