Research Note

Chemical evolution of the Milky Way: the origin of phosphorus

¹ Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
² Laboratoire d’Astrophysique, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland
e-mail: cescutti@aip.de
³ Dipartimento di Fisica, Sezione di Astronomia, Università di Trieste, via G.B. Tiepolo 11, 34131 Trieste, Italy
⁴ INAF Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34131 Trieste, Italy
⁵ Zentrum für Astronomie der Universität Heidelberg, Landessternwarte, König stuhl 12, 69117 Heidelberg, Germany
⁶ GEPI, Observatoire de Paris, CNRS, Université Paris Diderot, Place Jules Janssen, 92190 Meudon, France
⁷ Université de Picardie Jules Verne, 33 rue Saint Leu, Amiens, France

Received: 30 September 2011
Accepted: 19 January 2012

Abstract

Context. Recently, the abundance of P was measured for the first time in disk stars. This provides the opportunity of comparing the observed abundances with predictions from theoretical models.

Aims. We aim at predicting the chemical evolution of P in the Milky Way and compare our results with the observed P abundances in disk stars to derive constraints on the P nucleosynthesis.

Methods. We adopted the two-infall model of galactic chemical evolution, which is a good model for the Milky Way, and computed the evolution of the abundances of P and Fe. We adopted stellar yields for these elements from different sources. The element P is expected to form mainly in type-II supernovae, whereas Fe is mainly produced by type-Ia supernovae.

Results. Our results confirm that to reproduce the observed trend of [P/Fe] vs. [Fe/H] in disk stars, P must be formed mainly in massive stars. However, none of the available yields for P can reproduce the solar abundance of this element. In other words, to reproduce the data one needs to assume that massive stars produce three times more P than predicted.

Conclusions. We conclude that the entire available yields of P from massive stars are largely underestimated and that nucleosynthesis calculations should be revised. We also predict the [P/Fe] expected in halo stars.