I make use of [alpha/Fe] ratios derived from SEGUE spectra of 17,277 G-type dwarfs to separate them into likely thin- and thick-disk subsamples, and investigate the rotational velocity and eccentricity gradients with metallicity, [Fe/H], distance from the plane, |Z|, and Galactocentric distance, R. Some of the notable findings are that there is a rather strong rotational velocity gradient of -20 to -30 km/s/dex with [Fe/H] for the thin-disk population, and +40 to +50 km/s/dex for the thick-disk population. The rotational velocity decreases with |Z| for both disk components, with similar slopes (-9.0 +\- 1.0 km/s/kpc). A relatively strong gradient of orbital eccentricity with [Fe/H] (about -0.2/dex) is observed for the thick-disk stars, whereas the eccentricity is independent of [Fe/H] for the thin-disk subsample. The shapes of the eccentricity distributions for the thin- and thick-disk populations remain roughly unchanged with |Z|. Comparison with several contemporary models of disk evolution indicates that radial migration seems to have played a vital role in the evolution of the thin-disk population, but probably less so for the thick disk, relative to the gas-rich merger or disk heating scenarios. I emphasize that more physically realistic models and simulations are required to perform detailed quantitative comparisons.

Do submillimeter galaxies trace out the most massive dark matter halos at high redshift? Mounting evidence suggests that submillimeter galaxies are the most massive gas-rich systems at redshift z~2-3 with far-infrared luminosity of 10^12-10^13 L_Sun. To answer the question, however, the statistical and large-scale properties of submillimeter galaxies are required. We have used the AzTEC 1.1 mm-wavelength camera and the Atacama Submillimeter Telescope Experiment (ASTE) 10-m telescope to perform a wide-field extragalactic survey. We have mapped ~3 deg^2 regions on the sky and revealed more than 1000 millimeter sources, resulting in one of the largest millimeter surveys to date. In the first half of this talk, I introduce the ASTE project. In the latter half of this talk I will highlight recent findings of our deep 1.1-mm survey of submillimeter galaxies. I will also share with you recent development of instruments, especially a new mm/submm bolometer camera which makes use of TES technology and is to be installed on ASTE in early 2012.

The last phase of stellar evolution from the asymptotic giant branch (AGB) to proto-planetary nebulae, to planetary nebulae represents the most active period of synthesis of organic compounds in a star’s life. Both inorganic and organic molecules and solids are found to form in the circumstellar envelopes created by stellar winds. Over 60 gas-phase molecules, including rings, radicals, and molecular ions have been identified by millimeter-wave and infrared spectroscopic observations through their rotational and vibrational transitions. Infrared spectroscopic observations of emissions from the stretching and bending modes of aliphatic and aromatic compounds have revealed a continuous synthesis of organic material from the end of the AGB to proto-planetary nebulae, to planetary nebulae. These results show that complex carbonaceous compounds can be produced in a circumstellar environment over a period of only a few thousand years. Most interestingly, there are a number of unidentified emission features which are almost certainly carbonaceous in nature but their exact chemical composition is unknown. These include the 21 and 30 micron emission features, and the extended red emission observed in proto-planetary nebulae and planetary nebulae. Spectroscopic signatures of the stellar organics show strong similarity to the insoluble organic matter found in meteorites. Isotopic analysis of meteorites and interplanetary dust collected in the upper atmospheres have revealed the presence of pre-solar grains similar to those formed in evolved stars. This provides a direct link between star dust and the solar system and raises the possibility that the early solar system was chemically enriched by stellar ejecta with the potential of influencing the origin of life on Earth.

As surveys of galaxy populations at high redshifts progress, it becomes increasingly urgent to understand how observed galaxies at high redshift map into those at lower redshift. In this talk, I investigate how and where stellar mass builds up over cosmic time by showing recent studies of the changing star forming properties of galaxies as a function of stellar mass and environment from redshift three to present.

The Spitzer Survey of Stellar Structure in Galaxies (S4G) uses mid-infrared imaging with the Spitzer Space Telescope to trace the stellar structure in a large sample of over 2300 local galaxies. The images are very deep and cover a large area. I will describe the progress of the project, and present examples of scientific results being obtained, on topics as varied as galaxy morphology, dark matter, and cosmological disk formation. In this seminar, I will also briefly introduce the Astrophysical Institute of the Canary Islands (IAC) and its observatories on Tenerife and La Palma.

Mars Odyssey, launched on April 7, 2001, had been successfully conducting its mission, including the determination of the elemental composition of the surface of Mars and understanding of water ice distributions on Mars. Mars Odyssey Gamma?Ray Spectrometer (GRS) Suite has confirmed the presence of water ice at the north and south poles as well as fairly high hydrogen concentrations for parts of the equatorial regions. Mars Odyssey GRS results provided elemental maps of Mars and new findings of Mars including confirmation of an ancient ocean on Mars. SELENE?1 (KAGUYA) mission is known to be one of the most successful orbital missions in history. Recently KAGUYA GRS team published radioactive maps of the Moon, and other elemental maps are under investigation at present. Understanding lunar surface using GRS is important with respect to both unravel geological history of the Moon and obtain elemental maps of lunar surface regions. New era of lunar exploration after the Apollo programs has started already by several countries. KAGUYA GRS team is planning on its next challenging task on SELENE?2 Rover with a gamma?ray?neutron?X?ray (GNX) system for new surface investigation of the Moon. This presentation demonstrates a summary of Mars Odyssey GRS results, current status of KAGUYA GRS data analysis.

This seminar introduces the climatology, anomalies, turbulence, and storm-time disturbances in the Earth’s ionosphere. Many ionospheric phenomena are associated with the variation of ionospheric height and atmospheric composition. Plasma density is sensitive to those factors because the plasma loss rate is sensitive to the molecular gas (O2 and N2) number density which varies with height. Atmospheric winds induce electric fields and plasma motion along the magnetic field lines by which the ionospheric height varies. Neutral composition is variable with season and hemisphere owing to the variation of the solar zenith angle and the Sun-Earth distance. During geomagnetic storms, the solar wind and magnetospheric energy deposition into the polar atmosphere causes an expansion of atmosphere, and the increase of molecular gases in the ionosphere induces plasma depletion in high latitudes. In low and middle latitudes, the plasma density either increases or decreases by the effects of storm-induced winds and electric fields. The goal of this seminar is to help an understanding of the plasma-neutral interaction and its effect on the ionosphere.

최근 SKA(Square Kilometre Array), LSST(Large Synoptic Survey Telescope), LHC(Large Hadron Collider) 등 대규모의 과학 프로젝트에서는 폭발적인 규모로 대량의 데이터가 생산되어 이를 중심으로 과학 연구의 패러다임을 바꿀 것으로 예상되고 있다. 이를 위해서는 대용량 데이터의 관리 및 전송을 위한 하드웨어 및 소프트웨어 기술의 발전이 수반되어야 하며, 대규모 데이터의 분석을 위한 유연하고 확장성 있는 컴퓨팅 시스템이 또한 필요하게 된다. 최근 각광을 받고 있는 클라우드 컴퓨팅은 인터넷을 기반으로 IT 자원 및 소프트웨어 등을 서비스 형태로 제공하게 하는 기술이다. 클라우드 컴퓨팅은 가상화 기술을 활용하여 자원의 유연성을 제공하고 활용성을 높이며 사용자 환경의 다양성을 제공할 수 있는 특징이 있다. 이러한 클라우드 컴퓨팅의 장점은 산업체의 IT 서비스를 넘어서 과학 계산 응용을 위한 서비스에도 적용될 수 있다. 클라우드 컴퓨팅은 기존의 고정된 시스템에서 지원하기 힘든 다양한 요구의 과학 연구를 지원할 수 있는 유연성과 확장성 등의 특징으로 인해 이미 여러 분야에서 클라우드 컴퓨팅의 장점을 살려 과학 연구를 지원하기 위한 노력을 하고 있다. 본 발표에서는 과학 응용에 클라우드 컴퓨팅 기술을 적용하려는 활동에 대한 최근 동향에 대해서 소개하고 현재 KISTI에서 수행하고 있는 사이언스 클라우드 연구에 대해서 소개하고자 한다.

Taking advantage of the superb capabilities of Chandra and XMM-Newton, during the last decade we have dramatically increased our knowledge on various aspects of the galaxy formation and evolution. I will review recent results on early-type galaxies based on X-ray observations, including both diffuse hot gas and point sources (stellar binaries and AGNs). In particular, I will focus on (1) the X-ray luminosity function of los-mass X-ray binaries, (2) X-ray scaling relations between the physical quantities of the hot ISM (LX and TX) and those of galaxies (LK, ?*), and (3) metal abundances and abundance ratios of the hot ISM. I will further address the implications of X-ray observational results, e.g., star formation episodes, dynamical and chemical evolutionary states of hot gas in early-type galaxies.

The talk is composed of two topics; one is about Ultra-High Energy Cosmic Rays (UHECRs) and the other is about Supernova Remnants (SNRs). As for the UHECR part, first I will present simulations of propagation of UHE-protons from nearby bright galaxies taking account of extra-galactic magnetic fields and galactic ones. Next I will present numerical study on the propagation of UHE-Nuclei in a cluster of galaxies. Finally, I will discuss the possible contributions of past Gamma-Ray Bursts in Milky Way to the spectrum and composition of UHECRs around/below 3E+19eV. As for the SNR part, I will discuss our motivation to study SNRs, what we have done for the study of supernova explosion and explosive nucleosyhtnesis, and what we plan to do for the study of supernova remnants. Some preliminary results of our SNR study are also presented.

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According to the current paradigm of cosmological structure formation, the observable large scale matter distribution arose via gravitational amplification from tiny primordial density fluctuations. Especially modern numerical simulations reveal that cold dark matter aggregates to form a filamentary cosmic web consisting of huge empty regions, the so called voids, filaments and clusters. Hence, precision analysis of three dimensional large scale structure (LSS) data will help us to identify and understand the physical processes governing cosmological structure formation leading to a more complete theoretical picture of our Universe. However, contact between theory and observations cannot be made directly, since observational data is subject to a variety of systematic effects and statistical uncertainties. Most notably of those are the survey geometry and selection effects as well as statistical noise. Mapping the three dimensional matter distribution in the Universe thus requires accurate statistical data analysis methods. In my talk I will present new full Bayesian data analysis methods designed to provide detailed cosmographic descriptions of the large scale structure in the Universe while accounting for all observational uncertainties. As a result these methods provide sampled representation of the LSS posterior distribution, which enables us to report any desired statistical summary such as mean, mode or variance of the density field. Application of our method to the latest Sloan Digital Sky Survey data lead to the generation of detailed cosmographic maps for the three dimensional matter distribution and the possibility to accurately quantify its significance. These results permit a variety of following scientific projects to analyze the clustering behavior of matter in the Universe. In summary, the presented methods provide an efficient and flexible basis for high-precision LSS inference.

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Debris from asteroids and comets continually bombards the Earth. Impacts by big bodies launches ejecta on trajectories that transports it thousands of kilometers from the impact site. These events are recorded in discrete layers of sub-millimeter size spherules in sea floor sediments. Larger, rarer, and interestingly shaped objects are found on land. I will describe the physical processes that occur in energetic impacts. Emphasis will be given to the mechanisms that determine the sizes and shapes of the ejecta and the cooling of the fireball. An analogy with structure formation in the expanding universe will be exploited, and a possible relation to the origin of chondrules will be explored.

Stars more than about 10 times the mass of the Sun are responsible for creating most of the heavy elements in the universe, for governing the evolution of galaxies, and quite possibly for re-ionizing the universe a few hundred million years after the Big Bang. The formation of these stars can be understood as an extension of the theory of low-mass star formation, generalized to include the effects of interstellar turbulence. However, a major problem must be overcome: For massive stars, the outward force due to radiation pressure exceeds the inward force due to gravity; how can gas accrete onto the protostar in that case? Circumstellar disks, outflow cavities, and radiative Rayleigh-Taylor instabilities all contribute to the solution of this problem. These conclusions are validated by means of 3D radiation-hydrodynamic simulations of high-mass star formation. The effects of ionizing radiation and variations in metallicity are also discussed. Observational predictions include (1) Massive stars should form in cores with surface densities of order 1 g cm^-2; (2) the stellar initial mass function (IMF) should follow the mass function of cores in the host molecular cloud, scaled down by a factor of a few; (3) and massive, turbulent disks detectable by ALMA, the EVLA, and large IR telescopes should occur around massive protostars.

스마트그리드와 관련하여 스마트그리드의 정의, 스마트그리드의 추진 배경, 스마트그리드로 인한 주요 변화, 스마트그리드 국가로드맵을 간략히 소개하고 현재 제주도 구좌읍 일대에서 진행 중인 스마트그리드 제주실증사업에 대하여 자세히 소개하고자 합니다.

태양 플래어는 태양 표면에서 일어나는 가장 강력한 폭발 현상이다. 태양 플래어에 부수되어 일어나는 여러 가지 현상은 지구와 지구 주위를 돌고 있는 많은 인공위성에 있는 장비들에게 위험을 제공할 수 있다. 그러므로 태양 플레어가 일어나는 원인과 현상을 잘 이해할 필요가 있다. 태양 플레어의 발생이 무작위적인 것이 아니고 그 발생하는 시간에 주기성이 있는 것이 발견되었다. 이런 주기들은 25.5일의 정수배로서 25.5일이 근본 주기인 것을 암시한다. 이러한 태양의 주기성은 무엇에 기인하는 것일까? 태양 플래어가 일어나는 장소도 무작위 적인 것이 아니고 어떠한 특정한 장소에 더 자주 일어나는 것이 발견되었다. 이 두 현상 간의 관계는 무엇일까?

See attached file

Located on the summit ridge of Mauna Kea, the Canada-France-Hawaii Telescope (CFHT) offers a suite of excellent instruments which benefit from the exceptional qualities of its site. With wide-field imaging cameras in the visible and near-infrared, a high-resolution spectro-polarimeter, and natural guide star adaptive optics capabilities, the current instrumentation and associated reduction pipelines allow CFHT to be one of the leading observatories of today’s astronomy. Queued service observing and remote operations make for very efficient operations leading to excellent data and exciting science. New instruments are in development to offer even more possibilities to its users’ base, which now reach beyond the three communities of its namesake to include Taiwan, Brazil, and recently China. CFHT is also preparing the redevelopment of its facility, studying the option of building an 8- to 10-m class telescope dedicated to wide-field multi-object spectroscopy. As exemplified by its many achievements, CFHT strongly believes in the virtue of joining forces to achieve much more than anyone would have achieved alone. This talk will give us a chance to interact and exchange ideas on a potential involvement of Korea in the current and future activities of the observatory.

Over the last few years, first systematic blind searches in the halo of the Milky Way based on the Sloan Digital Sky Survey data have uncovered a surprisingly large number of ultra-faint dwarf galaxies, members of a previously unseen class of stellar systems with extremely low star densities and less stellar content than a typical globular cluster. It is believed that these optically highly elusive aggregates of shining baryons hold the greatest leverage for testing dark matter theory and galaxy formation models. I will give an overview about the most recent findings in this research field and discuss the role of the new Stromlo Milky Way Satellites (SMS) Survey in providing the empirical input crucial to better understand and possibly reconcile the severe discrepancies that currently exist between observations and Cold Dark Matter model predictions on galaxy scales.

I report on an ongoing project that intends to bring together the galaxy content of observed and modeled galaxy clusters of the present-day universe. The known nearby, massive galaxy clusters serve as our observational reference. The model galaxies are provided by a recent semi-analytic model that combines galaxy formation physics with simulated hierarchical structure formation in a standard Lambda-CDM universe. We are particularly interested in the question whether the properties of the observed large and diverse dwarf galaxy population are reproduced in the model, something that could hardly be investigated with earlier models. Should the model fail to reproduce them, would it mean that many dwarf galaxies are created by environmental mechanisms not included in the model? Or would it merely indicate that the complex physics of galaxy formation is not yet fully understood?

천문학자가 꿈인 청소년들이 많다. 그들의 꿈이 먼 곳에 대한 동경을 핵으로 하고 있다 하여도, 천문학은 그만큼 매력적으로 보이는 분야라는 뜻일 것이다. 그리고 그들의 일부는 앞으로 천문학의 길로 들어서게 될 것이다. 그렇다면 천문학을(또는 넓게 과학을) 한다는 것은 어떤 뜻인가? 그것을 뛰어나게 하기 위해 어떤 준비가 필요한가?(특히 한국에서) 우리 청소년들은 그러한 준비를 하고 있는가? 만약 그렇지 않다면 어떻게 하여야 하는가? 이에 대한 답의 실마리는 현재 천문학자들만이 제공할 수 있다. 다음의 질문에 대한 천문학자들의 답이 현재 우리 청소년들이 서 있는 곳을 정확히 평가하고, 바라보아야 하는 방향을 제시하며, 바른 계획을 세우고 수행하여, 미래에 뛰어난 인재들이 천문학을 연구하며 행복한 삶을 영위하게 하는 초석이 될 것이다. “내가 교육을 받는 기간 동안 배웠으면 하고 지금 바라는 것들(하지만 배우지 못한 것들)은?”

Pre-main sequence clusters are excellent laboratories for studying dynamical interactions. Examples are the nearby eta Cha and epsilon Cha clusters,; sparse, compact, 5-10 Myr-old systems deficient by a factor of 2 in low-mass stars and brown dwarfs. Sensitive searches have completed the core population and found no members in the immediate field, to 2-3 times the core radius. The latest photometric and proper motion catalogues have sufficient precision to reliably detect members distant from the core. The observational constraints are severe; candidate members must be photometrical consistent with core members, have Li and other spectral indicators consistent with the cluster age, and have space velocities consistent with ejection early in the clusters life. In the case of eta Cha, candidates members have now been detected up to 5.5 deg spatial separation from the cluster core.

I present the mid-infrared (mid-IR) properties and environments of red-sequence galaxies within a supercluster in North Ecliptic Pole (NEP) area at redshift ~0.087, using AKARI NEP-Wide (5.8 deg2) IR imaging survey in conjunction with ultraviolet-near-IR spectral energy distributions. Most importantly, such mid-IR flux allows us to trace not only star formation rate (SFR), but also the presence of intermediate age populations showing excess emission over the stellar light in mid-IR. As such, we find that the red-sequence samples do not only contain passively evolving red early-type galaxies, but also contaminated with: 1) disk-dominated star-forming galaxies which have SFRs per unit stellar mass lower than blue-cloud galaxies, and 2) early-type galaxies showing broad non-stellar emission in mid-IR compared to normal red early-type galaxies. Those two populations may represent transition objects between blue spiral galaxies and red early-type galaxies. We present how those two transition galaxies depend on their local density and stellar mass, and discuss which factor is the primary predictor of star formation activity and the morphological transformation.

Newly formed massive stars can affect the parental molecular cloudsthrough ionization, heating, and expansion of the H II regions, stellarwinds, and supernova-driven shocks. For a better understanding of the feedback process in the interstellar medium, detailed observationsof the molecular clouds and identification of embedded young stellarobjects (YSOs) are required. In this talk, I will present results ofan extensive observational study of the active star-forming complex W51. First, I will show the spatial distribution and mass function ofembedded YSOs near the W51 giant molecular cloud over an area of 1.25deg × 1.00 deg selected from Spitzer Space Telescope data. Secondly, Iwill present the CO maps that was observed in the J = 2 - 1 transition of the 12CO and 13CO molecules with the University of Arizona HeinrichHertz Submillimeter Telescope and compare the molecular cloud morphologywith the distribution of infrared and radio continuum sources. Finally, I will explain the process of star formation triggered by the expansionof an H II region near W51A.

Participating in the "Dark Matter awareness week", a worldwide effort for disseminating specific information about Dark Matter, I will discuss the details of the mass discrepancy phenomenon in galaxies usually accounted by postulating the presence of a non luminous component. In the theoretical framework of Newtonian gravity and Dark matter halos, we start by recalling the properties of the latter as emerging from the state-of-the-art numerical simulations performed in the current LCDM scenario of cosmological structure formation. We then report the complex and much-telling phenomenology of the distribution of dark matter in spirals, ellipticals, and dwarf spheroidals. We will then highlight the impressive evidence that the distribution of dark and luminous matter are closely correlated, and finally point out some shortcomings of the model.

Gravitational Waves which arise from the fluctuating gravitational field have never been directly detected so far. I will briefly introduce what the gravitational wave is, the current status for the detection of gravitational waves and the prospect to use gravitational wave for the study of astronomical objects. Also some portion of this talk will be devoted to the research achievements in numerical relativity within the Korean Gravitational Wave Group.

Super smooth surfaces have been demanded on various optical materials in industry and science fields. Pitch polishing has been used for making glass optics for hundreds years in the world, though it is not suitable for modern optics in some cases. The new optics manufacturing technologies, such as, single point diamond turning, ultra-precision grinding and ultra-precision polishing will be described as well as manufacturing processes of X-ray mirrors.

Violent astronomical phenomena have been mostly explored by X-ray observations. Black hole is one of most exciting objects in the high energy Universe. Especially super massive black holes harbored in active galactic nuclei are deeply examined by ASCA and SUZAKU to provide us with direct evidence of strong gravitational field around black holes. In the latter half of the talk, developments of X-ray telescopes onboard previous and future missions will be described.

The cumulative distribution of stellar ages showed a distinct difference among star forming regions in NGC 2264. A Kolmogorov-Smirnov test gave a very low probability of them being from the same population. The results indicate that star formation in NGC 2264 started at the surface region (Halo and Field regions) about 6 -- 7 Myr ago, propagated into the molecular cloud and finally triggered the recent star formation in the Spokes cluster. The kind of sequential star formation that started in the low-density surface region (Halo and Field regions) implies that star formation in NGC 2264 was triggered by an external source.