Journal of the Korean Astronomical Society最新文献_第6页

RE-ACCELERATION MODEL FOR THE ‘TOOTHBRUSH’ RADIO RELIC “牙刷”无线电遗迹的重新加速模型

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-03-24 DOI: 10.5303/JKAS.2016.49.3.083

Hyesung Kang

引用次数: 14

A New Method to Determine the Temperature of CMEs Using a Coronagraph Filter System 利用日冕仪滤波系统确定日冕物质抛射温度的新方法

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-03-23 DOI: 10.5303/JKAS.2016.49.1.045

Kyuhyoun Cho, J. Chae, E. Lim, Kyungsuk Cho, S. Bong, Heesu Yang

引用次数: 3

NON-GREY RADIATIVE TRANSFER IN THE PHOTOSPHERIC CONVECTION : VALIDITY OF THE EDDINGTON APPROXIMATION 光球对流中的非灰色辐射传输:eddington近似的有效性

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-02-29 DOI: 10.5303/JKAS.2016.49.1.1

K. Bach

{"title":"NON-GREY RADIATIVE TRANSFER IN THE PHOTOSPHERIC CONVECTION : VALIDITY OF THE EDDINGTON APPROXIMATION","authors":"K. Bach","doi":"10.5303/JKAS.2016.49.1.1","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.1.1","url":null,"abstract":"The aim of this study is to describe the physical processes taking place in the solar photosphere. Based on 3D hydrodynamic simulations including a detailed radiation transfer scheme, we investigate thermodynamic structures and radiation fields in solar surface convection. As a starting model, the initial stratification in the outer envelope calculated using the solar calibrations in the context of the standard stellar theory. When the numerical fluid becomes thermally relaxed, the thermodynamic structure of the steady-state turbulent flow was explicitly collected. Particularly, a non-grey radiative transfer incorporating the opacity distribution function was considered in our calculations. In addition, we evaluate the classical approximations that are usually adopted in the onedimensional stellar structure models. We numerically reconfirm that radiation fields are well represented by the asymptotic characteristics of the Eddington approximation (the diffusion limit and the streaming limit). However, this classical approximation underestimates radiation energy in the shallow layers near the surface, which implies that a reliable treatment of the non-grey line opacities is crucial for the accurate description of the photospheric convection phenomenon.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"1-8"},"PeriodicalIF":1.0,"publicationDate":"2016-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70737108","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

KMTNET: A NETWORK OF 1.6 M WIDE-FIELD OPTICAL TELESCOPES INSTALLED AT THREE SOUTHERN OBSERVATORIES Kmtnet:安装在三个南方天文台的1.6米宽视场光学望远镜网络

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-02-29 DOI: 10.5303/JKAS.2016.49.1.37

Seung-Lee Kim, Chung-Uk Lee, Byeong-Gon Park, Dong Jin Kim, S. Cha, Yongseok Lee, C. Han, M. Chun, I. Yuk

{"title":"KMTNET: A NETWORK OF 1.6 M WIDE-FIELD OPTICAL TELESCOPES INSTALLED AT THREE SOUTHERN OBSERVATORIES","authors":"Seung-Lee Kim, Chung-Uk Lee, Byeong-Gon Park, Dong Jin Kim, S. Cha, Yongseok Lee, C. Han, M. Chun, I. Yuk","doi":"10.5303/JKAS.2016.49.1.37","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.1.37","url":null,"abstract":"The Korea Microlensing Telescope Network (KMTNet) is a wide-field photometric system installed by the Korea Astronomy and Space Science Institute (KASI). Here, we present the overall technical specifications of the KMTNet observation system, test observation results, data transfer and image processing procedure, and finally, the KMTNet science programs. The system consists of three 1.6 m wide-field optical telescopes equipped with mosaic CCD cameras of 18k by 18k pixels. Each telescope provides a 2.0 by 2.0 square degree field of view. We have finished installing all three telescopes and cameras sequentially at the Cerro-Tololo Inter-American Observatory (CTIO) in Chile, the South African Astronomical Observatory (SAAO) in South Africa, and the Siding Spring Observatory (SSO) in Australia. This network of telescopes, which is spread over three different continents at a similar latitude of about -30 degrees, enables 24-hour continuous monitoring of targets observable in the Southern Hemisphere. The test observations showed good image quality that meets the seeing requirement of less than 1.0 arcsec in I-band. All of the observation data are transferred to the KMTNet data center at KASI via the international network communication and are processed with the KMTNet data pipeline. The primary scientific goal of the KMTNet is to discover numerous extrasolar planets toward the Galactic bulge by using the gravitational microlensing technique, especially earth-mass planets in the habitable zone. During the non-bulge season, the system is used for wide-field photometric survey science on supernovae, asteroids, and external galaxies.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"37-44"},"PeriodicalIF":1.0,"publicationDate":"2016-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70737606","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: 146

STRUCTURE OF A MAGNETIC DECREASE OBSERVED IN A COROTATING INTERACTION REGION 在旋转相互作用区域中观察到的磁衰减结构

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-02-29 DOI: 10.5303/JKAS.2016.49.1.19

Ensang Lee, G. Parks

引用次数: 1

DISCOVERY OF WHITE DWARFS IN THE GLOBULAR CLUSTERS M13 AND M22 USING HST ACS PHOTOMETRIC DATA 利用HST acs光度数据在球状星团m13和m22中发现白矮星

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-12-31 DOI: 10.5303/JKAS.2015.48.6.333

D. Cho, T. Yoon, Sanggak Lee, H. Sung

{"title":"DISCOVERY OF WHITE DWARFS IN THE GLOBULAR CLUSTERS M13 AND M22 USING HST ACS PHOTOMETRIC DATA","authors":"D. Cho, T. Yoon, Sanggak Lee, H. Sung","doi":"10.5303/JKAS.2015.48.6.333","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.6.333","url":null,"abstract":"A search for hot and bright white dwarfs (WDs) in the Milky Way globular clusters M13 (NGC 6205) and M22 (NGC 6656) is carried out using the deep and homogeneous V I photometric catalog of Anderson et al. and and Sarajedini et al., based on data taken with the ACS/WFC aboard the Hubble Space Telescope (HST). V versus V − I color-magnitude diagrams (CMDs) of M13 and M22 are constructed and numerous spurious detections are rejected according to their photometric quality parameters qfit(V ) and qfit(I). In the case of M13, further radial restriction is applied to reject central stars with higher photometric errors due to central crowding. From each resultant V versus V −I CMD, sixteen and thirteen WD candidates are identified in M13 and M22, respectively. They are identified as stellar objects in the accompanying ACS/WFC images and are found to be randomly distributed across the central regions of M13 and M22. Their positions in the CMDs are in the bright part of the DA WD cooling sequences indicating that they are true WDs. In order to confirm their nature, follow-up spectroscopic observations are needed.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"333-341"},"PeriodicalIF":1.0,"publicationDate":"2015-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736856","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: 1

COMPACT GROUPS OF GALAXIES WITH COMPLETE SPECTROSCOPIC REDSHIFTS IN THE LOCAL UNIVERSE 在局部宇宙中具有完全光谱红移的致密星系群

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-12-31 DOI: 10.5303/JKAS.2015.48.6.381

J. Sohn, H. Hwang, M. Geller, A. Diaferio, K. Rines, M. Lee, Gwang-Ho Lee

{"title":"COMPACT GROUPS OF GALAXIES WITH COMPLETE SPECTROSCOPIC REDSHIFTS IN THE LOCAL UNIVERSE","authors":"J. Sohn, H. Hwang, M. Geller, A. Diaferio, K. Rines, M. Lee, Gwang-Ho Lee","doi":"10.5303/JKAS.2015.48.6.381","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.6.381","url":null,"abstract":"Dynamical analysis of compact groups provides important tests of models of compact group formation and evolution. By compiling 2066 redshifts from FLWO/FAST, from the literature, and from SDSS DR12 in the fields of compact groups in McConnachie et al. (2009), we construct the largest sample of compact groups with complete spectroscopic redshifts in the redshift range 0.01 −1 kpc, smaller than the radii typically sampled by members of massive clusters of galaxies. The physical properties of our sample compact groups include size, number density, velocity dispersion, and local environment; these properties slightly differ from those derived for the original Hickson compact groups and for the DPOSS II compact groups. Differences result from subtle differences in the way the group candidates were originally selected. The abundance of the compact groups changes little with redshift over the range covered by this sample. The approximate constancy of the abundance for this sample is a potential constraint on the evolution of compact groups on a few Gigayear timescale .","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"381-398"},"PeriodicalIF":1.0,"publicationDate":"2015-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736815","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: 16

MOLECULAR OUTFLOWS FROM NEWLY FORMED MASSIVE STARS 新形成的大质量恒星的分子外流

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-12-31 DOI: 10.5303/JKAS.2015.48.6.365

Kee-Tae Kim, Won-Ju Kim, Chang-Hee Kim

{"title":"MOLECULAR OUTFLOWS FROM NEWLY FORMED MASSIVE STARS","authors":"Kee-Tae Kim, Won-Ju Kim, Chang-Hee Kim","doi":"10.5303/JKAS.2015.48.6.365","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.6.365","url":null,"abstract":"We map 6 massive young stellar objects (YSOs) in the CO J=2–1 line and survey 18 massive YSOs, including the six, in the HCO+ J=1−0, SiO J=2−1, H₂O 6 16 − 5 23 maser, and CH₃OH 7 0 − 6 1 A + maser lines. We detect CO bipolar outflows in all the six mapped sources. Four of them are newly discovered (07299−1651, 21306+5540, 22308+5812, 23133+6050), while 05490+2658 is mapped in the CO J=2–1 line for the first time. The detected outflows are much more massive and energetic than outflows from low-mass YSOs with masses >20 M ⊙ and momenta >300 M⊙ km s −1 . They have mass outflow rates (3−6)×10 −4 M ⊙ yr −1 , which are at least one order of magnitude greater than those observed in low-mass YSOs. We detect HCO+ and SiO line emission in 18 (100%) and 4 (22%) sources, respectively. The HCO + spectra show high-velocity wings in 11 (61%) sources. We detect H₂O maser emission in 13 (72%) sources and 44 GHz CH₃OH maser emission in 8 (44%) sources. Of the detected sources, 5 H₂O and 6 CH₃OH maser sources are new discoveries. 20081+3122 shows high-velocity (>30 km s −1 ) H₂O maser lines. We find good correlations of the bolometric luminosity of the central (proto)star with the mechanical force, mechanical luminosity, and mass outflow rate of molecular outflow in the bolometric luminosity range of 10 −1 −10 6 L ⊙ , and identified 3 intermediate- or high-mass counterparts of Class O objects.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"365-380"},"PeriodicalIF":1.0,"publicationDate":"2015-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736654","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

LATITUDINAL DISTRIBUTION OF SUNSPOTS AND DURATION OF SOLAR CYCLES 太阳黑子的纬向分布和太阳周期的持续时间

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-12-31 DOI: 10.5303/JKAS.2015.48.6.325

Heon-Young Chang

{"title":"LATITUDINAL DISTRIBUTION OF SUNSPOTS AND DURATION OF SOLAR CYCLES","authors":"Heon-Young Chang","doi":"10.5303/JKAS.2015.48.6.325","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.6.325","url":null,"abstract":"We study an association between the duration of solar activity and characteristics of the latitude distribution of sunspots by means of center-of-latitude (COL) of sunspots observed during the period from 1878 to 2008 spanning solar cycles 12 to 23. We first calculate COL by taking the area-weighted mean latitude of sunspots for each calendar month to determine the latitudinal distribution of COL of sunspots appearing in the long and short cycles separately. The data set for the long solar cycles consists of the solar cycles 12, 13, 14, 20, and 23. The short solar cycles include the solar cycles 15, 16, 17, 18, 19, 21, and 22. We then fit a double Gaussian function to compare properties of the latitudinal distribution resulting from the tw° data sets. Our main findings are as follows: (1) The main component of the double Gaussian function does not show any significant change in the central position and in the full-width-at-half-maximum (FWHM), except in the amplitude. They are all centered at ~ 11° with FWHM of ~ 5°. (2) The secondary component of the double Gaussian function at higher latitudes seems to differ in that even though their width remains fixed at ~ 4°, their central position peaks at ~ 22.1° for the short cycles and at ~ 20.7◦ for the long cycles with quite small errors. (3) No significant correlation could be established between the duration of an individual cycle and the parameters of the double Gaussian. Finally, we conclude by briefly discussing the implications of these findings on the issue of the cycle 4 concerning a lost cycle.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"325-331"},"PeriodicalIF":1.0,"publicationDate":"2015-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736776","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: 1

SIMULTANEOUS OBSERVATIONS OF H 2 O AND SIO MASERS TOWARD KNOWN EXTRAGALACTIC WATER MASER SOURCES 同时观测h2o和sio脉泽对已知的河外水脉泽源

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-12-31 DOI: 10.5303/JKAS.2015.48.6.357

Se-Hyung Cho, Dong-Hwan Yoon, Jaeheon Kim, D. Byun, J. Wagner

引用次数: 0