Astrophysics (Index)About

metal

(in astrophysics, any element more massive than helium)

Within astrophysics, the term metal is used differently: it is any element other than hydrogen or helium. Metallicity is a measure of the amount of such elements in an astronomical body such as a star. Such metal was nearly non-existent in the early universe, and has since been produced within stars as well as supernovae and other cataclysmic events. Its abundance relative to hydrogen and helium is still low in the universe, including in stars and clouds, but it is key to the occurrence of rocky planets.


The more common meaning of metal is a particular class of substances that are hard, opaque, transmit heat and electricity, and can be heated to the point of malleability, a usage that definitely has applications within planetary science. Science refines this usage to mean elements in which the electrons in the outer orbit are easily removed, which is the basis of the electrical and heat conductivity. Under extremely high pressure (millions of atm), hydrogen and helium are theorized to have a metal-like phase that conducts electricity, called metallic hydrogen (or conductive hydrogen) and metallic helium, which are believed to be present within Jupiter and Saturn.


(atoms)
Further reading:
https://en.wikipedia.org/wiki/Metallicity
https://en.wikipedia.org/wiki/Metal
https://en.wikipedia.org/wiki/Metallic_hydrogen
http://astronomy.swin.edu.au/cosmos/M/Metals

Referenced by pages:
alpha process (α process)
Am star
Ap star
bolometer
bracket notation
carbon star (C)
chemical tagging
chemically peculiar star (CP star)
electron screening
extremely metal poor galaxy (XMPG)
first galaxies
G-type star (G)
galaxy age determination
gas-to-dust ratio (GDR)
globular cluster (GC)
habitability
helium (He)
HZE ion
K-type star (K)
L-type star (L)
line blanketing
mass fraction
mass ratio (μ)
metallicity (Z)
Milky Way (MW)
Milky Way chemical evolution
planet formation
Population I (Pop I)
Population II (Pop II)
Population III (Pop III)
sedimentation
solar energetic particle (SEP)
spectral class
stellar age determination
stellar population
Sun
weak-line star
white dwarf (WD)

Index