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.

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.

Spectroscopic observations of barium star ζ Capricornus (HD204075) obtained at the 8.2 m telescope of the European Southern Observatory, with a spectral resolving power R = 80,000 and signal to noise ratio greater than 300, were used to refine the atmospheric parameters. We found new values for effective temperature (Teff = 5,300 ± 50 K), surface gravity (log g = 1.82 ± 0.15), micro-turbulent velocity (vmicro = 2.52 ± 0.10 km/s), and iron abundance (log N (Fe) = 7.32 ± 0.06). Previously published abundances of chemical elements in the atmosphere of HD204075 were analyzed and no correlations of these abundances with the second ionization potentials of these elements were found. This excludes the possible influence of accretion of hydrogen and helium atoms from the interstellar or circumstellar environment to the atmosphere of this star. The accretion of nuclear processed matter from the evolved binary companion was primary cause of the abundance anomalies. The young age of HD204075 allows an estimation of the time-scale for the creation of the abundance anomalies arising from accretion of interstellar hydrogen and helium as is the case of stars with low magnetic fields; which we estimate should exceed 108 years.

본 연구에서는 VFSMOD-W 모형을 활용하여 새만금 유역의 초생대 기법 적용에 따른 유사저감효과를 예측하고자 하였다. 먼저 모형의 신뢰도 확보를 위해 새만금 유역 내 초생대 실측치를 활용하여 매개변수를 보정하였으며, 새만금 유역 내 밭경지 특성을 파악하여 이를 토대로 모의 시나리오를 개발하였다. 다양한 밭경지 특성을 반영하기 위해 개발된 모의시나리오는 밭경지 규모 1 ha, 5 ha, 10 ha로 밭의 폭과 길이 비는 1 : 1를 적용 하였으며, 밭의 경사는 7%, 15%를 고려하였다. 또한 강우조건은 50 mm, 100 mm, 150 mm, 200 mm 일강우량을 적용하였다. 그 결과, 초생대의 유출저감효과는 밭경사 7%와 15%에 대해 2.9~13.5%, 2.9~12.1%로 각각 나타났으며, 유사저감효과는 33.8~97.0%, 27.1~85.9%로 각각 나타나 유출저감효과에 비해 상대적으로 높은 저감효과를 나타내었다. 유출 및 유사 발생에 영향을 미치는 밭규모, 경사 및 강우량 인자에 따라 초생대 효과는 큰 차이를 나타내었다. 본 모의 결과를 바탕으로 새만금 유역내 밭경지 규모 10 ha 미만, 경사 15% 이내의 조건에서 밭면적 10% 규모로 초생대를 조성할 경우 유사저감 효과를 기대할 수 있을 것으로 사료된다.