This element was discovered in 1669 by H. Brandt in Hamburg, Germany. The name phosphorus in Greek means bringer of light, which was also the name given to the planet Venus.

Ionization energies
PI 10.5 eV, PII 19.7 eV, PIII 30.2 eV.

Absorption lines of PI
The equivalent width of PI 9796(2) in the sun is 0.012. According to Underhill (1977) it is present in an A 2Ia star.

Absorption lines of PII
The PII line 4127(16) is presentin B 5Ia stars and ultraviolet lines are also visible in B 7 and B 9V stars (Artru et al. 1989).

Absorption lines of PIII
The equivalent width of PIII 4280(1) in a B 8V star is W = 0.005. PIII has its ultraviolet resonance line at 1334 (UV M.1).

Behavior in non-normal stars
P II is very enhanced in some early type He-strong stars, like 3 Cen A, where it was discovered by Bidelman (1960). According to Smith (1981) the line 4127 has W = 0.028. PII and P III are also highly enhanced in many but not all Bp stars of the Hg-Mn type (Adelman 1987). According to Kodaira and Takada (1978) one has W(4127) = 0.050 and W(4080) = 0.040. The phosphorus enhancement has led to the introduction of a subgroup of Bp stars, the so-called `P-strong stars' Jaschek and Jaschek 1974). In some, but not all, HB stars, P is enhanced (Heber 1991).

P has one stable isotope, P31, and six short-lived isotopes.

P can be produced by both Ne burning and explosive nucleosynthesis.

Published in "The Behavior of Chemical Elements in Stars", Carlos Jaschek and Mercedes Jaschek, 1995, Cambridge University Press.