Abundance

The abundance contains information about the overall metallicity of the star as well as the individual abundances of each element. SME can simulate and fit the first 99 elements of the periodic table (from Hydrogen H to Einsteinium Es).

Abundance formats

PySME supports a variety of formats to input the abundance. However they are all internally converted to the ‘H=12’ type before use.

H=12:

Abundance values are log10 of the fraction of nuclei of each element in any form relative to the number of hydrogen in any form plus an offset of 12. For the Sun, the nuclei abundance values of H, He, and Li are approximately 12, 10.9, and 1.05.

n/nTot:

Abundance values are the fraction of nuclei of each element in any form relative to the total for all elements in any form. For the Sun, the abundance values of H, He, and Li are approximately 0.92, 0.078, and 1.03e-11.

n/nH:

Abundance values are the fraction of nuclei of each element in any form relative to the number of hydrogen nuclei in any form. For the Sun, the abundance values of H, He, and Li are approximately 1, 0.085, and 1.12e-11.

sme:

For hydrogen, the abundance value is the fraction of all nuclei that are hydrogen, including all ionization states and treating molecules as constituent atoms. For the other elements, the abundance values are log10 of the fraction of nuclei of each element in any form relative to the total for all elements in any form. For the Sun, the abundance values of H, He, and Li are approximately 0.92, -1.11, and -11.0.

Fe=12:

Abundance values are log10 of the fraction of nuclei of each element in any form relative to the number of iron in any form plus an offset of 12. For the Sun, the nuclei abundance values of H, He, and Li are approximately 16.5, 15.43, and 5.55.

n/nFe:

Abundance values are the fraction of nuclei of each element in any form relative to the number of iron nuclei in any form. For the Sun, the abundance values of H, He, and Li are approximately 3.16e4, 2.69e3, and 3.55e-7.

Solar metallicity

PySME contains three pre defined sets of solar abundances, for you to choose from. They are:

asplund2009:

Asplund, Grevesse, Sauval, Scott (2009, Annual Review of Astronomy and Astrophysics, 47, 481)

grevesse2007:

Grevesse, Asplund, Sauval (2007, Space Science Review, 130, 105)

lodders2003:

Lodders 2003 (ApJ, 591, 1220)

They can be initialized by passing their name during the creation of the abundance. E.g. Abund(“grevesse2007”). The default solar abundance is ‘asplund2009’ and is also available using Abund.solar().