臺北天文館學報 JTAM Vol.4 中國天文學會 2006 年研討會論文摘要 Abstracts of CAST Symposium 2006

SMA Observations of Star Forming Regions [Oral 1-1] Sheng-Yuan Liu ASIAA The SMA Team Abstract The Submillimeter Array (SMA) located atop of Mauna Kea in Hawaii is a collaborative project of the Smithsonian Astrophysical Observatory (SAO) and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA). With its coverage over the submillimeter regime of the EM spectrum, the SMA best probes in high angular resolution the dense and warm material (including both gas and dust) particularly associated with the dynamical and often energetic processes in the formation of stars and planetary systems. This presentation gives recent results obtained with the SMA in the area of star formation. These studies covers phenomena associated with low- and high-mass young stellar objects such as dense cores, circumstellar disks, jet and outflows, as well as the complex chemical processes within.

ASIAA-SMA Seyfert Survey [Oral 1-2] Matsushita, S. Inst. of Astronomy and Astrophysics, Academia Sinica, Taiwan ASIAA-SMA Extragalactic Group Abstract Seyfert activity is believed to be powered by a supermassive black hole, and the fuel for the activity is believed to be supplied from dusty disk/torus surrounding the supermassive black hole. In addition, a broadly accepted model (unified scheme) suggests that the type of the Seyfert (type 1 and 2) can be explained with the viewing angle of the circumnuclear dusty disk/torus (whether it obscures the supermassive black hole or not). Molecular gas in submillimeter-wave, such as higher-J CO lines, can trace warmer and denser molecular gas selectively, and therefore it is suitable to study the distributions, kinematics, and physical conditions of the circumnuclear disk/torus, and the relation between the Seyfert activities and also the large-scale strucutres. Here, we present the current status of the ASIAA-SMA Seyfert Survey. So far, we observed one Seyfert 1 galaxy and three Seyfert 2 galaxies. Most of the galaxies (three out of four) show possible molecular gas concentrations with rotating features at the nuclei, and multi-line CO studies show these central components are warm and dense. We will discuss more details in the talk.

Instrumentation and Science with the CFHT [Oral 1-3] Jeremy Lim ASIAA Abstract Taiwan astronomers have access to the Canadian-France-Hawaii Telescope (CFHT) through participation in the Wide Field Infrared Camera (WIRCam) project. Here I give an overview of the telescope, focussing in particular on the instruments that are especially competitive or unique, and examples of the science being conducted with these instruments. I also briefly review the process of applying and allocating time on the telescope. The CFHT provides an opportunity to develop a broader optical/IR community in Taiwan, and we hope this review will encourage more Taiwan astronomers to conduct research with this telescope.

- 45 - 中國天文學會 2006 年研討會論文摘要 Abstracts of CAST Symposium 2006 CFHT Megacam I and z Survey of DEEP2 Field [Oral 1-4] Hsieh, B. C. Inst. of Astronomy and Astrophysics, Academia Sinica, Taiwan Lin, Lihwai Inst. of Physics, National Taiwan Univ., Taiwan Abstract The photometric redshift technique is a good utility for extragalactic studies. However, the redshift limitations of most published photometric redshift catalogs are less than 0.7. Although there are few catalogs containing objects with redshift higher than 1.0, the templates for these photometric redshift estimations are inadequate to derive accurate photometric redshifts for high-z objects. The DEEP2 project provides tens of thousands spectroscopic redshifts up to z=1.5, which is an excellent template for the photometric redshift method to estimate the redshift at high-z. Therefore, we proposed the CFHT Megacam observation of DEEP2 field for filter i and z for 21 hours. By combining the data with the B, R, I observation of DEEP2 field, a photometric redshift catalog for DEEP2 field is generated. The catalog is ideal for studies of large scale structure, galaxy formation/evolution, and galaxy cluster/group/pair finding. In this talk, we will present the latest results of our studies.

Iapetus and Enceladus as seen from Cassini [Oral 1-5] Wing-Huen Ip Inst. of Astronomy and Space Science, National Central Univ., Taiwan Wei-Ling Tseng Inst. of Astronomy, National Central Univ., Taiwan Lily Lin Inst. of Space Science, National Central Univ., Taiwan Jinnee Wang Inst. of Astronomy, National Central Univ., Taiwan Abstract While Titan remains to be the central focus of the Cassini-Huygens mission, two rising stars have been found. They are Iapetus and Enceladus, respectively. Iapetus is interesting because of the remarkable dichotomy in its surface brightness distribution with the albedo on the leading emisphere a factor of ten darker than the trailing hemisphere. The origin of such albedo asymmetry is still to be explained satisfactorily. But recent Cassini observations by the imaging SSI experiment onboard has shown that this medium-sized satellite (radius ~ 720 km) has a slightly ellipsoidal shape which might be indicative of an unusual tidal despinning history. In addition, Iapetus equator is lined up with a curious mountain ridge system probably as old as the satellite itself. The formation of this equatorial ridge system could be related to the tectonic process accompanying the tidal despinning or the collisional imprint of a primordial ring system. Iapetus is thus a representation of the satellite formation process in the days long gone. On the contrary, the small icy satellite Enceladus (radius ~ 250 km) displays an amazing level of outgassing activity. The recent Cassini SSI report of possible presence of liquid water on its surface is even more of a shock to planetary science. In this talk some of these interesting results will be summarized.

AMiBA Science [Oral 2-1] Jiun-Huei Proty Wu Dept. of Phys. NTU, Taiwan Abstract The Array for Microwave Background Anisotropy (AMiBA) is a Taiwanese project to observe the Cosmic Microwave Background (CMB). It is led by a joint effort from the Academic Sinica Institute of Astronomy and Astrophysics (ASIAA) and the Institute of Astrophysics at National Taiwan University (IoAp, NTU). I will give an overview on the science goals of the project, with particular emphasis on the Sunyaev-Zel'dovich effect, the CMB polarization, and the cosmic strings. We expect the project to enhance not only our understanding of the universe, but also the competitiveness of Taiwan in the

- 46 - 臺北天文館學報 JTAM Vol.4 international cosmology community.

Ultra-Wideband Digital Correlator of Upgraded AMiBA [Oral 2-2] H.H. Li, S.K. Wong & T. Chiueh Institute of Astrophysics & Department of Physics, National Taiwan University Abstract In the upgraded AMiBA to begin operation in early 2007, the bandwidth will increase from 18Ghz to 35Ghz so as to compensate for the sensitivity loss of a 13-element array compared with the original 19-element array. In addition, to circumvent the 50% efficiency loss of analog correlation present in the current version of AMiBA due to its wide band, a world fastest digital correlator, able to process signals of 10Ghz bandwidth, is being developped. We report the design and progress of this digital correlator.

SZ Effect from Secondary Electrons in Clusters of Galaxies [Oral 2-3] Hwang, Chorng-Yuan Graduate Institute of Astronomy, National Central University, Taiwan Abstract Secondary electrons will be produced in interactions between cosmic rays and thermal plasma. This process in galaxy clusters will continuously last longer than a Hubble time because the cosmic ray protons contained within the galaxy clusters have a lifetime longer than the age of the cluster. These secondary particles in the galaxy clusters will scatter the cosmic micro-wave background photons and produce a non-thermal SZ effect in addition to the thermal SZ effect caused by the thermal plasma in the clusters. We derive the non-thermal SZ effect from the secondary electrons under a variety of scenarios and discuss our findings in relation to observations.

X-shaped sources: An unusual result at low radio frequency [Oral 2-4] Lal, D.V. Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan, R.O.C. Rao, A.P. National Centre for Radio Astrophysics, TIFR, Pune, India. Abstract Lal & Rao (2005) reported an unusual result for 3C~223.1, an X-shaped radio source, i.e., the wings (or the low-surface-brightness jets) have flatter spectral indices with respect to the high-surface-brightness (active) jets, using low frequency data from Giant Metrewave Radio Telescope (GMRT). This clearly shows the value of mapping the sample of X-shaped radio sources at low frequencies to understand the formation scenario of these sources. We have now obtained GMRT data for almost all of the X-shaped radio sources, performed in a uniform way. Here, we will present our results from the GMRT radio images at 240 and 610 MHz for these sources with an aim to test the formation models of these sources.

Dynamical History of Galaxy Encounters [Oral 2-5] Sun, W.H. Institute of Astronomy, National Central University Abstract I will review the several cases of interacting galaxies in which low surface brightness extension around the galaxies and/or faint, diffuse emission have been detected. Multi-wavelength observations of these galaxies reveal the fact that often the diffuse emission are both gaseous and stellar in nature. By studying the spectral energy distributions of the stellar components and comparing to that of the member galaxies,

- 47 - 中國天文學會 2006 年研討會論文摘要 Abstracts of CAST Symposium 2006 as we have done using the BATC archive, the origin of the scattered stars can be studied, which allows us to trace back and delineate the interacting process among the participating galaxies.

Structure and Kinematics of CO 2-1 Emission in the Central Region of NGC4258 [Oral 2-6] Sawada-Satoh, S. ASIAA Ho,P.T.P. ASIAA/Harvard-Smithsonian CfA Muller, S., Matsushita, S., Lim, J. ASIAA Abstract We present 12CO(2-1) observations towards the central region of the Seyfert 2 galaxy NGC4258 with the Submillimeter Array (SMA). Our interferometric maps show that two arm-like elongated components along the major axis of the galaxy, with no strong nuclear concentration. The CO(2-1) morphology and kinematics are similar to previous CO (1-0) results. Velocity field agree well with the general galactic rotation, except that on the east elongated component. The significant velocity gradient along the east-west direction is detected on the component. In order to account for the velocity field, we propose the kinematic models with expanding warped rotation disk. The line ratio of CO(2-1)/CO(1-0) reveals that the higher line ratio on the component where the large velocity offset is seen. It supports that the gas on the component could be closer to the center and heated by the central engine, or the gas could be excited by jet or expansion.

SMA Observations of the Herbig Ae Star HD 142527 [Oral 2-7] Ohashi, N. ASIAA Abstract HD 142527 (F7IIIe) is an Herbig Ae star with strong infrared excess. According to its spectral energy distribution, it is categorized as Group I object, suggesting that it is associated with a flared circumstellar disk. A coronagraphic image at 1.6 micron recently taken with the Subaru telescope has revealed that it is associated with a circumstellar disk having a possible spiral arm and a central hole (Fukagawa et al. 2005). Furthermore, recent VLTI observations have suggested building blocks of planets within the terrestrial region of the circumstellar disk around HD 142527 (van Boekel et al. 2004). In order for us to study circumstellar structures and its kinematics in detail, we have observed HD 142527 in 12CO 3-2 line and 850 micron continuum emissions using the Submillimter Array (SMA). The circumstellar disk around HD 142527 was spatially resolved in both the 12CO line and continuum emissions. The map of the continuum emission showed an arclike structure surrounding the central star, which resembles the Subaru coronagraphic image. The size of the arclike structure is ~200 AU. There are two distinct peaks in the arclike structure, one on the northeast side and the other on the northwest side of the arc. The 12CO 3-2 integrated intensity map, on the other hand, shows a gaseous condensation ~twice larger than the arclike structure seen in dust, with a single peak at the stellar position. The condensation is elongated from northeast to southwest at higher contour levels, while it shows extensions toward northwest and southeast at lower contour levels. A clear velocity gradient was detected in the condensation from northwest to southeast, with a projected maximum velocity of ~1 km/s at 800 AU from the central star. The amount of velocity gradient is basically consistent with Kepler rotation around a 1Mo star. At the meeting we will discuss the nature of the circumstellar disk around HD 142527.

Polarization of high-energy photons from the Crab pulsar [Oral 3-1]

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J. Takata TIARA-ASIAA/NTHU, Taiwan H.-K. Chang NTHU, Taiwan K.S. Cheng Hong Kong university, Hong Kong Abstract High-energy emission mechanism in the pulsar magnetosphere is one of the unresolved issue in high-energy astrophysics. We discuss polarization characteristics of high-energy photons from the Crab pulsar. For the Crab pulsar, the polarization in the optical band has been measured, and the next generation Compton telescope may be able to do that in soft gamma-ray bands. So, polarization measurements will play an important role to discriminate the various high-energy radiation models that successfully explain observed spectra or light curves. We examine the polarization characteristic predicted by synchrotron emission from the Crab pulsar in the frame works of the plausible models. We calculate correctly emission direction and the Stokes parameters with special relativity effects. We find that the degree of polarization and the position angle pattern are consistent with the Crab optical data. However, none of the models explained the pattern of polarization degree of the Crab data. The Crab polarization data may reflect more detailed structure of the magnetosphere of the Crab pulsar.

X-ray spectra from accreting black holes: general relativistic radiative transfer calculations [Oral 3-2] Wu, K. MSSL, University College London, UK & TIARA, National Tsing Hua University, Taiwan Fuerst, S. V. KIPAC, Stanford University, USA Nishikawa, K. NASA-NSSTC, USA Branduardi-Raymont, B. MSSL, University Collge Lonodn, UK Abstract Emission from accreting gas near the event horizon of a black hole is affected by various relativistic effects. The Broad asymmetric Fe K alpha line in the X-ray spectrum of AGN MCG-6-30-15 has been considered as evidence of the influence of strong gravity of the central black hole and relativistic accretion flows around it. We argue that the X-ray continuum is also affected by the relativistic effects. We consider a general relativistic radiative transfer formulation to investigate spectral formation in AGN environment in the presence internal and line-of-sight absorption. We present line and continuum spectra for various parameters appropriate for accretion flows around black holes in AGN.

X-ray Emitting Young Stars in the Carina Nebula [Oral 3-3] Sanchawala, K. Inst. of Astronomy, National Central Univ., Taiwan Chen, W. P. Inst. of Astronomy, National Central Univ., Taiwan Lee, H. T. Inst. of Astronomy, National Central Univ., Taiwan Nakajima, Y. National Astronomical Observatory of Japan, Japan Abstract The Carina Nebula is one of the most active star-forming regions of the Milky Way Galaxy, harboring more than a dozen known star clusters. The massive star-forming region, with 64 O stars including 6 exceedingly rare O3 stars and 2 Wolf-Rayet stars, provides a unique laboratory to study the interplay

- 49 - 中國天文學會 2006 年研討會論文摘要 Abstracts of CAST Symposium 2006 among massive stars, interstellar media and low-mass star formation. We have conducted a multiwavelength study to understand how star formation has proceeded in this violent environment and the role massive stars play in inducing next generation of star formation. In this talk, I shall summarize the results of our analysis of the Chandra observations covering clusters Trumpler 14 and Trumpler 16, complemented by the deep near- infrared (NIR) photometry, carried out at the IRSF in South Africa. Our X-ray sample contains 40 known OB stars. I will describe the X-ray properties of these known OB stars. By using the NIR and X-ray properties, we discovered some 17 candidate OB stars, which seem to have escaped detection in optical observations due to excessive dust extinction. In addition, more than 300 sources are found to have X-ray and NIR characteristics of T Tauri stars. Our study leads to the most comprehensive sample of young stellar populations of the Carina Nebula, which will be used to study the star-formation history of the region.

The Nuclear Compton Telescope (NCT) project [Oral 3-4] Chang, Hsiang-Kuang Department of Physics and Institute of Astronomy, National Tsing Hua University, Taiwan Boggs, Steven Department of Physics and Space Sciences Lab, UC Berkeley, USA Chang, Yuan-Hann Department of Physics, National Central University, Taiwan representing the NCT collaboration Abstract The Nuclear Compton Telescope (NCT) is a balloon-borne telescope designed to study astrophysical sources of hard X-ray and gamma-ray emission with high spectral resolution, moderate angular resolution, and novel sensitivity to gamma-ray polarization. The heart of NCT is an array of novel cross-strip germanium detectors, each of 15-mm thickness and 5400 mm^2 active area, with full 3D position resolution < 2 mm^3. NCT will perform Compton imaging in the 0.2-10 MeV gamma-ray band, and simultaneously perform coded-mask imaging in the 20-100 keV hard X-ray band. We are currently planning a 12-detector long duration balloon flight of the NCT instrument from Australia in 2008. We will present the scientific goals of this flight, as well as the design, simulated performance and current status of the project. NCT is a join effort of several institutions in US and in Taiwan.

Photolysis of ices irradiated by synchrotron radiation [Oral 3-5] Tai-Sone Yih (易台生) 1, Yu-Jung Chen (陳俞融)1, Wing H. Ip (葉永烜) 1, Chung-Yung Robert Wu (吳中榮)2, Hok-Sum Fung (馮學深)3, Su-Yu Chiang (江素玉)3, Yin-Yu Lee (李英裕)3, Jin-Ming Chen (陳錦明)3 1. Department of Physics, National Central University, Chung-Li, Taiwan, ROC. 2. Space Sciences Center, University of Southern California,USA 3. National Synchrotron Radiation Research Center, Hsinchu, Taiwan, ROC. Abstract Study of the formation of large molecules from most simple cosmic ice analogues consisting of H2O, CO2 and NH3 irradiated by extreme ultraviolet (EUV) photons were conducted in this work. Icy samples were condensed on a KBr substrate mounted on a closed cycle helium cryostat kept at 16K. This ice analogue was photo-irradiated by EUV photons provided by the High-Flux beamline of National Synchrotron Radiation Research Center (NSRRC). After exposure to a 1020 photon dose, the sample was warmed up under dynamic vacuum kept below 1×10-7torr to room temperature. The residue left over on the substrate was then analyzed by a high performance liquid chromatography. Traces of a few amino acids were found in the residue, for example, glycine, serine, alanine..etc. Also an exploration of EUV photolysis on more complex molecules was conducted lately. The starting sample was naphthalene and H2O mixed ice. White EUV photon was provided by NSRRC High-Flux beamline as mentioned above. We found in FTIR spectrum that CO, HCO, CO2, and CH3OH were formed during EUV photolysis. Also some massive molecules, for example, 144amu and 197amu..etc., were found by a quadruple mass spectrometer during thawing period. Detailed mass spectra and ir spectra will be presented.

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The light emission of sputtered particles produced by using different ion species bombarding various mixed ices [Oral 3-6] Chin Shuang Lee1, W. H. Ip2, S. Z. Hsu3, S. H. Liu3 1Department of Physics, National Central University 2Institute of Astronomy, National Central University 3Department of Mechanical Engineering, National Central University Abstract In the solar system, water (the most abundant of materials) and many other gases formed into grains and dusts, they are contained in the interstellar medium and planets. They experienced constant irradiation by solar wind and radiation and could have induced some organic products. There are some arguments that those organic products might be the origin of life in the earth. In order to simulate the above condition in the earth laboratory, several ion species are applied to bombard several condensed samples of gases (for examples, CH4 and NH3) mixed with water and the optical spectroscopy of sputtered particles from the surface of mixed ices has been measured. According to the P. Sigmund’s model, if the projectiles with the same beam energy, then heavier ion will generate more sputtered particles. It turned out that in this measurement the heavier incident ion produced stronger light intensity, which should be proportional to sputtered particles.

The optical emissions produce by ion species can be classified two categories: (a) Light emissions of hydrogen molecular spectroscopy are generated by hydrogen molecular ion species bombarding mixed + + + ices with water. (b) Light emissions of atomic transitions are produced by projectiles of He 、N 、H2O 、 + + N2 , and Ar . We also measured the variation of light emissions dependent on different incident angles. It indicates that the iced water has some characteristics of crystal.

The experiment of ion interaction with mixed ices can be used to simulate conditions occurred in the astrophysics.

Dependence of relativistic accretion on black hole spin. [Oral 4-1] Das, Tapas K. TIARA, Taiwan., & HRI, Govt. of India, India Abstract I show that the black hole spin in general influences the properties of general relativistic accretion onto astrophysical black holes. I calculate various dynamical and thermodynamic accretion parameter as a function of the Kerr parameter, for both pro-grade as well as retro-grade flows, for general relativistic accretion in Kerr metric. I discuss how this calculation may be useful in determining the black hole spin by studying the accretion process. I will also discuss how the black hole spin influences another very interesting phenomena, the analogue gravity effect.

Morphology of Galactic Globular Clusters [Oral 4-2] Chen, C.W Inst. of Astronomy, National Central Univ., Taiwan Abstract We analyze the morphology of 101 Galactic Globular Clusters (GCs) with 2MASS point source catalogue. In general, Galactic GCs have spherical halos, with a median flattening of 0.1. GCs away from the bulge have larger physical sizes and more circular in shapes. Six bulge GCs are found to be highly flattened with the elongation pointing to the Galactic center. Pal,5 is known to be cannibalized by the Milky Way, NGC,2419 is a halo GC 90~kpc away from the Galactic center. Its flattened shape may imply that NGC 2419 is associated with a dissolved dwarf galaxy.

- 51 - 中國天文學會 2006 年研討會論文摘要 Abstracts of CAST Symposium 2006 Chemical Structure of the Hot Core, W3(H2O), containing a High-Mass Protobinary [Oral 4-3] Minh, Y. C. ASIAA and KASI Chen, H.-R. Vivien ASIAA Abstract The hot molecular core, W3(H2O), has been known to contain a massive protobinary system, associated with energetic features, such as a very rare synchrotron emission outflow and water masers of dynamic timescales of only 500 years. This source, however, has been cocooned by dense gas with size scales less than 1 arcsec (~ 2000 AU at the distance 2.04 kpc of W3(H2O)), which hinders understanding the inside structure associated with the protobinary system. We investigate chemical properties of the gas components inside of this cocoon using the millimeter-wave transitions from complex molecules, CH3CN, SiO, HNCO and CH3CH2CN, observed with the BIMA array. We also suggest the chemical evolution of this protobinary system.

Molecular Hydrogen Jets, Filaments, and Haloes in Planetary Nebulae with CFHT [Oral 4-4] Mei-Yan Wang Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan C. Muthu Mariappan Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan Sun Kwok Department of Physics, University of Hong Kong, Hong Kong, China Abstract We present deep molecular hydrogen images of planetary nebulae obtained with the CFHTIR camera of the Canada-France-Hawaii Telescope. Molecular hydrogen emissions are seen in the equatorial torus, bipolar lobes, as well as in extended haloes. Radial equatorial jets are also detected in a number of bipolar nebulae.

Structure and dynamics of circumstellar envelopes around AGB and post-AGB stars AGB and post-AGB stars [Oral 4-5] Dinh-V-Trung Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan Abstract In this talk I will summarize recent results of our program using the Sub-millimeter array to study the structure and dynamics of circumstellar envelopes around AGB (asymptotic giant branch) and post-AGB stars. It is commonly believed that the envelopes around AGB stars are spherically symmetric and asymmetric structures appear later during the short transition phase (proto-planetary nebula or PPN) as the stars evolve rapidly toward higher temperatures and eventually emerge as planetary nebulae (PNs). The SMA with its unique capabilities allows us to probe at high angular resolution the morphological changes of the envelopes at different evolutionary stages. Our detection and imaging of an expanding equatorial disk and collimated high velocity bipolar outflow in S star Pi Gru suggest that asymmetric structures already exist in envelopes around normal AGB stars. The envelope around supergiant VY CMa is also imaged and for the first time resolved into a massive high velocity bipolar outflow and an elongated disk-like structure. The expanding molecular torus around the well-known PPN IRAS 07134+1005 and the detached envelope around supergiant IRC+10420 are also imaged at high angular resolution, allowing for the first time a detailed comparison with mid-IR and optical images. By

- 52 - 臺北天文館學報 JTAM Vol.4 modelling the CO emission using a multi-dimensional radiative transfer code, we are able to constrain the geometry and mass loss history of the observed envelopes.

Brown dwarf variability: R and I band observarions [Oral 4-6] Mondal, Soumen Institute of Astronomy, National Central University, Taiwan Chen, W. P. Institute of Astronomy, National Central University, Taiwan Abstract Photometric monitoring of brown dwarfs have shown that some, but not all brown dwarfs are variable on time-scales of hours to days. Such studies not only explore why some objects are variable while others are not, but can also help constrain rotation period or timescales for the evolution of their atmospheric features. We carried out R and I band time-series CCD observations of 6 brown dwarfs over a period of four nights using the Lulin 1m Telescopes. Our preliminary results show a possible evidence of the variability in I-band in two L dwarfs 2MASS 0045+16 (L3.5 V) and 2MASS 0602+39 (L1 V). Possible reasons for such variability in brown dwarfs are discussed.

Inhomogeneity-Induced Cosmic Acceleration in a Dust Universe [Poster-01] Chia-Hsun Chuang Inst. of Astronomy and Astrophysics, Academia Sinica, Taiwan Je An Gu Dept. of Physics, National Taiwan Univ.,Taiwan W-Y. P. Hwang Dept. of Physics, National Taiwan Univ.,Taiwan Abstract We studied the relation between the "accelerating expansion" and the inhomogeneities. We found that a particle can even accelerate outward in a spherically symmetry dust model. In addition, considering the proposition that no-go theorem still holds in a finite domain, Nambu and Tanimoto provided a counter example to prove it false. However, we found the example is improper, because there was some incorrect ignoring when they calculated. Therefore, we found another example with no singularity or ignoring to show that the proposition is indeed false. In this paper, we focus on discussing the possibility of accelerating expansion without dark energy by using exact solution, but not directly explain the observation data. In the examples we found, one can see that the consensus that the gravity is universally attractive is doubtful, and the effect of inhomogeneities should be restudied.

Constraints on Supra-Thermal Electrons in Clusters of Galaxies Imposed by SZ effect [Poster-02] Chen, Y.-J. Inst. of Astronomy, National Central Univ., Taiwan Hwang, C.-Y. Inst. of Astronomy, National Central Univ., Taiwan Abstract Hard X-ray excesses are observed in several clusters of galaxies. One interpretation of hard X-ray excess is bremsstrahlung emission from supra-thermal electrons in galaxy clusters. We estimate the Sunyaev-Zeldovich effect from the supra-thermal electrons in the Coma cluster & Abell 2256, and compare the results with observations. We find that the Sunyaev-Zeldovich spectra caused by total electrons, including the thermal component and the supra-thermal electrons, are inconsistent with the

- 53 - 中國天文學會 2006 年研討會論文摘要 Abstracts of CAST Symposium 2006 observations. Therefore, we suggest that the hard X-ray excesses in the clusters of galaxies might not be attributed by the bremsstrahlung emission from the supra-thermal electrons.

Gravitational Lensing in Bekenstein's Relativistic Tensor Vector Scalar Theory [Poster-03] Sheng-Feng Yen Institute of Astronomy, National Central University Mu-Chen Chiu Institute of Astronomy, National Central University Chung-Ming Ko Institute of Astronomy, Department of Physics and Center for Complex System, Abstract Bekenstein's (2004) Tensor-Vector-Scalar theory (TeVeS) has redeemed the long time embarrassment of lacking a relativistic version for the Modified Newtonian Dynamics (MOND). It provides an enhancement of gravitational lensing, which could not be achieved by other MONDian theories. We investigate the phenomena of gravitational lensing for a point mass model. We find a new deflection angle relation in the deep MOND regime. Based on this deflection angle relation, we study the magnification and the microlensing light curves. We find that the difference in the magnification of the two images in the point mass model is not a constant. Besides, in the deep MOND regime microlensing light curves could deviate significantly from those of GR. We also study the magnification under the Hernquist model in order to compare with future observations.

Host Galaxies of Supernovae in the Taiwan Supernovae Search at Lulin [Poster-04] Chen, Ying-Tung Inst. of Astronomy, National Central Univ., Taiwan Ip, Wing Inst. of Astronomy, National Central Univ., Taiwan Abstract The sample of target galaxies in the Taiwan Supernovae Search (TSS) contains 1573 neaby galaxies most of which are spiral galaxies. Since the scientific operation of the TSS project in 2003, 58 supernovae have been detected amongst them with 10 discovered at Lulin. This data set, even though still limited in size, can be used to study the demography of the host galaxies of different types of supernovae. From the point of view of cosmological study, the Type Ia supernovae are of particular interest because this sample of nearby host galaxies can shed important light on the similarities and dissimilarities of Type Ia supernovae from low redshift to high redshift. We will report on the correlation of the formation rates and lightcurves with the galactocentric distances which might, in turn, relate to the physical properties (i.e., metallicity and chemical composition) of the progenitors and their evolutionary histories.

Supernovae Follow-up Observation at Lulin [Poster-05] Chen ,T. W Department of Earth Science, National Central University, Taiwan Chen,Y. T Institute of Astronomy, National Central University, Taiwan Lin,H. C Institute of Astronomy, National Central University, Taiwan Ip,W. H Institute of Astronomy, National Central University, Taiwan

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Abstract The one-meter telescope (LOT) on Lulin is being employed to perform follow-up observation of supernovae in near-by galaxies at a part of the CosPA (Cosmology and Particle Astrophysics) project. In this work, we will report on the progress in the analysis of the B,V,R-band light curves of SN 2005cs in M51 (Whirlpool Galaxy). M51 is very important, because it is a face on galaxy, we can observe the distribution of star formation. The supernova rate of M51 is also high, because it is an interaction galaxy.

Stability of Cosmic Rays and Waves System [Poster-06] Lo, Ying Yi Graduate Institute of Astronomy, NCU Ko, C. M. Department of Physics and Instability of Astronomy, NCU Abstract We investigate the the stability of cosmic-ray plasma system in the hydrodynamic approach. The system we are considering comprises cosmic rays and two oppositely propagating Alfv'en waves. The thermal plasma flow is treated as a background, such that the feedback of the cosmic rays and waves is neglected. Steady state solutions exist for the system, and when two waves are present, the steady state is non-uniform. Linear stability analysis on the steady state solutions shows that for short wavelength, large cosmic ray energy density, and small wave energy density the system is stable. We present in detail the case of uniform background flow. The system is most unstable in the upstream region and becomes stable in the downstream region in the linear regime for short enough wavelengths. We also speculate on the implication of the instability.

On the Correlation between E_γ and E_peak of Gamma-Ray Bursts [Poster-07] Lee, Y.H Depart of Earth Science, National Central University, Taiwan Y. Urata RIKEN ( The Institute of Physical and Chemical Research) 2-1 Hirosawa, Wako, Saitama 351-0198 Japan Huang, K.Y Institute of Astronomy, National Central University, Taiwan Ip, W.H. Institute of Astronomy, National Central University, Taiwan Abstract After their first discovery in the sixties, Gamma-ray burst (GRBs) which represent the most powerful cosmic explosions after the Big Bang still present many puzzles. From the observational results of several high-energy astrophysical satellites (BATSE, BeppoSAX, HETE-2 and SWIFT), it has now been well established that the distribution of GRBs is isotropic in nature. Moreover, the burst durations display a bimodal structure. The spectral peak energy (Epeak) and the total isotropic energy (Eiso) have been found to follow a certain linear dependence in log-log scale (Amati et al A&A 390, 81-89 2002). Of equal importance, the collimation-corrected energy (Eγ) is found to have a tight correlation with Epeak (Ghirlanda et al The Astrophysical Journal, 616:331-338, 2004). We have used a much larger data set to examine this effect with a view to apply this result to derive the red-shifts (z) of GRBs from the observed values of Epeak and Eγ.

Searching for dust in the intracluster medium [Poster-08] Wu, S. Y. Academia Sinica, Institute of Astronomy & Astrophysics, Taipei, Taiwan Muller, S.

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Academia Sinica, Institute of Astronomy & Astrophysics, Taipei, Taiwan Hsieh, B. C. Academia Sinica, Institute of Astronomy & Astrophysics, Taipei, Taiwan Yee, H. K. C. Department of Astronomy & Astrophysics, University of Toronto, Canada Abstract Whether there is dust in galaxy clusters remains an open question in spite of all the efforts for direct or indirect detections. In this work, we propose to search for extinction and reddening by intracluster medium dust. Our method is based on statistical comparisons of counts and colors of galaxies in the background of clusters and field galaxies. We used The Red-Sequence Cluster Survey data on selected nearby galaxy clusters and present the preliminary results.

Development of Millimeter-wave and Submillimeter-wave instrumentation in ASIAA [Poster-09] Hwang, Y. J. ASIAA Chen, M.T. ASIAA Wang, M.J. ASIAA Li, C.T. ASIAA Abstract Starting from 1994, Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) starting her research and development on the millimeter-wave and submillimeter-wave heterodyne instrumentation for radio astronomical observation. In this poster, we demonstrate the key devices and systems developed by ASIAA for the Submillimeter Array (SMA) , and the Array for Microwave Background Anisotropy (AMiBA).

Deep CO(1-0) Imaging of Starburst Galaxy NGC 2146 [Poster-10] TSAI, A.-L. Department of Earth Science, National Taiwan Normal University, Taipei, Taiwan / Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan Matsushita, S. Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan Nakanishi, K. Nobeyama Radio Observatory, Nagano, Japan Peck, A.B., et al. Harvard-Smithsonian Center for Astrophysics, MA, U.S.A., et al. Abstract We present deep CO(1-0) interferometric images of the central region of the edge-on starburst galaxy NGC 2146 observed with the Nobeyama Millimeter Array. The result shows one bubble and one outflow outside the galactic disk, which are well correlated with the soft X-ray images obtained by the Chandra X-ray Observatory. In addition, we present the residual velocity map in the central region after subtracting a usual galactic rotation model. Our data indicates the normal galactic rotation and found no evidence of molecular outflows in the central disk region of NGC 2146.

Searching for Circumnuclear Molecular Torus in Seyfert 2 Galaxy NGC 4945 [Poster-11]

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Richard C. Y. Chou ASIAA, Taiwan Peck A. SAO, Harvard, USA Muller S. ASIAA, Taiwan Matsushita S. ASIAA, Taiwan Abstract Seyfert galaxies exhibit luminous nuclear activity which is thought to result from the accretion of matter onto a central supermassive black hole. The Unification Model predicts the AGN is surrounded by a torus or warped disk that is opaque at optical/near-IR wavelengths, and the observed properties of the AGN is determined by our line of sight. Through the high angular resolution offered by the SMA at mm/submm wavelength, we would like to study the properties and kinematics of this torus/disk. NGC 4945, which is one of the nearest Seyfert 2 galaxy with the distance of ~3.9 Mpc, lies at southern hemisphere (DEC=-49). Our CO(2-1) observation shows a central molecular gas concentration, and within inner 380 pc region the gas resides in a flatted and rigidly rotating structure. It could be the putative circumnuclear torus predicted by the unification model. Near the systemic velocity the channel maps show the signature of ring with diameter of 10" which is associated with the 6" starburst ring revealed by Pa alpha observations. Outside the inner 20" region, the molecular gas seen in CO(2-1) exhibits complex non-circular motion. This non-circular motion may delineate inward gas motion, and if so provides an important clue to the fueling of the AGN.

Circumnuclear molecular gas in the Seyfert 1 galaxy NGC 1097 [Poster-12] Hsieh, Pei-Ying Institute of Astrophysics, National Taiwan University Matsushita, Satoki Academia Sinica Institute of Astronomy and Astrophysics Lim, Jeremy Academia Sinica Institute of Astronomy and Astrophysics Kohno, Kotaro Institute of Astronomy, University of Tokyo Abstract We mapped the central region of the Seyfert 1 galaxy NGC 1097 with Submillimeter Array in 12CO(2-1). NGC 1097 is a nearby galaxy with a large-scale bar, and hosts a circumnuclear starburst ring. Straight dust lanes along the leading edge of the bar connect the ring with the spiral arms. Our CO map revealed a circumnuclear molecular ring with a radius of 700 pc, which corresponds to the starburst ring, and a strong central concentration of molecular gas with a radius of 140 pc, which is coincident with the Seyfert nucleus. We also detected the weak molecular gas along the bar. The azimuthal averaged 12CO(2-1)/(1-0) line ratios of the central concentration and the ring are about 2 and 1, respectively. The high line ratio means the temperature is warm enough to excite the CO molecule to higher population, and a quantitatively analysis with the large velocity gradient method suggest that the physical condition of the gas in the central concentration is warmer (Tkin = 250 K) and denser (n(H_2) = 104 cm^-3) than that in the starburst ring. The H_2 column density derived from our data is 1023 cm^-2, which is inconsistent with it derived from the X-ray observation (1020 cm^-2) and this may suggest that the central disk/torus is inhomogeneous. A velocity gradient shows that the central concentration is rotating with the ring in the same sense but much steeper than in the ring. The steep velocity gradient in the central concentration was interpreted as a highly-inclined rotating disk/torus or a low-inclined disk/torus with very high rotating velocity. In case of a highly-inclined disk/torus, our data suggest that the central disk/torus is clumpy enough to see through the Seyfert nucleus, as modeled by Wada and Norman (2002).

- 57 - 中國天文學會 2006 年研討會論文摘要 Abstracts of CAST Symposium 2006 SMA and Spitzer observation in Arp 302 [Poster-13] Ao, Yi-Ping ASIAA, Taiwan Dinh-Van-Trung ASIAA, Taiwan Lim, Jeremy ASIAA, Taiwan Abstract New results from SMA and spitzer are presented for the edge-on galaxy of the early merging system, Arp 302. Combined with VLA archive data, it is clear that the star forming activities are mainly contributed from the off-nucleus region. The spitzer MIPS data shows that the properties of the dust component in this system.

The Properties of Narrow-Line Syfert 1 AGNs [Poster-14] Chih-Pin Huang Graduate Institute of Astronomy, National Central University, Jhong-Li, Taiwan, R.O.C Chorng-Yuan Hwang Graduate Institute of Astronomy, National Central University, Jhong-Li, Taiwan, R.O.C Abstract We have used the VLA FIRST survey and the Veron-Cetty & Veron AGN catalog(2006) to construct a new optical-selected sample of radio-bright AGNs. In this study, we focus on the radio properties of narrow-line Syfert 1 AGNs. The origin of the radio power of AGNs is still unclear. While only four radio-loud narrow-line Syfert 1 AGNs were identified so far from literatures, we further identify several more candidates through our works. We find the radio detection rate of narrow-line Syfert 1s is 23% while that of normal Syfert 1s is 11%. Meanwhile, we find the radio-to-optical ratio r* of narrow-line Syfert 1 AGNs is similar to normal Syfert 1s; We suggest this is due to detecting effect.

Merging galaxies in RCS2 [Poster-15] Ming-Yan Chang Graduate Institute of Astronomy, National Central University, Taiwan Chorng-Yuan Hwang Graduate Institute of Astronomy, National Central University, Taiwan Abstract We search for merging galaxies in the Red Sequence Cluster Survey 2 (RCS2). The RCS2 is a large sky survey using the CFHT in three filters to look for galaxy clusters out to z~1. In the dense regions of galaxy clusters, galaxies tend to interact or merge with nearby companies and thus affect the evolution of these sources. In this study, we modified the pattern recognition software originally developed by Tan (2004) to search for merging galaxies in the RCS2 data set. We present our preliminary results and discuss their implication.

The merging structure of Abell S0721 [Poster-16] Ho, Pei-Li Department of Earth Sciences, National Taiwan Normal University & Astronomical Observatory, Central Weather Bureau Chen, Lin-Wen Department of Earth Sciences, National Taiwan Normal University Abstract We present a correlation analysis between the optical and X-ray structures of the central region (~1.25h100-1Mpc) of Abell S0721 by using the photometric observations of one-meter telescope at Lulin

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Observatory and the ROSAT all sky survey (RASS) data. The X-ray emission shows that there are five loosely connected clumps in the central region, of which one clump is listed in RASS bright source catalogue (BSC) and has been suggested as a cluster, while the other four are in faint sources catalogue without optical identification. A further X-ray hardness ratio study to trace the large scale temperature distribution indicates that there are two X-ray-soft clumps (including the RASS BSC object) connected by a harder clump. In comparison with the distribution of galaxies obtained from Lulin, the soft extended sources are likely two groups of galaxies, but there is no obvious optical sources brighter than mR=19 and mB=20 associated with the hard one. Based on the strong merging evidence of Abell S0721, we propose that a future high resolution X-ray observation can reveal the properties of this hard source and can be a key to understanding the merging history of the poor cluster.

Cumulative luminosity function of point sources from 2MASS [Poster-17] Peng, T. H Inst. of Astronomy, National Central Univ., Taiwan Ko, C. M Inst. of Astronomy, Dep. of Physics and Center of Complex System, National Central Univ., Taiwan Chang, C. K Inst. of Astronomy, National Central Univ., Taiwan Abstract Star count is one of the basic methods to study the structure of our Galaxy. The Two Micron All Sky Survey (2MASS) offers a better view of the global distribution of stars in our Galaxy than optical survey, because the extinction of near infrared is only 10% of that in the visible. We use 2MASS Point Source Catalogue to construct the cumulative luminosity function (number of stars per projected area per apparent magnitude) of the sky at one degree resolution. We use the cumulative luminosity function to examine different galaxy models.

Interstellar Beta-Alanine [Poster-18] Fang-Chun Liu(劉芳君) National Taiwan Normal University, Taiwan Yi-Jehng Kuan(管一政) National Taiwan Normal University and Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), Taiwan Steven Charnley NASA/Ames, USA Kazuyoshi Sunada Nobeyama Radio Observatory, Japan Abstract Interstellar Beta-Alanine Fang-Chun Liu(劉芳君){1}, Yi-Jehng Kuan(管一政){1,2}, Steven Charnley{3}, Kazuyoshi Sunada{4}, Zbigniew Kisiel{5}, Masatoshi Ohishi{6} 1. National Taiwan Normal University 2. Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) 3. NASA/Ames, USA 4. Nobeyama Radio Observatory, Japan 5. Polish Academy of Science, Poland 6. National Astronomical Observatory of Japan (NAOJ) Evidence from carbonaceous meteorites, laboratory experiments, observations of interstellar carboxylic and amino acids, as well as chemical models, strongly suggests that the beta isomer of the amino acid alanine should be present in hot molecular cores, perhaps at an abundance comparable to that of those organic acids which have already been identified. We therefore used the Nobeyama Radio Observatory 45m telescope to perform a sensitive Q-band search for beta-alanine. Some of our preliminary results will be presented.

- 59 - 中國天文學會 2006 年研討會論文摘要 Abstracts of CAST Symposium 2006 Search for Interstellar PO Molecule [Poster-19] Tzu-Cheng Peng Institute of Astrophysics, National Taiwan University Sun Kwok Academia Sinica Institute of Astronomy & Astrophysics Yi-Jehng Kuan Department of Earth Sciences, National Taiwan Normal University Abstract Even though phosphorus is abundant in the Universe, only PN and CP are detected in the interstellar medium. PO, which could be the most plentiful phosphorus-bearing molecule, has not been successfully detected yet. We have therefore searched for the J = 5/2→3/2 and 3/2→ 2/1 transitions of PO at 2 mm and 3 mm in the Orion KL hot molecular core by using the ARO 12 meter telescope. Our tentative results show there are some possible detections of PO in Orion KL.

Organic Molecules in the Orion KL Hot Molecular Core [Poster-20] Wang, K.-S NTU; ASIAA Kuan, Y.-J NTNU; ASIAA Liu, S.-Y ASIAA Abstract Hot molecular cores in massive star-forming regions are known to contain various complex organic molecules. To explain the high fractional abundances of organic molecules observed, grain-surface chemistry is often needed. However, grain chemistry alone cannot produce the observed abundances of many organics to a satisfactory level. Grain-mantle evaporation, hence the release of organic molecules formed on grains, followed by formation paths in gas phase has thus been proposed. To test gas-grain chemistry in hot cores, we have therefore conducted arcsecond-resolution Submillimeter Array (SMA) observations of Orion KL. Here we present spectral images of Orion KL. The spatial distribution of different organic molecular species in Orion KL will also be discussed.

3mm and 1mm molecular line survey of NGC 7027 [Poster-21] Huang, Yu-Chin Academia Sinica Institute of Astronomy and Astrophysics Kwok, Sun Academia Sinica Institute of Astronomy and Astrophysics Dinh, Van-Trung Academia Sinica Institute of Astronomy and Astrophysics Abstract We present the spectral line survey of NGC 7027 in 3mm and 1.3mm bands using the Arizona Radio Observatory 12m and HHT 10m telescopes. NGC 7027 is a young carbon-rich planetary nebula with high surface brightness. There is no spectral line survey of NGC 7027 in these bands until now, thus detailed characteristics of this source will be analyzed through the survey. We plan to identify features and measure the line strengths which can be used to estimate the abundance of important molecular species.

Imaging photodissociation region of NGC 7027 with SMA [Poster-22]

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Huang, Zhen-Yuan Institute of astronomy and astrophysics, Academia Sinica Dinh, Van-Trung Institute of astronomy and astrophysics, Academia Sinica Abstract NGC 7027 is a well-known young planetary nebular with a hot star (T_eff=200,000 K) and plentiful molecular emission. The nebula is very luminous from X-ray to cm wavelength. Its strong molecular line emission from the photodissociation region (PDR) associated with strong magnetic fields and high gas-temperatures can improve our understanding of chemical models in extreme cases. The characteristic size of PDR of NGC 7027 is around 13" with the geometric thickness 1" ~ 3" from the previous JCMT observations (Hasegawa et al. 2000; Hasegawa & Kwok 2001). To probe this thin and hot region where various molecules are suggested to emerge, our SMA observations focus on two dense gas tracer species, HCO+ and HCN (J=3-2), in this region. From our results, two molecules both show the bright knots which are heated by the shock fronts of the outflow while HCO+ also traced the dense shell.

Search Candidates of Binary Origin in the Nuclei of Planetary Nebulae [Poster-23] Hsia, C. H. Inst. of Astronomy, National Central Univ., Taiwan Ip, Wing Inst. of Astronomy, National Central Univ., Taiwan Li, J. Z. National Astronomical Observatories, Chinese Academy of Sciences, China Abstract Planetary nebulae play an important role in stellar evolution when intermediate- to low mass stars (0.8 ~ 8M⊙) evolve from the asymptotical giant branch (AGB) phase to the white dwarf (WD) phase (Iben & Renzini, 1983, ARA&A, 21, 271). Many planetary nebulae (PNe) display distinct bipolar structures as they evolve away from the proto-planetary nebulae (PPNe) phase. One possible cause of their bipolarity could be due to a binary origin of its energy source. To search for the possible presences of the binary components, we have initiated an absorption-line survey of planetary-nebula nuclei (PNNi) with the NAOC 2.16 m telescope and OMR spectrograph, which is aimed at discovering the features of binary components. Here we report our initial results showing that 8 out of 15 well-observed bipolar PNNi ( A78, LoTr 5, M1-77, M 2-54, M 4-18, NGC 6790, NGC 6891, Tweedy 1) have absorption lines characteristic of late type stars (CN λ4216, CaⅠ 4226, G Band, Mg b) and other 6 targets that have composite or B/A type spectra, suggesting that a significant binary population may be present. However, further observations are required to confirm these results because some of the absorption-line features might be due to interstellar matter (ISM) or neutral envelopes of some of our PNNi.

Millimeterwave Sample Spectral-line Survey of Three Evolved Stars [Poster-24] Jin-Hua Shen Department of Earth Sciences, National Taiwan Normal University Yi-Jehng Kuan Department of Earth Sciences, National Taiwan Normal University;Academia Sinica, Institute of Astronomy and Astrophysics Fang-Chun Liu Department of Earth Sciences, National Taiwan Normal University Abstract Sample bandscans at millimeter wavelength of three evolved stars were conducted from December 2000 to March 2003. The Kitt Peak 12m telescope of the Arizona Radio Observatory was used for this spectral-line survey. The 391 kHz/ch high spectral-resolution 600-MHz wide-bandwidth Millimeter

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Autocorrelator was employed. In total 24 spectral frequency bands covering the frequency range from 86 to 169 GHz were observed toward IRC+10216, CRL2688 and CRL618, a carbon-rich AGB star and two PPNe, respectively. The preliminary result indicates detections of molecular emission from NaCl, NaCN, SiS, CCS, SiC2, HCN, C3N, C4H, C4H2, C6H and HC7N.

Evolutionary Status of Classical Be Stars in the Open Cluster NGC 1857 [Poster-25] Hsiao, W. S. Inst. of Astronomy, National Central Univ., Taiwan Chen, W. P. Inst. of Astronomy, National Central Univ., Taiwan Abstract NGC 1857 is a poorly studied open cluster located at the anti-Galactic center direction. Here we present our UBV CCD photometric study of NGC 1857 and derived, from isochrone fitting, an age between 108.25 to 108.45 years. This is much younger than the 109.3 years determined by Colegrove (1994). We have identified probable photometric cluster members, including a few red giants. In addition, 2 classical Be stars have been found, one of which is a new discovery. Classical Be stars are known as rapid rotators and have hydrogen emission lines in their spectra. In general their spectral energy distribution shows IR excess, believed to originate mostly from thermal emission by cool dust in a circumstellar disk, and to a lesser level from free-free emission from ionized gas. The Be star we discover has an unusually large amount of near-IR excess --- yet suffers little optical extinction --- and is on the verge to evolve off the main sequence. In contrast, the other Be star, with much less near-IR excess, is at an earlier evolutionary stage. We suggest that the fast rotation results in a non-spherically symmetrical mass loss as the Be star evolves on its way to puff off its envelope.

The UBV photometry of Open Clusters NGC2244 NGC2301 and IC348 [Poster-26] H-Y Hsiao National Taiwan Normal University Hsieh-Hai Fu National Taiwan Normal University Abstract The CCD photometry of three open clusters NGC2244 NGC2301 and IC348 are presented in Johnson UBV pass-bands. The observations were carried out with the Lulin one meter telescope (LOT) in the periods of October 28, 2003 to February 10, 2004, the total 7 nights. The reddening and extinction of these open clusters are corrected from (U-B)-(B-V) diagram, and then, the distance modulus and age of these three open clusters are derived from CMD of reddening and extinction corrected by fitting the zero-age main sequence (William A., Robert J and Rudolph E.,1976).

The BV photometry of BP Peg and CY Aqr [Poster-27] Chi-Shin Lee The Department of Earth Sciences, NTNU Hsieh-Hai Fu The Department of Earth Sciences, NTNU Abstract The B and V photometry of variable star CY Aqr and V photometry of BP Peg are presented in this work. BP Peg, a kind of dwarf variable star, observed with the RC-16 telescope of observatory on campus of NTNU on September 8-20, 2005 and CY Aqr observed with the Lulin One-meter Telescope (LOT) on October 3, 2005, respectively. The light curves of B, V photometry and color of (B-V) with the time of both stars are found. The more accuracy period of BP Peg is 0.0195 days modified from the O-C diagram.

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The light curve of CY Aqr is fit using the Fourier decomposition method to decompose the pulsation mode.

Preliminary result of the EAST Network [Poster-28] Chang, C. S Institute of Astronomy, National Tsin Hua University, Taiwan Wang, L.H Institute of Astronomy, National Tsin Hua University, Taiwan Chou, D.Y Institute of Astronomy, National Tsin Hua University, Taiwan Abstract The light curves of BI CMi & GN And have been obtained from the Tenerife site of the Earthshine and AsteroSeismology Telescopes(EAST) network. The reduction method will be presented. Moreover, the FFT result will be discussed.

The percolating phenomenon on the solar surface. [Poster-29] Chia-Hsien Liao Institute of Astronomy, National Central University Wing-Huen Ip Institute of Astronomy, National Central University Abstract We use the percolating model to simulate the appearance of active region at the solar surface. There are three main factors in this model: (1) the probability of one flux which stimulate the neighboring cell, (2) the spontaneous probability to decide the initial state, (3) the probability of the disappearance. Finally, we use the variation of total magnetic cells and the process of single active region our result.

Speckle interferometry of selected binaries using webcam CCD [Poster-30] Yen, Y. C Department of Earth Sciences, National Taiwan Normal University Fu, H. H Department of Earth Sciences, National Taiwan Normal University Abstract The observed image resolution of optical band is restricted about 1”~2” because the wavefront from the objects is distorted by atmosphere turbulence. Speckle images of binaries are frozen with ~15ms exposure time using CCD taken from Philip 840K webcam. We modify a webcam with B/W CCD chip that contain high speed shutter and high frame rate to satisfy our requirement for speckle observations. In our observation in NTNU flat roof observatory, we successfully resolve γVir with ~0.4” angular separation that the angle is approaching to the diffraction limit of 14” telescope (0.3”~). In the examination of our observation on FRO since March, 2004, the resolution is suitable for most of the small telescopes (20cm-40cm) and commercial CCD cameras to grab binaries which magnitude is less than 4 and magnitude difference with the two stars is less than 3.

Young Stellar Population in the Lupus 3 Dark Cloud [Poster-31] Fong-Yi, Huang Institute of Astronomy, National Central University, Taiwan Wen-Ping, Chen Institute of Astronomy, National Central University, Taiwan

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Abstract The Lupus dark clouds are among the nearest star-forming regions. We analyzed a 30’x30’ field of the UK Schmidt H-alpha images centered around the 2 A- type stars of the Lupus 3 cloud to identify H-alpha emission stars. Together with the 2MASS infrared colors, a list of 46 candidate T Tauri stars have been identified, among which 22 are new identifications. We also report on the spectroscopic observations used to ascertain the T Tauri nature of these candidates.

SMA Observations of Organic Molecules in the IRAS 16293-2422 Hot Corino [Poster-32] Chian-Chou Chen Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan; Department of Physics, National Taiwan University, Taipei, Taiwan Yi-Jehng Kuan Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan; Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan Sheng-Yuan Liu Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan Miao-Ling Pen Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan Abstract Results from a millimeter spectral-line survey of the low-mass protobinary source IRAS 16293-2422 (hereafter IRAS16293) are presented. At a distance of 160 pc from the Sun, IRAS16293 is known to consist of a cold molecular envelope, an inner warm gas envelope, and a hot corino with a rich inventory of complex organic molecules. Arcsecond-resolution SMA (the Submillimeter Array) observations in the 230-GHz band were carried out in February 2005. Spectral emission from organic molecules HNCO, CH3OH, CH3CN and C2H5CN is detected. Our findings concerning large organics in IRAS16293 are thus important to the study of chemical evolution of solar-type protostellar disks similar to the Solar Nebular.

Radiation Driven Implosion model for high luminosities of protostars [Poster-33] Motoyama, K Theoretical Institute for Advanced Research in Astrophysics Umemoto, T Nobeyama Radio Observatory Hsien Shang ASIAA Abstract We investigated how radiation driven implosion(RDI) affects on star formation nearby massive star. Luminosities of protostars in molecular clouds near HII regions are orders of magnitude higher than in other region. This high luminosities indicate high accretion rates of prtostars in these region, because luminosities are mainly produced by accretion in protostellar phase. UV radiation from massive star ionizes surface of molecular cloud and compress it. This process is known as RDI. If RDI trigger star formation, accretion rate and final mass of protostar would be affected by RDI. Using numerical simulation, we revealed that RDI enhanced accretion rate $> 10^{-4} M_{sun} yr^{-1}$. Observed high luminosities of protostars in molecular clouds near HII regions can be interpreted as results of RDI. We also reveled that final mass of protostar depends on initial density profile of cloud.

Star Formation in the Orion-Monoceros Complex [Poster-34]

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Lee, Hsu-Tai Inst. of Astronomy, National Central Univ., Taiwan Chen, W.P. Inst. of Astronomy, National Central Univ., Taiwan Abstract We find that young stars in the Orion-Monoceros Complex are tightly related to the Orion-Eridanus Superbubble, created by Wolf-Rayet winds and supernovae from in the Ori OB1 association. The shock fronts would compress molecular clouds and then trigger star formation. This phenomena can be found in the Orion A, Orion B, NGC 2149, VdB 64, and Crossbones. We propose that the star formation in the Orion-Monoceros Complex starts from Ori OB1a, propagates to 1b, 1c, and eventually to 1d. Star formation is spread out further by the expanding shock front, i.e., the Orion-Eridanus Superbubble, to NGC 2149, VdB 64, and Crossbones. As the shock fronts expand, they do not only induce star formation but also inject short-lived nculides, synthesized by Wolf-Rayet stars and supernovae, into protostellar nebulae. These now extinct short-lived nculides have been found in meteorites. Our solar system was likely formed in an environment similar to that of the Ori OB1 association.

Molecular Outflows of IRAS 16293-2422 Observed with the SMA [Poster-35] Yeh, S. C. C. Institute of Astronomy & Astrophysics, Academia Sinica, Taipei, Taiwan Hirano, N. Institute of Astronomy & Astrophysics, Academia Sinica, Taipei, Taiwan Ohashi, N. Institute of Astronomy & Astrophysics, Academia Sinica, Taipei, Taiwan Takakuwa, S. et al. National Astronomical Observatory of Japan, ALMA Project Office, Tokyo, Japan Abstract We present the Submillimeter Array (SMA) observations of the molecular outflows driven by the protobinary source IRAS 16293-2422. The high angular resolution observations in CO J=2-1 and CO J=3-2 provide an entirely new picture of the central region of IRAS 16293-2422. An angular resolution achieved by the SMA in CO J=2-1 is 3.3"x2.0" (530 AU X 310 AU), while in CO J=3-2 is 1.9"x1.1" (300 AU X 170 AU). The high resolution maps of CO J=2-1 and CO J=3-2 suggest that the southeastern source A is driving the E-W pair of the quadrupolar outflow, which is different from previous interpretation that the E-W pair is powered by the northwestern source B. On the other hand, no counterpart of the NE-SW pair is seen in our interferometric maps, suggesting the possibility that the NE-SW outflow may be currently inactive. An analytical model fitting result implies that the E-W pair feature could be explained by the wind-driven model. In addition, two new components are found in the vicinity of the binary. A blue-shifted component locates at the northwest of source A, while the red-shifted component appears at the southeast of source A. These newly discovered components are also seen in the SMA SiO J=5-4 observation, which suggests that they are shocked regions with high density. By comparing kinematic structures in CO and SiO results, the newly discovered components are likely to be young shock events that are associated with source A.

HST/STIS Archival Study of DG Tau Jet [Poster-36] Liu, Chun-Fan Academia Sinica, Institute of Astronomy and Astrophysics Shang, Hsien Academia Sinica, Institute of Astronomy and Astrophysics Sun, Yi-Hua Academia Sinica, Institute of Astronomy and Astrophysics, National Taiwan University Lin, Wei-Chieh Academia Sinica, Institute of Astronomy and Astrophysics, National Taiwan University

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Abstract High angular-resolution observations are essential in understanding the driving mechanisms of optical jets from young stars. The fobidden emission lines from the Classical T Tauri Stars (CTTSs) provide good probes to study the jet-launching region. We study the inner 1" region of the CTTS DG Tau with long-slit spectra obtained at sub-arcsecond resolution from the instrument Space Telescope Imaging and Spectrograph (STIS) on board of Hubble Space Telescope (HST). We compare the data with theoretical modelling using the X-wind model, a magnetocentrifugal wind launched near the innermost edge of the disk. By scanning the ranges of electron temperature (T) and ionization fraction (xe) that are inferred from existing optical jets, we reproduce emission profiles based on the X-wind. However, we note that the origins of the low-velocity component and the high velocity component found in DG Tau jet may arise in two separate, non-continuous flow identities.

Modeling Debris Disks Around Nearby Young Stars [Poster-37] Huang, H. F Institute of Astronomy, National Central University, Taiwan Chen, W. P Institute of Astronomy, National Central University, Taiwan Abstract Some main sequence stars, including late-type stars and more massive Vega-like ones, are known to have infrared excesses over their photospheric levels. This phenomenon is usually attributed to circumstellar debris disks, consisting of micron-sized grains to meter-sized planetesimals. The debris may be the remanence of collisions of Pluto-sized objects, rather than the primordial disk material from the star-forming process. Here we present our disk model calculations, by considering different grain sizes, to fit the spectral energy distributions of six targets (Vega, β Pictoris, Fomalhaut, ε Eri, AU Mic, and HD92945) with estimated ages 12-700 Myr. We show in each case several properties of the debris disks, e.g. the total dust mass and dominate grain size.

The Migration of A Planet Embedded in a Proto-stellar Disk with Self-gravity [Poster-38] Hui Zhang Department of Astronomy, Nan Jing university Chien Chang Yen Department of Mathematics, Fu Jen Catholic University Chi Yuan Institute of Astronomy and Astrophysics, Academia Sinica Abstract We investigate the migration of a Jupiter mass proto-planet embedded in a minimum mass solar nebula disk.

Exospheric Atomic Hydrogen Escape from Close-in Hot Jupiters under the Influence of Stellar Radiation Pressure [Poster-39] Lee, C. H Inst. of Astronomy, National Central Univ., Taiwan Ip, W. H Inst. of Astronomy, National Central Univ., Taiwan Sun, K. L Inst. of Astronomy, National Central Univ., Taiwan

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Abstract An important question in the evolutionary history of exoplanets with very small orbital distances (< 0.1 AU) concerns whether they have been subject to significant atmospheric loss process either via thermal or non-thermal mechanisms. The thermal Jeans escape process has been estimated to be of no consequence even with an exospheric temperature of a few to ten thousand K. However, the ballistic motion exospheric hydrogen atoms of a close-in exoplanet is influenced strongly by the radiation pressure acceleration of the intense Lyman alpha radiation of the central host star. Such modified Jeans escape rate could be of interest to the mass loss budget. In this work, we will present the statistical results from using a number of exospheric models and orbital configurations of the hot Jupiters with a view to clarify this issue.

Ejecta Dynamics near Asteroid 25143 Itokawa [Poster-40] Sun, K. L Institute of Astronomy, National Central University, Taiwan Ip, W. H Institute of Astronomy, National Central University, Taiwan Abstract The surface material of an asteroid could provide important information on the formation and evolution of our solar system. The Japanese spacecraft Hayabusa has just carried out a sample collect operation at the surface of the near earth asteroid 25143 Itokawa. From the imaging observations on Hayabusa, we now know that Itokawa has an irregular shape like an ellipsoid, with the major axis about 500m and minor axes about 300m. The surface of Itokawa is partial covered with smooth regolith and partial with blocks of boulders. In the present work, we have developed a multi-grid 3D shape model of Itokawa so that the motion of the ejecta produced by collisional impacts can be traced. In turn, such numerical computation will provide insight on the surface distribution of regolith and large fragments on Itokawa and other small asteroids under the influence of surface gravity and centrifugal force.

Photometric Observations of 2005 UD at Lulin Observatory [Poster-41] Kinoshita Daisuke Institute of Astronomy, National Central University and 2005 UD team Abstract We carried out photometric observations of 2005 UD using 1-m telescope at Lulin Observatory. A near-Earth asteroid 2005 UD was discovered by Catalina Sky Survey in October 2005. Orbital parameters of this asteroid is very similar to those of (3200) Phaethon. (3200) Phaethon has comet-like orbit, and thought to be a parent body of meteor shower. Orbital similarity of these asteroids may suggest that 2005 UD is a fragment of (3200) Phaethon. To test this hypothesis, we carried out photometric observations of 2005 UD in early-Novermber 2005. Results of multi-color photometry shows bluish surface of 2005 UD which is consistent with the surface of (3200) Phaethon. The lightcurve of 2005 UD shows rotational period of 5.23 hours and amplitude of 0.4 mag. The observations of dormant comet candidates provide opportunity to reveal properties of bare cometary nuclei which are difficult to be observed by comae contamination due to the cometary activities.

The Surface Temperature Profile and Sublimation Process of Iapetus [Poster-42] I-Ling Lin Inst. of Space Science, National Central Univ., Taiwan Wing-Huen Ip Insti. of Astronomy and Space Science, National Central Univ., Taiwan

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Abstract The Saturnian satellite, Iapetus, has been the focus of attention since its first discovery. The main reason has to do with the large dissimilarity of the suface albedos on the leading hemisphere (with A ~ 0.04) and the trailing hemisphere (with A~0.5). The most recent observations by instruments on the Cassini Orbiter have renewed our interest on the temperature variations across its surface and the resultant sublimation of water ice in regions where the temperature can be high (~ 130 K). In this work we will construct surface thermal model which accounts for the albedo dichotomy. In addition, we will consider the sublimation-driven transport of the surface material across the surface of Iapetus from the low-latitute region to the poles over the age of the solar system.

A Surface Thermal Model and Exospheric Ballistic Transport Code of Planet Mercury [Poster-43] Yung-Ching Wang Institutes of Astronomy, NCU, Taiwan Wing-Huen Ip Institutes of Astronomy and Space Science, NCU, Taiwan Abstract The atmosphere of Mercury is of exospheric nature. Its formation is due to several physical mechanisms including meteoroid impact, surface spattering by solar wind ions and photo spattering by solar UV radiation. The molecules and atoms emitted from the surface material are H, He, O, Ar, and S, etc. It is important to study their spatial distributions across the planetary surface via ballistic random walk. We develop a surface thermal model coupled with Hodges-type Monte Carlo calculations to simulate the exosphere of Mercury which will a major scientific target of the Bepi Colomb mission of ESA and JAXA.

High Deuterium Fractionation in Comet C/2002 T7 (LINEAR) [Poster-44] Hsiao-Er Chuang Department of Earth Sciences, National Taiwan Normal University Yi-Jehng Kuan Department of Earth Sciences, National Taiwan Normal University & Academic Sinica Institute of Astronomy and Astrophysics Hui-Chun Huang Department of Earth Sciences, National Taiwan Normal University Kuo-Song Wang Institute of Astrophysics, National Taiwan University & Academic Sinica Institute of Astronomy and Astrophysics Abstract High deuterium fractionation is an important chemical process which has been identified in low-mass dense cores where solar-type stars are formed. In the Solar System, the D/H ratio observed can be used to diagnose the physical conditions that were predominated during the formation of comets. We have successfully detected deuterated formaldehyde (HDCO) in comet C/2002 T7 and a high abundance of deuterium, close to the values found in low-mass sources, is derived. Hence it implies the Solar Nebula may have gone through evolutionary phases similar to that of these solar-type protostellar objects.

Coma Morphology and Jet Activity of Comet 2004 Q2 ( Machholz ) [Poster-45] Lin,Z.Y. Inst. of Astronomy, National Central Univ., Taiwan

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Weiler,M. Inst. of Space Sensor Technology and Planetary Exploration, DLR, Berlin, Germany Ip,W.H. Inst. of Astronomy, National Central Univ., Taiwan Abstract Comet 2004Q2 Machholz was the 10th comet discovered by the well-known comet hunter, Don Machholz. It was first detected on August 27, 2004. This bright new comet started to move rapidly northward in mid December and reached a maximum brightness of magnitude at the beginning of January 2005 due to its close proximity to Earth ( 0.35 A.U.) We monitored the coma activity of this unusual comet from November 2004 to January 2005 by using the One-meter Telescope on Lulin. A number quantity of photometric images were obtained in the narrow banded comet filters from ESA covering the line emission of C2, NH2, H2O+, BC and RC and broad-banded ( B, V, R ) filters. The gas coma displayed a certain degree of asymmetry. In addition, we have found spiral gas jets of C2 molecules but not in dust continuum. The Afρ parameter which is a measurement of the dust content of the coma ( 20000 km) has been estimate the 474.8 +/- 4.8 m from the RC filter centered at 685 nm and the 508.2 +/- 7.8 from the BC filter centered at 406 nm, respectively, on December 15, 2004. The production rate for C2 which is used by the Haser model is 1.6*1026 molecules/s and the scalelength for l(parent) is 4.70*104 km and l(daughter) is 1.02*105 km by assuming the canonical value of 1km/s for radial velocity.

The lightcurves of 2003 UB 313 [Poster-46] H.W. Lin Institute of Astronomy, National Central University, Taiwan Y.L. Wu Institute of Astronomy, National Central University, Taiwan W.H. Ip Institute of Astronomy, National Central University, Taiwan Abstract Transneptunian object (TNO) – 2003 UB313 – is the largest object found outside the orbit of Neptune. Its size (diameter~3000km) has been estimated to be larger than that of Pluto (diameter=2320km) The orbit of 2003 UB313 is characterized by high eccentricity( e=0.44) and high inclination (i=44 deg) indicating very interesting orbital evolutionary history. It surely will occupy an important place in the study of solar system formation. For this reason we have used the one-meter telescope (LOT) at Lulin to perform time series R-band photometric measurements with unprecedented cadence (~5min). These observation were carried out between Sept 6 and Sept 8, 2005, soon after the announce of the discovery of 2003 UB313. This data set of lightcurves provide useful information on the rotational state, sharp and surface structures if combined with photometric measurements in other wavelengths.

Report on Stellar Occultation by Asteroid (11) Parthenope on 2005/12/09 [Poster-47] Lin, C. L. National Museum of Natural Science Ma, Wayne Inst. of Astronomy, National Central Univ., Taiwan Kinoshita, D. Inst. of Astronomy, National Central Univ., Taiwan Lin, H. C. Inst. of Astronomy, National Central Univ., Taiwan Abstract We report the stellar occultation of TYC 128601615 by asteroid (11) Parthenope on 2005 December 9th (UTC). Two sites, KTO and Lulin, joined this observation. The result of KTO is positive with the occultation started at 15h58m53.73s (UTC) with a 7.38s duration recorded while the result of Lulin is

- 69 - 中國天文學會 2006 年研討會論文摘要 Abstracts of CAST Symposium 2006 negative. In this observation the KTO used an integrative video CCD to improve the equipment’s sensitivity and so we used a “partial-occultation time” way to make up its losing of time resolution. The modified trajectory of (11) Parthenope is demonstrated and discussed.

The Taiwan-America Occultation Survey -- Status Report [Poster-48] Chen, W. P. NCU TAOS Team Abstract The Taiwan-America Occultation Survey (TAOS) aims to conduct a census of small icy bodies in the outer reach of the Solar System, by means of stellar occultation. An array of 4 small (aperture 0.5 m), wide-field (f/2) telescopes have been installed at Lulin Observatory to monitor a couple thousand stars simultaneously for such rare occultation events. The scientific product of the TAOS project, the number and spatial distribution of the so-called Kuiper-belt objects (KBOs) --- the building blocks of planets and moons --- will provide crucial information about the formation and early dynamical evolution history of the Solar System. The TAOS project is an international collaboration that involves several institutions in Taiwan (Academia Sinica, NCU), the USA (U. Pennsylvannia, Harvard-Smithsonian CfA, Lawrence Livermore National Lab, NASA/Ames, UC-Berkeley), and Korea (Yonsei U.). The project presents unique hardware and software challenges. Because a typical occultation event by a KBO is expected to last for only a fraction of a second, fast photometry sampling is necessary. A true occultation event is considered securely detected if the flux drop is seen in all telescopes. Subsecond photometry for a few thousand stars, for which the data should be processed, analyzed, and correlated with each other telescopes almost in real time, is a daunting task. Routine observations began in early 2005, and so far we have collected some billion photometric measurements. No KBO occultation event has been detected. We expect a full survey of 3 years to get minimal statistics to estimate the distribution of KBOs. We will present the detection of a few predicted stellar occultation events by asteroids. In addition to KBO science, the huge TAOS database, tens of GB per night for each of the 4 telescopes, would be valuable in other, e.g., stellar variability, studies. Our telescope systems are also responding to transient events, such the gamma-ray bursts. The niche experience gained in processing, distribution and analysis of mass data volume also will be indispensable to step us into future involvement in other projects.

Automated Photometry and KBO Occultation Event Detection in the TAOS Project [Poster-49] Zhang, Z. W. Inst. of Astronomy, National Central Univ., Taiwan Chen, W. P. Inst. of Astronomy, National Central Univ., Taiwan Abstract The Taiwan-America Occultation Survey (TAOS), now with three telescopes fully operational, has been collecting scientific data from the beginning of 2005. We report here the data analysis and occultation event detection algorithms developed for the project. A special photometry pipeline, called Adaptive Aperture Photometry, devised to deal with crowded star fields, contamination by image streaks and image motion, is capable of processing thousands of light curves within the sampling rate of 5 Hz. A rank statistic is used to detect any possible occultation event. So far nearly a billion photometric measurements have been taken, and no occultation events are detected using the current analysis scheme. In 2006, the fourth telescope will be in service which will vastly increase the detection reliability.

The Probabilistic Event Rate of KBO Occultation in the TAOS project [Poster-50]

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Jian-Zheng Lin Inst. of Astronomy, National Central Univ., Taiwan Wen-Ping Chen Inst. of Astronomy, National Central Univ., Taiwan Zhi-Wei Zhang Inst. of Astronomy, National Central Univ., Taiwan Soumen Mondal Inst. of Astronomy, National Central Univ., Taiwan Abstract The TAOS project aims to estimate the number of Kuiper-belt objects (KBOs) by detecting chance stellar occultation. The detected rate of such occultation events depends on the actual occurrence rate and the detectable ability. Relevant parameters include: (1) the surface number density and angular size distribution of KBOs (our goal), (2) the surface number density and angular size distribution of background stars, (3) the shadow speed (e.g., observing toward opposition or quadrature), (4) CCD integration time (limiting magnitude) and sampling rate, etc. To interpret from the detected event rate to the actual KBO number requires a full simulation to explore the parameter space. Here we report our first attempt to derive the predicted event rate from a probabilistic computation by some certain sets of parameters.

The asteroid (286) Iclea occultation event and a TNO occultation simulator [Poster-51] King, S. K. Institute of astronomy and astrophysics, Academia Sinica TAOS team Abstract The majority of trans-Neptunian objects (TNOs) are probably small comets beyond the orbit of Neptune. A study of TNOs may enable a better understanding of the origin of short-period comets and of the process of planet formation and the early history of the solar system. An occultation survey is currently the only way to detect these objects down to a size of a few kilometers at such a distance. The status of the TAOS (Taiwan-America Occultation Survey) project is reported. In order to monitor thousands of stars on the order of a fraction of a second using CCD cameras, a novel CCD readout technique, the ``shutterless zipper mode', is applied. The asteroid (286) Iclea occultation event, which was observed by three TAOS telescopes in February, 2006, is presented in detail. Instead of a simple number count of occultation events, an interpretation of a TNO occultation survey result can be obtained by using the simulator described here. Through comparison of the results from an observation and from our simulator, a specific astronomical or astrophysical model can be constrained.

Sparse millisecond dips in the X-ray light curve of Scorpius X-1: possible signature of trans-neptunian object occultation? [Poster-52] Wu, Ping-Shien Institute of Astronomy, National Tsing Hua University, Taiwan Chang, Hsiang-Kuang Department of Physics, National Tsing Hua University, Taiwan King, Sun-Kun Institute of astronomy and astrophysics, Academia Sinica, Taiwan Liang, Jau-Shian Department of Physics, National Tsing Hua University, Taiwan Abstract Since the first discovery of the trans-neptunian objects in 1992, nearly one thousand new members have been added to our solar system, among which several are of size comparable to or even larger than Pluto.

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TNOs are objects in the outskirt of our solar system beyond the orbit of Neptune. Their population properties such as the size distribution and the total number are valuable information for understanding the formation of the solar system. For TNOs of typical comet size, which are even more abundant, occultation of the light from background stars is currently the only way to study their properties. Although the first detection of optical occultation by small TNOs has yet to come, here we report the discovery of sparse millisecond dips in the X-ray light curve of Scorpius X-1, which are very likely caused by the occultation of TNOs of hundred-meter size. Current optical observations, limited by photometry, might have problems to study TNOs below kilometre size. Our discovery opens up a new window for small TNO surveys and a possibility of resolving the X-ray source itself down to micro-arcsec or below, if this kind of dips can be further confirmed to be occultation events rather than any previously unknown intrinsic variation of Scorpius X-1.

Fine Orbital Parameters and Soft Phase Lags of Accretion Powered Millisecond Pulsar XTE J1814-338 [Poster-53] Y. Chung Institute of Astronomy, National Central University, Taiwan Y. Chou Institute of Astronomy, National Central University, Taiwan C. Y. Tsai Institute of Astronomy, National Central University, Taiwan Abstract The accretion-powered millisecond pulsar XTE J1814-338 was discovered by Rossi X-ray Timing Explorer (RXTE) in June 2003. To investigate its orbital properties and the accretion torque on the neutron star, we carried out pulse arrival-time analysis, based on the non-burst events within energy range 2-10 keV for the ~ 30d RXTE follow-up observations. We first corrected the event arrival times to the binary barycentre using preliminary circular orbital parameters yielded by Doppler effect, and the residual pulse phases were fitted to compute differential corrections of the orbital parameters, as well as the neutron star spin frequency. We derive that the pulsar has a barycentric pulsar period 3.18110573410(6) ms, orbital period 4.27464551(7) hr, and 390.626(2) lt-ms projected radius. Our analysis of pulsar phase evolution in the initial 23 days shows that the pulsar frequency has a first derivative of -(8.0+/-0.1)x10^-13 Hz/s , and a second derivative of (5.3+/-0.1)x10^-19 Hz/s^-2 . After applying the fine orbital parameters and removing pulsar phase evolution effects, we were able to find the pulses show energy-dependant phase delay, where soft energy pulses lag high energy pulses for up to ~ 40 microseconds.

Model Spectra of Neutron Star Surface Thermal Emission [Poster-54] Lun-Wen Yeh Department of Physics, National Tsing Hua University, Taiwan Gwan-Ting Chen Department of Physics, National Tsing Hua University, Taiwan Hsiang-Kuang Chang Department of Physics and Institute of Astronomy, National Tsing Hua University, Taiwan Abstract Many neutron star spectra reveal a thermal origin in the soft X-ray band, such as those of some radio pulsars (particularly of the middle-aged gamma-ray pulsars), and of radio-quiet isolated neutron stars. The thermal emission is believed to come from the atmospheres of neutron stars and it carries valuable information of physical properties of the surface. We construct a neutron star atmosphere model with the surface magnetic field of 10^11 to 10^13 gauss and the effective temperature of several million Kelvin. The fully ionized hydrogen with ideal gas equation of state is used for the composition of atmosphere. The radiative transfer equation is solved for two polarization modes in the plane-parellel and the radiative equilibrium atmosphere with opacities due to thermal bremsstrahlung and Thomson scattering only. We

- 72 - 臺北天文館學報 JTAM Vol.4 compute the radiative transfer equation with full angle dependence of both photon polarization modes and compare that with the radiative transfer equation adopting the diffusion approximation assumption. The orientation of magnetic filed can be arbitrary in our model and we disscuss spectra, beaming patterns and temperature profiles for different field orientaions. Near the electron cyclotron frequency the absorption feature in spectra for both ploarization modes are apparent. The next step for our model is to include the opacities that have higher harmonics. We would like to explore the absorption features, which are observed in the spectrum of 1E 1207.4-5209 and some other sources.

Long-term monitoring for the timing properties of the accretion-powered millisecond pulsar SAX J1808.4-3658 [Poster-55] C. Y. Tsai (蔡兆陽) Graduate Institute of Astronomy, National Central University Y. Chou (周翊) Graduate Institute of Astronomy, National Central University Y. Chung (鍾怡音) Graduate Institute of Astronomy, National Central University Abstract We present our analysis results of the spin and orbital properties of the first discovered accretion-powered millisecond pulsar SAX J1808.4-3658 observed by Rossi X-ray Timing Explorer (RXTE) during its 1998 and 2002 outbursts. The event arrival times are initially folded with an ephemeris consist of the neutron star spin frequency evolution plus the effect from the circular orbital motion and the parameters are then further refined according to the variation of the pulse phase. We obtain the binary barycenter neutron star spin frequency of ν=400.975210324(2)Hz , the orbital period of Porb = 7249.158(1)s and the project radius = 62.811(2)lt-ms from 2002 data. For the 1998 outburst, we get consistent project radius of = 62.814(2)lt-ms but significantly different orbital period (Porb = 7249.1558(9)s ), which indicates that the orbital period derivative is ~ (7 ± 4) × 10^-8yr^-1. No pulsation is able to significant detect for 2000 and 2005 outbursts due to their low fluxes. In addition, the pulse phase variation of 1998 outburst shows a large spin-down rate of -3.15(1) × 10^-12 Hz s^-1, about a factor of 100 larger than the theoretical expectation value (~10^-14 Hz s^-1), whereas no clear spin frequency derivative during 2002 outburst.

Electrodynamics of particle acceleration in pulsar magnetosphere [Poster-56] P. C. Hsu Inst. of Astronomy, National Tsing Hua University, Taiwan K. Hirotani TIARA-ASIAA/NTHU H. K. Chang Dep. of Physics and Inst. of Astronomy, National Tsing Hua University, Taiwan Abstract We study on the electrodynamics of particle acceleration in the pulsar magnetosphere. Mechanisms of particle acceleration and resultant gamma-ray emission in pulsar magnetosphere have not been understood very well. Electric field along the magnetic field line is generated in the charge depletion region in pulsar magnetosphere. Charged particles are accelerated to relativistic energy by this longitudinal electric field and radiate synchrotron/curvature gamma-ray photons. Some gamma-ray photons collide with soft X-ray photons and materialize into electron/positron pairs. These pairs screen out the electric field. We have to take into account all these physical process to understand the gamma-ray emission mechanism. Therefore, in this work we solve the Poisson equation, the motion of charged particles, and gamma-ray distribution together consistently.

- 73 - 中國天文學會 2006 年研討會論文摘要 Abstracts of CAST Symposium 2006 The IR-selected optical counterparts of HMXB around the Galactic plane [Poster-57] Kuo-Pin Huang NCUIA Chorng-Yuan Hwang NCUIA Abstract An unfinished business in the study of high-mass X-ray binaries is finding their optical counterparts. Most of the unidentified HMXB counterparts are around the Galactic plane. We search for the HMXB counterparts using the Spitzer legacy program. In particular, we have found some HMXB optical counterpart candidates in the GLIMPSE（Galaxtic Legacy infrared Mid-Plane Survey Extraordinaire） data set.

The Concept of Virtual Observatory [Poster-58] Chan-Kao Chang Institute of Astronomy, National Central University, Taiwan Chung-Ming Ko Dept. of Physics and Center for Complex System, National Central University, Taiwan Daisuke Kinoshita Institute of Astronomy, National Central University, Taiwan Abstract Astronomers faces data avalanche recently. Breakthroughs in telescope, detector, and computer technology, astronomical instruments produce terabytes of data of images and catalogues. These datasets cover sky in different wavebands, from gamma-ray, X-ray, ultra-violet, optical, infrared to radio. Owing to the advances in inexpensive storage technologies and the high-speed networks these datasets are practically distributed worldwide. In terms of knowledge generation, research results from online databases are as rich as those from “real” telescopes. Virtual Observatory was proposed several years ago. It is a concept to integrate data management, analysis, distribution and interoperability. It will provide astronomers an easy and efficient system to use the online datasets in their scientific works.

Lulin Observatory 2005, Year of International Collaboration [Poster-59] Ming-Hsin Chang(張明新), H.C. Lin(林宏欽), Kinoshita Daisuke(木下大輔), C.M. Ko(高仲明), W.P. Chen(陳文屏), K.H. Chang(張光祥), Y.H. Chang(張永欣) Institute of Astronomy, National Central University, Taiwan Abstract After few years of full operation of Lulin One-meter Telescope (LOT), international collaborations now play much more significant role in LOT's scientific results. The success of WET and WEBT campaign made Lulin an important member in global observation network. In July 2005, LOT equipped with special instrument from Japan, PICO (Polarimetric Imager for Comet), observed the most important event in astronomy and space science, the Deep Impact Mission. With Taiwan's geological advantage, LOT was the first telescope who observed the event after the big eyes in Mauna Kea. Besides of the event, LOT also did Gamma Ray Burst (GRB) optical follow-up observation for two years. Working with Japan and American teams, GRB observations started to pay off in scientific results. Lulin Observatory also hosted TAOS project as well, collaborated with Korea and US. In the ninth year of TAOS project, it collected more than 80GB optical image data by three remote controlled telescopes every night. Base on the success of WET and WBET campaign and the on-going projects in Lulin Observatory, we expect to have more international collaborations which could make great contributions to Taiwan's astronomy community in near future.

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