Journal of the Korean Astronomical Society最新文献_第3页

The Millimeter-Radio Emission of BL Lacertae During Two γ-ray Outbursts 两次γ射线爆发期间BL Lacertae的毫米无线电发射

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2017-11-16 DOI: 10.5303/JKAS.2017.50.6.167

Dae-Won Kim, S. Trippe, Sang-Sung Lee, Jong-ho Park, Jae-Young Kim, J. Algaba, J. Hodgson, M. Kino, Guangyao Zhao, K. Wajima, Sincheol Kang, Junghwan Oh, Taeseok Lee, D. Byun, Soon-Wook Kim, Jeong-Sook Kim

{"title":"The Millimeter-Radio Emission of BL Lacertae During Two γ-ray Outbursts","authors":"Dae-Won Kim, S. Trippe, Sang-Sung Lee, Jong-ho Park, Jae-Young Kim, J. Algaba, J. Hodgson, M. Kino, Guangyao Zhao, K. Wajima, Sincheol Kang, Junghwan Oh, Taeseok Lee, D. Byun, Soon-Wook Kim, Jeong-Sook Kim","doi":"10.5303/JKAS.2017.50.6.167","DOIUrl":"https://doi.org/10.5303/JKAS.2017.50.6.167","url":null,"abstract":"We present a study of the inexplicit connection between radio jet activity and gamma-ray emission of BL Lacertae (BL Lac; 2200+420). We analyze the long-term millimeter activity of BL Lac via interferometric observations with the Korean VLBI Network (KVN) obtained at 22, 43, 86, and 129 GHz simultaneously over three years (from January 2013 to March 2016); during this time, two gamma-ray outbursts (in November 2013 and March 2015) can be seen in gamma-ray light curves obtained from Fermi observations. The KVN radio core is optically thick at least up to 86 GHz; there is indication that it might be optically thin at higher frequencies. To first order, the radio light curves decay exponentially over the time span covered by our observations, with decay timescales of 411+/-85 days, 352+/-79 days, 310+/-57 days, and 283+/-55 days at 22, 43, 86, and 129 GHz, respectively. Assuming synchrotron cooling, a cooling time of around one year is consistent with magnetic field strengths B~2microT and electron Lorentz factors gamma~10,000. Taking into account that our formal measurement errors include intrinsic variability and thus over-estimate the statistical uncertainties, we find that the decay timescale tau scales with frequency nu like tau~nu^{-0.2}. This relation is much shallower than the one expected from opacity effects (core shift), but in agreement with the (sub-)mm radio core being a standing recollimation shock. We do not find convincing radio flux counterparts to the gamma$ray outbursts. The spectral evolution is consistent with the `generalized shock model' of Valtaoja et al. (1992). A temporary increase in the core opacity and the emergence of a knot around the time of the second gamma-ray event indicate that this gamma-ray outburst might be an `orphan' flare powered by the `ring of fire' mechanism.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"50 1","pages":"167-178"},"PeriodicalIF":1.0,"publicationDate":"2017-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44046674","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: 2

THE CYCLIC VARIATION OF SOLAR PHOTOSPHERIC INTENSITY FROM SOHO IMAGES 从SOHO图像看太阳光球强度的周期变化

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2017-08-31 DOI: 10.5303/JKAS.2017.50.4.105

Dong-Gwon Jeong, Hyungmin Park, Byeonghak Moon, Suyeon Oh

{"title":"THE CYCLIC VARIATION OF SOLAR PHOTOSPHERIC INTENSITY FROM SOHO IMAGES","authors":"Dong-Gwon Jeong, Hyungmin Park, Byeonghak Moon, Suyeon Oh","doi":"10.5303/JKAS.2017.50.4.105","DOIUrl":"https://doi.org/10.5303/JKAS.2017.50.4.105","url":null,"abstract":": The well-known solar cycle controls almost the entire appearance of the solar photosphere. We therefore presume that the continuous emission of visible light from the solar surface follows the solar cyclic variation. In this study, we examine the solar cyclic variation of photospheric brightness in the visible range using solar images taken by the Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI). The photospheric brightness in the visible range is quantiﬁed via the relative intensity acquired from in the raw solar images. In contrast to total solar irradiance, the relative intensity is out of phase with the solar cycle. During the solar minimum of solar cycles 23–24, the relative intensity shows enhanced heliolatitudinal asymmetry due to a positive asymmetry of the sunspot number. This result can be explained by the strength of the solar magnetic ﬁeld that controls the strength of convection, implying that the emission in the visible range is controlled by the strength of convection. This agrees with the photospheric brightness increasing during a period of long spotless days.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"50 1","pages":"105-109"},"PeriodicalIF":1.0,"publicationDate":"2017-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47366908","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

MORPHOLOGY OF DWARF GALAXIES IN ISOLATED SATELLITE SYSTEMS 孤立卫星系统中矮星系的形态

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2017-08-31 DOI: 10.5303/JKAS.2017.50.4.111

H. Ann

{"title":"MORPHOLOGY OF DWARF GALAXIES IN ISOLATED SATELLITE SYSTEMS","authors":"H. Ann","doi":"10.5303/JKAS.2017.50.4.111","DOIUrl":"https://doi.org/10.5303/JKAS.2017.50.4.111","url":null,"abstract":"The environmental dependence of the morphology of dwarf galaxies in isolated satellite systems is analyzed to understand the origin of the dwarf galaxy morphology using the visually classified morphological types of 5836 local galaxies with $z lesssim 0.01$. We consider six sub-types of dwarf galaxies, dS0, dE, dE$_{bc}$, dSph, dE$_{blue}$, and dI, of which the first four sub-types are considered as early-type and the last two as late-type. The environmental parameters we consider are the projected distance from the host galaxy ($r_{p}$), local and global background densities, and the host morphology. The spatial distributions of dwarf satellites of early-type galaxies are much different from those of dwarf satellites of late-type galaxies, suggesting the host morphology combined with $r_{p}$ plays a decisive role on the morphology of the dwarf satellite galaxies. The local and global background densities play no significant role on the morphology of dwarfs in the satellite systems hosted by early-type galaxies. However, in the satellite system hosted by late-type galaxies, the global background densities of dE and dSph satellites are significantly different from those of dE$_{bc}$, dE$_{blue}$, and dI satellites. The blue-cored dwarf satellites (dE$_{bc}$) of early-type galaxies are likely to be located at $r_{p} > 0.3$ Mpc to keep their cold gas from the ram pressure stripping by the hot corona of early-type galaxies. The spatial distribution of dE$_{bc}$ satellites of early-type galaxies and their global background densities suggest that their cold gas is intergalactic material accreted before they fall into the satellite systems.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"50 1","pages":"111-124"},"PeriodicalIF":1.0,"publicationDate":"2017-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44434241","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: 3

Solar Cycle Variation of Microwave Polar Brightening and EUV Coronal Hole Observed by Nobeyama Radioheliograph and SDO/AIA Nobeyama射电日图和SDO/AIA观测到的微波极地增亮和EUV日冕空洞的太阳周期变化

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2017-08-31 DOI: 10.5303/JKAS.2017.50.4.125

Sujin Kim, Jong-Yeop Park, Yeon-Han Kim

引用次数: 7

A New Catalog of AGB Stars Based on Infrared Two-Color Diagrams 基于红外双色图的AGB恒星新目录

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2017-08-31 DOI: 10.5303/JKAS.2017.50.4.131

K. Suh, Jinju Hong

引用次数: 8

PROPERTIES OF OPEN CLUSTERS CONTAINING BLUE STRAGGLERS 包含蓝离散星的疏散星团的性质

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2017-06-30 DOI: 10.5303/JKAS.2017.50.3.51

Hyun-Uk Lee, Heon-Young Chang

引用次数: 2

CLUSTERING OF EXTREMELY RED OBJECTS IN THE SUBARU GTO 2DEG2 FIELD 在斯巴鲁gto 2deg2场中聚集的极红色物体

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2017-06-30 DOI: 10.5303/JKAS.2017.50.3.61

Jihey Shin, Hyunjin Shim, H. Hwang, J. Ko, Jong Chul Lee, Y. Utsumi, N. Hwang, Byeong-Gon Park

引用次数: 4

PHOTOMETRIC STUDY OF NPA ROTATOR (5247) KRYLOV npa旋转体(5247)krylov的光度学研究

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2017-06-30 DOI: 10.5303/JKAS.2017.50.3.41

Hee-Jae Lee, H. Moon, Myung-Jin Kim, Chun-Hwey Kim, J. Ďurech, Young‐Jun Choi, Y. Oh, Jintae Park, D. Roh, H. Yim, S. Cha, Yongseok Lee

引用次数: 2

Shock Acceleration Model with Postshock Turbulence for Giant Radio Relics 巨型射电遗迹的激波加速度模型

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2017-06-10 DOI: 10.5303/JKAS.2017.50.4.93

Hyesung Kang

{"title":"Shock Acceleration Model with Postshock Turbulence for Giant Radio Relics","authors":"Hyesung Kang","doi":"10.5303/JKAS.2017.50.4.93","DOIUrl":"https://doi.org/10.5303/JKAS.2017.50.4.93","url":null,"abstract":"We explore the shock acceleration model for giant radio relics, in which relativistic electrons are accelerated via diffusive shock acceleration (DSA) by merger-driven shocks in the outskirts of galaxy clusters. In addition to DSA, turbulent acceleration by compressive MHD mode downstream of the shock is included as well as energy losses of postshock electrons by Coulomb scattering, synchrotron emission, and inverse Compton scattering off the cosmic background radiation. Considering that only a small fraction of merging clusters host radio relics, we favor the reacceleration scenario in which radio relics are generated preferentially when shocks encounter the regions containing low-energy ($gamma_{rm e} lesssim 300$) cosmic ray electrons (CRe). We perform time-dependent DSA simulations of spherically expanding shocks with physical parameters relevant for the Sausage radio relic, and calculate the radio synchrotron emission from the accelerated CRe. We find that significant level of postshock turbulent acceleration is required in order to reproduce broad profiles of the observed radio flux densities of the Sausage relic. Moreover, the spectral curvature in the observed integrated radio spectrum can be explained, if the putative shock should have swept up and exited out of the preshock region of fossil CRe about 10~Myr ago.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"50 1","pages":"93-103"},"PeriodicalIF":1.0,"publicationDate":"2017-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43132877","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: 7

PERFORMANCE OF THE AUTOREGRESSIVE METHOD IN LONG-TERM PREDICTION OF SUNSPOT NUMBER 自回归方法在太阳黑子数长期预报中的性能

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2017-04-30 DOI: 10.5303/JKAS.2017.50.2.21

J. Chae, Yeon-Han Kim

引用次数: 5