An abundance analysis of the symbiotic star CH Cygni

Schmidt, M.; Začs, L.; Mikołajewska, Joanna; Hinkle, Kenneth H.

doi:10.1051/0004-6361:20053219

Cited by 26 publications

(41 citation statements)

References 32 publications

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“…In Fig. 9 the position of our giants with highest 12 C/ 13 C ratio is less elevated in log N-log C plane similar to CH Cyg for which Schmidt et al (2006) obtained 12 C/ 13 C = 18. In Fig.…”

Section: Discussionsupporting

confidence: 63%

Chemical abundance analysis of symbiotic giants – III. Metallicity and CNO abundance patterns in 24 southern systems

Gałan

Mikołajewska

Hinkle

et al. 2015

Monthly Notices of the Royal Astronomical Society

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The elemental abundances of symbiotic giants are essential to address the role of chemical composition in the evolution of symbiotic binaries, to map their parent population, and to trace their mass transfer history. However, the number of symbiotic giants with fairly well determined photospheric composition is still insufficient for statistical analyses. This is the third in a series of papers on the chemical composition of symbiotic giants determined from high resolution (R ∼ 50000), near-infrared spectra. Here we present results for 24 S-type systems. Spectrum synthesis methods employing standard local thermal equilibrium analysis and atmosphere models were used to obtain photospheric abundances of CNO and elements around the iron peak (Fe, Ti, Ni, and Sc). Our analysis reveals metallicities distributed in a wide range from slightly supersolar ([Fe/H]∼ +0.35 dex) to significantly subsolar ([Fe/H]∼ −0.8 dex) but principally with near-solar and slightly subsolar metallicity ([Fe/H]∼ −0.4 to −0.3 dex). The enrichment in 14 N isotope, found in all these objects, indicates that the giants have experienced the first dredge-up. This was confirmed in a number of objects by the low 12 C/ 13 C ratio (5-23). We found that the relative abundance of [Ti/Fe] is generally large in red symbiotic systems.

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“…In Fig. 9 the position of our giants with highest 12 C/ 13 C ratio is less elevated in log N-log C plane similar to CH Cyg for which Schmidt et al (2006) obtained 12 C/ 13 C = 18. In Fig.…”

Section: Discussionsupporting

confidence: 63%

Chemical abundance analysis of symbiotic giants – III. Metallicity and CNO abundance patterns in 24 southern systems

Gałan

Mikołajewska

Hinkle

et al. 2015

Monthly Notices of the Royal Astronomical Society

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“…With a distance of 245 ± 40 pc (from the Hipparcos parallax; Perryman et al 1997), it is one of the nearest symbiotic stars. Of the two known photometric periods, the 756 day period is thought to be due to pulsation of the M giant (Schmidt et al 2006), and the 14.5 year period is probably the orbital period. CH Cyg was detected in the BAT survey.…”

Section: Symbiotic Star Identifications and Bat Resultsmentioning

confidence: 99%

SWIFTOBSERVATIONS OF HARD X-RAY EMITTING WHITE DWARFS IN SYMBIOTIC STARS

Kennea

Mukai

Sokoloski

et al. 2009

ApJ

102

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The X-ray emission from most accreting white dwarfs (WDs) in symbiotic binary stars is quite soft. Several symbiotic WDs, however, produce strong X-ray emission at energies greater than ∼20 keV. The Swift Burst Alert Telescope (BAT) instrument has detected hard X-ray emission from four such accreting WDs in symbiotic stars: RT Cru, T CrB, CD −57 3057, and CH Cyg. In one case (RT Cru), Swift detected X-rays out to greater than 50 keV at > 5σ confidence level. Combining data from the X-Ray Telescope (XRT) and BAT detectors, we find that the 0.3-150 keV spectra of RT Cru, T CrB, and CD −57 3057 are well described by emission from a single-temperature, optically thin thermal plasma, plus an unresolved 6.4-6.9 keV Fe line complex. The X-ray spectrum of CH Cyg contains an additional bright soft component. For all four systems, the spectra suffer high levels of absorption from material that both fully and partially covers the source of hard X-rays. The XRT data did not show any of the rapid, periodic variations that one would expect if the X-ray emission were due to accretion onto a rotating, highly magnetized WD. The X-rays were thus more likely from the accretion-disk boundary layer around a massive, nonmagnetic WD in each binary. The X-ray emission from RT Cru varied on timescales of a few days. This variability is consistent with being due to changes in the absorber that partially covers the source, suggesting localized absorption from a clumpy medium moving into the line of sight. The X-ray emission from CD −57 3057 and T CrB also varied during the nine months of Swift observations, in a manner that was also consistent with variable absorption.

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“…Since 1964, CH Cyg has displayed a number of outbursts. Schmidt et al (2006) showed both the photospheric features of the cool giant and the nebular emission lines in CH Cyg. The average C/N and O/N ratios of the cool giants in CH Cyg are respectively 1.6 and 4.0, which are typical abundance ratios of M giants.…”

Section: Chemical Abundance Of Symbiotic Nebulaementioning

confidence: 96%

Chemical Abundances in Symbiotic Stars

Zhu

Han

Wang

2008

Astrophysical Journal

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We have carried out a study of the chemical abundances of 1 H, 4 He, 12 C, 13 C, 14 N, 15 N, 16 O, 17 O, 20 Ne, and 22 Ne in symbiotic stars (SSs) by means of a population synthesis code. We find that the ratios of the number of O-rich SSs to that of C-rich SSs in our simulations are between 3.4 and 24.1, depending on the third dredge-up efficiency k and the terminal velocity of the stellar wind v(1). The fraction of SSs with extrinsic C-rich cool giants in C-rich cool giants ranges from 2.1% to 22.7%, depending on k, the common envelope algorithm, and the mass-loss rate. Compared with the observations, the distributions of the relative abundances of 12 C/ 13 C vs. [C/H] of the cool giants in SSs suggest that thermohaline mixing in low-mass stars may exist. The distributions of the relative abundances of C/N vs. O/N, Ne/O vs. N/O, and He/H vs. N/O in the symbiotic nebulae indicate that it is quite common for the nebular chemical abundances in SSs to be modified by the ejected materials from the hot components. Helium overabundance in some symbiotic nebulae may be relevant to a helium layer on the surfaces of white dwarf accretors.

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An abundance analysis of the symbiotic star CH Cygni

Cited by 26 publications

References 32 publications

Chemical abundance analysis of symbiotic giants – III. Metallicity and CNO abundance patterns in 24 southern systems

Chemical abundance analysis of symbiotic giants – III. Metallicity and CNO abundance patterns in 24 southern systems

SWIFTOBSERVATIONS OF HARD X-RAY EMITTING WHITE DWARFS IN SYMBIOTIC STARS

Chemical Abundances in Symbiotic Stars

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