Chemical Composition of RR Lyn – an Eclipsing Binary System with Am and λ Boo Type Components

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The dependencies of the chemical element abundances in stellar atmospheres with respect to solar abundances on the second ionization potentials of the same elements were investigated using the published stellar abundance patterns for 1,149 G and K giants in the Local Region of the Galaxy. The correlations between the relative abundances of chemical elements and their second ionization potentials were calculated for groups of stars with effective temperatures between 3,764 and 7,725 K. Correlations were identified for chemical elements with second ionization potentials of 12.5 eV to 20 eV and for elements with second ionization potentials higher than 20 eV. For the first group of elements, the correlation coefficients were positive for stars with effective temperatures lower than 5,300 K and negative for stars with effective temperatures from 5,300 K to 7,725 K. The results of this study and the comparison with earlier results for hotter stars confirm the variations in these correlations with the effective temperature. A possible explanation for the observed effects is the accretion of hydrogen and helium atoms from the interstellar medium.

Section: Discussionsupporting

confidence: 57%

The Possible Signs of Hydrogen and Helium Accretion from Interstellar Medium on the Atmospheres of F-K Giants in the Local Region of the Galaxy

Yushchenko¹,

Kim²,

Jeong³

et al. 2021

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“…The continuum placement was made by the URAN software (Yushchenko 1997). The details of the synthetic spectra calculations and reduction procedure are similar to those described by Yushchenko et al (2015), Kang et al (2013), andJeong et al (2017).…”

Section: Observations Atmosphere Parameters and Line Identificationsmentioning

confidence: 99%

Magellanic Clouds Cepheids: Thorium Abundances

Jeong,

Yushchenko,

Gopka

et al. 2018

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The analysis of the high-resolution spectra of 31 Magellanic Clouds Cepheid variables enabled the identification of thorium lines. The abundances of thorium were found with spectrum synthesis method. The calculated thorium abundances exhibit correlations with the abundances of other chemical elements and atmospheric parameters of the program stars. These correlations are similar for both Clouds. The correlations of iron abundances of thorium, europium, neodymium, and yttrium relative to the pulsational periods are different in the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC), namely the correlations are negative for LMC and positive or close to zero for SMC. One of the possible explanations can be the higher activity of nucleosynthesis in SMC with respect to LMC in the recent several hundred million years.

“…It is to be noted that the Greenstein (1949) hypothesis was mentioned to explain the peculiar abundances in binary stars (Kang et al 2012(Kang et al , 2013Jeong et al 2017). It was shown that the correlations between relative abundances and second ionization potentials of corresponding elements were observed not only in radiative atmospheres, but also in convective atmospheres in the case of strong flux accreted from the circumstellar envelope.…”

Section: δLognmentioning

confidence: 99%

Chemical Composition of RM_1-390 - Large Magellanic Cloud Red Supergiant

Yushchenko¹,

Jeong²,

Gopka³

et al. 2017

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A high resolution spectroscopic observation of the red supergiant star RM_1-390 in the Large Magellanic Cloud was made from a 3.6 m telescope at the European Southern Observatory. Spectral resolving power was R=20,000, with a signal-to-noise ratio S/N > 100. We found the atmospheric parameters of RM_1-390 to be as follows: the effective temperature Teff = 4,250 ± 50 K, the surface gravity log g = 0.16 ± 0.1, the microturbulent velocity vmicro = 2.5 km/s, the macroturbulence velocity vmacro = 9 km/s and the iron abundance [Fe/H] = -0.73 ± 0.11. The abundances of 18 chemical elements from silicon to thorium in the atmosphere of RM_1-390 were found using the spectrum synthesis method. The relative deficiencies of all elements are close to that of iron. The fit of abundance pattern by the solar system distribution of r- and s-element isotopes shows the importance of the s-process. The plot of relative abundances as a function of second ionization potentials of corresponding chemical elements allows us to find a possibility of convective energy transport in the photosphere of RM_1-390.