Chemical abundance analysis of symbiotic giants. Metallicity and CNO abundance patterns in 14 northern S-type systems

Abstract

In previous works, we computed abundances for the red giant in nearly four dozen S-type symbiotic systems (SySt). The abundances provide information about metallicity, evolutionary status, and possible memberships in Galactic stellar populations. Here, we extend our studies with a northern hemisphere sample of SySt. This northern sample is dominated by Galactic disk/halo objects, whereas our previous southern sample is heavily biased toward the bulge population. Spectrum synthesis of high-resolution (R$\sim$50000), near-$IR$ spectra using standard LTE analysis and atmospheric models have been used to measure abundances of CNO and elements around the iron peak (Fe, Ti, Ni, Sc) in the atmospheres of the red giant component. The SySt sample shows generally slightly sub-solar metallicity, as expected for an older disk population, with a median at [Fe/H]\,$\sim -0.2$ dex. Enhanced ${}^{14}$N, depleted ${}^{12}$C, and decreased ${}^{12}$C/${}^{13}$C indicate that all these giants have experienced the first dredge-up. Comparison with theoretical predictions indicates that additional mixing processes had to occur to explain the observed C and N abundances. Relative O and Fe abundances agree with those represented by Galactic disc and bulge giant populations in the {\sl APOGEE} data, with a few cases that can be attributed to membership in the extended thick-disc/halo. As an interesting byproduct of this study, we observed a blue-shifted additional component on the wings of absorption lines in the spectra of AG Peg which could be connected with accretion onto the hot component.

arXiv comment10 pages + 3 appendixes

References in corpus (37)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The chemical composition of the Sun
• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• Exploring the Milky Way stellar disk. A detailed elemental abundance study of 714 F and G dwarf stars in the Solar neighbourhood
• APOGEE Data and Spectral Analysis from SDSS Data Release 16: Seven Years of Observations Including First Results from APOGEE-South
• A Wide Symbiotic Channel to Type Ia Supernovae
• A catalogue of symbiotic stars
• The Updated BaSTI Stellar Evolution Models and Isochrones: I. Solar Scaled Calculations
• Thermohaline mixing: A physical mechanism governing the photospheric composition of low-mass giants
• The elemental composition of the Sun II. The iron group elements Sc to Ni
• Line lists for the A2PI-X2Sigma+ (red) and {B2Sigma+-X2Sigma} (violet) Systems of CN, 13C14N, and 12C15N, and Application to Astronomical Spectra
• Oscillator Strengths and Damping Constants for Atomic Lines in the J and H Bands
• Broad-band photometric colors and effective temperature calibrations for late-type giants. I. Z=0.02
• New binary parameters for the symbiotic recurrent nova T Coronae Borealis
• The Gaia-ESO survey: impact of extra-mixing on C- and N-abundances of giant stars
• Population synthesis to constrain Galactic and Stellar Physics- I- Determining age and mass of thin-disc red-giant stars
• The double-degenerate model for the progenitors of type Ia supernovae
• H-alpha variability of the recurrent nova T Coronae Borealis
• Roche-lobe filling factor of mass-transferring red giants - the PIONIER view
• The Massive CO White Dwarf in the Symbiotic Recurrent Nova RS Ophiuchi
• Symbiotic stars: Observations confront theory
• Infrared Spectroscopy of Symbiotic Stars. VII. Binary Orbit and Long Secondary Period Variability of CH Cygni
• The spectroscopic orbits and the geometrical configuration of the symbiotic binary AR Pavonis
• An abundance analysis of the symbiotic star CH Cyg
• Evolution of the Symbiotic Nova PU Vul -- Outbursting White Dwarf, Nebulae, and Pulsating Red Giant Companion
• Chemical abundance analysis of symbiotic giants - III. Metallicity and CNO abundance patterns in 24 southern systems
• Chemical abundance analysis of 13 southern symbiotic giants from high-resolution spectra at ~1.56 μm
• AG Pegasi - now a classical symbiotic star in outburst?
• Symbiotic stars on Asiago archive plates. II
• Chemical abundance analysis of symbiotic giants. I. RW Hya and SY Mus
• Line formation regions of the UV spectrum of CI Cygni
• EG Andromedae: A New Orbit and Additional Evidence for a Photoionized Wind
• First spatial resolution of the stellar components of the interacting binary CH Cygni
• An illumination effect and an eccentric orbit for the symbiotic binary PU Vul revealed by 32 years of optical spectroscopy

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