Systematic investigation of chemical abundances derived using IR spectra obtained with GIANO

Abstract

Context. Detailed chemical abundances of Galactic stars are needed in order to improve our knowledge of the formation and evolution of our galaxy, the Milky Way. Aims. We took advantage of the GIANO archive spectra to select a sample of Galactic disc stars in order to derive their chemical inventory and to compare the abundances we derived from these infrared spectra to the chemical pattern derived from optical spectra. Methods. We analysed high-quality spectra of 40 stars observed with GIANO. We derived the stellar parameters from the photometry and the Gaia data-release 2 (DR2) parallax; the chemical abundances were derived with the code MyGIsFOS. For a subsample of stars we compared the chemical pattern derived from the GIANO spectra with the abundances derived from optical spectra. We derived P abundances for all 40 stars, increasing the number of Galactic stars for which phosphorus abundance is known. Results. We could derive abundances of 14 elements, 8 of which are also derived from optical spectra. The comparison of the abundances derived from infrared and optical spectra is very good. The chemical pattern of these stars is the one expected for Galactic disc stars and is in agreement with the results from the literature. Conclusions. GIANO is providing the astronomical community with an extremely useful instrument, able to produce spectra with high resolution and a wide wavelength range in the infrared. 1 http://atlas.obs-hp.fr/sophie/ 2 V J = V T − 0.090 * (B − V) T z = B T − V T − 0.90 (B − V) J = (B T − V T ) − 0.115 − 0.229z + 0.043z 3

Stellar population astrophysics (SPA) with the TNG

“…The lack of systematic offsets in abundances between optical and NIR spectra (Fig. 4) for the species under consideration here is also evident from the solar spectrum analysis, and corroborates previous results by Caffau et al (2019), who reported a systematic investigation based on 40 stars (see that paper for details).…”

The GAPS Programme at TNG

“…The agreement between the optical and NIR abundances for the stars is overall good, within the uncertainties. Our results corroborate the previous findings of Caffau et al (2019) by analysing spectra from GIANO in its previous configuration (fibre-fed). However, we noted that for the star HIP 61205 we obtained larger discrepancies for Mg, Si and Ni between the optical and NIR abundance; the latter values are nearly solar.…”

Phosphorus Abundances in the Hyades and Galactic Disk

“…We also note inconsistencies at the high metallicity end, in particular our measurement of the Hyades open cluster and the previous abundance measurements from Caffau et al (2011);Maas et al (2017); Caffau et al (2019) lie above the chemical evolution model. Adjustments to the chemical evolution model, an additional production may be needed, or adjustments to the metallicity dependence of supernovae yields may be needed to match [P/Fe] ratios at solar metallicity, as shown in Fig.…”

“…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.…”