An Etymological Dictionary of Astronomy and Astrophysics

The amount of hydrogen necessary to form a star; more specifically the minimum mass to ignite → hydrogen fusion.
→ Hydrogen burning will start at a limit of about 0.08 Msun, or 75 → Jupiter masses. Below 0.08 Msun, the core never gets hot enough to trigger → hydrogen fusion.

→ Protostars less massive than this limit are known as → brown dwarfs or → planets if the mass is less than 13 Jupiter masses. Above 13 Jupiter masses, some minor nuclear reactions (→ deuterium burning) occur that do not provide much energy.

The minimum mass for → star formation is a critical parameter with profound astrophysical, cosmological, and even anthropic consequences.

See also: → minimum; → stellar; → mass.