M giants with IGRINS I. Stellar parameters and $\alpha$-abundance trends of the solar neighborhood population

Abstract

Cool stars, such as M giants, can only be analysed in the near-infrared (NIR) regime due to the ubiquitous TiO features in optical spectra of stars with Teff < 4000 K. In dust obscured regions, like the inner bulge and Galactic Center, the intrinsically bright M giants observed in the NIR is an optimal option to determine their stellar abundances. Due to uncertainties in photometric methods, a method to determine the stellar parameters for M giants from the NIR spectra themselves is needed. We have carried out new observations of 44 M giant stars (also in APOGEE DR17) with IGRINS (R=45,000) mounted on the Gemini South telescope. We also obtained HK band IGRINS spectra of six nearby well-studied M giants from the IGRINS spectral library. Using this sample, we have developed a method to determine the stellar parameters for M giants from the NIR spectra by spectral synthesis using SME. The method is validated using the six nearby well-studied M-giants. We demonstrate the accuracy and precision by determining stellar parameters and $\alpha$-element trends versus metallicity for solar neighbourhood M giants. The effective temperatures that we derive (tested for 3400$\lesssim$ Teff $\lesssim$4000\,K) agree excellently with the six nearby M giants which indicates that the accuracy is indeed high. For the 43 solar neighborhood M giants, our Teff, logg, [Fe/H], ${\xi }_{\mathrm{micro}}$, [C/Fe], [N/Fe], and [O/Fe] are in unison with APOGEE with mean differences and scatter (our method - APOGEE) of -67$\pm$33 K, -0.31$\pm$0.15 dex, 0.02$\pm$0.05 dex, 0.22$\pm$0.13 km/s, -0.05$\pm$0.06 dex, 0.06$\pm$0.06 dex, and 0.02$\pm$0.09 dex, respectively. The $\alpha$-element trends versus metallicity for Mg, Si, Ca and Ti are consistent with both APOGEE DR17 trends for the same stars as well as with the GILD optical trends. We also find clear enhancement in abundances for thick disc stars.

27 Pages including appendix of 10 pages, 15 figures, Accepted for publication in A&A

References in corpus (29)

• The NumPy array: a structure for efficient numerical computation
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• APOGEE Data and Spectral Analysis from SDSS Data Release 16: Seven Years of Observations Including First Results from APOGEE-South
• Synthetic Stellar Photometry - I. General considerations and new transformations for broad-band systems
• Gaia Data Release 3: Analysis of RVS spectra using the General Stellar Parametriser from spectroscopy
• Non-LTE line formation of Fe in late-type stars - III. 3D non-LTE analysis of metal-poor stars
• The Gaia-ESO Public Spectroscopic Survey: Implementation, data products, open cluster survey, science, and legacy
• Line lists for the A2PI-X2Sigma+ (red) and {B2Sigma+-X2Sigma} (violet) Systems of CN, 13C14N, and 12C15N, and Application to Astronomical Spectra
• The GALAH Survey: Non-LTE departure coefficients for large spectroscopic surveys
• VLT/X-shooter survey of near-infrared diffuse interstellar bands
• The relationship between mono-abundance and mono-age stellar populations in the Milky Way disk
• Detailed Abundances for the Old Population near the Galactic Center: I. Metallicity distribution of the Nuclear Star Cluster
• Chemical Abundances of M giants in the Galactic Center: a Single Metal-Rich Population with Low [alpha/Fe]
• Fluorine in the solar neighborhood - is it all produced in AGB-stars?
• The Galactic Chemical Evolution of phosphorus observed with IGRINS
• Method to Estimate the Effective Temperatures of Late-Type Giants using Line-Depth Ratios in the Wavelength Range 0.97-1.32$\mu$m
• The AMBRE Project: Spectrum normalisation influence on Mg abundances in the metal-rich Galactic disc
• CRIRES high-resolution near-infrared spectroscopy of diffuse interstellar band profiles. Detection of 12 new DIBs in the YJ band and the introduction of a combined ISM sight line and stellar analysis approach
• Chemical Evolution of Ytterbium in the Galactic Disk
• Survey of near-infrared diffuse interstellar bands in $Y$ and $J$ bands. I. Newly identified bands
• Carbon and Oxygen Isotopic Ratios. II. Semiregular Variable M Giants
• Angular Diameters and Fundamental Parameters of Forty-Four Stars from the Navy Precision Optical Interferometer
• The metallicity effect on line-depth ratios in APOGEE $H$-band spectra
• Detailed $\alpha$ abundance trends in the inner Galactic bulge
• Effective Temperature Estimations from Line Depth Ratios in the \H\ and \K-band Spectra of IGRINS
• Line-depth ratios as indicators of effective temperature and surface gravity
• New Temperature and Metallicity Scale of Cool Giants from K-band Spectra
• $H$-band Temperature and Metallicity Indicators for Cool Giants: Empirical Relations in Bayesian Framework

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