Phosphorus Abundances in FGK Stars

Abstract

We measured phosphorus abundances in 22 FGK dwarfs and giants that span -0.55 < [Fe/H] < 0.2 using spectra obtained with the Phoenix high resolution infrared spectrometer on the Kitt Peak National Observatory Mayall 4m telescope, the Gemini South Telescope, and the Arcturus spectral atlas. We fit synthetic spectra to the P I feature at 10581Å to determine abundances for our sample. Our results are consistent with previously measured phosphorus abundances; the average [P/Fe] ratio measured in [Fe/H] bins of 0.2 dex for our stars are within ∼ 1 σ compared to averages from other IR phosphorus studies. Our study provides more evidence that models of chemical evolution using the results of theoretical yields are under producing phosphorus compared to the observed abundances. Our data better fit a chemical evolution model with phosphorus yields increased by a factor of 2.75 compared to models with unadjusted yields. We also found average [P/Si] = 0.02 ± 0.07 and [P/S] = 0.15 ± 0.15 for our sample, showing no significant deviations from the solar ratios for [P/Si] and [P/S] ratios.

Phosphorus Abundances in the Hyades and Galactic Disk

“…The uncertainties associated with the fits to Si and P are consistent with the standard deviation of the average differences found when comparing the samples. For example, the difference of [P/Fe] = 0.00 ± 0.08 for P is similar to the uncertainty on the fit of 0.05 -0.07 dex for the MCMC fits in Table 3 and an average uncertainty on the fit of 0.05 dex from Maas et al (2017).…”

“…Targeted surveys with the Y-band P I features have confirmed an offset between chemical evolution models and abundance measurements over the -0.6 < [Fe/H] < 0.2 metallicity range (Caffau et al 2016;Maas et al 2017;Caffau et al 2019). Additional P abundances have also been measured in individual metal poor stars (Spite et al 2017) further constraining P production in the early Universe.…”

“…Spectra were obtained for nine dwarf stars with temperatures ranging from 5735 < T eff < 6291 K and three giants as shown in Table 1. Data reduction utilized the IRAF software suite 1 and followed the same procedures described in Maas et al (2017). To summarize the reduction steps, the images were trimmed, the flat images were dark-subtracted, and flats were median combined.…”

“…For the α elements, O and Mg are thought to made almost entirely in hydrostatic burning in massive stars while Si and Ti are predicted to be made significantly in explosive burning in CCSNe with some contributions from Type Ia SN (Woosley & Weaver 1995;Travaglio et al 2004). To make these comparisons, we use P and Si abundances in stars from Maas et al (2017) and this work. Oxygen abundances are adopted from Bensby et al (2014) for our stars and Ramírez et al (2013) for the Maas et al (2017) stars.…”

“…To make these comparisons, we use P and Si abundances in stars from Maas et al (2017) and this work. Oxygen abundances are adopted from Bensby et al (2014) for our stars and Ramírez et al (2013) for the Maas et al (2017) stars. Additionally, three stars from Caffau et al (2011) had corresponding oxygen abundances derived by Ramírez et al (2013).…”