Journal of the Korean Astronomical Society最新文献_第5页

RELATIVE AGE DIFFERENCE BETWEEN THE METAL-POOR GLOBULAR CLUSTERS M53 AND M92 贫金属球状星团m53和m92的相对年龄差异

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-10-31 DOI: 10.5303/JKAS.2016.49.5.175

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

{"title":"RELATIVE AGE DIFFERENCE BETWEEN THE METAL-POOR GLOBULAR CLUSTERS M53 AND M92","authors":"D. Cho, H. Sung, Sanggak Lee, T. Yoon","doi":"10.5303/JKAS.2016.49.5.175","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.5.175","url":null,"abstract":"CCD photometric observations of the globular cluster (GC), M53 (NGC 5024), are performed using the 1.8 m telescope at the Bohyunsan Optical Astronomy Observatory in Korea on the same nights (2002 April and 2003 May) as the observations of the GC M92 (NGC 6341) reported by Cho and Lee using the same instrumental setup. The data for M53 is reduced using the same method as used for M92 by Cho and Lee, including preprocessing, point-spread function fitting photometry, and standardization etc. Therefore, M53 and M92 are on the same photometric system defined by Landolt, and the photometry of M53 and M92 is tied together as closely as possible. After complete photometric reduction, the V versus B − V , V versus V − I, and V versus B − I color-magnitude diagrams (CMDs) of M53 are produced to derive the relative ages of M53 and M92 and derive the various characteristics of its CMDs in future analysis. From the present analysis, the relative ages of M53 and M92 are derived using the Δ(B − V ) method reported by VandenBerg et al. The relative age of M53 is found to be 1.6 ± 0.85 Gyr younger than that of M92 if the absolute age of M92 is taken to be 14 Gyr. This relative age difference between M53 and M92 causes slight differences in the horizontal-branch morphology of these two GCs.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"175-192"},"PeriodicalIF":1.0,"publicationDate":"2016-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738475","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

OPTICAL SURVEY WITH KMTNET FOR DUSTY STAR-FORMING GALAXIES IN THE AKARI DEEP FIELD SOUTH 用kmtnet对akari深场南部尘埃恒星形成星系的光学调查

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-10-31 DOI: 10.5303/JKAS.2016.49.5.225

W. Jeong, Kyeongyeon Ko, Minjin Kim, J. Ko, Sam Kim, J. Pyo, S. Kim, Tae Hyun Kim, H. Seo, W. Park, Sung-Joon Park, Min Gyu Kim, Dong-Jin Kim, S. Cha, Y. Lee, Chung-Uk Lee, Seung-Lee Kim, S. Matsuura, C. Pearson, H. Matsuhara

引用次数: 1

GAIA PARALLAX ZERO POINT FROM RR LYRAE STARS 盖亚距天琴座rr星视差零点

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-09-02 DOI: 10.5303/JKAS.2017.50.1.1

A. Gould, J. Kollmeier

引用次数: 5

A NOVEL PARALLEL METHOD FOR SPECKLE MASKING RECONSTRUCTION USING THE OPENMP 一种基于openmp的并行散斑遮蔽重建方法

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-08-31 DOI: 10.5303/JKAS.2016.49.4.157

Xuebao Li, Yan-fang Zheng

{"title":"A NOVEL PARALLEL METHOD FOR SPECKLE MASKING RECONSTRUCTION USING THE OPENMP","authors":"Xuebao Li, Yan-fang Zheng","doi":"10.5303/JKAS.2016.49.4.157","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.4.157","url":null,"abstract":"High resolution reconstruction technology is developed to help enhance the spatial resolution of observational images for ground-based solar telescopes, such as speckle masking. Near real-time reconstruction performance is achieved on a high performance cluster using the Message Passing Interface(MPI). However, much time is spent in reconstructing solar subimages in such a speckle reconstruction. We design and implement a novel parallel method for speckle masking reconstruction of solar subimage on a shared memory machine using the OpenMP. Real tests are performed to verify the correctness of our codes. We present the details of several parallel reconstruction steps. The parallel implementation between various modules shows a great speed increase as compared to single thread serial implementation, and a speedup of about 2.5 is achieved in one subimage reconstruction. The timing result for reconstructing one subimage with 256×256 pixels shows a clear advantage with greater number of threads. This novel parallel method can be valuable in real-time reconstruction of solar images, especially after porting to a high performance cluster.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"157-162"},"PeriodicalIF":1.0,"publicationDate":"2016-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738392","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

THE AUTOMATIC CALIBRATION OF KOREAN VLBI NETWORK DATA 韩国vlbi网络数据的自动标定

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-07-27 DOI: 10.5303/JKAS.2016.49.4.137

J. Hodgson, Sang-Sung Lee, Guangyao Zhao, J. Algaba, Young-Zoo Yun, T. Jung, D. Byun

引用次数: 11

OPTICAL PROPERTIES OF AMORPHOUS ALUMINA DUST IN THE ENVELOPES AROUND O-RICH AGB STARS 富氧agb星包层中无定形氧化铝尘埃的光学特性

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-07-19 DOI: 10.5303/JKAS.2016.49.4.127

K. Suh

引用次数: 6

RE-ACCELERATION MODEL FOR THE `SAUSAGE` RADIO RELIC “香肠”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 : 2016-07-02 DOI: 10.5303/JKAS.2016.49.4.145

Hyesung Kang

{"title":"RE-ACCELERATION MODEL FOR THE `SAUSAGE` RADIO RELIC","authors":"Hyesung Kang","doi":"10.5303/JKAS.2016.49.4.145","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.4.145","url":null,"abstract":"The Sausage radio relic is the arc-like radio structure in the cluster CIZA J2242.8+5301, whose observed properties can be best understood by synchrotron emission from relativistic electrons accelerated at a merger-driven shock. However, there remain a few puzzles that cannot be explained by the shock acceleration model with only in-situ injection. In particular, the Mach number inferred from the observed radio spectral index, M radio ≈ 4.6, while the Mach number estimated from X-ray observations, M X−ray ≈ 2.7. In an attempt to resolve such a discrepancy, here we consider the re-acceleration model in which a shock of Ms ≈ 3 sweeps through the intracluster gas with a pre-existing population of relativistic electrons. We find that observed brightness profiles at multi frequencies provide strong constraints on the spectral shape of pre-existing electrons. The models with a power-law momentum spectrum with the slope, s ≈ 4.1, and the cutoff Lorentz factor, γ e,c ≈ 3−5×10⁴, can reproduce reasonably well the observed spatial profiles of radio fluxes and integrated radio spectrum of the Sausage relic. The possible origins of such relativistic electrons in the intracluster medium remain to be investigated further.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"145-155"},"PeriodicalIF":1.0,"publicationDate":"2016-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738340","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: 6

NEW CCD OBSERVATIONS AND THE FIRST PHOTOMETRIC STUDY OF THE CONTACT BINARY AP UMI 新的CCD观测和接触双星的首次光度学研究

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-06-30 DOI: 10.5303/JKAS.2016.49.3.65

N. Awadalla, M. Hanna, M. N. Ismail, I. A. Hassan, M. A. Elkhamisy

引用次数: 0

KINETIC PROPERTIES OF MAGNETIC DECREASES OBSERVED IN THE SOLAR WIND AT ~1 AU 在~ 1au的太阳风中观测到磁场的动力学性质下降

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-04-30 DOI: 10.5303/JKAS.2016.49.2.59

Ensang Lee, G. K. Parks

{"title":"KINETIC PROPERTIES OF MAGNETIC DECREASES OBSERVED IN THE SOLAR WIND AT ~1 AU","authors":"Ensang Lee, G. K. Parks","doi":"10.5303/JKAS.2016.49.2.59","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.2.59","url":null,"abstract":"In this study, we investigate the kinetic properties of magnetic decreases observed in the solar wind at~1 AU using the Cluster observations. We study two different magnetic decreases: one with a short observation duration of~2.5 minutes and stable structure and the other with a longer observation duration of~40 minutes and some fluctuations and substructures. Despite the contrast in durations and magnetic structures, the velocity space distributions of ions are similar in both events. The velocity space distribution becomes more anisotropic along the direction parallel to the magnetic field, which differs from observations obtained at high heliographic latitudes. On the other hand, electrons show different features from the ions. The core component of the electrons shows similar anisotropy to the ions, though the anisotropy is much weaker. However, while ions are heated in the magnetic decreases, the core electrons are slightly cooled, especially in the perpendicular direction. The halo component does not change much in the magnetic decreases from the ambient solar wind. The strahl component is observed only in one of the magnetic decreases. The results imply that the ions and electrons in the magnetic decreases can behave differently, which should be considered for the formation mechanism of the magnetic decreases.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"59-64"},"PeriodicalIF":1.0,"publicationDate":"2016-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70737813","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

INFRARED [FE II] EMISSION LINES FROM RADIATIVE ATOMIC SHOCKS 辐射原子冲击的红外[fe]发射线

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-04-04 DOI: 10.5303/JKAS.2016.49.3.109

B. Koo, J. Raymond, Hyun-Jeong Kim

{"title":"INFRARED [FE II] EMISSION LINES FROM RADIATIVE ATOMIC SHOCKS","authors":"B. Koo, J. Raymond, Hyun-Jeong Kim","doi":"10.5303/JKAS.2016.49.3.109","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.3.109","url":null,"abstract":"[Fe II] emission lines are prominent in the infrared (IR) and important as diagnostic tools for radiative atomic shocks. We investigate the emission characteristics of [Fe II] lines using a shock code developed by Raymond (1979) with updated atomic parameters. We rst review general characteristics of the IR [Fe II] emission lines from shocked gas, and derive their uxes as a function of shock speed and ambient density. We have compiled available IR [Fe II] line observations of interstellar shocks and compare them to the ratios predicted from our model. The sample includes both young and old supernova remnants in the Galaxy and the Large Magellanic Cloud and several Herbig-Haro objects. We nd that the observed ratios of the IR [Fe II] lines generally fall on our grid of shock models, but the ratios of some mid-IR lines, e.g., [Fe II] 35.35 μm=[Fe II] 25.99 m, [Fe II] 5.340 μm=[Fe II] 25.99 μm, and [Fe II] 5.340 μm=[Fe II] 17.94 m, are signicantly oset from our model grid. We discuss possible explanations and conclude that while uncertainties in the shock modeling and the observations certainly exist, the uncertainty in atomic rates appears to be the major source of discrepancy.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"109-122"},"PeriodicalIF":1.0,"publicationDate":"2016-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70737628","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: 14