bracket notation
(bracket abundance notation, abundance notation)
(notation for a comparison of an abundance ratio with that of the Sun)
A bracket notation is used to characterize
abundances of nuclear species within an astronomical object,
specifically, the ratio of the abundances of two specific elements
(chemical abundance ratios or abundance ratios).
For example, a particular body's [Fe/He] is a measure of the ratio
of its number-count of iron atoms with that of its helium atoms.
The meaning:
[Fe/He] means
log10(NFe/NHe)body - log10(NFe/NHe)Sun
- NFe - number count of iron atoms.
- NHe - number count of helium atoms.
- body - the object for which we are specifying an abundance ratio.
- log10(A)B - for body B, the base-10 log of the value A.
If a body's [Fe/He] is 0, then its ratio of iron to helium
is identical to that of the Sun. If it is 1, then its ratio
is ten times that of the Sun, and if it is -3, then its ratio
is a thousandth of that of the Sun.
Sometimes rather than a specific element, a symbol for some
set of elements is specified; for example, M or Z for all metals,
or α (alpha) for all alpha elements.
(atoms,measure)
Further reading:
http://burro.case.edu/Academics/Astr222/Galaxy/Structure/metals.html
http://www-star.st-andrews.ac.uk/~kdh1/ce/ce11.pdf
http://astronomy.nmsu.edu/holtz/a555/pdf/lecture17_A555_F22_stellarEvolutionHR.pdf
https://ui.adsabs.harvard.edu/abs/2013pss5.book...55F/abstract
https://ui.adsabs.harvard.edu/abs/2002IAUS..187...91E/abstract
Referenced by pages:
alpha-enhanced
extremely metal poor galaxy (XMPG)
iron (Fe)
metallicity (Z)
Population III (Pop III)
rocky planet
stellar population
[α/Fe] versus [Fe/H] diagram
Index