Journal of the Korean Astronomical Society最新文献_第9页

MONTE-CARLO RADIATIVE TRANSFER MODEL OF THE DIFFUSE GALACTIC LIGHT 漫射星系光的蒙特卡罗辐射传递模型

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-02-28 DOI: 10.5303/JKAS.2015.48.1.57

K. Seon

{"title":"MONTE-CARLO RADIATIVE TRANSFER MODEL OF THE DIFFUSE GALACTIC LIGHT","authors":"K. Seon","doi":"10.5303/JKAS.2015.48.1.57","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.1.57","url":null,"abstract":"Monte-Carlo radiative models of the diffuse Galactic light (DGL) in our Galaxy are calcu-lated using the dust radiative transfer code MoCafe, which is three-dimensional and takes full account of multiple scattering. The code is recently updated to use a fast voxel traversal algorithm, which has dramatically increased the computing speed. The radiative transfer models are calculated with the gen-erally accepted dust scale-height of 0.1 kpc. The stellar scale-heights are assumed to be 0.1 or 0.35 kpc, appropriate for far-ultraviolet (FUV) and optical wavelengths, respectively. The face-on optical depth, measured perpendicular to the Galactic plane, is also varied from 0.2 to 0.6, suitable to the optical to FUV wavelengths, respectively. We find that the DGL at high Galactic latitudes is mostly due to backward or large-angle scattering of starlight originating from the local stars within a radial distance of r < 0.5 kpc from the Earth. On the other hand, the DGL measured in the Galactic plane is mostly due to stars at a distance range that corresponds to an optical depth of ? 1 measured from the Earth. Therefore, the low-latitude DGL at the FUV wavelength band would be mostly caused by the stars located at a distance of r . 0.5 kpc and the optical DGL near the Galactic plane mainly originates from stars within a distance range of 1 . r . 2 kpc. We also calculate the radiative transfer models in a clumpy two-phase medium. The clumpy two-phase models provide lower intensities at high Galactic latitudes compared to the uniform density models, because of the lower effective optical depth in clumpy media. However, no significant difference in the intensity at the Galactic plane is found.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"45 1","pages":"57-66"},"PeriodicalIF":1.0,"publicationDate":"2015-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

LARGE SDSS QUASAR GROUPS AND THEIR STATISTICAL SIGNIFICANCE 大型SDSS类星体群及其统计意义

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-02-12 DOI: 10.5303/JKAS.2015.48.1.075

Changbom Park, Hyunmi Song, M. Einasto, H. Lietzen, P. Heinamaki

{"title":"LARGE SDSS QUASAR GROUPS AND THEIR STATISTICAL SIGNIFICANCE","authors":"Changbom Park, Hyunmi Song, M. Einasto, H. Lietzen, P. Heinamaki","doi":"10.5303/JKAS.2015.48.1.075","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.1.075","url":null,"abstract":"We use a volume-limited sample of quasars in the Sloan Digital Sky Survey (SDSS) DR7 quasar catalog to identify quasar groups and address their statistical significance. This quasar sample has a uniform selection function on the sky and nearly a maximum possible contiguous volume that can be drawn from the DR7 catalog. Quasar groups are identified by using the Friend-of-Friend algorithm with a set of fixed comoving linking lengths. We find that the richness distribution of the richest 100 quasar groups or the size distribution of the largest 100 groups are statistically equivalent with those of randomly-distributed points with the same number density and sky coverage when groups are identified with the linking length of 70 h?1Mpc. It is shown that the large-scale structures like the huge Large Quasar Group (U1.27) reported by Clowes et al. (2013) can be found with high probability even if quasars have no physical clustering, and does not challenge the initially homogeneous cosmological models. Our results are statistically more reliable than those of Nadathur (2013), where the test was made only for the largest quasar group. It is shown that the linking length should be smaller than 50 h?1Mpc in order for the quasar groups identified in the DR7 catalog not to be dominated by associations of quasars grouped by chance. We present 20 richest quasar groups identified with the linking length of 70 h?1Mpc for further analyses.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"75-82"},"PeriodicalIF":1.0,"publicationDate":"2015-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70735801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 15

RADIO EMISSION FROM WEAK SPHERICAL SHOCKS IN THE OUTSKIRTS OF GALAXY CLUSTERS 星系团外围弱球形激波的射电辐射

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-02-10 DOI: 10.5303/JKAS.2015.48.2.155

Hyesung Kang

{"title":"RADIO EMISSION FROM WEAK SPHERICAL SHOCKS IN THE OUTSKIRTS OF GALAXY CLUSTERS","authors":"Hyesung Kang","doi":"10.5303/JKAS.2015.48.2.155","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.2.155","url":null,"abstract":"In Kang (2015) we calculated the acceleration of cosmic-ray electrons at weak spherical shocks that are expected to form in the cluster outskirts, and estimated the diffuse synchrotron radiation emitted by those electrons. There we demonstrated that, at decelerating spherical shocks, the volume integrated spectra of both electrons and radiation deviate significantly from the test-particle power-laws predicted for constant planar shocks, because the shock compression ratio and the flux of inject electrons decrease in time. In this study, we consider spherical blast waves propagating through a constant density core surrounded by an isothermal halo with p ∝ r ?n in order to explore how the deceleration of the shock affects the radio emission from accelerated electrons. The surface brightness profile and the volumeintegrated radio spectrum of the model shocks are calculated by assuming a ribbon-like shock surface on a spherical shell and the associated downstream region of relativistic electrons. If the postshock magnetic field strength is about 0.7 or 7 μG, at the shock age of ∼ 50 Myr, the volume-integrated radio spectrum steepens gradually with the spectral index from α inj to α inj + 0.5 over 0.1?10 GHz, where α inj is the injection index at the shock position expected from the diffusive shock acceleration theory. Such gradual steepening could explain the curved radio spectrum of the radio relic in cluster A2266, which was interpreted as a broken power-law by Trasatti et al. (2015), if the relic shock is young enough so that the break frequency is around 1 GHz.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"155-164"},"PeriodicalIF":1.0,"publicationDate":"2015-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 19

G192.8-1.1: A CANDIDATE OF AN EVOLVED THERMAL COMPOSITE SUPERNOVA REMNANT REIGNITED BY NEARBY MASSIVE STARS G192.8-1.1:由附近大质量恒星重新点燃的演化热复合超新星遗迹的候选者

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2014-12-31 DOI: 10.5303/JKAS.2014.47.6.259

Ji-hyun Kang, B. Koo, D. Byun

{"title":"G192.8-1.1: A CANDIDATE OF AN EVOLVED THERMAL COMPOSITE SUPERNOVA REMNANT REIGNITED BY NEARBY MASSIVE STARS","authors":"Ji-hyun Kang, B. Koo, D. Byun","doi":"10.5303/JKAS.2014.47.6.259","DOIUrl":"https://doi.org/10.5303/JKAS.2014.47.6.259","url":null,"abstract":"G192.8-1.1 has been known as one of the faintest supernova remnants (SNRs) in the Galaxy until the radio continuum of G192.8-1.1 is proved to be thermal by Gao et al. (2011). Yet, the nature of G192.8-1.1 has not been fully investigated. Here, we report the possible discovery of faint non-thermal radio continuum components with a spectral index α ~ 0.56 (S ν ∝ν -α ) around G192.8-1.1, while most of the radio continuum emission is thermal. Also, our Arecibo HI data reveal an HI shell, expanding with an expansion velocity of 20-60 km s -1 , that has an excellent morphological correlation with the radio continuum emission. The estimated physical parameters of the HI shell and the possible association of non-thermal radio continuum emission with it suggest G192.8-1.1 to be an ~ 0.3 Myr-old SNR. However, the presence of thermal radio continuum implies the presence of early-type stars in the same region. One possibility is that a massive star is ionizing the interior of an old SNR. If it is the case, the electron distribution assumed by the centrally-peaked surface brightness of thermal emission implies that G192.8-1.1 is a “thermal-composite” SNR, rather than a typical shell-type SNR, where the central hot gas that used to be bright in X-rays has cooled down. Therefore, we propose that G192.8-1.1 is an old evolved thermal-composite SNR showing recurring emission in the radio continuum due to a nearby massive star. The infrared image supports that the HI shell of G192.8-1.1 is currently encountering a nearby star forming region that possibly contains an early type star(s).","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"47 1","pages":"259-277"},"PeriodicalIF":1.0,"publicationDate":"2014-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

TWO MOLECULAR CLOUDS WITH ANOMALOUS VELOCITIES IN THE GALACTIC ANTICENTER 银河系反中心两个速度异常的分子云

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2014-12-31 DOI: 10.5303/JKAS.2014.47.6.319

Youngung Lee, Young Sik Kim, Hyung-Goo Kim, J. Jung, I. Yim, Hyun-Sil Kang, Changhoon Lee, Bong-Gyu Kim, Kwang-Tae Kim

引用次数: 0

STATISTICAL STUDY ON PERSONAL REDUCTION COEFFICIENTS OF SUNSPOT NUMBERS SINCE 1981 1981年以来太阳黑子数个人约简系数的统计研究

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2014-12-31 DOI: 10.5303/JKAS.2014.47.6.255

I. Cho, S. Bong, Kyungsuk Cho, Jaejin Lee, R. Kim, Young-deuk Park, Yeon-Han Kim

引用次数: 2

Development of 2.8-GHz Solar Flux Receivers 2.8 ghz太阳光通量接收机的研制

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2014-12-31 DOI: 10.5303/JKAS.2014.47.6.201

Y. Yun, Yong-Sun Park, Chang-Hee Kim, Bangwon Lee, Jung-Hoon Kim, Saeho Yoo, Chul-Hwan Lee, Jinwook Han, Young Yun Kim

引用次数: 0

ASTROPHYSICS OF DUSTY STELLAR WINDS FROM AGB STARS 来自agb恒星的尘埃恒星风的天体物理学

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2014-12-31 DOI: 10.5303/JKAS.2014.47.6.219

K. Suh

引用次数: 6

FORECAST OF SOLAR PROTON EVENTS WITH NOAA SCALES BASED ON SOLAR X-RAY FLARE DATA USING NEURAL NETWORK 基于太阳x射线耀斑数据的神经网络预测noaa尺度太阳质子事件

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2014-12-31 DOI: 10.5303/JKAS.2014.47.6.209

E. Jeong, Jin-Yi Lee, Y. Moon, Jong-Yeop Park

引用次数: 1

First Detection of 22 GHz H2O Masers in TX Camelopardalis 首次探测到TX Camelopardalis中的22 GHz H2O脉泽

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2014-12-29 DOI: 10.5303/JKAS.2014.47.6.293

Se-Hyung Cho, Jaeheon Kim, Y. Yun

{"title":"First Detection of 22 GHz H2O Masers in TX Camelopardalis","authors":"Se-Hyung Cho, Jaeheon Kim, Y. Yun","doi":"10.5303/JKAS.2014.47.6.293","DOIUrl":"https://doi.org/10.5303/JKAS.2014.47.6.293","url":null,"abstract":"Simultaneous time monitoring observations of H₂O 6 16 -5 23 , SiO J = 1-0, 2-1, 3-2, and 29 SiO v = 0, J = 1-0 lines are carried out in the direction of the Mira variable star TX Cam with the Korean VLBI Network single dish radio telescopes. For the first time, the H₂O maser emission from TX Cam is detected near the stellar velocity at five epochs from April 10, 2013 (o = 3.13) to June 4, 2014 (o = 3.89) including minimum optical phases. The intensities of H₂O masers are very weak compared to SiO masers. The variation of peak antenna temperature ratios among SiO v = 1, J = 1-0, J = 2-1, and J = 3-2 masers is investigated according to their phases. The shift of peak velocities of H₂O and SiO masers with respect to the stellar velocity is also investigated according to observed optical phases. The H₂O maser emission occurs around the stellar velocity during our monitoring interval. On the other hand, the peak velocities of SiO masers show a spread compared to the stellar velocity. The peak velocities of SiO J = 2-1, and J = 3-2 masers show a smaller spread with respect to the stellar velocity than those of SiO J = 1-0 masers. These simultaneous observations of multi-frequencies will provide a good constraint for maser pumping models and a good probe for investigating the stellar atmosphere and envelope according to their different excitation conditions.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"47 1","pages":"293-302"},"PeriodicalIF":1.0,"publicationDate":"2014-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70735787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9