58 research outputs found
First spatial resolution of the stellar components of the interacting binary CH Cygni
We report the first resolved bispectrum speckle interferometry of the
symbiotic binary CH Cyg. The measured component separation,
mas, is consistent with the one derived from the known spectroscopic orbit and
distance. In particular, our result implies a total mass of the binary of
M_{\rm t}=M_{\rm g}+M_{\rm wd}=3.7^{+3.5}_{-1.7} \rm M_{\sun}, which is in
good agreement with the value M_{\rm t}=2.7^{+1.2}_{-0.6} \rm M_{\sun}
derived from the spectroscopic orbit solution for the red giant and
evolutionary contraints. We also show that the radio jets and the bipolar
outflow are not orthogonal to the orbital plane of the binary system.Comment: 5 pages, 4 figures, submitted to MNRA
Chemical abundance analysis of symbiotic giants. Metallicity and CNO abundance patterns in 14 northern S-type systems
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 (R50000), near- 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]\, dex. Enhanced N, depleted C, and
decreased C/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.Comment: 10 pages + 3 appendixes. Accepted for publication at MNRA
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