Chemical Compositions of Red Giant Stars from Habitable Zone Planet Finder Spectroscopy

Abstract

We have used the Habitable Zone Planet Finder (HPF) to gather high resolution, high signal-to-noise near-infrared spectra of 13 field red horizontal-branch (RHB) stars, one open-cluster giant, and one very metal-poor halo red giant. The HPF spectra cover the 0.81$-$1.28 \micron\ wavelength range of the $zyJ$ bands, filling in the gap between the optical (0.4$-$1.0~\micron) and infrared (1.5$-$2.4~\micron) spectra already available for the program stars. We derive abundances of 17 species from LTE-based computations involving equivalent widths and spectrum syntheses, and estimate abundance corrections for the species that are most affected by departures from LTE in RHB stars. Generally good agreement is found between HPF-based metallicities and abundance ratios and those from the optical and infrared spectral regions. Light element transitions dominate the HPF spectra of these red giants, and HPF data can be used to derive abundances from species with poor or no representation in optical spectra (\eg, \species{C}{i}, \species{P}{i}, \species{S}{i}, \species{K}{i}). Attention is drawn to the HPF abundances in two field solar-metallicity RHB stars of special interest: one with an extreme carbon isotope ratio, and one with a rare very large lithium content. The latter star is unique in our sample by exhibiting very strong \species{He}{i} 10830~Å absorption. The abundances of the open cluster giant concur with those derived from other wavelength regions. Detections of \species{C}{i} and \species{S}{i} in HD~122563 are reported, yielding the lowest metallicity determination of [S/Fe] from more than one multiplet.

Astronomical Journal, in press

References in corpus (18)

• The GALAH Survey: Scientific Motivation
• Gaia Data Release 1: Catalogue validation
• Neutron-capture elements in the very metal-poor star HD122563
• Line lists for the A2PI-X2Sigma+ (red) and {B2Sigma+-X2Sigma} (violet) Systems of CN, 13C14N, and 12C15N, and Application to Astronomical Spectra
• Stellar Spectroscopy in the Near-infrared with a Laser Frequency Comb
• Fe I Oscillator Strengths for the Gaia-ESO Survey
• The GALAH Survey: Non-LTE departure coefficients for large spectroscopic surveys
• The forbidden 1082 nm line of sulphur: the photospheric abundance of sulphur in the Sun and 3D effects
• Fe I Oscillator Strengths for Transitions from High-lying Even-Parity Levels
• Empirical photometric calibration of the Gaia Red Clump: colours, effective temperature and absolute magnitude
• Survey of Li-rich giants among Kepler and LAMOST fields: Determination of Li-rich giants Evolutionary Phase
• Fe I oscillator strengths for transitions from high-lying odd-parity levels
• Chemical abundances of 1111 FGK stars from the HARPS-GTO planet search sample. III. Sulfur
• The Chemical Compositions and Evolutionary Status of Red Giants in the Open Cluster NGC 752
• Atmospheric composition of weak G band stars: CNO and Li abundances
• The chemical compositions and evolutionary status of red giants in the open cluster NGC 6940
• Chemical Abundances Of Open Clusters From High-Resolution Infrared Spectra. I. NGC 6940
• Stellar Population Astrophysics (SPA) with the TNG: Identification of a Sulphur line at lambda(air) = 1063.600nm in GIANO-B stellar spectra

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