Tremendous progresses have been made in recent years in extra solar planetary science
improving our understand of the planetary system formation and evolution. I have been involved
in direct imaging detections of exo-planets and discoveries of extreme debris disks.
I will discuss about progresses and future prospects in these two fields :
exoplanet imaging and extreme debris disks.

I present two recent observational results, which can provide

constraints on models of galaxy formation and evolution. First, I

report on photometric metal abundance estimates for individual

main-sequence stars in the Virgo Overdensity, which is believed to be

the remains of a merging dwarf galaxy in the Galactic halo. I discuss

the principles behind the technique that is based on a calibration of

the metallicity sensitivity of stellar isochrones in the Sloan Digital

Sky Survey (SDSS) passbands. Second, I report the detection of several

molecular gas-phase and ice absorption features in three

photometrically-selected young stellar object (YSO) candidates in the

central 280 pc of the Milky Way. Our spectra, obtained with the

Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope,

demonstrate the youth of these objects, and provide the first

spectroscopic identification of massive YSOs in the Galactic Center.

정향력(丁享曆,)은 에도(江戶) 시대의 역법 학자로 유명한 시부가와 하루미(澁川春海)가 수시력에 기초하여 만든 일본 최초의 역법으로 일본에서 정향 원년(1684)부터 사용되었다. 하루미는 이 역법을 제작하기까지 규표에 의한 그림자 관측과 관측지의 위도 측정 등, 수많은 관측과 의기의 제작 그리고 별자리들을 관측하여 1670년에 천상열차지도(天象列次之圖)를 그리고 1677년에 천문분야지도(天文分野之圖)를 제작하였다. 하루미가 제작한 이 두 천문도는 조선의 천상열차분야지도(天象列次分野之圖)를 참고로 하여 제작된 것으로 세차를 고려하여 천상열차분야지도 상의 별자리들을 시계방향으로 이동시키고 춘추분점의 위치를 두 천문도의 관측 시기로 바꾸었으며, 관측지의 위도를 나타내는 주극원 부분의 별자리 배치를 달리하는 등 관측에 의한 새로운 천문도 제작을 시도하였다. 하루미의 두 천문도는 28수(宿) 간의 거리를 나타내는 28수의 수도(宿度)는 모두 수시력(授時曆)의 값을 따랐으나 북극으로부터의 거리를 나타내는 거극도(距極圖)는 천상열차지도의 경우 송사(宋史) 천문지(天文志)를 따랐고 후에 제작된 천문분야지도의 경우는 천상열차지도의 오류를 개량하여 수시력의 값을 따랐다. 그러나 28수의 각 별자리의 시작점을 나타내는 수거성(宿距星)의 경우는 모두 수시력이 아닌 천상열차분야지도의 값을 그대로 사용하는 오류를 범하고 있어 하루미가 아직 별자리에 대한 정확한 지식 없이 수시력에 의한 천문도 제작을 시도한 것으로 해석된다. 이 연구는 두 천문도 중, 보다 수시력법에 가깝게 제작된 천문분야지도를 선택하여 천문분야지도의 제작에 영향을 미친 여러 천문도들과 비교 분석함으로써 천문분야지도의 배경과 특성을 알아보았다.

Recent discovery of the extended Lyman alpha sources, the so-called
Ly-alpha blobs, ignites harsh debates on their origins: what powers
their LyA emission over ~100 kpc scale, AGN vs. cooling radiation
(http://tinyurl.com/NYTimes-blob)?
However, despite this intense interest, even their basic properties,
e.g., number density and environment, are poorly constrained.
From our ultra-wide narrow-band imaging surveys with Steward Bok 2.3m
and NOAO\/s 4m telescopes, we find that blobs are extremely rare and
strongly clustered populations implying that they may be precursors of
today\/s rich cluster galaxies.
Furthermore, different studies (using the same data) often lead to the
contradictory conclusions on the kinematics of surrounding gas. I will
discuss our recent kinematic studies using the Magellan/MagE and the
VLT/SINFONI to distinguish the infall vs outflow kinematics in the blobs.

The use of statistics to report astronomical data analysis results
is more popular than ever. Such high volume of demands
and not enough time to comprehend has sometimes driven the misuse
of statistics. Occasionally observed is that a statistic with rigid
conditions are applied to any data in hand as if the panacea of
data analysis. In this talk, we will review common classical
statistics like p-value, correlation,
the likelihood ration test (LRT), and the F-test.
The statistical backgrounds and breakdowns of these statistics
juxtapose with their usage in astronomy.

Recent multi-wavelength observations of gamma-ray burst (GRB) afterglows revealed unexpected features such as the plateau in X-ray light curve, followed by a peculiar chromatic break. The standard model of afterglow production by the forward shock wave is difficult to reconcile with these data. This calls for revisiting the basic picture of GRB explosion. Theoretically, a long-lived reverse shock expected in the burst ejecta needs to be consistently described together with the forward shock even for a very general class of explosions. The mechanical model that we developed to describe relativistic blast waves meets this requirement. We perform detailed numerical simulations and calculate the emissions from both the forward and reverse shocks. We present the resulting X-ray and optical light curves, and discuss the characteristic features of the reverse-shock emission. We then propose a new model in which the forward shock is invisible and the afterglow is emitted by a long-lived reverse shock in the burst ejecta.

Massive stars are fundamental in determining the appearance and evolution of galaxies. For studying the Galactic rotation curve and earlier phase of massive star forming process, three massive star forming regions are selected. The Galactic rotation curve can be constrained with the rotation speed of stars and gas because massive stars and their associated molecular clouds trace the spiral arms of The Galaxy. I will introduce the VERA system and the results of the first astrometric observations toward three massive star forming regions. And, by using the results of the measurements of parallaxes and proper motions, constrain the rotation curve of outer galactic plane and discuss about earlier phase of stellar evolution in massive star forming regions.

The star formation history of low surface brightness galaxies (LSBGs) are
interesting but poorly constrained.
These objects tend to be rather blue, contradicting the initial impression
that they may simply be faded remnants of higher surface brightness galaxies
whose star formation has finished.
Other scenarios span a broad range: a young mean age, less dust, a lower
metallicity, perhaps even a variable initial mass function.
We have obtained near-infrared broadband photometry and H$\\alpha$ photometry
of a large sample of low surface brightness galaxies to measure the current
and the time-averaged star formation rate (SFR) in order to constrain their
star formation histories.
The current star formation rates of LSBGs generally are higher than their
past star formation rate, suggesting that the mean age of their stellar
population is relatively young.
This may stem from either a late epoch of formation or a sluggish evolution.
In the latter case, the star formation efficiency may be an increasing
function of time, perhaps due in part to the slow build up of metals and dust.
Nevertheless, star formation remains sporadic and is generally not well
organized across the disk.
We find a strong correlation between the ratio of current to past average
star formation rate and the gas mass fraction.
Galaxies with large reservoirs of gas have relatively high current SFRs.
There is a conspicuous absence of high gas mass fraction, low SFR galaxies,
suggesting that the observed trend is not driven by bursts of star formation
with short duty cycles.

광주파수 빗 (optical frequency comb) 기술은 2000년 탄생 이래로 가시광 광원의 주파수 (파장) 절대 측정에 획기적인 전기를 가져왔다. 또한 미세구조 상수와 같은 기초물리상수의 측정과 시간, 주파수 및 길이 측정 표준 확립에 기여하여 2005년도에 노벨 물리학상 수상이 주어진 새로운 초정밀 레이저 분광 기술이다. 본 강연에서는 최근 이러한 광주파수 빗 기술을 응용하여 관측 천문학에 활용할 수 있는 연구 내용을 소개하고자 한다. 이러한 기술은 광주파수 빗의 주파수 간격을 천문 관측용 분광기의 최소 분해능 이상을 갖도록 고 반복율로 동작시키게 된다. 본 강연에서는 광주파수 빗 기술의 원리에 대해서 설명하고 적외선, 가시광선, 자외선 영역의 파장을 갖는 광주파수 빗 발생과 이 영역 광원의 파장 절대 측정에 대해서 설명한다.

I will present the low-z BH mass - bulge luminosity relation by analyzing Hubble Space Telescope (HST) archival images for a sample of 237 Type I AGNs.?? I probed the BH-host relation of AGNs by comparing the relation to that of normal galaxies and by investigating the intrinsic scatter of the relation. Also, In order to investigate how the BH-host relation has been established, (1) an estimate of the star formation rate in AGNs and

(2) seeking signs of interactions in AGNs are important. For the former, I measured the strength of [O II] and other optical emission lines from a large sample (∼ 3600) of broad-line (Type 1) AGNs selected from the Sloan Digital Sky Survey. For the latter, I obtained

deep, multi-color ground based images of low-redshift AGNs for which HST images are available. Based on the results, I will discuss how black holes and host galaxies

coevolve.

Different wavelengths manifest different physics hidden in astronomical objects. Far-ultraviolet (~912-2000 A) includes numerous resonant cooling lines, while near- and mid-infrared (~1-40 mm) include numerous diagnostic fine-structure lines and thermal continuum. I will present diverse aspects of supernova remnants, observed with Far-ultraviolet Imaging Spectrograph (FIMS) onboard the Korean satellite STSAT-1 and InfraRed Camera (IRC) onboard the Japanese satellite AKARI. A special attention would be given to the interactions between supernova remnants and their ambient medium.

Meteors are generally described as an atmospheric phenomenon caused by the entrance of particles from space (meteoroids or space debris) into Earth’s atmosphere. Meteors are classified according to their mass and size. Current day estimate for the global meteor flux which impact and disintegrate from earth’s atmosphere vary from 2000-200,000 tons per year. The meteoroid influx into the Earth’s atmosphere has been divided into two different phenomena, meteor showers and sporadic meteors. Only about one quarter of visually observable meteors are shower meteors while the rest consist of sporadic meteors, which are coming from all directions and not connected to any specific known shower. Over past three decades, a significant progress has been made in understanding sporadic meteors, meteor showers and their associated comets. Still, there are questions which remain unanswered regarding the origin and their effect in interplanetary medium also in earth’s atmosphere. For instance, does the meteor flux rate vary with altitude, latitude, seasonally and also globally? What are the typical lifetimes? What is the source of observed meteor rate? What effect do they have on the dynamics of earth’s ionosphere? In this talk, I will present our recent efforts and results on the questions raised above.

Spiral arms are the most outstanding morphological features in disk galaxies. They not only provide information on the dynamical states of the background stellar disks, but also affect galactic evolution by triggering large-scale star formation in the gaseous component. Over past fifty years, a significant progress has been made in our understanding of spiral arms and associated star formation. Still, there remain outstanding questions regarding the nature, origin, pattern speed, and strength of spiral arms, and their effect on the gaseous medium. For instance, are spiral arms long-lived or transient?What drives spiral arms? Do arms rotate rigidly enough to construct a pattern? What effect do they make on the formation of spiral-arm substructures such as spurs, giant clouds, and OB associations? How do they interact with fluid instabilities to generate turbulence in the interstellar medium. In this talk, I will present our recent efforts and results on the questions listed above.

우주거대구조와 우주배경복사에 존재하는 요동은 우주의 진화 역사에 관한 물리적 정보를 담고 있는 대표적인 우주요동이다. 현대 우주론의 주요 목표 중 하나는 이 우주요동을 체계적으로 탐사함으로써 천문관측에 가장 잘 맞는 우주모형을 만드는 것이다. 최근의 관측 결과에 따르면, 대폭발로 생겨난 우리우주는 암흑에너지와 암흑물질로 가득 채워져 있고, 현재 가속팽창 중이라고 한다. 본 세미나에서는 우주배경복사 탐사위성 더블유맵(WMAP)의 최신 결과를 요약하고, 아직 그 실체를 알 수 없는 암흑에너지의 성질에 대해 논의한다. 또한, 스칼라 장으로 기술되는 동력학적인 암흑에너지 모형에서 암흑에너지 자체의 요동 진화가 빛, 물질의 요동 진화에 미치는 영향을 살펴보고자 한다.

Ultraviolet emission from the first generation of stars in the Universe ionized the intergalactic medium in a process which was completed by z~6; these photons have been redshifted into the near infrared today and can be measured using instruments situated above the Earth\/s atmosphere. First flying in February 2009, the Cosmic Infrared Background ExpeRiment (CIBER) comprises four instruments housed in a single reusable rocket-borne payload. CIBER will measure spatial anisotropies in the extragalactic IR background caused by cosmological structure from the epoch of reionization using two broadband imaging instruments, make a detailed characterization of the spectral shape of the IR background, and measure the absolute brightness of the Zodical light foreground in each of our six science fields. KASI is developing the Multi-purpose IR Imagin System (MIRIS), of which major objective is to detect the large scale spacial fluctuations of the extragalacticIR background. MIRIS is the main payload of STSAT-3, which will be launched in late 2010.

The Far-Infrared Surveyor (FIS) is one of the focal-plane instruments of the AKARI (formerly known as ASTRO-F) satellite, which was launched in February 2006. AKARI satellite is currently performing the warm mission. We present the spatially resolved Far-IR observations from AKARI mission. The FIS had performed the all-sky survey in 4 Far-IR
bands (50-200um ragne) during around 500 days as well as the deep pointed observations. From the all-sky survey, we extracted reliable point sources matched with IRAS catalogue. We found possibilities that flux measurements of some IRAS sources with a bad flux quality were overestimated and flux measurements are affected by a local background rather than a global background. Owing to its higher resolution, it resolved a cirrus background and an individual sources effectively, which will enable us to get more reliable point source catalogue and a detailed structure of background. Our deep pointed observations can explore the Cosmic Far-Infrared Background (CFIRB) which contains information about the number and distribution of contributing sources. AKARI Far-IR observation is expected to find new extragalactic sources and to understand the nature of CFIRB.

An Extensive Air Shower (EAS) is a cascade of ionized particles and photons produced in the atmosphere when a primary cosmic ray (CR) with energy higher than 10^{15} eV enters Earth atmosphere. Detection of EASs is an indirect, yet main observational method to study the energy, composition, and arrival directions of high energy CRs. Due to the stochastic nature of particle interactions involved in EAS, it can be studied only through vast numerical simulations based on Monte Carlo technique. In this talk, we will review observational and theoretical methods to study EASs and then discuss their roles in CR astrophysics.

We make observational studies of galaxy properties in various environments, particularly in clusters of galaxies and in galaxy-scale halos. The physical parameters of galaxies studied include luminosity, morphology, star formation activity parameters (color, equivalent width of the H-alpha line, color gradient), and internal structure parameters (concentration, stellar velocity dispersion, size). The dependence of these parameters on small and large-scale environments is studied, and the roles of the gravitational and hydrodynamical interactions in determining galaxy properties are inferred. We find that hydrodynamic interactions between galaxies are ubiquitously important in the fate of galaxies.

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하늘과 가까이 살아왔던 우리 역사 속의 천문 이야기를 역사천문학 관점에서 다음 몇가지 주제로 풀어본다. 첫째, 고구려 벽화 속에 다채롭게 묘사된 별자리 유물자료는 우리 역사에서 가장 분명하고도 체계적인 천문 관측학의 표상이다. 특히 중국의 천문 전통과는 구별되는 북극3성 별자리, 중국의 고금 천문도에는 묘사되지 않았던 카시오페이아 별자리 등은 고구려 스스로의 천문학 전통을 상정케 한다. 또한 동서남북의 네 방위마다 고유한 수호성이 있다는 고구려의 사숙도(四宿圖) 별자리는 우리 역사에서 처음 제출된 매우 독창적인 천문사상의 일환이다. 그리고 천문과 신화, 비선(飛仙)과 도교, 역사와 문화 등과 같은 인문학의 관점이 왜 역사천문학 연구에 접목될 필요가 있는지를 살펴본다. 둘째, 아울러 고구려에서 고려로 전승되는 천문 흐름을 살펴봄으로써 한국의 고대 천문학사 연구가 더욱 다각적으로 접근되어야할 것을 제기한다. 백제 무녕왕릉 묘지석의 재해석을 통해 역사천문학의 방법론이 가지는 의의를 제고한다. 셋째, 나아가 서양의 하늘이 세계의 중심이 된 현대 사회에서 동양의 천문학과 비교할 수 있는 관점을 모색한다. 동서양의 천문신화 차이에 기반한 적도 중심의 동양과 황도 중심의 서양이 어떻게 다른지, 적도 28수와 황도 12궁은 언제 서로 만나는지, 그리고 중국과 일본, 우리 역사 속의 천문학 연구는 어떻게 풀어가는 것이 더욱 정합적인 방향인지를 살펴본다.

강의교재 :
1. 고구려 별자리와 신화 (사계절, 2008. 12)
2. 우리 역사의 하늘과 별자리 (고즈윈, 2008. 9)
3. 동양천문사상 하늘의 역사 (예문서원, 2007. 10)
4. 동양천문사상 인간의 역사 (예문서원, 2007. 10)

With the continuing discovery of extrasolar planets and an expectation that the majority


of solar-type stars reside in binary or multiple systems, planetary formation in binary systems has become an important matter. Recent theoretical studies have predicted that circumbinary planets (i.e., those orbiting two stars which are tightly bound gravitationally)


can form and survive over long time scales. The presence of a third body orbiting an eclipsing binary causes a periodic variation of the eclipsing period due to the increasing and decreasing light-travel times (LTT) to the observer. Because the historical data base is very large and for many binaries very long, we can potentially discover numerous eclipsing systems with circumbinary companions. Also, it should be possible to detect additional planets or exomoons by using transit timings in systems with known transiting planets. In this talk, I will present the discovery of a circumbinary planetary system orbiting around a close binary system, based on historical eclipse timings.

과학적 상상력을 문학의 형식으로 펼쳐보이는 과학소설(SF)은 21세기로 접어든 현 시대에 주목할만한 문명사적 의미를 지니고 있다. 과학소설의 역사를 간단히 살펴본 뒤 이 분야 특유의 시각과 정서, 그리고 전망의 스펙트럼을 고찰해본다. 아울러 과학자의 상상력과 과학소설가의 상상력이 서로 피드백을 주고받는 양상도 소개한다.

Star clusters are destined to evaporate eventually.
I will discuss the disruption mechanisms of star clusters in detail,
and talk about the dynamical evolution of globular cluster systems
in the Milky Way and Virgo Cluster Galaxies.
I will also discuss the initial mass function of the Arches clusters,
one of the most extraordinary clusters found so far, and its evolution.
A novel method to estimate the low-end luminosity function of
a star cluster from a background-limited image will be introduced as well.

I will review recent progress in direct detection of supermassive
black holes in the centers of galaxies, including a new population of intermediate-mass black holes in dwarf galaxies. Special emphasis will be placed on black hole-host galaxy scaling relations and their implication for black hole growth and galaxy coevolution. I describe efforts to characterize the interstellar medium of the host galaxies and constraints they place on AGN feedback models.

I\/ll review the angular correlation function results
from previous X-ray and optical surveys
and present the angular correlation function of the X-ray point sources
in the Spitzer Wide-area InfraRed Extragalactic survey (SWIRE) field
observed with the Chandra X-ray observatory.
The Chandra/SWIRE survey is a moderate-depth (70 ksec) observation,
contiguously covering 0.6 square degrees
in the Lockman Hole field of the Spitzer/SWIRE Legacy Survey.
I will discuss the angular correlations of the X-ray point sources
in the broad (0.5-8 keV), soft (0.5-2 keV), and hard (2-8 keV) band,
and the flux dependent clustering of the X-ray point source.

Studies of compact radio sources since the discovery of quasars
have revealed a variety of physical properties:
both in morphology and kinematics from sub-parsec to Mega-parsec scales,
radiation mechanisms at frequencies from the radio to gamma-rays,
theoretical models for relativistic jets, etc.
The frontier discovery of VLBI observations for
the compact extragalactic radio sources have triggered
the extensive studies to investigate the underlying physics of
the relativistic jets. In this context, the highest resolution
VLBI surveys of ultra-compact radio sources provides
the potentially important statistical basis for future
study.In this talk, I would like to review recent VLBI surveys
of compact radio sources. As one of the scientific topics for
Korean VLBI Network (KVN), high-resolution VLBI survey
of compact radio sources and its applications will then be discussed.

Our improved understanding of dark-matter halo statistics can be effectively
used to extract useful physical information directly from the observed galaxy
statistics commonly measured from large galaxy surveys, such as luminosity
function and clustering properties (luminosity-dependent trend and overall shape)
of galaxies. I will discuss a simple formalism to constrain the scaling laws between
UV luminosity and halo mass (local gravity), and the typical duration of
star-formation at z~4 and 5. From these results, possible dominant mechanisms
responsible for star-formation activity in the majority of galaxies (L discussed.

The 21-cm hyperfine line of neutral hydrogen from the high-redshift Universe (6 < z 20)
promises to probe a new era in cosmology, the epoch of reionization (EoR).
It will provide more detailed, less ambiguous and more complete three-dimensional
informations than other observations of the EoR (such as the QSO absorption lines,
or the secondary scattering of CMB). It also traces many different physical processes.
The next generation radio telescopes, SKA and its precursors, will start to operate
within one decade, and will observe this signal.
Numerical simulations predicting the 21-cm emission are important to optimize
the design of the instruments, and interpret the observations.

In this work, we develop a continuum radiative transfer part for the LICORICE
cosmological code to study the epoch of reionization, where radiative transfer is
an essential tool. We use a Monte-Carlo ray-tracing algorithm on an adaptive grid.
Several tests, both for static density field cases and radiative hydrodynamic cases
have been performed to validate the code.
Then we compute the 21-cm signal during the EoR, which provides a direct probe
on reionization and contains a lot of informations on the sources of ionization and
heating.