The Chemical Evolution of Phosphorus
  Phosphorus is one of the few remaining light elements for which little is
known about its nucleosynthetic origin and chemical evolution, given the lack
of optical absorption lines in the spectra of long-lived FGK-type stars. We
have identified a P I doublet in the near-ultraviolet (2135/2136 A) that is
measurable in stars of low metallicity. Using archival Hubble Space
Telescope-STIS spectra, we have measured P abundances in 13 stars spanning -3.3
<= [Fe/H] <= -0.2, and obtained an upper limit for a star with [Fe/H] ~ -3.8.
Combined with the only other sample of P abundances in solar-type stars in the
literature, which spans a range of -1 <= [Fe/H] <= +0.2, we compare the stellar
data to chemical evolution models. Our results support previous indications
that massive-star P yields may need to be increased by a factor of a few to
match stellar data at all metallicities. Our results also show that hypernovae
were important contributors to the P production in the early universe. As P is
one of the key building blocks of life, we also discuss the chemical evolution
of the important elements to life, C-N-O-P-S, together.
