An Etymological Dictionary of Astronomy and Astrophysics

A member of a class of galaxies of relatively small size (→ compact galaxy) having very strong → emission lines especially the → [O III] doublet and an unusually large → equivalent width of up to 1000 Å. They were first noted because of their peculiar bright green color and small size, unresolved in → Sloan Digital Sky Survey imaging.

Green Peas are similar to high-→ redshift  → Lyman alpha emitting galaxies (LAEs) in many respects (small sizes, low → stellar masses, 10^8-10 → solar masses (Msun), low metallicities for their stellar masses, high → specific star formation rates (sSFR), and large [O III] λ5007/[O II]λ3727 ratios. Green Peas are relatively luminous and massive galaxies compared to the faint-end → dwarf starburst galaxies and LAEs (See Yang et al, 2017, arxiv/1706.02819, and references therein).

See also: Such called because of their appearance and green color (mainly due to very strong optical emission line [O III] 5007 Å) in composite images;
→ green; → pea;
→ galaxy.