• 천문학회지
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• 제53권1호
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• pp.9-26
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• 2020

At q = 1.81 ± 0.20 × 10^-5, KMT-2018-BLG-0029Lb has the lowest planet-host mass ratio q of any microlensing planet to date by more than a factor of two. Hence, it is the first planet that probes below the apparent "pile-up" at q = 5-10 ×10^-5. The event was observed by Spitzer, yielding a microlens-parallax π_E measurement. Combined with a measurement of the Einstein radius θ_E from finite-source effects during the caustic crossings, these measurements imply masses of the host M_host = 1.14^+0.10_-0.12 M_⊙ and planet M_planet = 7.59^+0.75_-0.69 M_⊕, system distance D_L = 3.38^+0.22_-0.26 kpc and projected separation a_⊥ = 4.27^+0.21_-0.23 AU. The blended light, which is substantially brighter than the microlensed source, is plausibly due to the lens and could be observed at high resolution immediately.

• 천문학회지
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• 제55권4호
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• pp.123-130
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• 2022

We present the analysis of a planetary microlensing event OGLE-2019-BLG-0362 with a shortduration anomaly (~0.4 days) near the peak of the light curve, which is caused by the resonant caustic. The event has a severe degeneracy with ∆𝜒² = 0.9 between the close and the wide binary lens models both with planet-host mass ratio q ≃ 0.007. We measure the angular Einstein radius but not the microlens parallax, and thus we perform a Bayesian analysis to estimate the physical parameters of the lens. We find that the OGLE-2019-BLG-0362L system is a super-Jovian-mass planet $M_p=3.26^{+0.83}_{-0.58}M_J $ orbiting an M dwarf $M_h=0.42^{+0.34}_{-0.23}M_{\odot}$ at a distance $D_L=5.83^{+1.04}_{-1.55}kpc$. The projected star-planet separation is ${\alpha}_{\bot}= 2.18^{+0.58}_{-0.72}AU$, which indicates that the planet lies beyond the snow line of the host star.

• 한국환경복원기술학회지
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• 제14권6호
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• pp.57-69
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• 2011

The present paper deals with a research of life form and vegetation of the plants extant in the habitat of endangered Parnassius bremeri in Uiseong, Gyeongsangbuk-do with a view to restore their habitat and create substitute habitats. The research found that there are a total of 130 vascular plants including 47 families, 96 genera, 113 species, 1 subspecies and 16 varieties. In terms of their life form, hemicryptophytes (H) is the majority of dormancy form with 41 species or 31.54%, while $R_5$ is majority of radicoid form with 72 species or 55.38%, gravitational disseminule form ($D_4$) is majority among the disseminule forms with 68 species or 52.31% and erect type (e) is majority of growth form with 57 species or 43.85%. Major constituents of the habitat are Sedum kamtschaticum, Selaginella tamariscina, Orostachys japonica, Arundinella hirta, Cymbopogon tortilis var. goeringii, Themeda triandra var. japonica, Carex humilis, Indigofera kirilowii, Imperata cylindrica var. koenigii, Festuca ovina, Artemisia capillaris, etc., all of species which are in the initial stage of succession and show simultaneously features characteristic of vegetation on the rock. In the habitat 1. Sedum kamtschaticum- Selaginella tamariscina community and Pinus densiflora community are distributed whereas, in the habitat 2. Sedum kamtschaticum-Selaginella tamariscina community, Sedum kamtschaticum-Carex humilis community, Sedum kamtschaticum-Cymbopogon tortilis var. goeringii community and Sedum kamtschaticum-Imperata cylindrica var. koenigii community are growing and in the habitat 3. Sedum kamtschaticum-Selaginella tamariscina community, Selaginella tamariscina community, Sedum kamtschaticum-Indigofera kirilowii community and Quercus acutissima community are seen distributed there, too. Typical of food plants growing in the habitat is Sedum kamtschaticum, found mostly in the rocky area and its surroundings. Absorption plants are those that usually bloom in the season when imagoes emerge. From the research, it becomes evident that the blooming season of Sedum kamtschaticum, obviously a food plant, corresponds exactly to the emergence timing of imagoes. Cirsium japonicum var. ussuriense, Rosa multiflora, Erigeron annuus, Spiraea prunifolia var. simpliciflora are found to belong to these plants.

• 천문학회지
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• 제55권5호
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• pp.173-194
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• 2022

We complete the survey for finite-source/point-lens (FSPL) giant-source events in 2016-2019 KMTNet microlensing data. The 30 FSPL events show a clear gap in Einstein radius, 9 𝜇as < 𝜃_E < 26 𝜇as, which is consistent with the gap in Einstein timescales near t_E ~ 0.5 days found by Mróz et al. (2017) in an independent sample of point-source/point-lens (PSPL) events. We demonstrate that the two surveys are consistent. We estimate that the 4 events below this gap are due to a power-law distribution of free-floating planet candidates (FFPs) dN_FFP/d log M = (0.4 ± 0.2) (M/38 M_⊕)^-p/star, with 0.9 ≲ p ≲ 1.2. There are substantially more FFPs than known bound planets, implying that the bound planet power-law index 𝛾 = 0.6 is likely shaped by the ejection process at least as much as by formation. The mass density per decade of FFPs in the Solar neighborhood is of the same order as that of 'Oumuamua-like objects. In particular, if we assume that 'Oumuamua is part of the same process that ejected the FFPs to very wide or unbound orbits, the power-law index is p = 0.89 ± 0.06. If the Solar System's endowment of Neptune-mass objects in Neptune-like orbits is typical, which is consistent with the results of Poleski et al. (2021), then these could account for a substantial fraction of the FFPs in the Neptune-mass range.

• 분석과학
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• 제27권1호
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• pp.34-40
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• 2014

SPLITT 분획법(Split-flow thin cell fractionation, SF)은 입자성 물질이나 거대분자를 크기에 따라 연속적으로 분획할 수 있는 유용한 기술이다. SF에서는 얇은 리본 모양 채널의 입구와 출구에 존재하는 흐름분할기(flow stream splitter)에 의하여 시료의 분리가 이뤄진다. 대용량 중력장 FFD-SF 시스템(New large scale splitter-less FFD-SF system)은 흐름분할기를 사용하지 않고, 전액공급 모드(FFD mode) 로 작동하도록 디자인되었다. 전액공급 모드는 용매의 공급 없이 시료만을 채널 내로 주입함으로써 시료의 희석을 방지할 수 있는 장점을 가진다. 본 연구에서는 산업용 polyurethane (PU)입자를 시료로 이용하여, FFD-SF 장치의 성능에 미치는 시료의 주입유속과 채널두께의 영향을 확인하였다. Carrier 용액으로는 시료간 응집과 박테리아 생성을 방지하기 위하여 0.1% FL-70와 0.02% sodium azide ($NaN_3$)를 함유하는 수용액을 사용하였다. 시료농도는 0.02% (wt/vol)로 고정, 주입 양은 4.2~7.2 L/hr, 채널두께는 $900{\sim}1300{\mu}m$의 범위에서 실험하였다. 분획효율(Fractionation efficiency, FE)은 optical microscopy (OM)을 사용하여 입자의 수를 확인하여 계산하였으며, 시료회수율(sample recovery)은 membrane filter를 이용하여 분획된 시료의 무게로부터 계산하였다. 채널두께가 두꺼울수록 fraction-a의 분획효율이 증가하였고, 유속이 증가할수록 fraction-b의 분획효율 증가하였다. 시료회수율은 평균 95%를 보였다. 본 연구 결과는 새로운 splitter-less FFD-SF system은 다양한 마이크론 크기의 입자의 분획에 유용한 방법임을 보여준다.