Chemical abundance inventory in phosphorus-rich stars

Abstract

We provide an overview of the latest advances in the study of phosphorus-rich stars, covering their detailed chemical abundance analyses and innovative mining approaches. Following the discovery of 16 low-mass and low-metallicity stars rich in P, we expanded this sample by demonstrating that a recently identified group of Si-rich giants is also P-rich. A detailed abundance analysis was conducted on the near-infrared spectra from APOGEE-2 DR17, encompassing 13 elements. Subsequently, a similar analysis was performed on the optical UVES spectra of four P-rich stars, resulting in the abundance determination of 48 light and heavy elements. This comprehensive analysis further refined the chemical fingerprint of these peculiar stars, which was employed to evaluate the plausibility of various nucleosynthetic formation scenarios. In order to obtain a statistically more reliable chemical fingerprint in the future, we explored the use of unsupervised machine learning algorithms to identify additional P-rich stars in extensive spectroscopic surveys, such as APOGEE-2. The primary objective of this research is to identify the progenitor of these stars and determine whether current nucleosynthetic models require revision or if a completely new source of P in the Galaxy is responsible for the existence of the P-rich stars.