Pub Date : 2020-02-01DOI: 10.5303/JKAS.2020.53.1.27
Byeong-Cheol Lee, Myeong-Gu Park, I. Han, T. Bang, Hyeong-Il Oh, Yeon-Ho Choi
{"title":"A SEARCH FOR EXOPLANETS AROUND NORTHERN CIRCUMPOLAR STARS VI. DETECTION OF PLANETARY COMPANIONS ORBITING THE GIANTS HD 60292 AND HD 112640","authors":"Byeong-Cheol Lee, Myeong-Gu Park, I. Han, T. Bang, Hyeong-Il Oh, Yeon-Ho Choi","doi":"10.5303/JKAS.2020.53.1.27","DOIUrl":"https://doi.org/10.5303/JKAS.2020.53.1.27","url":null,"abstract":"","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"53 1","pages":"27-34"},"PeriodicalIF":1.0,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42011639","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}
Pub Date : 2020-02-01DOI: 10.5303/JKAS.2020.53.1.1
Yoo Jung Kim, R. Kwon, J. Chae
{"title":"A Study of Small Flares Associated with Plasma Blobs Outflowing along Post-CME Rays","authors":"Yoo Jung Kim, R. Kwon, J. Chae","doi":"10.5303/JKAS.2020.53.1.1","DOIUrl":"https://doi.org/10.5303/JKAS.2020.53.1.1","url":null,"abstract":"","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"53 1","pages":"1-7"},"PeriodicalIF":1.0,"publicationDate":"2020-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43315820","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}
Pub Date : 2020-01-01DOI: 10.5303/JKAS.2020.53.6.125
Sang-Hyeon Ahn
We determine the observing sites for eclipses of large magnitude recorded in ancient Chinese chronicles from 200 BCE to 900 CE, by adopting the difference between terrestrial time and universal time, ∆T , given by Morrison & Stephenson (2004). The records of solar eclipses with large magnitude are divided into four groups in accordance with the historical variations of the capital cities of ancient Chinese dynasties. We determine areas in which all the eclipses in each group, with an eclipse magnitude larger than a certain threshold value, could be observed. We find that these areas coincide with the historical capitals, which agrees with the general idea that the solar eclipses were observed at the capital of each dynasty. This result also verifies the ∆T values during the period from 100 BCE to 400 CE, during which historical records of eclipses are so rare that the ∆T values can only be obtained by interpolating the long-term data. Moreover, we show that the eclipses described by the term Ji in East-Asian history are not all total eclipses; their mean magnitude is 0.96± 0.04. We find that complementary expressions, such as dark daytime and appearance of stars during the eclipse, strengthen the possibility that eclipses described by the term Ji were total. We also provide quantitative definitions for expressions such as ‘being not complete and like a hook’, ‘being almost complete’, ‘visibility of stars during the eclipse’, and ‘darkness during an eclipse.’ The literal meanings of these expressions are in agreement with the recent physical modeling of sky brightness during total eclipses provided by Können & Hinz (2008).
{"title":"OBSERVING SITES FOR THE CENTRAL SOLAR ECLIPSES IN ANCIENT CHINESE HISTORY","authors":"Sang-Hyeon Ahn","doi":"10.5303/JKAS.2020.53.6.125","DOIUrl":"https://doi.org/10.5303/JKAS.2020.53.6.125","url":null,"abstract":"We determine the observing sites for eclipses of large magnitude recorded in ancient Chinese chronicles from 200 BCE to 900 CE, by adopting the difference between terrestrial time and universal time, ∆T , given by Morrison & Stephenson (2004). The records of solar eclipses with large magnitude are divided into four groups in accordance with the historical variations of the capital cities of ancient Chinese dynasties. We determine areas in which all the eclipses in each group, with an eclipse magnitude larger than a certain threshold value, could be observed. We find that these areas coincide with the historical capitals, which agrees with the general idea that the solar eclipses were observed at the capital of each dynasty. This result also verifies the ∆T values during the period from 100 BCE to 400 CE, during which historical records of eclipses are so rare that the ∆T values can only be obtained by interpolating the long-term data. Moreover, we show that the eclipses described by the term Ji in East-Asian history are not all total eclipses; their mean magnitude is 0.96± 0.04. We find that complementary expressions, such as dark daytime and appearance of stars during the eclipse, strengthen the possibility that eclipses described by the term Ji were total. We also provide quantitative definitions for expressions such as ‘being not complete and like a hook’, ‘being almost complete’, ‘visibility of stars during the eclipse’, and ‘darkness during an eclipse.’ The literal meanings of these expressions are in agreement with the recent physical modeling of sky brightness during total eclipses provided by Können & Hinz (2008).","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"53 1","pages":"125-138"},"PeriodicalIF":1.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738131","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}
Pub Date : 2020-01-01DOI: 10.5303/JKAS.2020.53.6.139
Lingling Peng
{"title":"SUNSPOT AREA PREDICTION BASED ON COMPLEMENTARY ENSEMBLE EMPIRICAL MODE DECOMPOSITION AND EXTREME LEARNING MACHINE","authors":"Lingling Peng","doi":"10.5303/JKAS.2020.53.6.139","DOIUrl":"https://doi.org/10.5303/JKAS.2020.53.6.139","url":null,"abstract":"","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"53 1","pages":"139-147"},"PeriodicalIF":1.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738998","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}
Pub Date : 2020-01-01DOI: 10.5303/JKAS.2020.53.3.77
Y. Minh, H. Liu, H. Chen
{"title":"CHEMICAL DIAGNOSTICS OF THE MASSIVE STAR CLUSTER-FORMING CLOUD G33.92+0.11. IV. HIERARCHICAL STRUCTURE","authors":"Y. Minh, H. Liu, H. Chen","doi":"10.5303/JKAS.2020.53.3.77","DOIUrl":"https://doi.org/10.5303/JKAS.2020.53.3.77","url":null,"abstract":"","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"53 1","pages":"77-85"},"PeriodicalIF":1.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738461","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}
Pub Date : 2020-01-01DOI: 10.5303/JKAS.2020.53.6.117
Hannah L. Morgan, Sungsoo S. Kim, Jihye Shin, Kyungwon Chun, So-Myoung Park, Joowon Lee, Y. Minh
{"title":"MECHANISM INDUCING GAS SUPPLY TO THE CENTRAL 10 PARSEC OF THE MILKY WAY","authors":"Hannah L. Morgan, Sungsoo S. Kim, Jihye Shin, Kyungwon Chun, So-Myoung Park, Joowon Lee, Y. Minh","doi":"10.5303/JKAS.2020.53.6.117","DOIUrl":"https://doi.org/10.5303/JKAS.2020.53.6.117","url":null,"abstract":"","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"53 1","pages":"117-123"},"PeriodicalIF":1.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738513","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}
Pub Date : 2018-10-01DOI: 10.5303/JKAS.2018.51.5.165
Chunglee Kim, M. Davies
The Galactic Center is one of the most dense stellar environments in the Galaxy and is considered to be a plausible place to harbor many neutron stars. In this brief review, we summarize observational efforts in search of neutron stars within a few degrees about the Galactic Center. Up to 10% of Galactic neutron stars may reside in this central region and it is possible that more than a thousand neutron stars are located within only ~ 25′′ (≤ 1 pc) about the Galactic Center. Based on observations, we discuss prospects of detecting neutron stars in the Galactic Center via gravitational waves as well as electromagnetic waves.
{"title":"NEUTRON STARS IN THE GALACTIC CENTER","authors":"Chunglee Kim, M. Davies","doi":"10.5303/JKAS.2018.51.5.165","DOIUrl":"https://doi.org/10.5303/JKAS.2018.51.5.165","url":null,"abstract":"The Galactic Center is one of the most dense stellar environments in the Galaxy and is considered to be a plausible place to harbor many neutron stars. In this brief review, we summarize observational efforts in search of neutron stars within a few degrees about the Galactic Center. Up to 10% of Galactic neutron stars may reside in this central region and it is possible that more than a thousand neutron stars are located within only ~ 25′′ (≤ 1 pc) about the Galactic Center. Based on observations, we discuss prospects of detecting neutron stars in the Galactic Center via gravitational waves as well as electromagnetic waves.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"51 1","pages":"165-170"},"PeriodicalIF":1.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44942888","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}
Pub Date : 2018-06-01DOI: 10.5303/JKAS.2018.51.3.65
Yan-fang Zheng, Xuebao Li, Tian Huifeng, Qiliang Zhang, C. Su, Lingyi Shi, Zhou Ta
The near real-time speckle masking reconstruction technique has been developed to accelerate the processing of solar images to achieve high resolutions for ground-based solar telescopes. However, the reconstruction of solar subimages in such a speckle reconstruction is very time-consuming. We design and implement a new parallel speckle masking reconstruction algorithm based on the Compute Unified Device Architecture (CUDA) on General Purpose Graphics Processing Units (GPGPU). Tests are performed to validate the correctness of our program on NVIDIA GPGPU. Details of several parallel reconstruction steps are presented, and the parallel implementation between various modules shows a significant speed increase compared to the previous serial implementations. In addition, we present a comparison of runtimes across serial programs, the OpenMP-based method, and the new parallel method. The new parallel method shows a clear advantage for large scale data processing, and a speedup of around 9 to 10 is achieved in reconstructing one solar subimage of 256×256 pixels. The speedup performance of the new parallel method exceeds that of OpenMP-based method overall. We conclude that the new parallel method would be of value, and contribute to real-time reconstruction of an entire solar image.
{"title":"GPU-ACCELERATED SPECKLE MASKING RECONSTRUCTION ALGORITHM FOR HIGH-RESOLUTION SOLAR IMAGES","authors":"Yan-fang Zheng, Xuebao Li, Tian Huifeng, Qiliang Zhang, C. Su, Lingyi Shi, Zhou Ta","doi":"10.5303/JKAS.2018.51.3.65","DOIUrl":"https://doi.org/10.5303/JKAS.2018.51.3.65","url":null,"abstract":"The near real-time speckle masking reconstruction technique has been developed to accelerate the processing of solar images to achieve high resolutions for ground-based solar telescopes. However, the reconstruction of solar subimages in such a speckle reconstruction is very time-consuming. We design and implement a new parallel speckle masking reconstruction algorithm based on the Compute Unified Device Architecture (CUDA) on General Purpose Graphics Processing Units (GPGPU). Tests are performed to validate the correctness of our program on NVIDIA GPGPU. Details of several parallel reconstruction steps are presented, and the parallel implementation between various modules shows a significant speed increase compared to the previous serial implementations. In addition, we present a comparison of runtimes across serial programs, the OpenMP-based method, and the new parallel method. The new parallel method shows a clear advantage for large scale data processing, and a speedup of around 9 to 10 is achieved in reconstructing one solar subimage of 256×256 pixels. The speedup performance of the new parallel method exceeds that of OpenMP-based method overall. We conclude that the new parallel method would be of value, and contribute to real-time reconstruction of an entire solar image.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"421 1","pages":"65-71"},"PeriodicalIF":1.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41291406","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}
Pub Date : 2018-04-20DOI: 10.5303/JKAS.2018.51.2.37
Jeong-Se Seo, Hyesung Kang, D. Ryu
Massive stars blow powerful stellar winds throughout their evolutionary stages from the main sequence to Wolf-Rayet phases. The amount of mechanical energy deposited in the interstellar medium by the wind from a massive star can be comparable to the explosion energy of a core-collapse supernova that detonates at the end of its life. In this study, we estimate the kinetic energy deposition by massive stars in our Galaxy by considering the integrated Galactic initial mass function and modeling the stellar wind luminosity. The mass loss rate and terminal velocity of stellar winds during the main sequence, red supergiant, and Wolf-Rayet stages are estimated by adopting theoretical calculations and observational data published in the literature. We find that the total stellar wind luminosity due to all massive stars in the Galaxy is about $L_wapprox 1.1times 10^{41}$ erg/s, which is about 1/4 of the power of supernova explosions, $L_{SN} approx 4.8times 10^{41}$ erg/s. If we assume that $sim 1-10$ % of the wind luminosity could be converted to Galactic cosmic rays (GCRs) through collisonless shocks such as termination shocks in stellar bubbles and superbubbles, colliding-wind shocks in binaries, and bow-shocks of massive runaway stars, stellar winds might be expected to make a significant contribution to GCR production, though lower than that of supernova remnants.
{"title":"The Contribution of Stellar Winds to Cosmic Ray Production","authors":"Jeong-Se Seo, Hyesung Kang, D. Ryu","doi":"10.5303/JKAS.2018.51.2.37","DOIUrl":"https://doi.org/10.5303/JKAS.2018.51.2.37","url":null,"abstract":"Massive stars blow powerful stellar winds throughout their evolutionary stages from the main sequence to Wolf-Rayet phases. The amount of mechanical energy deposited in the interstellar medium by the wind from a massive star can be comparable to the explosion energy of a core-collapse supernova that detonates at the end of its life. In this study, we estimate the kinetic energy deposition by massive stars in our Galaxy by considering the integrated Galactic initial mass function and modeling the stellar wind luminosity. The mass loss rate and terminal velocity of stellar winds during the main sequence, red supergiant, and Wolf-Rayet stages are estimated by adopting theoretical calculations and observational data published in the literature. We find that the total stellar wind luminosity due to all massive stars in the Galaxy is about $L_wapprox 1.1times 10^{41}$ erg/s, which is about 1/4 of the power of supernova explosions, $L_{SN} approx 4.8times 10^{41}$ erg/s. If we assume that $sim 1-10$ % of the wind luminosity could be converted to Galactic cosmic rays (GCRs) through collisonless shocks such as termination shocks in stellar bubbles and superbubbles, colliding-wind shocks in binaries, and bow-shocks of massive runaway stars, stellar winds might be expected to make a significant contribution to GCR production, though lower than that of supernova remnants.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"51 1","pages":"37-48"},"PeriodicalIF":1.0,"publicationDate":"2018-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46369824","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}
Pub Date : 2018-01-01DOI: 10.5303/JKAS.2018.51.6.171
C. Hui
{"title":"A GOLDEN DECADE OF GAMMA-RAY PULSAR ASTRONOMY","authors":"C. Hui","doi":"10.5303/JKAS.2018.51.6.171","DOIUrl":"https://doi.org/10.5303/JKAS.2018.51.6.171","url":null,"abstract":"","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"51 1","pages":"171-183"},"PeriodicalIF":1.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738573","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}
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