  The recently discovered phosphorus-rich stars pose a challenge to stellar
evolution and nucleosynthesis theory, as none of the existing models can
explain their extremely peculiar chemical abundances pattern. Apart from the
large phosphorus enhancement, such stars also show enhancement in other light
(O, Mg, Si, Al) and heavy (e.g., Ce) elements. We have obtained high-resolution
optical spectra of two optically bright phosphorus-rich stars (including a new
P-rich star), for which we have deter-mined a larger number of elemental
abundances (from C to Pb). We confirm the unusual light-element abundance
pattern with very large enhancements of Mg, Si, Al, and P, and possibly some Cu
enhancement, but the spectra of the new P-rich star is the only one to reveal
some C(+N) enhancement.When compared to other appropriate metal-poor and
neutron-capture enhanced stars, the two P-rich stars show heavy-element
overabundances similar to low neutron density s-process nucleosynthesis,with
high first- (Sr, Y, Zr) and second-peak (Ba, La, Ce, Nd) element enhancements
(even some Pb enhancement in one star) and a negative [Rb/Sr] ratio. However,
this s-process is distinct from the one occurring in asymptotic giant branch
(AGB) stars. The notable distinctions encompass larger[Ba/La] and lower Eu and
Pb than their AGB counterparts. Our observations should guide stellar
nucleosynthesis theoreticians and observers to identify the P-rich star
progenitor, which represents anew site for s-process nucleosynthesis, with
important implications for the chemical evolution of our Galaxy.
