First spatial resolution of the stellar components of the interacting binary CH Cygni

Mikołajewska, Joanna; Balega, Y. Y.; Hofmann, K.-H.; Weigelt, G.

doi:10.1111/j.1745-3933.2009.00807.x

Cited by 8 publications

(7 citation statements)

References 32 publications

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Section: A8 Ch Cygmentioning

confidence: 99%

“…The binary system was resolved for the first time (the components are separated by 42 ± 2 mas) by Mikołajewska et al (2010), giving a total binary mass of about 3.7 M ⊙ , in good agreement with the mass resulting from the spectroscopic orbit derived by Hinkle et al (2009). The distance estimated by Mikołajewska et al (2010) 220 +40 −28 pc is consistent with the new value 205 +3 −4 pc derived by Gaia DR 3 (Table B1) as well as with the previous Hipparcos result 244 +49 −35 pc. The 2MASS magnitudes of CH Cyg, 𝐽 = 1.07 ± 0.29 and 𝐾 = −0.42 ± 0.19 are in fairly good agreement with with 𝐽 = 1.14 ± 0.09, 𝐾 = −0.43 ± 0.13 (Ananth & Leahy 1993) and 𝐽 ∼ 492 Jy, 𝐾 ∼ 953 Jy (Price et al 2010), which when converted with the use of calibrations by Jarrett et al (2011) and Bessell et al (1998) give equivalent magnitudes 𝐽 ∼ 1.25 and 𝐾 ∼ −0.44, respectively.…”

Section: A8 Ch Cygmentioning

confidence: 99%

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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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Section: A8 Ch Cygmentioning

confidence: 99%

Section: A8 Ch Cygmentioning

confidence: 99%

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 equivalent widths of Hβ and [O III] 5007 were −10.8 Å and −2.3 Å at that date. Mikolajewska et al (2010) estimated the luminosity of the faint object to have been about 2 mag fainter than the M-type giant in the optical region. They claimed that CH Cyg was in a mild active stage because the emission lines of H I, Fe II, and [O III] were detected (Yoo 2007), and therefore the hot component had a high luminosity in the optical region.…”

Section: Radial Velocities Of Absorption and Emissionmentioning

confidence: 99%

“…Balega et al (2007) performed interferometric observations in October 2004 and found a faint object of 43 or 41 milliarcseconds (mas) detached from the M-type giant. Detailed analyses of their images were made by Mikolajewska et al (2010) who concluded that the faint object was the hot component on the outer orbit with the period of 15 years. Such an object, however, was not confirmed by the infrared interferometry performed by Pedretti et al (2009) in the same year.…”

Section: Radial Velocities Of Absorption and Emissionmentioning

confidence: 99%

High-velocity equatorial mass ejections and some other spectroscopic phenomena of the symbiotic star CH Cygni in an active stage

Iijima

Naito

Narusawa

2019

A&A

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Context. CH Cyg is one of the most studied symbiotic stars. Its properties, however, are still not well known. Two main periods, about 15 years and 750 days, are known in the photometric and spectroscopic variations, and two models are proposed for these origins. One is a binary system with an orbital period of 15 years consisting of a hot component and pulsating red giant with a 750-day period. The other is a triple system consisting of an inner symbiotic binary with an orbital period of about 750 days and third component with an orbital period of 15 years. Several active stages have been observed since the 1970s during which the object brightened up by ΔU = 3−5 mag and prominent emission lines appeared. Large mass outflows were observed at some active stages. Aims. The spectral variation of CH Cyg has been monitored at Asiago Observatories to understand the problems mentioned above. We have analysed spectra obtained in the time period from 1995 to 2004 which covers an active stage during the years 1998−2000. Methods. High- and low-resolution optical spectra obtained at the Asiago Observatories are used. Results. Narrow absorption lines of Fe I, Cr I, Ti I, and so on appeared in 1998 at an early phase of the active stage. These lines are clearly distinguished from those of the M-type giant and are typically found on the spectrum of early A-type dwarfs. They were redshifted by about 30 km s−1 with respect to the absorption lines of the M-type giant. Assuming that their radial velocities represent the orbital motion of the hot component, its semi-amplitude is estimated to be 37.0 ± 0.5 km s−1. The masses of the hot component and the M-type giant are estimated to be 0.32 ± 0.02 M⊙ and 4.6 ± 0.2 M⊙, respectively, where a circular orbit with a period of 756 days is adopted. If the inner binary system has an elliptical orbit, e = 0.33, and a period of 750.1 days, the masses of the two components are 0.21 ± 0.01 M⊙ and 2.2 ± 0.1 M⊙, respectively. Our results lend support to the triple system model, because if the period of the symbiotic binary were 15 years, the mass of the hot component would be expected to exceed the Chandrasekhar limit. Highly blueshifted absorption components of H I and He I lines appeared at a later phase of the active stage. Mass ejections with velocities on the order of 1000 km s−1 seem to have occurred along the orbital plane from December 1998 to March 1999. The highest outflow velocity, − 2383 km s−1, was observed on 1999 February 26. Narrow absorption components of Na I D1, D2, and Fe II lines redshifted by 10−15 km s−1 coexisted with the highly blueshifted broad absorption components of H I and He I lines. This phenomenon might have been related to an inner disc inflow expected in wind-compressed discs. In contrast to the bipolar mass outflows at the past active stages, high-velocity equatorial mass ejections likely occurred at the active stage during the years 1998−2000. There should have been an eclipse of the hot component by the M-type giant in the inner binary system in the time period of December 1998 to January 1999. A clear light curve of the eclipse, however, was not detected. Possibly, the luminosity of the hot component was due mainly to free-free emission from the ejected circumstellar matter which was likely more extended than the M-type giant. On the other hand, another eclipse by the third component with the period of 15 years began at the end of May 1999 during which the hot component as well as the emitting regions of Hβ and Fe II lines were well eclipsed. The obscuring matter around the third component should have been much more extended than the M-type giant, and it was likely semi-transparent, because the spectrum of the M-type giant was well seen during the eclipse. The third component appears to be similar to the invisible secondary component in the long-period eclipsing binary ϵ Aur.

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“…CH Cyg is an eclipsing symbiotic star composed of a M6-7 III star and an accreting white dwarf, so the system belongs to the S-type symbiotics. The binary separation is 8.7 +1.1 −0.7 AU (Miko lajewska et al, 2010). The masses of the components are M rg = 2 +1 −0.5 M ⊙ and M wd = 0.70 +0.22 −0.09 M ⊙ (Miko lajewska et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Optical flickering of the symbiotic star CH Cyg

Stoyanov,

Marti,

Zamanov

et al. 2017

Preprint

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First spatial resolution of the stellar components of the interacting binary CH Cygni

Cited by 8 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

High-velocity equatorial mass ejections and some other spectroscopic phenomena of the symbiotic star CH Cygni in an active stage

Optical flickering of the symbiotic star CH Cyg

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