http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Yushchenko, Alexander,Doikov, Dmytry,Andrievsky, Sergei,Jeong, Yeuncheol,Yushchenko, Volodymyr,Rittipruk, Pakakaew,Kovtyukh, Valery,Demessinova, Aizat,Gopka, Vira,Raikov, Alexander,Jeong, Kyung Sook The Korean Space Science Society 2022 Journal of astronomy and space sciences Vol.39 No.4
We investigated the chemical composition of the planetary host halo star HD47536 via high-resolution spectral observations recorded using a 1.5 meter Cerro Tololo Inter-American Observatory (CTIO) telescope (Chile). Furthermore, we determined the abundances of 38 chemical elements. Both light and heavy elements were overabundant compared to the iron group elements. The abundance pattern of HD47536 was similar to that of halo-type stars, with an enrichment of heavy elements. We analyzed the relationships between the relative abundances of chemical elements and their second ionization potentials and condensation temperatures. We demonstrated that the interplay of charge-exchange reactions owing to the accretion of interstellar matter and the gas-dust separation mechanism can influence the initial abundances and can be used to qualitatively explain the abundance patterns in the atmosphere of HD47536.
Yushchenko, Alexander,Kim, Seunghyun,Jeong, Yeuncheol,Demessinova, Aizat,Yushchenko, Volodymyr,Doikov, Dmytry,Gopka, Vira,Jeong, Kyung Sook,Rittipruk, Pakakaew The Korean Space Science Society 2021 Journal of Astronomy and Space Sciences Vol.38 No.3
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.
THE ATMOSPHERE PARAMETERS AND THE LINE PROFILE VARIATIONS OF ρ PUPPIS
Yushchenko, A.V.,Dorokhova, T.N.,Gopka, V.F.,Kim, Chul-Hee,Lee, B.C.,Yushchenko, V.A.,Doikov, D.N. The Korean Astronomical Society 2010 Journal of The Korean Astronomical Society Vol.43 No.3
We investigate ${\rho}$ Pup using the high resolution spectral observations taken from the VLT archive and observations at a 1.8m-Korean telescope with BOES spectrograph. The atmospheric parameters are determined using the iron-line abundance analysis. We derive an effective temperature value of $T_{eff}=6890{\pm}250K$, surface gravity of log g=$3.28{\pm}0.3$ dex, microturbulent velocity of ${\upsilon}_{micro}=4.1{\pm}0.4km\;s^{-1}$, and the iron abundance of log N=$7.82{\pm}0.15$. The projected rotational velocity of the star is close to ${\upsilon}$ sin i=3.5km $s^{-1}$. Asymmetric line profiles in the observed spectra and variation of this asymmetry with time show that both strong radial pulsation and weak non-radial pulsations are present in ${\rho}$ Pup.
Yushchenko, Alexander,Kim, Seunghyun,Jeong, Yeuncheol,Demessinova, Aizat,Yushchenko, Volodymyr,Doikov, Dmytry,Gopka, Vira,Jeong, Kyung Sook,Rittipruk, Pakakaew The Korean Space Science Society 2021 Journal of astronomy and space sciences Vol.38 No.3
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.
Constant Acceleration in Fractal Structures with Fractal Dimension D = 2
Alexander Yushchenko,Yeuncheol Jeong,Volodymyr Yushchenko,Aizat Demessinova,Kyung Sook Jeong The Korean Space Science Society 2023 Journal of Astronomy and Space Sciences Vol.40 No.1
An unexplained acceleration on the order of 10<sup>-8</sup> cm s<sup>-2</sup>, which is close to cH, where c is the speed of light and H is the Hubble constant, is detected in gravitationally bound systems of different scales, from the solar system to clusters of galaxies. We found that any test body located inside a fractal structure with fractal dimension D = 2 experiences acceleration of the same order and confirmed the previous work that photons propagating through this structure decrease the frequency owing to gravitational redshift. The acceleration can be directed against the movement of the test body. The fractal distribution of the matter should be at scales of at least hundreds of megaparsecs to a few gigaparsecs for the existence of this acceleration.
Alexander Yushchenko,Dmytry Doikov,Sergei Andrievsky,Yeuncheol Jeong,Volodymyr Yushchenko,Pakakaew Rittipruk,Valery Kovtyukh,Aizat Demessinova,Vira Gopka,Alexander Raikov,Kyung Sook Jeong 한국우주과학회 2022 Journal of Astronomy and Space Sciences Vol.39 No.4
We investigated the chemical composition of the planetary host halo star HD47536 via high-resolution spectral observations recorded using a 1.5 meter Cerro Tololo Inter-American Observatory (CTIO) telescope (Chile). Furthermore, we determined the abundances of 38 chemical elements. Both light and heavy elements were overabundant compared to the iron group elements. The abundance pattern of HD47536 was similar to that of halo-type stars, with an enrichment of heavy elements. We analyzed the relationships between the relative abundances of chemical elements and their second ionization potentials and condensation temperatures. We demonstrated that the interplay of charge-exchange reactions owing to the accretion of interstellar matter and the gas-dust separation mechanism can influence the initial abundances and can be used to qualitatively explain the abundance patterns in the atmosphere of HD47536.
Alexander V. Yushchenko,Chulhee Kim,Yeuncheol Jeong,Dmytry N. Doikov,Volodymyr A. Yushchenko,Sergii V. Khrapatyi,Aizat Demessinova 한국우주과학회 2020 Journal of Astronomy and Space Sciences Vol.37 No.3
High resolution spectroscopic observation of V1719 Cyg were made at 1.8 meter telescope of Bohyunsan Optical Astronomy observatory in Korea. Spectral resolving power was R=45,000, signal to noise ratio S/N>100. The abundances of 28 chemical elements from carbon to dysprosium were found with the spectrum synthesis method. The abundances of oxygen, titanium, vanadium and elements with Z>30 are overabundant by 0.2–0.9 dex with respect to the solar values. Correlations of derived abundances with condensation temperatures and second ionization potentials of these elements are discussed. The possible influence of accretion from interstellar environment is not so strong as for ρ Pup and other stars with similar temperatures. The signs of accretion are absent. The comparison of chemical composition with solar system r- & s-process abundance patterns shows the enhancement of the photosphere by s-process elements.
Chemical Composition of RM_1-390 - Large Magellanic Cloud Red Supergiant
Alexander V. Yushchenko,정연철,Vira F. Gopka,Svetlana V. Vasil’eva,Sergey M. Andrievsky,Volodymyr O. Yushchenko 한국우주과학회 2017 Journal of Astronomy and Space Sciences Vol.34 No.3
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.
CHEMICAL ABUNDANCE PATTERNS FOR SHARP-LINED STARS
YUSHCHENKO ALEXANDER,GOPKA VERA,KIM CHULHEE,KHOKHLOVA VERA,SHAYRINA ANGELINA,MUSAEV FAIG,GALAZUTDINOV GAZINUR,PAYLENKO YAKOY,MISHENINA TAMARA,POLOSUKHINA NINA,NORTH PITER The Korean Astronomical Society 2002 Journal of The Korean Astronomical Society Vol.35 No.4
In order to increase the completeness of the investigations of stellar abundances, we can use spectrum synthesis method, new atomic data and observation of stellar spectra with resolution comparable to solar spectral atlases. We made a brief review of main problems of these three ways. We present new results of abundance determinations in the atmospheres of four stars. The first is the implementation of new atomic data to well known Przybylski's star. We show that the number of spectral lines, which can be identificated in the spectrum of this star, can be significantly higher. The second example is the investigation of $\zeta$ Cyg. We found the abundances of 51 elements in the atmosphere of this mild barium star. The third example is halo star HD221170. Our preliminary abundance pattern consists of 42 elements. The heaviest elements in this pattern are U and Th. The last star is the spectroscopic binary HD153720. The number of elements investigated in the spectra of components of this star is not large, but the results show that the components are Am-stars.