Journal of the Korean Astronomical Society最新文献_第7页

SEJONG OPEN CLUSTER SURVEY (SOS) - V. THE ACTIVE STAR FORMING REGION SH 2-255 - 257 世宗疏散星团巡天(sos) - v.活跃恒星形成区sh 2-255 - 257

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-11-02 DOI: 10.5303/JKAS.2015.48.6.343

B. Lim, H. Sung, H. Hur, Byeong-Cheol Lee, M. Bessell, J. Kim, K. Lee, Byeong-Gon Park, G. Jeong

{"title":"SEJONG OPEN CLUSTER SURVEY (SOS) - V. THE ACTIVE STAR FORMING REGION SH 2-255 - 257","authors":"B. Lim, H. Sung, H. Hur, Byeong-Cheol Lee, M. Bessell, J. Kim, K. Lee, Byeong-Gon Park, G. Jeong","doi":"10.5303/JKAS.2015.48.6.343","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.6.343","url":null,"abstract":"There is much observational evidence that active star formation is taking place in the Hii regions Sh 2-255 – 257. We present a photometric study of this star forming region (SFR) using imaging data obtained in passbands from the optical to the mid-infrared, in order to study the star formation process. A total of 218 members were identified using various selection criteria based on their observational properties. The SFR is reddened by at least E(B −V ) = 0.8 mag, and the reddening law toward the region is normal (R V = 3.1). From the zero-age main sequence fitting method it is confirmed that the SFR is 2.1 ± 0.3 kpc from the Sun. The median age of the identified members is estimated to be about 1.3 Myr from a comparison of the Hertzsprung-Russell diagram (HRD) with stellar evolutionary models. The initial mass function (IMF) is derived from the HRD and the near-infrared (J, J −H) color-magnitude diagram. The slope of the IMF is about Г = −1.6 ± 0.1, which is slightly steeper than that of the Salpeter/Kroupa IMF. It implies that low-mass star formation is dominant in the SFR. The sum of the masses of all the identified members provides the lower limit of the cluster mass (169M ⊙ ). We also analyzed the spectral energy distribution (SED) of pre-main sequence stars using the SED fitting tool of Robitaille et al., and confirm that there is a significant discrepancy between stellar mass and age obtained from two different methods based on the SED fitting tool and the HRD.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"343-355"},"PeriodicalIF":1.0,"publicationDate":"2015-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736927","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: 4

MEASURING THE CORE SHIFT EFFECT IN AGN JETS WITH THE EXTENDED KOREAN VLBI NETWORK 用扩展的韩国vlbi网络测量agn喷气机的核心转移效应

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-10-31 DOI: 10.5303/JKAS.2015.48.5.277

T. Jung, R. Dodson, Seog-Tae Han, M. Rioja, D. Byun, M. Honma, J. Stevens, P. Vicente, B. Sohn

引用次数: 9

A SEARCH FOR AGN INTRA-DAY VARIABILITY WITH KVN 用KVN寻找agn的日变异性

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-10-28 DOI: 10.5303/JKAS.2015.48.5.313

Taeseok Lee, S. Trippe, Junghwan Oh, D. Byun, B. Sohn, Sang-Sung Lee Snu Seoul, Kasi Daejeon

{"title":"A SEARCH FOR AGN INTRA-DAY VARIABILITY WITH KVN","authors":"Taeseok Lee, S. Trippe, Junghwan Oh, D. Byun, B. Sohn, Sang-Sung Lee Snu Seoul, Kasi Daejeon","doi":"10.5303/JKAS.2015.48.5.313","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.5.313","url":null,"abstract":"Active galactic nuclei (AGN) are known for irregular variability on all time scales, down to intra-day variability with relative variations of a few percent within minutes to hours. On such short timescales, unexplored territory, such as the possible existence of a shortest characteristic time scale of activity and the shape of the high frequency end of AGN power spectra, still exists. We present the results of AGN single-dish fast photometry performed with the Korean VLBI Network (KVN). Observations were done in a “anti-correlated” mode using two antennas, with always at least one antenna pointing at the target. This results in an effective time resolution of less than three minutes. We used all four KVN frequencies, 22, 43, 86, and 129 GHz, in order to trace spectral variability, if any. We were able to derive high-quality light curves for 3C 111, 3C 454.3, and BL Lacertae at 22 and 43 GHz, and for 3C 279 at 86 GHz, between May 2012 and April 2013. We performed a detailed statistical analysis in order to assess the levels of variability and the corresponding upper limits. We found upper limits on flux variability ranging from ∼1.6% to ∼7.6%. The upper limits on the derived brightness temperatures exceed the inverse Compton limit by three to six orders of magnitude. From our results, plus comparison with data obtained by the University of Michigan Radio Astronomy Observatory, we conclude that we have not detected source-intrinsic variability which would have to occur at sub-per cent levels.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"313-323"},"PeriodicalIF":1.0,"publicationDate":"2015-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736684","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

KVN MONITORING OBSERVATIONS TOWARD THE RECENT OUTBURST SYMBIOTIC STAR V407 CYGNI 最近爆发共生星天鹅座v407的KVN监测观测

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-10-26 DOI: 10.5303/JKAS.2015.48.5.267

Se-Hyung Cho, Jaeheon Kim, Y. Yun

{"title":"KVN MONITORING OBSERVATIONS TOWARD THE RECENT OUTBURST SYMBIOTIC STAR V407 CYGNI","authors":"Se-Hyung Cho, Jaeheon Kim, Y. Yun","doi":"10.5303/JKAS.2015.48.5.267","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.5.267","url":null,"abstract":"Simultaneous time monitoring observations of H₂O and SiO maser lines were performed toward the D-type symbiotic binary system V407 Cyg with the Korean VLBI Network single dish radio telescope. These monitoring observations were carried out from March 2, 2010 (optical phase ∅ = 0.0), 8 days before the nova outburst on March 10, 2010 to June 5, 2014 ( = 2.13). Eight days before the nova outburst, we detected the SiO v = 1, 2, J = 1–0 maser lines which exhibited values of 0.51 K (~ 6.70 Jy) and 0.71 K ( 9.30 Jy), respectively, while after the outburst we could not detect them on April 2 (∅ = 0.04), May 5 ( = 0.09), May 8 (∅ = 0.09), or on June 5, 2010 ( ∅ = 0.13) within the upper limits of our KVN observations. After restarting our monitoring observations, we detected SiO v = 2, J = 1–0 masers starting on October 20, 2011 (∅ = 0.83) and detected SiO v = 1, J = 1–0 masers starting on December 22, 2011 (∅ = 0.92). These results provide clear evidence of the interaction between the shock from the nova outburst and the SiO maser regions of the Mira envelope. The peak emission of SiO v = 1, 2, J = 1–0 masers always occurred at blueshifted velocities with respect to the stellar velocity except for that of SiO v = 1 at one epoch. These phenomena may be related to the redistribution of SiO maser regions after the outburst. The peak velocity variations of SiO masers associated with stellar pulsation phases show an increasing blueshifted trend during our monitoring interval after the outburst.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"267-275"},"PeriodicalIF":1.0,"publicationDate":"2015-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70737057","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

INTERFEROMETRIC MONITORING OF GAMMA–RAY BRIGHT ACTIVE GALACTIC NUCLEI II: FREQUENCY PHASE TRANSFER 伽马射线明亮活动星系核的干涉监测ii:频率相位转移

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-10-20 DOI: 10.5303/JKAS.2015.48.5.237

J. Algaba, Guangyao Zhao, Sang-Sung Lee, D. Byun, Sincheol Kang, Dae-Won Kim, Jae-Young Kim, Jeong-Sook Kim, Soon-Wook Kim, M. Kino, A. Miyazaki, Jongho Park, S. Trippe, K. Wajima

引用次数: 19

LEE SANG GAK TELESCOPE (LSGT): A REMOTELY OPERATED ROBOTIC TELESCOPE FOR EDUCATION AND RESEARCH AT SEOUL NATIONAL UNIVERSITY 李相阁望远镜(lsgt):首尔大学的远程遥控机器人望远镜，用于教育和研究

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-10-12 DOI: 10.5303/JKAS.2015.48.4.207

M. Im, Changsu Choi, Kihyun Kim

引用次数: 10

a Study of a Tidally Interacting BCD Pair: ESO 435-IG20 and ESO435-IG16 潮汐相互作用BCD对ESO 435-IG20和ESO435-IG16的研究

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-09-30 DOI: 10.5303/PKAS.2015.30.2.513

Jinhyub Kim, E. Sung, A. Chung, L. Staveley-Smith

引用次数: 0

PRE-PROCESSING OF GALAXIES IN THE FILAMENTS AROUND THE VIRGO CLUSTER 室女座星系团周围细丝中的星系的预处理

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-09-30 DOI: 10.5303/PKAS.2015.30.2.495

H. Yoon, A. Chung, C. Sengupta, O. I. Wong, M. Bureau, S. Rey, J. Gorkom

{"title":"PRE-PROCESSING OF GALAXIES IN THE FILAMENTS AROUND THE VIRGO CLUSTER","authors":"H. Yoon, A. Chung, C. Sengupta, O. I. Wong, M. Bureau, S. Rey, J. Gorkom","doi":"10.5303/PKAS.2015.30.2.495","DOIUrl":"https://doi.org/10.5303/PKAS.2015.30.2.495","url":null,"abstract":"Galaxies can be pre-processed\" in the low-density outskirts by ambient medium in the laments or tidal interactions with other galaxies while falling into the cluster. In order to probe how early on and by which mechanisms galaxies can be aected before they enter high-density cluster environments, we are carrying out an atomic hydrogen (Hi) imaging study of a sample of galaxies selected from three lamentary structures around the Virgo cluster. Our sample consists of 14 late-type galaxies, which are potentially interacting with their surroundings. The Hi observations have been done using the Westerbork Synthesis Radio Telescope, the Giant Metrewave Radio Telescope, and the Jansky Very Large Array with column density sensitivity of 3-5 10 19 cm 2 in 3 per channel, which is low enough to detect faint Hi features in the outer disks of galaxies. In this work, we present the Hi data of two galaxies that were observed with GMRT. We examine the Hi morphology and kinematics to nd the evidence for gas-gas and/or tidal interactions, and discuss which mechanism(s) could be responsible for pre-processing in these cases.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"30 1","pages":"495-497"},"PeriodicalIF":1.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70739048","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

ANALYSIS OF THE LUNAR ECLIPSE RECORDS FROM THE GORYEOSA 高丽书院月食记录分析

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-08-01 DOI: 10.5303/JKAS.2016.49.4.163

Ki-Won Lee, Byeong-Hee Mihn, Y. Ahn, Sang-Hyeon Ahn

{"title":"ANALYSIS OF THE LUNAR ECLIPSE RECORDS FROM THE GORYEOSA","authors":"Ki-Won Lee, Byeong-Hee Mihn, Y. Ahn, Sang-Hyeon Ahn","doi":"10.5303/JKAS.2016.49.4.163","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.4.163","url":null,"abstract":"In this paper, we study the lunar eclipse records in the Goryeosa (History of the Goryeo Dynasty), an official history book of the Goryeo dynasty (A.D. 918 – 1392). In the history book, a total of 228 lunar eclipse accounts are recorded, covering the period from 1009 to 1392. However, we find that two accounts are duplications and four accounts correspond to no known lunar eclipses around the dates. For the remaining lunar eclipses, we calculate the magnitude and the time of the eclipse at different phases using the DE406 ephemeris. Of the 222 lunar eclipse accounts, we find that the minimum penumbral magnitude was 0.5583. For eclipses which occurred after midnight, we find that some accounts were recorded on the day before the eclipse, like the astronomical records of the Joseonwangjosillok (Annals of the Joseon Dynasty), while others were on the day of the lunar eclipse. We also find that four accounts show a difference in the Julian dates between this study and that of Ahn et al., even though it is assumed that the Goryeo court did not change the dates in the accounts for lunar eclipses that occurred after midnight. With regard to the contents of the lunar eclipse accounts, we confirm that the accounts recorded as total eclipses are accurate, except for two accounts. However, both eclipses were very close to the total eclipse. We also confirm that all predicted lunar eclipses did occur, although one eclipse happened two days after the predicted date. In conclusion, we believe that this study is very helpful for investigating the lunar eclipse accounts of other periods in Korea, and furthermore, useful for verifying the calendar dates of the Goryeo dynasty.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"163-173"},"PeriodicalIF":1.0,"publicationDate":"2015-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738432","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

AMPLITUDE CORRECTION FACTORS OF KOREAN VLBI NETWORK OBSERVATIONS 韩国vlbi网观测的幅值校正因子

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2015-07-13 DOI: 10.5303/JKAS.2015.48.5.229

Sang-Sung Lee, D. Byun, C. Oh, H. Kim, Jongsoo Kim, T. Jung, Se-jin Oh, D. Roh, Dong-Kyu Jung, J. Yeom

{"title":"AMPLITUDE CORRECTION FACTORS OF KOREAN VLBI NETWORK OBSERVATIONS","authors":"Sang-Sung Lee, D. Byun, C. Oh, H. Kim, Jongsoo Kim, T. Jung, Se-jin Oh, D. Roh, Dong-Kyu Jung, J. Yeom","doi":"10.5303/JKAS.2015.48.5.229","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.5.229","url":null,"abstract":"We report results of investigation of amplitude calibration for very long baseline interferome-try (VLBI) observations with Korean VLBI Network (KVN). Amplitude correction factors are estimated based on comparison of KVN observations at 22 GHz correlated by Daejeon hardware correlator and DiFX software correlator in Korea Astronomy and Space Science Institute (KASI) with Very Long Base-line Array (VLBA) observations at 22 GHz by DiFX software correlator in National Radio Astronomy Observatory (NRAO). We used the observations for compact radio sources, 3C 454.3, NRAO 512, OJ 287, BL Lac, 3C 279, 1633+382, and 1510−089, which are almost unresolved for baselines in a range of 350-477 km. Visibility data of the sources obtained with similar baselines at KVN and VLBA are se-lected, fringe-fitted, calibrated, and compared for their amplitudes. We find that visibility amplitudes of KVN observations should be corrected by factors of 1.10 and 1.35 when correlated by DiFX and Daejeon correlators, respectively. These correction factors are attributed to the combination of two steps of 2-bit quantization in KVN observing systems and characteristics of Daejeon correlator.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"229-236"},"PeriodicalIF":1.0,"publicationDate":"2015-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736599","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