• 제목/요약/키워드: H II regions

검색결과 136건 처리시간 0.033초

A Study of Galactic Molecular Clouds through Multiwavelength Observations

  • 박성준;민경욱;선광일;한원용;이대희
    • 천문학회보
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    • 제35권1호
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    • pp.68.1-68.1
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    • 2010
  • We focus on two Galactic molecular clouds that are located in wholly different environments and both are observed by FIMS instrument onboard STSAT-1. The Draco cloud is known as a translucent molecular cloud at high Galactic latitude. The FUV spectra show important ionic lines of C IV, Si IV+O IV], Si II* and Al II, indicating the existence of hot and warm interstellar gases in the region. The enhanced C IV emission inside the Draco cloud region is attributable to the turbulent mixing of the interacting cold and warm/hot media, which is supported by the detection of the O III] emission line and the $H{\alpha}$ feature in this region. The Si II* emission covers the remainder of the region outside the Draco cloud, in agreement with previous observations of Galactic halos. Additionally, the H2 fluorescent map is consistent with the morphology of the atomic neutral hydrogen and dust emission of the Draco cloud. In the Aquila Rift region near Galactic plane, FIMS observed that the FUV continuum emission from the core of the Aquila Rift suffers heavy dust extinction. The entire field is divided into three sub-regions that are known as the- "halo," "diffuse," and "star-forming" regions. The "diffuse" and "star-forming" regions show various prominent H2 fluorescent emission lines, while the "halo" region indicates the general ubiquitous characteristics of H2. The CLOUD model and the FUV line ratio are included here to investigate the physical conditions of each sub-region. Finally, the development of an infrared imaging system known as the MIRIS instrument onboard STSAT-3 is briefly introduced. It can be used in WIM studies through $Pa{\alpha}$ observations.

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PROPERTIES OF THE MOLECULAR CLUMP AND THE ASSOCIATED ULTRACOMPACT H II REGION IN THE GAS SHELL OF THE EXPANDING H II REGION SH 2-104

  • Minh, Young Chol;Kim, Kee-Tae;Yan, Chi-Hung;Park, Yong-Sun;Lee, Seokho;Lal, Dharam Vil;Hasegawa, Tatsuhiko;Zhang, X.Z.;Kuan, Yi-Jeng
    • 천문학회지
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    • 제47권5호
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    • pp.179-185
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    • 2014
  • We study the physical and chemical properties of the molecular clump hosting a young stellar cluster, IRAS 20160+3636, which is believed to have formed via the "collect and collapse" process. Physical parameters of the UC H II region associated with the embedded cluster are measured from the radio continuum observations. This source is found to be a typical Galactic UC H II region, with a B0.5 type exciting star, if it is ionized by a single star. We derive a CN/HCN abundance ratio larger than 1 over this region, which may suggest that this clump is being affected by the UV radiation from the H II region.

북한 지역의 콩 기상 생태형 설정 연구 (Estimation of Meteorological Ecology of Soybean (Glycine max Merrill) for Crop Cultivation Regions of North Korea)

  • 김보환;이혜지;김욱;박세준
    • 한국작물학회지
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    • 제65권1호
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    • pp.56-62
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    • 2020
  • 본 연구는 북한 지역에 적합한 콩 품종의 기상생태형을 설정하고 그 특성을 제시하기 위하여 실시하였다. 지역의 일별 최저온도를 기준으로 콩 수확 한계기와 최대 재배일수를 결정하였으며, 이를 적용하여 지역별 콩 기상생태형을 분류하였고 그 특성은 다음과 같다. 1. 북한 지역의 콩 기상생태형 군은 총 8군으로 분류하였다. I군은 서해안 남부와 동해안 남부지역으로, II-1군은 서해 내륙의 남부에서 북부에 걸친 지역으로, II-2군은 동해안 중부지역으로, III-1군은 중부 내륙지역으로, III-2군은 동해안 북부지역으로, IV-1군은 중부 내륙 산간지역으로, IV-2군은 북부 내륙지역으로, IV-3군은 동해안 최북단과 북부 내륙 산간지역으로 결정되었다. 2. 수확 한계기는 I군에 속하는 남부 서해안과 동부 동해안 지역이 10월 21일~29일로 가장 늦었고, 중부 내륙과 산간지역으로 갈수록 짧아져 IV군에서는 9월 18일~10월 2일로 가장 빨랐다. 3. 최대 생육일수는 I군은 153~160일로 가장 길었으며, 북부산간 지역인 IV-3군은 100~111일로 가장 짧았다. 4. 총 생육일수를 110일로 가정하였을 때, 기상생태형 I군의 개화 한계기는 8월 12일~19일로 일장은 13.5~13.8 h이었으며, II군은 8월 2일~6일에 14~14.2 h, III군은 7월 27일~8월 2일에 14.2~14.4 h, IV군은 7월 10일~22일에 14.5~14.8 h이었다. 5. 총 생육일수를 110일로 가정하였을 때 적산온도는 서해 내륙에 있는 2-1군이 2,400℃ 이상으로 높았으며, 청진, 선봉, 중강 지역을 제외한 모든 지역에서 2,300℃ 이상을 보였다. 6. 최대 재배일수를 기준으로 산정한 적산온도는 I군과 II-1군은 3,000℃ 이상의 적산온도를 보였으며, II-2군, III-1군, 및 IV-1군은 2,500℃ 이상의 적산온도를 기록하였다.

Catalog of the Paα-emitting Sources observed in the Carina Region

  • Kim, Il-Joong;Pyo, Jeonghyun;Jeong, Woong-Seob
    • 천문학회보
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    • 제46권2호
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    • pp.66.2-66.2
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    • 2021
  • We list up the Paα-emitting sources observed in the Carina Region (l = 276°-296°) using the MIRIS Paα Galactic Plane Survey data. A total of 201 sources are cataloged. Out of them, 118 sources are coincident with those in the WISE H II region catalog. 52 H II region candidates are newly confirmed as definite H II regions by detecting the Paα recombination lines. For the remaining 83 sources, we search the corresponding objects in the SIMBAD database. 26 point-like sources are associated with planetary nebulae or emission-line stars (such as Wolf-Rayet and Blue supergiant stars). Also, we carry out aperture photometry to measure Paα fluxes for the sources that show circular features without overlapping with other bright sources. For the whole Galactic Plane, the complete Paα-emitting source catalog is in progress.

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고주파유도결합플라즈마 반응기에서 물로부터 수소생성효율을 높이기 위한 공정변수에 대한 연구 (Study on Process Parameters for Effective H2 Production from H2O in High Frequency Inductively Coupled Plasma Reactor)

  • 권성구;정용호
    • 한국수소및신에너지학회논문집
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    • 제22권2호
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    • pp.206-212
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    • 2011
  • The effect of process parameters on $H_2$ production from water vapor excited by HF ICP has been qualitatively examined for the first time. With the increase of ICP power, characteristics of $H_2$ production from $H_2O$ dissociation in plasma was divided into 3 regions according to both reaction mechanism and energy efficiency. At the edge of region (II) in the range of middle ICP power, energy effective hydrogen production from $H_2O$ plasma can be achieved. Furthermore, within the region (II) power condition, heating of substrate up to $500^{\circ}C$ shows additional increase of 70~80% in $H_2$ production compared to $H_2O$ plasma without substrate heating. This study have shown that combination of optimal plasma power (region II) and wall heating (around $500^{\circ}C$) is one of effective ways for $H_2$ production from $H_2O$.

CO Observations of H II Regions Sh 254-258

  • Jung, Dong-Kyu;Kim, Kwang-Tae
    • 천문학회보
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    • 제40권2호
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    • pp.53.1-53.1
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    • 2015
  • The molecular clouds associated with bright optical HII regions Sh 254-258 are studied with the TRAO CO observations and with the WISE near-infrared emission. Based on the morphology of the clouds and the basic physical parameters derived with the LTE analysis, Pieces of evidences for physical interactions with its surroundings are investigated.

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Oxidation Behavior of $Ni_xFe_{1-x}(OH)_2$ in $C\Gamma$-containing Solutions

  • Chung, Kyeong Woo;Kim, Kwang Bum
    • Corrosion Science and Technology
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    • 제2권3호
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    • pp.148-154
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    • 2003
  • The addition of Ni leads to the formation of protective rust layer on steel and subsequently high corrosion resistance of steel in $Cl^-$-containing environment. $\alpha$-FeOOH, $\beta$-FeOOH, $\gamma$-FeOOH and $Fe_3O_4$ are formed mainly on steels exposed to $Cl^-$-containing environment. As the first work of this kind, this study reports the influence of Ni on the oxidation behavior of $Ni_xFe_{1-x}(OH)_2$ in $Cl^-$-containing solution at two different pH regions(condition I under which the solution pH is allowed to decrease and condition I under which solution pH is maintained at 8) where $\gamma$-FeOOH and $Fe_3O_4$ are predominantly formed, respectively, upon oxidation of $Fe(OH)_2$, In the presence of Ni(II) in the starting solution, the formation of $\beta$-FeOOH was facilitated and the formation of $\gamma$-FeOOH was suppressed with increasing Ni(II) content and with increasing oxidation rate of Fe(II). Ni(II) was found to have $Fe_3O_4$-suppressing effect under condition II.

FAR-INFRARED [C II] EMISSION FROM THE CENTRAL REGIONS OF SPIRAL GALAXIES

  • MOCHIZUKI KENJI
    • 천문학회지
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    • 제37권4호
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    • pp.193-197
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    • 2004
  • Anomalies in the far-infrared [C II] 158 ${\mu}m$ line emission observed in the central one-kiloparsec regions of spiral galaxies are reviewed. Low far-infrared intensity ratios of the [C II] line to the continuum were observed in the center of the Milky Way, because the heating ratio of the gas to the dust is reduced by the soft interstellar radiation field due to late-type stars in the Galactic bulge. In contrast, such low line-to-continuum ratios were not obtained in the center of the nearby spiral M31, in spite of its bright bulge. A comparison with numerical simulations showed that a typical column density of the neutral interstellar medium between illuminating sources at $hv {\~} 1 eV $ is $N_H {\le}10^{21}\;cm^{-2}$ in the region; the medium is translucent for photons sufficiently energetic to heat the grains but not sufficiently energetic to heat the gas. This interpretation is consistent with the combination of the extremely high [C Il]/CO J = 1-0 line intensity ratios and the low recent star-forming activity in the region; the neutral interstellar medium is not sufficiently opaque to protect the species even against the moderately intense incident UV radiation. The above results were unexpected from classical views of the [C II] emission, which was generally considered to trace intense interstellar UV radiation enhanced by active star formation.

Surface Hardness Measurement of Anodic Oxide Films on AA2024 based an Ink-Impregnation Method

  • Moon, Sungmo;Rha, Jong-joo
    • 한국표면공학회지
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    • 제53권2호
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    • pp.80-86
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    • 2020
  • This paper is concerned with type of imperfections present within the anodic oxide films on AA2024 and surface hardness of the anodic film measured after ink-impregnation. The anodic oxide films were formed for 25 min at 40 mA/㎠ and 15±0.5℃ and 300 rpm of magnet stirring rate in 20% sulfuric acid solution. The ink-impregnation allows clear observations of not only the imperfections within the anodic oxide films but also an indentation mark on the oxide film surface made by a pyramidal-diamond penetrator for the hardness measurement. There were observed four different regions in the anodic oxide films on AA2024 and the surface hardness of the anodic oxide films appeared to be crucially dependent on the type of defects, showing 60~100 Hv on the oxide surface region I with large size black defect, 100~140 Hv on the oxide surface region II with large size grey defect, 140~170 Hv on the oxide surface region III with mall size black and/or grey defects and 170~190 Hv on the oxide surface region IV without defects. The pyramidal indentation marks were observed to be distorted in the regions with a large size black and grey defects, while no distortion of the indentation mark was observed in the regions with small size defects and without visible defects.

SH 2-128, AN H II AND STAR FORMING REGION IN AN UNLIKELY PLACE

  • BOHIGAS JOAQUIN;TAPIA MAURICIO
    • 천문학회지
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    • 제37권4호
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    • pp.285-288
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    • 2004
  • Near-infrared imaging photometry supplemented by optical spectroscopy and narrow-band imaging of the H II region Sh 2-128 and its environment are presented. This region contains a developed H II region and the neighboring compact H II region S 128N associated with a pair of water maser sources. Midway between these, the core of a CO cloud is located. The principal ionizing source of Sh 2-128 is an 07 star close to its center. A new spectroscopic distance of 9.4 kpc is derived, very similar to the kinematic distance to the nebula. This implies a galactocentric distance of 13.5 kpc and z = 550 pc. The region is optically thin with abundances close to those predicted by galactocentric gradients. The $JHK_s$ images show that S 128N contains several infrared point sources and nebular emission knots with large near-infrared excesses. One of the three red Ks knots coincides with the compact H II region. A few of the infrared-excess objects are close to known mid- and far-infrared emission peaks. Star counts in J and $K_s$ show the presence of a small cluster of B-type stars, mainly associated with S 128N. The $JHK_s$ photometric properties together with the characteristics of the other objects in the vicinity suggest that Sh 2-128 and S 128N constitute a single complex formed from the same molecular cloud, with ages ${\~}10^6$ and < $3 {\times} 10^5$ years respectively. No molecular hydrogen emission was detected at 2.12 ${\mu}m$. The origin of this remote star forming region is an open problem.