Astrophysics (index)


(in astrophysics, any element more massive than helium)

In astrophysics, the term Metal is used for 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.

The 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. Science (outside astrophysics) refines the term to mean elements for whom the electrons in the outer orbit are easily removed, which is the basis of the electrical and heat conductivity.

Under certain characteristics which includes very high pressure (thousands of ATM), hydrogen and helium are theorized to have a metal-like phase, called Metallic Hydrogen and Metallic Helium, but neither has been unequivocally produced in the lab. Jupiter and Saturn are theorized to provide the necessary pressure internally to the point that they make up a significant portion of their masses.


Referenced by:
Alpha Process
Ap Star
Electron Screening
First Galaxies
Globular Cluster (GC)
L-Type Star (L)
Metallicity (Z)
Milky Way Chemical Evolution
Reducing Atmosphere
Solar Energetic Particle (SEP)
Stellar Age Determination
Stellar Population
Tillotson Equation
White Dwarf