Pub Date : 2016-03-24DOI: 10.5303/JKAS.2016.49.3.083
Hyesung Kang
The Toothbrush radio relic associated with the merging cluster 1RXS J060303.3 is presumed to be produced by relativistic electrons accelerated at merger-driven shocks. Since the shock Mach number inferred from the observed radio spectral index, M radio ≈ 2.8, is larger than that estimated from X-ray observations, M X ≲ 1.5, we consider the re-acceleration model in which a weak shock of M s ≈ 1.2 - 1.5 sweeps through the intracluster plasma with a preshock population of relativistic electrons. We nd the models with a power-law momentum spectrum with the slope, s ≈ 4.6, and the cutoff Lorentz factor,γ e,c ≈ 7-8 x 10 4 can reproduce reasonably well the observed proles of radio uxes and integrated radio spectrum of the head portion of the Toothbrush relic. This study conrms the strong connection between the ubiquitous presence of fossil relativistic plasma originated from AGNs and the shock-acceleration model of radio relics in the intracluster medium.
与合并星团1RXS J060303.3相关的牙刷无线电遗迹被认为是由合并驱动激波加速的相对论性电子产生的。由于从观测到的射电光谱指数推断出的激波马赫数M radio≈2.8比X射线观测估计出的激波马赫数M X > 1.5要大，因此我们考虑再加速模型，在该模型中，一个弱激波M s≈1.2 - 1.5扫过星系团内等离子体，并带着相对论性电子的预激波群。我们发现，斜率为s≈4.6的幂律动量谱和截止洛伦兹因子γ e,c≈7-8 x 10 4的模型可以较好地再现观测到的射电光谱和牙刷遗迹头部部分的综合射电频谱。这项研究证实了普遍存在的源自agn的相对论性等离子体化石与星系团内介质中射电遗迹的冲击加速模型之间的紧密联系。
{"title":"RE-ACCELERATION MODEL FOR THE ‘TOOTHBRUSH’ RADIO RELIC","authors":"Hyesung Kang","doi":"10.5303/JKAS.2016.49.3.083","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.3.083","url":null,"abstract":"The Toothbrush radio relic associated with the merging cluster 1RXS J060303.3 is presumed to be produced by relativistic electrons accelerated at merger-driven shocks. Since the shock Mach number inferred from the observed radio spectral index, M radio ≈ 2.8, is larger than that estimated from X-ray observations, M X ≲ 1.5, we consider the re-acceleration model in which a weak shock of M s ≈ 1.2 - 1.5 sweeps through the intracluster plasma with a preshock population of relativistic electrons. We nd the models with a power-law momentum spectrum with the slope, s ≈ 4.6, and the cutoff Lorentz factor,γ e,c ≈ 7-8 x 10 4 can reproduce reasonably well the observed proles of radio uxes and integrated radio spectrum of the head portion of the Toothbrush relic. This study conrms the strong connection between the ubiquitous presence of fossil relativistic plasma originated from AGNs and the shock-acceleration model of radio relics in the intracluster medium.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"83-92"},"PeriodicalIF":1.0,"publicationDate":"2016-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70737928","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 : 2016-03-23DOI: 10.5303/JKAS.2016.49.1.045
Kyuhyoun Cho, J. Chae, E. Lim, Kyungsuk Cho, S. Bong, Heesu Yang
The coronagraph is an instrument that enables the investigation of faint features in the vicinity of the Sun, particularly coronal mass ejections (CMEs). So far coronagraphic observations have been mainly used to determine the geometric and kinematic parameters of CMEs. Here, we introduce a new method for the determination of CME temperature using a two filter (4025 A and 3934 A) coronagraph system. The thermal motion of free electrons in CMEs broadens the absorption lines in the optical spectra that are produced by the Thomson scattering of visible light originating in the photosphere, which affects the intensity ratio at two different wavelengths. Thus the CME temperature can be inferred from the intensity ratio measured by the two filter coronagraph system. We demonstrate the method by invoking the graduated cylindrical shell (GCS) model for the 3-dimensional CME density distribution and discuss its significance.
{"title":"A New Method to Determine the Temperature of CMEs Using a Coronagraph Filter System","authors":"Kyuhyoun Cho, J. Chae, E. Lim, Kyungsuk Cho, S. Bong, Heesu Yang","doi":"10.5303/JKAS.2016.49.1.045","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.1.045","url":null,"abstract":"The coronagraph is an instrument that enables the investigation of faint features in the vicinity of the Sun, particularly coronal mass ejections (CMEs). So far coronagraphic observations have been mainly used to determine the geometric and kinematic parameters of CMEs. Here, we introduce a new method for the determination of CME temperature using a two filter (4025 A and 3934 A) coronagraph system. The thermal motion of free electrons in CMEs broadens the absorption lines in the optical spectra that are produced by the Thomson scattering of visible light originating in the photosphere, which affects the intensity ratio at two different wavelengths. Thus the CME temperature can be inferred from the intensity ratio measured by the two filter coronagraph system. We demonstrate the method by invoking the graduated cylindrical shell (GCS) model for the 3-dimensional CME density distribution and discuss its significance.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"45-51"},"PeriodicalIF":1.0,"publicationDate":"2016-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70737555","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 : 2016-02-29DOI: 10.5303/JKAS.2016.49.1.1
K. Bach
The aim of this study is to describe the physical processes taking place in the solar photosphere. Based on 3D hydrodynamic simulations including a detailed radiation transfer scheme, we investigate thermodynamic structures and radiation fields in solar surface convection. As a starting model, the initial stratification in the outer envelope calculated using the solar calibrations in the context of the standard stellar theory. When the numerical fluid becomes thermally relaxed, the thermodynamic structure of the steady-state turbulent flow was explicitly collected. Particularly, a non-grey radiative transfer incorporating the opacity distribution function was considered in our calculations. In addition, we evaluate the classical approximations that are usually adopted in the onedimensional stellar structure models. We numerically reconfirm that radiation fields are well represented by the asymptotic characteristics of the Eddington approximation (the diffusion limit and the streaming limit). However, this classical approximation underestimates radiation energy in the shallow layers near the surface, which implies that a reliable treatment of the non-grey line opacities is crucial for the accurate description of the photospheric convection phenomenon.
{"title":"NON-GREY RADIATIVE TRANSFER IN THE PHOTOSPHERIC CONVECTION : VALIDITY OF THE EDDINGTON APPROXIMATION","authors":"K. Bach","doi":"10.5303/JKAS.2016.49.1.1","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.1.1","url":null,"abstract":"The aim of this study is to describe the physical processes taking place in the solar photosphere. Based on 3D hydrodynamic simulations including a detailed radiation transfer scheme, we investigate thermodynamic structures and radiation fields in solar surface convection. As a starting model, the initial stratification in the outer envelope calculated using the solar calibrations in the context of the standard stellar theory. When the numerical fluid becomes thermally relaxed, the thermodynamic structure of the steady-state turbulent flow was explicitly collected. Particularly, a non-grey radiative transfer incorporating the opacity distribution function was considered in our calculations. In addition, we evaluate the classical approximations that are usually adopted in the onedimensional stellar structure models. We numerically reconfirm that radiation fields are well represented by the asymptotic characteristics of the Eddington approximation (the diffusion limit and the streaming limit). However, this classical approximation underestimates radiation energy in the shallow layers near the surface, which implies that a reliable treatment of the non-grey line opacities is crucial for the accurate description of the photospheric convection phenomenon.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"1-8"},"PeriodicalIF":1.0,"publicationDate":"2016-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70737108","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 : 2016-02-29DOI: 10.5303/JKAS.2016.49.1.37
Seung-Lee Kim, Chung-Uk Lee, Byeong-Gon Park, Dong Jin Kim, S. Cha, Yongseok Lee, C. Han, M. Chun, I. Yuk
The Korea Microlensing Telescope Network (KMTNet) is a wide-field photometric system installed by the Korea Astronomy and Space Science Institute (KASI). Here, we present the overall technical specifications of the KMTNet observation system, test observation results, data transfer and image processing procedure, and finally, the KMTNet science programs. The system consists of three 1.6 m wide-field optical telescopes equipped with mosaic CCD cameras of 18k by 18k pixels. Each telescope provides a 2.0 by 2.0 square degree field of view. We have finished installing all three telescopes and cameras sequentially at the Cerro-Tololo Inter-American Observatory (CTIO) in Chile, the South African Astronomical Observatory (SAAO) in South Africa, and the Siding Spring Observatory (SSO) in Australia. This network of telescopes, which is spread over three different continents at a similar latitude of about -30 degrees, enables 24-hour continuous monitoring of targets observable in the Southern Hemisphere. The test observations showed good image quality that meets the seeing requirement of less than 1.0 arcsec in I-band. All of the observation data are transferred to the KMTNet data center at KASI via the international network communication and are processed with the KMTNet data pipeline. The primary scientific goal of the KMTNet is to discover numerous extrasolar planets toward the Galactic bulge by using the gravitational microlensing technique, especially earth-mass planets in the habitable zone. During the non-bulge season, the system is used for wide-field photometric survey science on supernovae, asteroids, and external galaxies.
{"title":"KMTNET: A NETWORK OF 1.6 M WIDE-FIELD OPTICAL TELESCOPES INSTALLED AT THREE SOUTHERN OBSERVATORIES","authors":"Seung-Lee Kim, Chung-Uk Lee, Byeong-Gon Park, Dong Jin Kim, S. Cha, Yongseok Lee, C. Han, M. Chun, I. Yuk","doi":"10.5303/JKAS.2016.49.1.37","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.1.37","url":null,"abstract":"The Korea Microlensing Telescope Network (KMTNet) is a wide-field photometric system installed by the Korea Astronomy and Space Science Institute (KASI). Here, we present the overall technical specifications of the KMTNet observation system, test observation results, data transfer and image processing procedure, and finally, the KMTNet science programs. The system consists of three 1.6 m wide-field optical telescopes equipped with mosaic CCD cameras of 18k by 18k pixels. Each telescope provides a 2.0 by 2.0 square degree field of view. We have finished installing all three telescopes and cameras sequentially at the Cerro-Tololo Inter-American Observatory (CTIO) in Chile, the South African Astronomical Observatory (SAAO) in South Africa, and the Siding Spring Observatory (SSO) in Australia. This network of telescopes, which is spread over three different continents at a similar latitude of about -30 degrees, enables 24-hour continuous monitoring of targets observable in the Southern Hemisphere. The test observations showed good image quality that meets the seeing requirement of less than 1.0 arcsec in I-band. All of the observation data are transferred to the KMTNet data center at KASI via the international network communication and are processed with the KMTNet data pipeline. The primary scientific goal of the KMTNet is to discover numerous extrasolar planets toward the Galactic bulge by using the gravitational microlensing technique, especially earth-mass planets in the habitable zone. During the non-bulge season, the system is used for wide-field photometric survey science on supernovae, asteroids, and external galaxies.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"37-44"},"PeriodicalIF":1.0,"publicationDate":"2016-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70737606","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 : 2016-02-29DOI: 10.5303/JKAS.2016.49.1.19
Ensang Lee, G. Parks
Magnetic decreases are often observed in various regions of interplanetary space. Many studies are devoted to reveal the physical nature and generation mechanism of the magnetic decreases, but still we do not fully understand magnetic decreases. In this study, we investigate the structure of a magnetic decrease observed in a corotating interaction region using multi-spacecraft measurements. We use three spacecraft, ACE, Cluster, and Wind, which were widely separated in the x- and y-directions in the geocentric solar ecliptic (GSE) coordinates. The boundaries of the magnetic decrease are the same at the three locations and can be identified as tangential discontinuities. A notable feature is that the magnetic decrease has very large dimension, &268 RE, along the boundary, which is much larger than the size, 6 RE, along the normal direction. This suggests that the magnetic decrease has a shape of a long, thin rod or a wide slab.
{"title":"STRUCTURE OF A MAGNETIC DECREASE OBSERVED IN A COROTATING INTERACTION REGION","authors":"Ensang Lee, G. Parks","doi":"10.5303/JKAS.2016.49.1.19","DOIUrl":"https://doi.org/10.5303/JKAS.2016.49.1.19","url":null,"abstract":"Magnetic decreases are often observed in various regions of interplanetary space. Many studies are devoted to reveal the physical nature and generation mechanism of the magnetic decreases, but still we do not fully understand magnetic decreases. In this study, we investigate the structure of a magnetic decrease observed in a corotating interaction region using multi-spacecraft measurements. We use three spacecraft, ACE, Cluster, and Wind, which were widely separated in the x- and y-directions in the geocentric solar ecliptic (GSE) coordinates. The boundaries of the magnetic decrease are the same at the three locations and can be identified as tangential discontinuities. A notable feature is that the magnetic decrease has very large dimension, &268 RE, along the boundary, which is much larger than the size, 6 RE, along the normal direction. This suggests that the magnetic decrease has a shape of a long, thin rod or a wide slab.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"49 1","pages":"19-23"},"PeriodicalIF":1.0,"publicationDate":"2016-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70737917","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 : 2015-12-31DOI: 10.5303/JKAS.2015.48.6.333
D. Cho, T. Yoon, Sanggak Lee, H. Sung
A search for hot and bright white dwarfs (WDs) in the Milky Way globular clusters M13 (NGC 6205) and M22 (NGC 6656) is carried out using the deep and homogeneous V I photometric catalog of Anderson et al. and and Sarajedini et al., based on data taken with the ACS/WFC aboard the Hubble Space Telescope (HST). V versus V − I color-magnitude diagrams (CMDs) of M13 and M22 are constructed and numerous spurious detections are rejected according to their photometric quality parameters qfit(V ) and qfit(I). In the case of M13, further radial restriction is applied to reject central stars with higher photometric errors due to central crowding. From each resultant V versus V −I CMD, sixteen and thirteen WD candidates are identified in M13 and M22, respectively. They are identified as stellar objects in the accompanying ACS/WFC images and are found to be randomly distributed across the central regions of M13 and M22. Their positions in the CMDs are in the bright part of the DA WD cooling sequences indicating that they are true WDs. In order to confirm their nature, follow-up spectroscopic observations are needed.
{"title":"DISCOVERY OF WHITE DWARFS IN THE GLOBULAR CLUSTERS M13 AND M22 USING HST ACS PHOTOMETRIC DATA","authors":"D. Cho, T. Yoon, Sanggak Lee, H. Sung","doi":"10.5303/JKAS.2015.48.6.333","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.6.333","url":null,"abstract":"A search for hot and bright white dwarfs (WDs) in the Milky Way globular clusters M13 (NGC 6205) and M22 (NGC 6656) is carried out using the deep and homogeneous V I photometric catalog of Anderson et al. and and Sarajedini et al., based on data taken with the ACS/WFC aboard the Hubble Space Telescope (HST). V versus V − I color-magnitude diagrams (CMDs) of M13 and M22 are constructed and numerous spurious detections are rejected according to their photometric quality parameters qfit(V ) and qfit(I). In the case of M13, further radial restriction is applied to reject central stars with higher photometric errors due to central crowding. From each resultant V versus V −I CMD, sixteen and thirteen WD candidates are identified in M13 and M22, respectively. They are identified as stellar objects in the accompanying ACS/WFC images and are found to be randomly distributed across the central regions of M13 and M22. Their positions in the CMDs are in the bright part of the DA WD cooling sequences indicating that they are true WDs. In order to confirm their nature, follow-up spectroscopic observations are needed.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"333-341"},"PeriodicalIF":1.0,"publicationDate":"2015-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736856","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 : 2015-12-31DOI: 10.5303/JKAS.2015.48.6.381
J. Sohn, H. Hwang, M. Geller, A. Diaferio, K. Rines, M. Lee, Gwang-Ho Lee
Dynamical analysis of compact groups provides important tests of models of compact group formation and evolution. By compiling 2066 redshifts from FLWO/FAST, from the literature, and from SDSS DR12 in the fields of compact groups in McConnachie et al. (2009), we construct the largest sample of compact groups with complete spectroscopic redshifts in the redshift range 0.01 −1 kpc, smaller than the radii typically sampled by members of massive clusters of galaxies. The physical properties of our sample compact groups include size, number density, velocity dispersion, and local environment; these properties slightly differ from those derived for the original Hickson compact groups and for the DPOSS II compact groups. Differences result from subtle differences in the way the group candidates were originally selected. The abundance of the compact groups changes little with redshift over the range covered by this sample. The approximate constancy of the abundance for this sample is a potential constraint on the evolution of compact groups on a few Gigayear timescale .
紧群的动力学分析为紧群的形成和演化模型提供了重要的检验。通过编译来自FLWO/FAST、文献和SDSS DR12在McConnachie et al.(2009)的致密群领域的2066个红移，我们构建了最大的致密群样本，其完全光谱红移范围为0.01 - 1 kpc，小于大质量星系团成员通常采样的半径。我们的样品致密群的物理性质包括大小、数量密度、速度弥散和局部环境;这些性质与原始希克森紧群和DPOSS II紧群的性质略有不同。这些差异是由最初选择小组候选人的方式的细微差异造成的。在本样本覆盖的范围内，紧星团的丰度随红移变化不大。该样品丰度的近似恒定性是在几十亿年时间尺度上致密群演化的一个潜在约束。
{"title":"COMPACT GROUPS OF GALAXIES WITH COMPLETE SPECTROSCOPIC REDSHIFTS IN THE LOCAL UNIVERSE","authors":"J. Sohn, H. Hwang, M. Geller, A. Diaferio, K. Rines, M. Lee, Gwang-Ho Lee","doi":"10.5303/JKAS.2015.48.6.381","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.6.381","url":null,"abstract":"Dynamical analysis of compact groups provides important tests of models of compact group formation and evolution. By compiling 2066 redshifts from FLWO/FAST, from the literature, and from SDSS DR12 in the fields of compact groups in McConnachie et al. (2009), we construct the largest sample of compact groups with complete spectroscopic redshifts in the redshift range 0.01 −1 kpc, smaller than the radii typically sampled by members of massive clusters of galaxies. The physical properties of our sample compact groups include size, number density, velocity dispersion, and local environment; these properties slightly differ from those derived for the original Hickson compact groups and for the DPOSS II compact groups. Differences result from subtle differences in the way the group candidates were originally selected. The abundance of the compact groups changes little with redshift over the range covered by this sample. The approximate constancy of the abundance for this sample is a potential constraint on the evolution of compact groups on a few Gigayear timescale .","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"381-398"},"PeriodicalIF":1.0,"publicationDate":"2015-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736815","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 : 2015-12-31DOI: 10.5303/JKAS.2015.48.6.365
Kee-Tae Kim, Won-Ju Kim, Chang-Hee Kim
We map 6 massive young stellar objects (YSOs) in the CO J=2–1 line and survey 18 massive YSOs, including the six, in the HCO+ J=1−0, SiO J=2−1, H₂O 6 16 − 5 23 maser, and CH₃OH 7 0 − 6 1 A + maser lines. We detect CO bipolar outflows in all the six mapped sources. Four of them are newly discovered (07299−1651, 21306+5540, 22308+5812, 23133+6050), while 05490+2658 is mapped in the CO J=2–1 line for the first time. The detected outflows are much more massive and energetic than outflows from low-mass YSOs with masses >20 M ⊙ and momenta >300 M⊙ km s −1 . They have mass outflow rates (3−6)×10 −4 M ⊙ yr −1 , which are at least one order of magnitude greater than those observed in low-mass YSOs. We detect HCO+ and SiO line emission in 18 (100%) and 4 (22%) sources, respectively. The HCO + spectra show high-velocity wings in 11 (61%) sources. We detect H₂O maser emission in 13 (72%) sources and 44 GHz CH₃OH maser emission in 8 (44%) sources. Of the detected sources, 5 H₂O and 6 CH₃OH maser sources are new discoveries. 20081+3122 shows high-velocity (>30 km s −1 ) H₂O maser lines. We find good correlations of the bolometric luminosity of the central (proto)star with the mechanical force, mechanical luminosity, and mass outflow rate of molecular outflow in the bolometric luminosity range of 10 −1 −10 6 L ⊙ , and identified 3 intermediate- or high-mass counterparts of Class O objects.
{"title":"MOLECULAR OUTFLOWS FROM NEWLY FORMED MASSIVE STARS","authors":"Kee-Tae Kim, Won-Ju Kim, Chang-Hee Kim","doi":"10.5303/JKAS.2015.48.6.365","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.6.365","url":null,"abstract":"We map 6 massive young stellar objects (YSOs) in the CO J=2–1 line and survey 18 massive YSOs, including the six, in the HCO+ J=1−0, SiO J=2−1, H₂O 6 16 − 5 23 maser, and CH₃OH 7 0 − 6 1 A + maser lines. We detect CO bipolar outflows in all the six mapped sources. Four of them are newly discovered (07299−1651, 21306+5540, 22308+5812, 23133+6050), while 05490+2658 is mapped in the CO J=2–1 line for the first time. The detected outflows are much more massive and energetic than outflows from low-mass YSOs with masses >20 M ⊙ and momenta >300 M⊙ km s −1 . They have mass outflow rates (3−6)×10 −4 M ⊙ yr −1 , which are at least one order of magnitude greater than those observed in low-mass YSOs. We detect HCO+ and SiO line emission in 18 (100%) and 4 (22%) sources, respectively. The HCO + spectra show high-velocity wings in 11 (61%) sources. We detect H₂O maser emission in 13 (72%) sources and 44 GHz CH₃OH maser emission in 8 (44%) sources. Of the detected sources, 5 H₂O and 6 CH₃OH maser sources are new discoveries. 20081+3122 shows high-velocity (>30 km s −1 ) H₂O maser lines. We find good correlations of the bolometric luminosity of the central (proto)star with the mechanical force, mechanical luminosity, and mass outflow rate of molecular outflow in the bolometric luminosity range of 10 −1 −10 6 L ⊙ , and identified 3 intermediate- or high-mass counterparts of Class O objects.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"365-380"},"PeriodicalIF":1.0,"publicationDate":"2015-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736654","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 : 2015-12-31DOI: 10.5303/JKAS.2015.48.6.325
Heon-Young Chang
We study an association between the duration of solar activity and characteristics of the latitude distribution of sunspots by means of center-of-latitude (COL) of sunspots observed during the period from 1878 to 2008 spanning solar cycles 12 to 23. We first calculate COL by taking the area-weighted mean latitude of sunspots for each calendar month to determine the latitudinal distribution of COL of sunspots appearing in the long and short cycles separately. The data set for the long solar cycles consists of the solar cycles 12, 13, 14, 20, and 23. The short solar cycles include the solar cycles 15, 16, 17, 18, 19, 21, and 22. We then fit a double Gaussian function to compare properties of the latitudinal distribution resulting from the tw° data sets. Our main findings are as follows: (1) The main component of the double Gaussian function does not show any significant change in the central position and in the full-width-at-half-maximum (FWHM), except in the amplitude. They are all centered at ~ 11° with FWHM of ~ 5°. (2) The secondary component of the double Gaussian function at higher latitudes seems to differ in that even though their width remains fixed at ~ 4°, their central position peaks at ~ 22.1° for the short cycles and at ~ 20.7◦ for the long cycles with quite small errors. (3) No significant correlation could be established between the duration of an individual cycle and the parameters of the double Gaussian. Finally, we conclude by briefly discussing the implications of these findings on the issue of the cycle 4 concerning a lost cycle.
{"title":"LATITUDINAL DISTRIBUTION OF SUNSPOTS AND DURATION OF SOLAR CYCLES","authors":"Heon-Young Chang","doi":"10.5303/JKAS.2015.48.6.325","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.6.325","url":null,"abstract":"We study an association between the duration of solar activity and characteristics of the latitude distribution of sunspots by means of center-of-latitude (COL) of sunspots observed during the period from 1878 to 2008 spanning solar cycles 12 to 23. We first calculate COL by taking the area-weighted mean latitude of sunspots for each calendar month to determine the latitudinal distribution of COL of sunspots appearing in the long and short cycles separately. The data set for the long solar cycles consists of the solar cycles 12, 13, 14, 20, and 23. The short solar cycles include the solar cycles 15, 16, 17, 18, 19, 21, and 22. We then fit a double Gaussian function to compare properties of the latitudinal distribution resulting from the tw° data sets. Our main findings are as follows: (1) The main component of the double Gaussian function does not show any significant change in the central position and in the full-width-at-half-maximum (FWHM), except in the amplitude. They are all centered at ~ 11° with FWHM of ~ 5°. (2) The secondary component of the double Gaussian function at higher latitudes seems to differ in that even though their width remains fixed at ~ 4°, their central position peaks at ~ 22.1° for the short cycles and at ~ 20.7◦ for the long cycles with quite small errors. (3) No significant correlation could be established between the duration of an individual cycle and the parameters of the double Gaussian. Finally, we conclude by briefly discussing the implications of these findings on the issue of the cycle 4 concerning a lost cycle.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"325-331"},"PeriodicalIF":1.0,"publicationDate":"2015-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736776","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 : 2015-12-31DOI: 10.5303/JKAS.2015.48.6.357
Se-Hyung Cho, Dong-Hwan Yoon, Jaeheon Kim, D. Byun, J. Wagner
We observe ten known 22GHz H₂O maser galaxies during February 19–22, 2011 using the 21 m Tamna telescope of the Korean VLBI Network and a new wide-band digital spectrometer. Simultaneously we searched for 43GHz SiO v = 1, 2, J = 1–0 maser emission. We detect H₂O maser emission towards five sources (M 33, NGC 1052, NGC 1068, NGC 4258, M 82), with non-detections towards the remaining sources (UGC 3193, UGC 3789, Antennae H₂O-West, M 51, NGC 6323) likely due to sensitivity. Our 22GHz spectra are consistent with earlier findings. Our simultaneous 43GHz SiO maser search produced non-detections, yielding – for the first time – upper limits on the 43GHz SiO maser emission in these sources at a 3 σ sensitivity level of 0.018K–0.033K (0.24 Jy–0.44 Jy) in a 1.75 km s −1 velocity resolution. Our findings suggest that any 43GHz SiO masers in these sources (some having starburst-associated H₂O kilomasers) must be faint compared to the 22GHz H₂O maser emission.
{"title":"SIMULTANEOUS OBSERVATIONS OF H 2 O AND SIO MASERS TOWARD KNOWN EXTRAGALACTIC WATER MASER SOURCES","authors":"Se-Hyung Cho, Dong-Hwan Yoon, Jaeheon Kim, D. Byun, J. Wagner","doi":"10.5303/JKAS.2015.48.6.357","DOIUrl":"https://doi.org/10.5303/JKAS.2015.48.6.357","url":null,"abstract":"We observe ten known 22GHz H₂O maser galaxies during February 19–22, 2011 using the 21 m Tamna telescope of the Korean VLBI Network and a new wide-band digital spectrometer. Simultaneously we searched for 43GHz SiO v = 1, 2, J = 1–0 maser emission. We detect H₂O maser emission towards five sources (M 33, NGC 1052, NGC 1068, NGC 4258, M 82), with non-detections towards the remaining sources (UGC 3193, UGC 3789, Antennae H₂O-West, M 51, NGC 6323) likely due to sensitivity. Our 22GHz spectra are consistent with earlier findings. Our simultaneous 43GHz SiO maser search produced non-detections, yielding – for the first time – upper limits on the 43GHz SiO maser emission in these sources at a 3 σ sensitivity level of 0.018K–0.033K (0.24 Jy–0.44 Jy) in a 1.75 km s −1 velocity resolution. Our findings suggest that any 43GHz SiO masers in these sources (some having starburst-associated H₂O kilomasers) must be faint compared to the 22GHz H₂O maser emission.","PeriodicalId":49994,"journal":{"name":"Journal of the Korean Astronomical Society","volume":"48 1","pages":"357-364"},"PeriodicalIF":1.0,"publicationDate":"2015-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70736981","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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