Symbol Z
Z is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Read this term in its guide →Published equation contexts
Why this formula appears here
Zoom out from individual nuclei to the gas that forms whole generations of stars, and the genealogy becomes explicit rather than metaphorical. Astronomers describe the abundance of everything heavier than helium in a star or a cloud of gas with a single number, metallicity, defined through the mass fractions of hydrogen ( X ), helium ( Y ) and “metals” ( Z ): . A gas cloud’s metallicity is, quite literally, an inherited character: it is the accumulated, largely unerased record of every previous generation of stars that lived, burned and returned processed material to the interstellar medium before that cloud collapsed to form new stars. The first stars, Population III,…
Read the representative guide
Symbol X
X is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Read this term in its guide →Symbol Y
Y is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Read this term in its guide →How to interpret it
Read this expression with the definitions, units, and assumptions supplied by the article.
Research cited beside this formula
Published contexts (1)
A symbol can carry a different meaning in another article. Each occurrence keeps its own guide and term definitions.
Equation 8 · Evolutionary Nuclear Physics
Nucleosynthesis Is Descent With Modification
This mathematical expression combines the displayed quantities; its precise role follows from the surrounding article text.
Zoom out from individual nuclei to the gas that forms whole generations of stars, and the genealogy becomes explicit rather than metaphorical. Astronomers describe the abundance of everything heavier than helium in a star or a cloud of gas with a single number, metallicity, defined through the mass fractions of hydrogen ( X ), helium ( Y ) and “metals” ( Z ): . A gas cloud’s metallicity is, quite literally, an inherited character: it is the accumulated, largely unerased record of every previous generation of stars that lived, burned and returned processed material to the interstellar medium before that cloud collapsed to form new stars. The first stars, Population III,…
Equation guide → · Article →