• Title/Summary/Keyword: H II regions

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The Emission-line Properties of Young Radio Galaxies

  • Son, Dong-Hoon;Woo, Jong-Hak;Bennert, Vardha N.;Fu, Hai;Nagao, Tohru;Park, Dae-Seong
    • The Bulletin of The Korean Astronomical Society
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    • v.36 no.2
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    • pp.71.2-71.2
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    • 2011
  • To investigate the properties of the narrow-line regions and the accretion disks of YRGs, we study a sample of 28 young radio galaxies (YRGs) observed with the Kast Double Spectrograph at the Shane 3-m telescope and with the DBSP (Double Spectrograph for the Palomar 200-inch Telescope) at Palomar observatory. In addition we collect an addition sample of 15 YRGs with the optical spectra from the SDSS archive. We present the measured narrow-line region properties based on the various emission line ratios, i.e., [O III]/$H{\beta}$, [N II]/$H{\alpha}$, [S II] 6716/6731, [O I]/[O III], [O II]/[O III] and [Ar III]/[O III], which are useful to constrain the gas properties and the states of the accretion disk. We will discuss the characteristics of YRG.

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PROBING STAR FORMATION IN ULTRALUMINOUS INFRARED GALAXIES USING AKARI NEAR-INFRARED SPECTROSCOPY

  • Yano, Kenichi;Nakagawa, Takao;Isobe, Naoki;Shirahata, Mai
    • Publications of The Korean Astronomical Society
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    • v.32 no.1
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    • pp.189-191
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    • 2017
  • We performed systematic observations of the H $\small{I}$ $Br{\alpha}$ line ($4.05{\mu}m$) in 51 nearby (z<0.3) ultraluminous infrared galaxies (ULIRGs), using AKARI near-infrared spectroscopy. The $Br{\alpha}$ line is predicted to be the brightest among the H ${\small{I}}$ recombination lines in ULIRGs with visual extinction higher than 15 mag. We detected the $Br{\alpha}$ line in 33 ULIRGs. In these galaxies, the relative contribution of starburst to the total infrared luminosity ($L_{IR}$) is estimated on the basis of the ratio of the $Br{\alpha}$ line luminosity ($L_{Br{\alpha}}$) to $L_{IR}$. The mean $L_{Br{\alpha}}/L_{IR}$ ratio in LINERs or Seyferts is significantly lower (~50%) than that in H $\small{II}$ galaxies. This result indicates that active galactic nuclei contribute significantly (~50%) to $L_{IR}$ in LINERs, as well as Seyferts. We also estimate the absolute contribution of starburst to $L_{IR}$ using the ratio of star formation rates (SFRs) derived from $L_{Br{\alpha}}$ ($SFR_{Br{\alpha}}$) and those needed to explain $L_{IR}$ ($SFR_{IR}$). The mean $SFR_{Br{\alpha}}/SFR_{IR}$ ratio is only 0.33 even in H $\small{II}$ galaxies, where starburst is supposed to dominate the luminosity. We attribute this apparently low $SFR_{Br{\alpha}}/SFR_{IR}$ ratio to the absorption of ionizing photons by dust within H $\small{II}$ regions.

A Numerical Study for the Variation of Cortical Bone Thickness with Several Dental Implants (인공치아에 있어 피질골의 두께 변화가 미치는 영향에 관한 연구)

  • Choi, J.B.;Moon, H.J.;Choi, K.
    • Proceedings of the KOSOMBE Conference
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    • v.1996 no.11
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    • pp.323-326
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    • 1996
  • Dental implant is increasingly used to recover the mastication function of tooth. Several types of implant were designed to give an optimal stress distribution in surrounding bony regions. In this study, six types of implant were investigated using finite element method and it was studied i) how the variation of cortical bone thickness affects the stress distribution in surrounding bony regions depending upon implant types, ii) which type gives the best characteristics in the sence of stress distribution and stability. The hybrid-type implant with cylinder and screw gave the optimum properties in view of stability and response to the variation of cortical bone thickness.

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1.64 ${\mu}m$ features of Jets and Outflows from Young Stellar Objects in the Carina Nebula

  • Shinn, Jong-Ho;Pyo, Tae-Soo;Lee, Jae-Joon;Lee, Ho-Gyu;Kim, Hyun-Jeong;Koo, Bon-Chul;Sung, Hwankyung;Chun, Moo-Young;Lyo, A. Ran;Moon, Dae-Sik;Kyeong, Jaemann;Park, Byeong-Gon;Hur, Hyeonoh;Lee, Yong-Hyun
    • The Bulletin of The Korean Astronomical Society
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    • v.39 no.1
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    • pp.56.2-56.2
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    • 2014
  • We present [Fe II] 1.64 ${\mu}m$ imaging observations for jets and outflows from young stellar objects over the northern part (${\sim}24^{\prime}{\times}45^{\prime}$) of the Carina Nebula, a massive star forming region. The observations were performed with IRIS2 of Anglo-Australian Telescope and the seeing was ~1.5". Eleven jets and outflows features are detected at eight different regions, and are termed as Ionized Fe Objects (IFOs). The [Fe II] features have knotty or elongated shapes, and the detection rate of IFOs against previously identified YSOs is 1.4%. Four IFOs show anti-correlated peak intensities in [Fe II] and $H{\alpha}$, where the ratio I([Fe II])/I($H{\alpha}$) is higher for longish IFOs than for knotty IFOs. We estimate the outflow mass loss rate from the [Fe II] flux using two different methods. The jet-driving objects are identified for three IFOs (IFO-2, -4, and -7). The ratios of the outflow mass loss rate over the disk accretion rate for IFO-4 and -7 are consistent with the previously reported values ($10^{-2}-10^{+1}$), while the ratio is higher for IFO-2. This excess may result from underestimating the disk accretion rate. Other YSO physical parameters show reasonable relations or trends.

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Genetic Diversity of Hard Ticks (Acari: Ixodidae) in the South and East Regions of Kazakhstan and Northwestern China

  • Yang, Yicheng;Tong, Jin;Ruan, Hongyin;Yang, Meihua;Sang, Chunli;Liu, Gang;Hazihan, Wurelihazi;Xu, Bin;Hornok, Sandor;Rizabek, Kadyken;Gulzhan, Kulmanova;Liu, Zhiqiang;Wang, Yuanzhi
    • Parasites, Hosts and Diseases
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    • v.59 no.1
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    • pp.103-108
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    • 2021
  • To date, there is no report on the genetic diversity of ticks in these regions. A total of 370 representative ticks from the south and east regions of Kazakhstan (SERK) and Xinjiang Uygur Autonomous Region (XUAR) were selected for molecular comparison. A fragment of the mitochondrial cytochrome c oxidase subunit I (cox1) gene, ranging from 631 bp to 889 bp, was used to analyze genetic diversity among these ticks. Phylogenetic analyses indicated 7 tick species including Hyalomma asiaticum, Hyalomma detritum, Hyalomma anatolicum, Dermacentor marginatus, Rhipicephalus sanguineus, Rhipicephalus turanicus and Haemaphysalis erinacei from the SERK clustered together with conspecific ticks from the XUAR. The network diagram of haplotypes showed that i) Hy. asiaticum from Almaty and Kyzylorda Oblasts together with that from Yuli County of XUAR constituted haplogroup H-2, and the lineage from Chimkent City of South Kazakhstan was newly evolved; and ii) the R. turanicus ticks sampled in Israel, Almaty, South Kazakhstan, Usu City, Ulugqat and Baicheng Counties of XUAR were derivated from an old lineage in Alataw City of XUAR. These findings indicate that: i) Hy. asiaticum, R. turanicus and Ha. erinacei shared genetic similarities between the SERK and XUAR; and ii) Hy. marginatum and D. reticulatus show differences in their evolution.

A study on the manufacture and dielectric of the polyvinylidene fluoride thin films through vapor deposition method (진공증착법을 이용한 PVDF박막의 제작과 유전 특성에 관한 연구)

  • Park, S.H.;Im, U.C.;Cho, K.S.;Lee, D.C.
    • Proceedings of the KIEE Conference
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    • 1995.11a
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    • pp.420-422
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    • 1995
  • PVDF (polyvinylidene fluoride) has at least from known crystalline structure ( ; they are referred to as the $\alpha$, $\beta$, $\gamma$ and $\alpha_p$ phase or forms II, I, III and $IV_p$). In this study, the manufactured PVDF thin films through vapor deposition method had for II ( ; the substrate temperature at 30$^{\circ}C$). The dielectric behavior of poly(vinylidene fluoride) is affected by orientation and crystal modification. The very high value of the dielectric constant for high temperature conditioned film is believed to be due to the orientation effect. The loss peak caused by molecular motion of the molecules in crystalline regions.

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IGRINS Observations of Star Forming Clouds in NGC 6822 Hubble V

  • Pak, Soojong;Lee, Hye-In;Le, Huynh Anh N.;Lee, Sungho;Chung, Aeree;Kaplan, Kyle;Jaffe, Daniel T.
    • The Bulletin of The Korean Astronomical Society
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    • v.39 no.2
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    • pp.92.2-92.2
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    • 2014
  • NGC 6822 is a dwarf irregular galaxy in the Local Group. Unlike clouds in the Large Magellanic Cloud and the Small Magellanic Cloud, molecular clouds in NGC 6822 are not influenced by the Galactic tidal force. Therefore the star forming processes are only dictated by local conditions. Hubble V is the brightest of the several bright H II region complexes in NGC 6822. The core of Hubble V, surrounded by a molecular cloud complex, contains compact clusters of bright blue stars. During the commissioning runs of the new high-resolution near-infrared spectrometer, IGRINS (Immersion GRating near-INfrared Spectrometer), we observed Hubble V and detected many emission lines from the H II regions and from the photodissociation region at the interface between the ionized gas and the molecular cloud. In this presentation, we report preliminary results of the IGRINS observations. We discuss the implications of the observed lines ratios and kinematics for our understanding of the evolution of star forming molecular clouds.

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Submillimeter Observations of the Infrared Dark Cloud G049.40-00.01

  • Kang, Mi-Ju;Choi, Min-Ho;Bieging, John H.;Rho, Jeong-Hee;Lee, Jeong-Eun;Tsai, Chao-Wei
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.1
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    • pp.77.2-77.2
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    • 2012
  • Infrared dark clouds(IRDCs) are believed to be the progenitors of massive stars and clusters. We obtained 350 and 850 ${\mu}m$ continuum maps of the IRDC G049.40-00.01 using SHARC-II on CSO. Twenty-one dense clumps were identified within G049.40-00.01 based on the 350 ${\mu}m$ continuum map with an angular resolution of about 9.6". We present submillimeter continuum maps and report physical properties of the clumps. The masses of clumps are from 50 to 600 solar mass. About 70% of the clumps are associated with bright 24 ${\mu}m$ emission sources indicating protostars. The most massive two clumps show enhanced, extended 4.5 ${\mu}m$ emission representing on-going star forming activity. The size-mass distribution of the clumps suggests that many of them are forming high-mass stars. G049.40-00.01 contains numerous objects in various evolutionary stages of star formation, from pre-stellar clumps to H II regions.

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사람의 Serine palmitoryl transferase II 및 ceramidase의 promoter에 대한 연구

  • Kim, Hui-Suk;Song, Seong-Gwang;Lee, Eun-Yeol;Lee, Sang-Do;Linn, Steve;Merrill, Alfred H.
    • 한국생물공학회:학술대회논문집
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    • 2000.04a
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    • pp.588-591
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    • 2000
  • Serine palmitoyl transferase(SPT) and ceramidase are the key enzymes in sphingolipid biosynthesis. To study sphingolipid metabolism, we have got the 5'-upstream regions of human serine palmitoyl transferase subunit II and acid ceramidase gene by using GenomeWalker kits(Clontech Co.). Human genomic DNA was purified from HT29, human colon canser cell line by using DNAzol. We got several bands after secondary PCR and subcloned them to T7bule vector. Human SPTII promoter which we got was 2690bp but we cut it with Bgl II and vector with Bgl II and BamH I, and subcloned 1782bp to pGL2-enhancer vector and pGL2-basic vector with luciferase reporter gene. Human acid ceramidase promoter which we got were 2028bp and 1034bp and subcloned to pGL2-enhancer vector and pGL2-basic vector. We transfected these promoters to HT29 cell and assayed luciferase activity. For measuring transfection efficiency, pRL-TK vector with seapancy luciferase reproter gene was cotransfected with these promoters.

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LARGE-SCALE [OIII] AND [CII] DISTRIBUTIONS OF THE LARGE MAGELLANIC CLOUD WITH FIS-FTS

  • Takahashi, A.;Yasuda, A.;Kaneda, H.;Kawada, M.;Kiriyama, Y.;Mouri, A.;Mori, T.;Okada, Y.;Takahashi, H.
    • Publications of The Korean Astronomical Society
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    • v.27 no.4
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    • pp.219-220
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    • 2012
  • We present the results of far-infrared spectroscopic observations of the Large Magellanic Cloud (LMC) with FIS-FTS. We covered a large area across the LMC, including 30 Doradus (30 Dor) and N44 star-forming regions, by 191 pointings in total. As a result, we detect the [OIII] and [CII] line emission as well as far-infrared dust continuum emission throughout the LMC. We find that the [OIII] emission is widely distributed around 30 Dor. The observed size of the distribution is too large to be explained by massive stars in 30 Dor, which are assumed to be enshrouded by clouds with the constant gas density estimated from the [OIII] line intensities. Therefore the surrounding structure is likely to be highly clumpy. We also find a global correlation between the [OIII] and the far-infrared continuum emission, suggesting that the gas and dust are well mixed in the highly-ionized region where the dust survives in clumpy dense clouds shielded from energetic photons. Furthermore we find that the ratios of [CII]/CO are as high as 110,000 in 30 Dor, and 45,000 even on average, while they are typically 6,000 for star-forming regions in our Galaxy. The unusually high [CII]/CO is also consistent with the picture of clumpy small dense clouds.