Journal of the Korean Astronomical Society最新文献_第4页

Impact of the Icme-Earth Geometry on the Strength of the Associated Geomagnetic Storm: The September 2014 and March 2015 Events Icme-Earth几何对伴生地磁风暴强度的影响:2014年9月和2015年3月事件

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.2017.50.2.29

Kyungsuk Cho, K. Marubashi, R. Kim, Sung-Hong Park, E. Lim, Sujin Kim, Pankaj Kumar, V. Yurchyshyn, Y. Moon, J. Lee

引用次数: 15

PROPERTIES OF THE SCUBA-2 850㎛ SOURCES IN THE XMM-LSS FIELD 在xmm-lss领域中，scuba-2 850um源的特性

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2017-02-28 DOI: 10.5303/JKAS.2017.50.1.7

H. Seo, W. Jeong, S. Kim, J. Pyo, Min Gyu Kim, J. Ko, Minjin Kim, Sam Kim

引用次数: 1

TIME-SERIES PHOTOMETRY OF VARIABLE STARS IN THE GLOBULAR CLUSTER NGC 288 球状星团NGC 288中变星的时间序列光度测定

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-12-31 DOI: 10.5303/JKAS.2016.49.6.295

Dong-Joo Lee, J. Koo, K. Hong, Seung-Lee Kim, Jae Woo Lee, Chung-Uk Lee, Y. Jeon, Yun-Hak Kim, B. Lim, Y. Ryu, S. Cha, Yongseok Lee, Dong Jin Kim, Byeong-Gon Park, Chun-Hwey Kim

{"title":"TIME-SERIES PHOTOMETRY OF VARIABLE STARS IN THE GLOBULAR CLUSTER NGC 288","authors":"Dong-Joo Lee, J. Koo, K. Hong, Seung-Lee Kim, Jae Woo Lee, Chung-Uk Lee, Y. Jeon, Yun-Hak Kim, B. Lim, Y. Ryu, S. Cha, Yongseok Lee, Dong Jin Kim, Byeong-Gon Park, Chun-Hwey Kim","doi":"10.5303/JKAS.2016.49.6.295","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.6.295","url":null,"abstract":"We present the results of BV time-series photometry of the globular cluster NGC 288. Ob-servations were carried out to search for variable stars using the Korea Microlensing Telescope Network (KMTNet) 1.6-m telescopes and a 4k pre-science CCD camera during a test observation from August to December, 2014. We found a new SX Phe star and confirmed twelve previously known variable stars in NGC 288. For the semi-regular variable star V1, we newly determined a period of 37.3 days from light curves spanning 137 days. The light-curve solution of the eclipsing binary V10 indicates that the system is probably a detached system. The pulsation properties of nine SX Phe stars were examined by applying multiple frequency analysis to their light curves. We derived a new Period-Luminosity (P-L) relation, = −2.476(±0.300) logP −0.354(±0.385), from six SX Phe stars showing the fundamental mode. Additionally, the period ratios of three SX Phe stars that probably have a double-radial mode were investigated; P FO /P F = 0.779 for V5, P TO /P FO = 0.685 for V9, P SO /P FO = 0.811 for V11. This paper is the first contribution in a series assessing the detections and properties of variable stars in six southern globular clusters with the KMTNet system.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2016-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738359","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

Long-Term Variation of the Shutter Delay Time of Y4KCAM of the CTIO 1.0 M Telescope CTIO 1.0 M望远镜Y4KCAM快门延时时间的长期变化

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-12-31 DOI: 10.5303/JKAS.2016.49.6.289

Jae-Woo Lee, R. Pogge

引用次数: 5

The Fractal Dimension of the ρ Ophiucus Molecular Cloud Complex 蛇夫座ρ分子云复合体的分形维数

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-12-31 DOI: 10.5303/JKAS.2016.49.6.255

Y. Lee, Di Li, Yongdai Kim, J. H. Jung, H. Kang, C. -. Lee, I. Yim, Hyun-Chul Kim

{"title":"The Fractal Dimension of the ρ Ophiucus Molecular Cloud Complex","authors":"Y. Lee, Di Li, Yongdai Kim, J. H. Jung, H. Kang, C. -. Lee, I. Yim, Hyun-Chul Kim","doi":"10.5303/JKAS.2016.49.6.255","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.6.255","url":null,"abstract":"We estimate the fractal dimension of the ρ Ophiuchus Molecular Cloud Complex, associated with star forming regions. We selected a cube (v, l, b) database, obtained with J = 1−0 transition lines of 12 CO and 13 CO at a resolution of 22′′ using a multibeam receiver system on the 14-m telescope of the Five College Radio Astronomy Observatory. Using a code developed within IRAF, we identified slice-clouds with two threshold temperatures to estimate the fractal dimension. With threshold temperatures of 2.25 K (3σ) and 3.75 K (5σ), the fractal dimension of the target cloud is estimated to be D = 1.52–1.54, where P ∝ A D/2 , which is larger than previous results. We suggest that the sampling rate (spatial resolution) of observed data must be an important parameter when estimating the fractal dimension, and that narrower or wider dispersion around an arbitrary fit line and the intercepts at NP = 100 should be checked whether they relate to rms noise level or characteristic structure of the target cloud. This issue could be investigated by analysing several high resolution databases with different quality (low or moderate sensitivity).","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2016-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738294","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

ENVIRONMENTAL DEPENDENCE OF WARPS IN SPIRAL GALAXIES 螺旋星系中翘曲的环境依赖性

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-12-31 DOI: 10.5303/JKAS.2016.49.6.239

H. Ann, H. Bae

引用次数: 2

MONITORING OBSERVATIONS OF H2O AND SiO MASERS TOWARD POST-AGB STARS 对后agb恒星的H2O和SiO脉泽的监测观测

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-12-31 DOI: 10.5303/JKAS.2016.49.6.261

Jaeheon Kim, Se-Hyung Cho, Dong-Hwan Yoon

{"title":"MONITORING OBSERVATIONS OF H2O AND SiO MASERS TOWARD POST-AGB STARS","authors":"Jaeheon Kim, Se-Hyung Cho, Dong-Hwan Yoon","doi":"10.5303/JKAS.2016.49.6.261","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.6.261","url":null,"abstract":"We present the results of simultaneous monitoring observations of H₂O 6 1,6 –5 2,3 (22GHz) and SiO J=1–0, 2–1, 3–2 maser lines (43, 86, 129GHz) toward five post-AGB (candidate) stars, using the 21-m single-dish telescopes of the Korean VLBI Network. Depending on the target objects, 7 – 11 epochs of data were obtained. We detected both H₂O and SiO maser lines from four sources: OH16.1−0.3, OH38.10−0.13, OH65.5+1.3, and IRAS 19312+1950. We could not detect H₂O maser emission toward OH13.1+5.1 between the late OH/IR and post-AGB stage. The detected H₂O masers show typical double-peaked line profiles. The SiO masers from four sources, except IRAS 19312+1950, show the peaks around the stellar velocity as a single peak, whereas the SiO masers from IRAS 19312+1950 occur above the red peak of the H₂O maser. We analyzed the properties of detected maser lines, and investigated their evolutionary state through comparison with the full widths at zero power. The distribution of observed target sources was also investigated in the IRAS two-color diagram in relation with the evolutionary stage of post-AGB stars. From our analyses, the evolutionary sequence of observed sources is suggested as OH65.5+1.3 → OH13.1+5.1→ OH16.1−0.3 → OH38.10−0.13, except for IRAS 19312+1950. In addition, OH13.1+5.1 from which the H₂O maser has not been detected is suggested to be on the gateway toward the post-AGB stage. With respect to the enigmatic object, IRAS 19312+1950, we could not clearly figure out its nature. To properly explain the unusual phenomena of SiO and H₂O masers, it is essential to establish the relative locations and spatial distributions of two masers using VLBI technique. We also include the 1.2 – 160 μm spectral energy distribution using photometric data from the following surveys: 2MASS, WISE, MSX, IRAS, and AKARI (IRC and FIS). In addition, from the IRAS LRS spectra, we found that the depth of silicate absorption features shows significant variations depending on the evolutionary sequence, associated with the termination of AGB phase mass-loss.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2016-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738309","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 Korean 1592-1593 Record of a Guest Star: An 'Impostor' of the Cassiopeia A Supernova? 韩国1592-1593年的客串星记录:仙后座a超新星的“骗子”?

IF 1 4区物理与天体物理

Journal of the Korean Astronomical Society Pub Date : 2016-11-11 DOI: 10.5303/JKAS.2016.49.6.233

Changbom Park, Sung-Chul Yoon, B. Koo

{"title":"The Korean 1592-1593 Record of a Guest Star: An 'Impostor' of the Cassiopeia A Supernova?","authors":"Changbom Park, Sung-Chul Yoon, B. Koo","doi":"10.5303/JKAS.2016.49.6.233","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.6.233","url":null,"abstract":"The missing historical record of the Cassiopeia A (Cas A) supernova (SN) event implies a large extinction to the SN, possibly greater than the interstellar extinction to the current SN remnant. Here we investigate the possibility that the guest star that appeared near Cas A in 1592{1593 in Korean history books could have been an `impostor\" of the Cas A SN, i.e., a luminous transient that appeared to be a SN but did not destroy the progenitor star, with strong mass loss to have provided extra circumstellar extinction. We first review the Korean records and show that a spatial coincidence between the guest star and Cas A cannot be ruled out, as opposed to previous studies. Based on modern astrophysical findings on core-collapse SN, we argue that Cas A could have had an impostor and derive its anticipated properties. It turned out that the Cas A SN impostor must have been bright (M V = -14.7 ± 2:2 mag) and an amount of dust with visual extinction of ≥ 2.8 ± 2:2 mag should have formed in the ejected envelope and/or in a strong wind afterwards. The mass loss needs to have been spherically asymmetric in order to see the light echo from the SN event but not the one from the impostor event.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2016-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738249","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

Three-Site Photometric Monitoring of the δ Sct-Type Pulsating Star V1162 Orionis: Period Change and its Implications for Pre-Main Sequence Evolution 猎户座δ sct型脉动星V1162的三点光度监测:周期变化及其对前主序演化的意义

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.2016.49.5.199

Seung-Lee Kim, S. Cha, B. Lim, Jae Woo Lee, Chung-Uk Lee, Yongseok Lee, Dong Jin Kim, Dong-Joo Lee, J. Koo, K. Hong, Y. Ryu, Byeong-Gon Park

{"title":"Three-Site Photometric Monitoring of the δ Sct-Type Pulsating Star V1162 Orionis: Period Change and its Implications for Pre-Main Sequence Evolution","authors":"Seung-Lee Kim, S. Cha, B. Lim, Jae Woo Lee, Chung-Uk Lee, Yongseok Lee, Dong Jin Kim, Dong-Joo Lee, J. Koo, K. Hong, Y. Ryu, Byeong-Gon Park","doi":"10.5303/JKAS.2016.49.5.199","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.5.199","url":null,"abstract":"We present photometric results of the δ Sct star V1162 Ori, which is extensively monitored for a total of 49 nights from mid-December 2014 to early-March 2015. The observations are made with three KMTNet (Korea Microlensing Telescope Network) 1.6 m telescopes installed in Chile, South Africa, and Australia. Multiple frequency analysis is applied to the data and resulted in clear detection of seven frequencies without an alias problem: five known frequencies and two new ones with small amplitudes of 1.2-1.7 mmag. The amplitudes of all but one frequency are significantly different from previous results, confirming the existence of long-term amplitude changes. We examine the variations in pulsation timings of V1162 Ori for about 30 years by using the times of maximum light obtained from our data and collected from the literatures. The O − C (Observed minus Calculated) timing diagram shows a combination of a downward parabolic variation with a period decreasing rate of (1/P)dP/dt = −4.22 × 10 −6 year −1 and a cyclic change with a period of about 2780 days. The most probable explanation for this cyclic variation is the light-travel-time effect caused by an unknown binary companion, which has a minimum mass of 0.69 M ⊙ . V1162 Ori is the first δ Sct-type pulsating star of which the observed fast period decrease can be interpreted as an evolutionary effect of a pre-main sequence star, considering its membership of the Orion OB 1c association.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2016-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738184","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

KMTNET SUPERNOVA PROGRAM VARIABLE OBJECTS I. NGC 2784 FIELD Kmtnet超新星程序变量对象i . ngc2784场

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.2016.49.5.209

M. He, D. moon, H. Neilson, Jaejoon Lee, Sang Chul Kim, M. Pak, H. S. Park, Dong Jin Kim, Yongseok Lee, Seung-Lee Kim, Chung-Uk Lee

{"title":"KMTNET SUPERNOVA PROGRAM VARIABLE OBJECTS I. NGC 2784 FIELD","authors":"M. He, D. moon, H. Neilson, Jaejoon Lee, Sang Chul Kim, M. Pak, H. S. Park, Dong Jin Kim, Yongseok Lee, Seung-Lee Kim, Chung-Uk Lee","doi":"10.5303/JKAS.2016.49.5.209","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.5.209","url":null,"abstract":"We present analyses of ~1250 variable sources identified in a 20 square degree field toward NGC 2784 by the KMTNet Supernova Program. We categorize the variable sources into three groups based on their B-band variability. The first group consists of 31 high variability sources with their B-band RMS variability greater than 0.3 magnitudes. The second group of medium variability contains 265 sources with RMS variability between 0.05 and 0.3 magnitudes. The remaining 951 sources belong to the third group of low variability with an RMS variability smaller than 0.05 magnitudes. Of the entire ~1250 sources, 4 clearly show periods of variability greater than 100 days, while the rest have periods shorter than ~51 days or no reliable periods. The majority of the sources show either rather irregular variability or short periods faster than 2 days. Most of the sources with reliable period determination between 2 and 51 days belong to the low-variability group, although a few belong to the medium-variability group. All the variable sources with periods longer than 35 days appear to be very red with B-V > 1.5 and V-I > 2.1 magnitudes. We classify candidates of 51 Cepheids, 17 semi-regular variables, 3 Mira types, 2 RV(B) Tauri stars, 26 eclipsing binary systems and 1 active galactic nucleus. The majority of long-term variables in our sample belong to either Mira or semi-regular types, indicating that long-term variability may be more prominent in post-main sequence phases of late-type stars. The depth of the eclipsing dips of the 26 candidates for eclipsing binaries is equivalent to ~0.61 as the average relative size of the two stars in the binary system. Our results illustrate the power of the KMTNet Supernova Program for future studies of variable objects.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2016-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70738201","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