Pea

The pea is most commonly the small spherical seed or the seed-pod of the pod fruit Pisum sativum. Each pod contains several peas. Pea pods are botanically fruit, since they contain seeds and developed from the ovary of a (pea) flower. The name is also used to describe other edible seeds from the Fabaceae such as the pigeon pea (Cajanus cajan), the cowpea (Vigna unguiculata), and the seeds from several species of Lathyrus.

P. sativum is an annual plant, with a life cycle of one year. It is a cool season crop grown in many parts of the world; planting can take place from winter to early summer depending on location. The average pea weighs between 0.1 and 0.36 grams. The immature peas (and in snow peas the tender pod as well) are used as a vegetable, fresh, frozen or canned; varieties of the species typically called field peas are grown to produce dry peas like the split pea shelled from the matured pod. These are the basis of pease porridge and pea soup, staples of medieval cuisine; in Europe, consuming fresh immature green peas was an innovation of Early Modern cuisine.

Pea galaxy

A Pea galaxy, also referred to as a Pea or Green Pea, might be a type of Luminous Blue Compact Galaxy which is undergoing very high rates of star formation. Pea galaxies are so-named because of their small size and greenish appearance in the images taken by the Sloan Digital Sky Survey (SDSS).

Pea Galaxies were first discovered in 2007 by the volunteer users within the forum section of the online astronomy project Galaxy Zoo (GZ).

Description

The Pea galaxies, also known as Green Peas (GPs), are compact oxygen-rich emission line galaxies that were discovered at redshifts between z = 0.112 and 0.360. These low-mass galaxies have an upper size limit generally no bigger than 16,300 light-years (5,000 pc) across, and typically they reside in environments less than two-thirds the density of normal galaxy environments. An average GP has a redshift of z = 0.258, a mass of ~3,200 million M_☉ (~3,200 million solar masses), a star formation rate of ~10 M_☉/yr (~10 solar masses a year), an [O III] equivalent width of 69.4 nm and a low metallicity. A GP is purely star-forming, rather than having an Active Galactic Nucleus. They have a strong emission line at the [OIII] wavelength of 500.7 nm. [OIII], O⁺⁺ or doubly ionized oxygen, is a forbidden line of the visual spectrum and is only possible at very low densities. When the entire photometric SDSS catalogue was searched, 40,222 objects were returned, which leads to the conclusion the GPs are rare objects.