List of Poster Presentations

No.	Name	Presentation title
01	Carmona, Gonzalez Andres	Upper limits on CO 4.7 micron emission from disks around five Herbig Ae/Be stars
02	Plavchan, Peter	Where are the M Dwarf Debris Disks Older than 10 Million Years?
03	Narita, Norio	Subaru HDS Transmission Spectroscopy of the Transiting Extrasolar Planet HD 209458b
04	Grigorieva, Anna	Collisional Dust Avalanches in Debris Disks
05	Lane, Caoilfhionn	Simulating an Observational System to Search for Exoplanets in Globular Clusters
06	Vanden Heuvel, Andrew	Searching for Planets: 100 Stars at a Time
07	Broeg, Christopher	Giant Proto-Planets in arbitrary nebulae
08	Lee, Chien-Hsiu	Orbital Evolution of Hot Jupiters with Atmosphere Blow-off
09	Yasuda, Seiji	Inhomogeneou s Temperature Distribution in Chondrules in the shock-wave heating model
10	Hu, Juei-Hwa	Search for Exoplanets and Variables in the Open Cluster, NGC381
11	Siegler, Nick	Across the Transition Age: Protostellar Disk Evolution at ~6 and 55 Myr
12	Moorhead, Althea	Giant Planet Migration Through Disk Torques and Planet-Planet Scattering
13	Huang, Hsiang-Fu	Infrared Studies of Circumstellar Dust Grains around Vega-like Stars
14	Lykawka, Patryk Sofia	The transneptunian region architecture: revelations from observations and theoretical results
15	Ishibashi, Ko	Oxidation of carbon compounds by oxygen released from SiO2 within large impact-induced vapor clouds
16	Fukui, Takashi	Evolution of isotopic and chemical composition in the early inner solar nebula due to fluctuation of mass accretion rate
17	Fujiwara, Hideaki	Mid-infrared spectroscopy of Herbig Ae/Be stars
18	Yamoto, Fumiharu	Numerical Simulation of the Gravitational Instability in the Dust Layer of a Protoplanetary Disk under the Assumptions of the Axisymmetry using the One-Fluid Model of the Dust and the Gas
19	Miura, Hitoshi	Chondrule formation by X-ray flare induced shock waves
20	Kaspi, Yohai	Baroclinic Instability as a source for Jupiter's zonal Jets
21	Saito, Kimiko	The estimation of the lunar radiance based on the ground-based observatio n
22	Mayama, Satoshi	SUBARU Near Infrared Coronagraphic Images of T Tauri
23	Calderon, Maria Morales	Variability in very low mass stars and brown dwarfs.
24	Murata, Keisuke	Infrared spectroscopic study of crystallization of chondritic amorphous silicates
25	Fukue, Tsubasa	Condensation mode of Thermal Instability in Weakly Ionized Gas
27	Nagaoka, Akihiro	Laboratory studies of the formation of interstellar molecules on grain surfaces
28	Turnbull, Margaret Carol	Planet Formation Studies and The Search For Habitable Worlds: Questions for the Next Generation of Scientists
29	Moro-Martin, Amaya	Signatures of planets in debris disks
30	Hattori, Maki	Mass loss of close-in Giant Planets
31	Okazaki, Takahide	Three-dimensional structures of dust samples captured in silica aerogel and their tracks in EuReCa using SR microtomography
32	Braiding, Catherine	Star Formation and the Hall Effect
33	Fujita, Kenta	Laboratory experiment of the stellar coronagraph for the Infrared-satellite SPICA
34	Tamanai, Akemi	Experiment al Infrared Spectroscopic Extinction Measurements of Amorphous SiO_2 particles in Aerosols
35	Matsuyama, Isamu Manuel	Rotational Stability of Dynamic Planets with Lithospheres
36	Ishitsu, Naoki	Two- Dimensional Numerical Simulations of the Shear Instability of the Dust Layer in a Protoplanetary Disk
37	Toyota, Eri	Search for extrasolar planets in binary systems.
38	Ohta, Yasuhiro	The Rossiter-McLaughlin Effect for Extrasolar Ringed Planets
39	Liu, Yujuan	Searching for planets accompany to Late G type giant stars
40	Takahashi, Keisuke	Migration mechanism of Neptune
41	Ogawa, Kazunori	Basic development of a miniaturized X-ray tube for in-situ X-ray analysis of planetary surface material
42	Takeda, Genya	Structure and Evolution of Nearby Stars with Planets
43	Vicente, Silvia	Size Distribution of Disks in the Trapezium Cluste
44	Higuchi, Arika	Formation of a Comet Cloud -Scattering of Planetesimals by a Planet-
45	Knutson, Heather	Using Stellar Limb-darkening to Improve the Radius Estimate of HD209458b
46	Fujiwara, Daisuke	Numerical Simulations of Dust Circulation in Protoplanetary Disks
47	Kobayashi, Hiroshi	Evidence of a Stellar Encounter on Edgeworth-Kuiper Belt

Upper limits on CO 4.7 micron emission from disks around five Herbig Ae/Be stars

Carmona, Gonzalez Andres

We present the results of medium-resolution spectroscop y of five nearby Herbig Ae/Be stars at 4.7 micron: UX Ori, HD 34282, HD 50138, V380 Ori, HK Ori. The goal was to search for CO fundamental ro-vibrational emission. None of the targets show CO features, either in absorption nor in emission. We derive a 5 sigma upper limit of < 10^-12 cm-2 to the column density of hot CO (T~1500 K) in the sources. These upper limits are considerably lower than the values of Herbig Ae/ Be stars for which warm and hot CO emission has been reported. The non-detection of CO v = 1-0 emission in these five targets suggest that Herbig Ae/Be stars are not a homogeneous group with respect to the structure of the gaseous disk and/or the amount of CO in the inner 50 AU of their disks.

Where are the M Dwarf Debris Disks Older than 10 Million Years?

Plavchan, Peter

We present 11.7-micron observations of nine late-type dwarfs obtained at the Keck I 10-meter telescope in December 2002 and April 2003. Our targets were selected for their youth or apparent IRAS 12-micron excess. For all nine sources, excess infrared emission is not detected. We find that stellar wind drag can dominate the circumstellar grain removal and plausibly explain the dearth of M Dwarf systems older than 10 Myr with currently detected infrared excesses. We predict M dwarfs possess fractional infrared excess on the order of $10^{-5}$ to $10^{-6}$ and this may be detectable with future efforts.

Subaru HDS Transmission Spectroscopy of the Transiting Extrasolar Planet HD 209458b

Narita, Norio

We have searched for absorption in several commom atomic species due to the atmosphere or exosphere of the transiting extrasolar planet HD 209458b, using high precision optical spectra obtained with the Subaru High Dispersion Spectrograph (HDS). Previously we reported an upper limit on H-alpha absorption of 0.1% (3 sigma) within a 5.1\AA band. Using same procedure, we now report upper limits on absorptiondue to the optical transitions of Na D, Li, H\alpha, H\beta, H\gamma, Fe, and Ca. The 3 sigma upper limit
for each transition is approximately 1% within a 0.3\AA band (the core of the line), and a few tenths of a per cent within a 2 \AA band (the full line width). The wide-band results are close to the expected limit due to photon-counting (Poisson) statistics, although in the narrow-band case we have encountered unexplained systematic errors at a few times the Poisson level. These results are consistent with all previously reported detections (Charbonneau et al. 2002) and upper limits (Bundy & Marcy 2000; Moutou et al. 2001), but are significantly more sensitive yet achieved from ground based observations.

Collisional Dust Avalanches in Debris Disks

Grigorieva, Anna

It is known from observation that dust distribution in debris disks is not always smooth and symmetric. These dust structures can provide hints on important ongoing processes in the disks and improve our understanding of the circumstellar disk evolution and planetary formation. In our study we investigate the role of so-called collisional avalanches in the disks' structure formation. Collisional avalanches are believed to be triggered by a localized disruptive event, such as the collisional breakup of a large cometary or planetesimal-like object. A fraction of the dust then produced is driven out on highly eccentric or even unbound orbits, by radiation pressure. These grains, moving away from the star with a significant radial velocities, can break-up or craterize other particles further out in the disk, creating even more small particles propagating outwards and colliding with other grains. A significant multiplication of the number of small dust grains can be expected. We have explored a large range of initial parameters and derived estimates of the changes in the dust surface densities and flux profiles induced by such processes. From these, we propose conditions under which avalanche events might be observable.

Simulating an Observational System to Search for Exoplanets in Globular Clusters

Lane, Caoilfhionn

We plan to use the transit method to search for extrasolar planets in a large sample of Globular Cluster (GC) stars. No exoplanets have been found orbiting 'normal stars' in these old, low metallicity systems. Using new L3-CCD imaging technology and image-subtraction analysis methods, we hope to overcome the inherent difficulties in imaging GCs that have hindered previous photometric surveys. To predict the limits of transit detectability for our system, we have developed a method of simulating realistic time-series images of GC starfields, using output from N-body evolutionary codes. Model transit lightcurves were added to selected stars in our GC time-series. Standard image-subtraction techniques were used to search for the transits. The recovery rates of transits involving faint stars and stars in the GC core are particularly interesting. These simulations, along with our subsequent observations, will address the question of the apparent lack of planets in GCs. Possible causes of this deficit are inhibited planet formation in low metallicity conditions, low survival rates due to dynamical encounters in these systems, or simply limitations in imaging. Using our results, we hope to evaluate these possibilities and answer fundamental questions about planetary systems.

Searching for Planets: 100 Stars at a Time

Vanden Heuvel, Andrew

At the University of Florida, we are developing a next generation precision radial velocity instrument known as the Exoplanet Tracker. The ET instrument consists of a fiber-fed Michelson interferometer followed by a medium resolution spectrograph. This design allows the instrument to observe numerous stellar spectra simultaneously with high radial velocity precision. We have recently completed a feasability study at the Sloan 2.5m telescope demonstrating multi-object capabilities by observing ~15 stars simultaneously at high RV precision (<30m/s). We are currently developing the prototype full-scale instrument which will be capable of searching 100 stars simultaneously for extrasolar planets.

Giant Proto-Planets in arbitrary nebulae

Broeg, Christopher

In the core accretion model, it is assumed that giant planets form around a solid core which builds up a gaseous envelope. Up to the so-called static critical core mass, beyond which no equilibrium state exits, the accretion process is usually found to proceed quasi-statically, i.e. accretion takes place in a sequence of equilibrium states.

Dynamic calculations are very time-consuming and require specific environmental conditions , such as nebula densities, temperatures, and so on. As more and more extrasolar planets and circumstellar disks are discovered, it appears that there is a wide range of possible nebulae in which planets form. Therefore it is very difficult if not impossible to specify "correct" nebula conditions for dynamic calculations.

Consequently, we chose a statistical approach: By studying all allowed equilibria that are the progenitors of mature planets, we can make predictions about the formation and possibly relative numbers of giant planets. Using the relative frequency of progenitor states in combination with an ensemble of nebula models, the final states can be predicted statistically.

Orbital Evolution of Hot Jupiters with Atmosphere Blow-off

Inhomogeneous Temperature Distribution in Chondrules in the shock-wave heating model

Yasuda, Seiji

Chondrules are millimeter-sized, once molten, spherical shaped objects contained in chondritic meteorites. It is considered that dust particles in the solar nebular were heated and melted through flash heating events, cooled again, and formed chondrules.

There are various studies for chondrule formation in the framework of the shock wave heating model (one of the plausible models for chondrule formation). Although almost all studies assumed that dust particles melt spatially homogeneously, in recent years, some researchers notice the effects of inhomogeneous melting. For example, Kadono and Arakawa 2005 experimentally examined breakup of liquid on the dust particle. In order to investigate the inhomogeneous melting, it is important to take into account the heat transfer in dust particles.

We calculate that the temperature distribution in the dust particle heated by the shock-wave heating event by numerically solving the time-depending three-dimensional heat conduction equation, and investigate how the dust particle begins to melt.

We find that the temperature distribution in the dust particle heated is generally inhomogeneous and the dust particle starts melting from surface of it. And more, the spatial structure of temperature distributions depends on the radius and rotational velocity of the dust particle and the condition of shock waves.

Search for Exoplanets and Variables in the Open Cluster, NGC381

Hu, Juei-Hwa

We present the result of the search for exoplanets and variable stars in the open cluster star fields, NGC 381, with the Lulin One-meter Telescope (LOT), Taiwan. The main scientific goal is to use time series CCD photometry measurements to detect exoplanets via transit effects. Observations of open clusters would give us important information on the formation of planets in different stellar environments. The secondary scientific goal is to discover and study variable stars with the similar data analysis process. From our preliminary analysis, two variables were discovered in the NGC 381 star field. They were identified as the suspected cluster members, CT 122 & CT 123, by Crinklaw & Talbert, 1988. We will also report on the most recent progress made including the installation of a 40-cm telescope for robotic exoplanets observations at Lulin.

Across the Transition Age: Protostellar Disk Evolution at ~6 and 55 Myr

Siegler, Nick

We present preliminary results from a Spitzer Space Telescope study of disk evolution in two young open clusters of different ages - ~6 and 55 million years. By measuring the emitted infrared flux from cluster members at different wavelengths we can measure the fraction of stars possessing disks, characterize the disk type, and in certain cases, infer the possible presence of planets. By conducting this investigation in ~20 young open clusters spanning ~3-150 million years, we will eventually better understand how disks evolve, around which types of stars, and the constraints these results will place on planetary system formation.

IC 2395 is a poorly-studied cluster ~2600 light years away. We reveal for the first time the pre-main sequence population and confirm a cluster age of 5-10 million years. The analysis is ongoing; however, initial results are painting a tantalizing picture of a cluster in transition revealing evidence for both accretion and debris disks. IC 2391 is among the closest open clusters at ~470 light years and is older at ~55 million years. We report initial results searching for evidence of more evolved planetary systems as revealed by regenerated dust emission from collisions between protoplanetary objects, similar to the Earth/Moon event.

Giant Planet Migration Through Disk Torques and Planet- Planet Scattering

Moorhead, Althea

We present a parametric study of giant planet migration through the combined action of disk torques and planet-planet scattering. The torques exerted on planets during Type II migration in circumstellar disks readily decrease the semi-major axes a, whereas scattering between planets increases the orbital eccentricities. We present a parametric exploration of the possible parameter space for this migration scenario using two initial planetary mass distributio ns and a range of time scales for eccentricity damping due to the disk. For each class of systems, we perform hundreds of simulations in order to determine orbital element distributions of surviving planets. Our goal is to study the physics of this migration mechanism and to test it against observations of extrasolar planets. Our mechanism results in a distribution of final orbital elements that fills the a-e plane, in rough agreement with the observed distributions. We also investigate distributions of inclination angles of surviving planets, ejection speeds for exiled planets, system end states, and time spent in resonances.

Infrared Studies of Circumstellar Dust Grains around Vega- like Stars

Huang, Hsiang-Fu

Sun-like stars are known to have circumstellar disks left over from the star or planet formation processes. The class of Vega-like stars, including Vega and Beta Pictoris, are massive stars with much shorter evolutionary timescales, more destructive stellar radiation and stellar winds than sun- like stars. These stars are also thought to possess debris star-forming material or even planets, so study of these young disks may shed light on early planet formation. Here we report our studies of the spectral energy distribution (SED) of the Vega-like stars from optical to far-infrared wavelengths, including possible infrared molecular line features, to investigate how the dust grains around these stars might have agglomerated to grow versus disperse away during early stellar evolution.

The transneptunian region architecture: revelations from observations and theoretical results

Lykawka, Patryk Sofia

A myriad of bodies orbiting beyond Neptune represents leftovers after planetary formation. These transneptunian objects (TNOs) offer important clues on the origin and evolution of the solar system. We probe the transneptunian region by comparing up-to- date observations with our theoretical results, which consist of dynamical features (4-5Gyr simulations) and physical properties (statistical analysis). Our main results are:

The classical region is structured in inner (a<45AU) and outer (a>45AU) portions with inclination dependence. For the former, bodies suffer severe dynamical sculpting, especially those with low inclinations and/or associated with the 5:3, 7:4 and 9:5 resonances. In the outer portion, except near the 2:1 resonance, stable regions are abundant. Finally, there is an anomalous preference of large classical TNOs at a<43.5AU strengthening the dual radial configuratio n of the classical region. Other peculiarities are also discussed;

Scattered TNOs' evolution is determined by resonance sticking, including extended ones' (q>40AU) if trapping in p:1 or p:2 resonances happened and lasted longer than 3Gyr;

Large TNOs have albedos greater than the long assumed p=0.04 and increasing with size. Since all big bodies (>700km) would be able to sustain icy frosts or thin atmospheres composed of CH4, CO or N2, surface rejuvenation could explain the observed higher albedos.

Oxidation of carbon compounds by oxygen released from SiO2 within large impact-induced vapor clouds

Ishibashi, Ko

Hypervelocity impacts on the surface of terrestrial planets generate impact-induced vapor clouds. Chemical reactions within impact-induced vapor clouds may be important for the surface environment of planets. However, chemical reactions within vapor clouds are not well understood. In particular, chemical interactions between silicates and carbon compounds have not been studied extensively. Most theoretical studies on chemical reactions within vapor clouds neglect the effect of oxygen released from silicates because no detailed knowledge exists on the behavior of silicates within vapor clouds. In addition, silicates are thought to condense at high temperatures and do not contribute to the reactions of carbon compounds. However, laser irradiation experiments on rocks and chondrites by Mukhin et al. (1989) show that the resulting gases were composed mainly of the oxidized species (CO and CO2). They propose that oxygen from silicates may oxidize carbon. However, since such an oxidation process has not been investigated in detail, we cannot tell whether oxygen from silicates reacts with carbon. In this study, we investigate the oxidation of carbon compounds by oxygen released from SiO2 within vapor clouds generated by a laser-pulse heating on SiO2-polyethylene targets. The results show that oxygen from SiO2 combines with carbon.

Evolution of isotopic and chemical composition in the early inner solar nebula due to fluctuation of mass accretion rate

Mid-infrared spectroscopy of Herbig Ae/Be stars

Fujiwara, Hideaki

We have carried out mid-infrared N-band spectroscopic observations of 15 Herbig Ae/Be stars with the Cooled Mid-Infrared Camera and Spectrometer on the 8.2 m Subaru Telescope. We made the compositional model fitting to the obtained specra and derived the contributions of sub-micron-sized amorphous silicate, micron-sized amorphous silicate, crystalline forsterite, crystalline enstatite and polycyclic aromatic hydrocarbon. The fitting results of most sample stars show the crystallinity of circumstellar silicate of 10~40% and no dependence of the crystallinity on the stellar age was found. This indicates that dust crystallization has already started in very early stages of the pre-main sequence, for example, before the stellar age turns 1 Myr.

Numerical Simulation of the Gravitational Instability in the Dust Layer of a Protoplanetary Disk under the Assumptions of the Axisymmetry using the One-Fluid Model of the Dust and the Gas

Yamoto, Fumiharu

The formation of planetesimals through the gravitational instability is investigated. This work treats the nonlinear evolution after the dust layer exceeds the critical density of the gravitational instability. As a first step of the research, the dust layer is assumed to be axisymmetric. Dust radii are assumed to be smaller than 1cm so that the dust and the gas couple firmly, and the one-fluid model is used. A Gaussian initial density distribution vertical to the midplane is assumed. The radial pressure gradient of the unperturbed state is assumed to be zero, i.e. the region where the pressure is maximum with respect to the radial distance from the central star is supposed (Haghighipou r and Boss, 2003), because the shear instability inhibits the dust settling and the dust density never reaches to the critical value of the gravitational instability for the typical value of the radial pressure gradient.

The following results are obtained: (1) The initial development of the instability agrees well with the linear solution of the gravitational instability by Yamoto and Sekiya (2004). (2) The gravitational and the Coriolis forces vary smoothly, but the pressure gradient force varies abruptly depending on the density.

Chondrule formation by X-ray flare induced shock waves

Baroclinic Instability as a source for Jupiter's zonal Jets

The estimation of the lunar radiance based on the ground- based observation

Saito, Kimiko

The estimation of the absolute radiance of the moon by a ground- based observation is presented and the accuracy of our estimated lunar radiance is discussed. A Japanese lunar orbiter SELENE carrying 13 scientific instruments is scheduled to be launched in 2007. To determine the exposure time of its optical instruments, a lunar absolute radiance is necessary. We observed the moon in Osaka with a telescope equipped with a cooling CCD camera and a 650nm band-pass filter. The earth atmosphere scatters and absorbs the moonlight, so the atmospheric correction is indispensable. We observed some fixed stars to obtain an atmospheric absorption coefficient. After the atmospheric correction with the coefficient and photometric correction which removes the effects of observation geometry, the absolute radiance and the reflectance of the lunar surface was derived. Our reflectance data suggest that the lunar reflectance image obtained by Clementine lunar orbiter are too bright.

SUBARU Near Infrared Coronagraphic Images of T Tauri

Mayama, Satoshi

For better understanding of the enigmatic natures of a T Tauri star, T Tau and its circumstellar structures, high angular resolution near-infrared (JHK) adaptive optics images of T Tau were obtained with the Subaru 8.2m Telescope and an infrared camera, CIAO in 2002 and 2004. Our high-resolution, high-contrast and relatively deep observations made us detect the inner and dense region of a complex circumstellar structure around a multiple system T Tau. The structure within 300 AU is interpreted as an asymmetric warped circumbinary disk or inner part of the envelope which encompasses whole multiple system T Tau. Cavity structure is also detected along the axis of P.A.~300 degree. We also successfully resolved T Tau N and S as well as T Tau Sa and Sb. The curvature and orientation of path of T Tau Sb probably indicate that it has been, and is still, bound to T Tau Sa. The flux of T Tau S at the time of our observations in 2002 obviously decreased in the K band by about 1.7 Jy since 2001. The flux decrease of the whole T Tau S system from 2000 to 2002 is mainly caused by T Tau Sa.

Variability in very low mass stars and brown dwarfs.

Calderon, Maria Morales

We present the results of the optical and NIR photometric observations of the Pleiades (125 Myr) and the Collinder 69 (5 Myr) clusters. The aim of this research is to look for variability, both due rotation and eclipsing binaries. We have used differential photometry and a statistical analysis of the data in R,I,J bands and white light. We have found variability in the Pleiades cluster with amplitudes of about 50mmag without filter, and in Collinder 69 with amplitudes of about 70mmag with uncertainties of 5 mmag until Imag=17.9, in both cases well within the brown dwarf regime. The data in the J band, corresponding to the Collinder 69 cluster, has allowed us to explore the variability in the planetary mass domain.

Infrared spectroscopic study of crystallization of chondritic amorphous silicates

Murata, Keisuke

We will report infrared absorption spectra of amorphous silicate with chondritic composition and their spectral variation involved with annealing process.

The initial amorphous sample was synthesized by Sol-Gel method that has an advantage to get homogeneous amorphous materials at relatively low temperature without dilution of volatile elements. Annealed samples with different crystallization degree were prepared from the initial sample for infrared absorption spectroscopy. The measurements were carried out by use of FT-IR spectrometer (Nicolet Nexus 670) at Kyoto Pharmaceutical University. The measured wave number range and resolution were 7000-50 cm-1 and 1.0 cm-1, respectively.

On the spectrum of the initial amorphous sample, broad and smooth absorption features appeared at approximately 10 and 20 micro meters, that are typical for amorphous silicate originated from Si-O stretching and O-Si-O bending vibration modes. While on the spectra of annealed samples, sharp and prominent features appeared.

We will discuss the spectral behavior with crystallizat ion degree and difference of spectral features from previous works.

Condensation mode of Thermal Instability in Weakly Ionized Gas

Fukue, Tsubasa

Thermal instability in weakly ionized gas is investigated with linear analysis. We assume that the gas consists of neutral gas and ion gas. We find that magnetic field can suppress thermal instability of even weakly ionized gas. The instability of ion gas is directly suppressed by magnetic field, and the instability of neutral gas can be also suppressed through dragging of ion gas suppressed by magnetic field. And the effect of dragging of the components does not affect critical length of thermal instability at all. The effect is mainly suppression of instability. We also confirm the scale length at maximum growth rate of the instability diminishes as the growth rate diminishes with suppression , even if we think of thermal instability in weakly ionized gas.

Laboratory studies of the formation of interstellar molecules on grain surfaces

Nagaoka, Akihiro

Simple organic molecules, formaldehyde (H2CO) and methanol (CH3OH), have been observed in some comets and interstellar ices. The gas-phase production and subsequent freeze on to cold interstellar grains is insufficient to explain the observed abundances in interstellar ices and thus surface processes such as atom-molecule surface reactions on cold (~10 K) grains are required to produce these molecules. Theoretical models have suggested that the successive hydrogenation of CO on a grain-surface; CO -> HCO -> H2CO -> CH3O -> CH3OH, is a key process to produce H2CO and CH3OH in dense molecular clouds where photon field is very weak. Employing a cold atomic hydrogen (H) beam apparatus, we demonstrated experiment ally for the first time that H2CO and CH3OH are produced efficiently by the hydrogenation of CO on interstellar grain analogues at 10-20 K. Under the appropriate experimental conditions representing the chemical and physical conditions of molecular clouds, the obtained yields of H2CO and CH3OH are fairly consistent with observations of comets and molecular clouds.

Recently, deuterium (D) fractionation in formaldehyde and methanol was found in molecular clouds and some comets. For example, the ratios of deuterated species to normal counterparts in low-mass protostar IRAS16293-2422 are up to approximately 0.2 and 0.4 for formaldehyde and methanol, respectively. Although several models have been proposed to reproduce the D- fractionations in formaldehyde and methanol, these are somewhat ambiguous due to the lack of information regarding grain-surface reactions (e.g., reaction channels and the rates of hydrogenation/deuteration). It is therefore highly desirable to clarify experimentally the role of the surface reactions in D-fractionations. We report our experimental results demonstrating that the H-D substitution in solid methanol proceeds more efficiently than successive H and D addition to solid CO to produce deuterated methanol at 10 K. These results indicate a key route for deuteration of methanol on icy grains, which could explain the observed abundance of deuterated methanol isotopologues in molecular clouds.

References: Watanabe, N., Nagaoka, A., Shiraki, T., & Kouchi, A., ApJ, 616, 638 (2004); Nagaoka, A., Watanabe, N., & Kouchi, A., ApJL, 624, L29 (2005)

Planet Formation Studies and The Search For Habitable Worlds: Questions for the Next Generation of Scientists

Turnbull, Margaret Carol

Planetary science is quickly expanding its scope throughout the Solar Neighborhood and Galaxy, and credit for this is due almost entirely to the success of radial velocity searches for giant exoplanets. However, the driver for this line of inquiry is to find out: How common are Earth-like, habitable worlds in the Galaxy? In terms of planet formation theory, that question becomes many questions: Does habitable terrestrial planet formation require the prior formation of giant planets in particular orbits? How does overall metallicity affect the planet formation process? How do specific abundance ratios, e.g. silicon: carbon, determine the nature (and habitability) of resulting terrestrial planets? Is it possible to create a "giant terrestrial" planet? Are the metallicity and abundance ratio gradients throughout the Galaxy significant enough to create a "frequency gradient" of habitable worlds? How many stars escape their formation clusters with a full set of planets? Can habitable worlds form within binary star systems, and if so, how does that depend on binary orbital parameters? These questions, and discoveries by upcoming planet search missions, will encourage the next generation of "planetary astrophysicists" to look wholistically at "star + planet" systems. This poster is a collection of ideas presented in the recent literature regarding many of the above contemplations.

Signatures of planets in debris disks

Moro-Martin, Amaya

Main sequence stars are commonly surrounded by debris disks, composed of cold far-IR emitting dust presumably generated by a reservoir of undetected dust-producing planetesimals. In debris disks harboring massive planets, the trapping of dust in gravitationa l resonances with the planet creates a density enhancement in a ring-like structure outside the orbit of the planet, while gravitational scattering with the planet creates a clearing of dust inside the planet's orbit. Massive planets, therefore, can create structure in the dust disk, and the study of this structure can help us survey a range of planetary parameters that are not detected by other methods. The Spitzer infrared space telescope has began to obtain spatially unresolved spectrophoto metric observations of many potentially diverse debris disk systems with embedded planets. In this talk, we will briefly summarize some of these results. In view of these observations we will discuss how the structure carved by massive planets affects the shape of a debris disk's spectral energy distribution (SED), and consequently how the SED may be used to infer the presence and properties of planets. However, we will see that the SED modeling presents some degeneracies that can only be broken if spatially resolved images of the dust disks are obtained.

Mass loss of close-in Giant Planets

Hattori, Maki

In 2003 Vidal-Madjar et. al. announced the discovery of an extended atmosphere for HD209458b reaching beyond the Roche Lobe of the planet. Thus, the hydrogen atmosphere is not bound to the planet and can consequently be thought of as escaping. Close-in planets, such as HD209458b, are highly affected by the XUV flux of the central star and this energy flux can be translated into a mass loss rate for these planets. This mass loss implies that there must be a threshold mass, below which a planet would not remain stable on Gigayear timescales. We have established minimum stable masses for different distance close-in planets and have defined some important criteria for the definition of these stable masses.

Three-dimensional structures of dust samples captured in silica aerogel and their tracks in EuReCa using SR microtomography

Star Formation and the Hall Effect

Braiding, Catherine

The magnetic field in molecular clouds provides pressure support against gravity and carries away angular momentum prior to and during the collapse of cloud cores into protostars. The effect of Hall diffusion on the breakdown of flux freezing within the clouds has not been examined in previous models of gravitational collapse, where the effect of the magnetic field is usually approximated by ambipolar diffusion at low densities or resistive diffusion at high densities. The Hall effect has been shown to control the evolution of the magnetic field in molecular gas, and is expected to alter the dynamics of gravitational collapse.

This poster presents the first results from a model of the self-similar collapse of rotating isothermal molecular cloud cores with a full conductivity tensor.

Laboratory experiment of the stellar coronagraph for the Infrared-satellite SPICA

Experimental Infrared Spectroscopic Extinction Measurements of Amorphous SiO_2 particles in Aerosols

Akemi Tamanai 1 ,Harald Mutschke 1 , Jurgen Blum 2

2. Institut fur Geophysik und Extraterrestrische Physik, Technische Universitut Braunschweig, Mendelssohnstr. 3, D-38106 Braunschweig, Germany

The infrared absorption and scattering (extinction) properties of small solid grains plays an important role for controlling the thermal balance in astrophysical environments such as protoplanet ary accretion disks, molecular clouds, the interstellar medium and atmospheres of stars. Extinction features are strongly influenced by morphological aspects of grains (particle size, shape and agglomeration). In our project, we have experimentally investigated the morphological effect of clustering of amorphous silica ( SiO_2 ) and measured the infrared extinction spectra of particles dispersed in aerosols between 2 mm and 25 mm in wavelength. Particularly, the morphological effects of 9.0 mm band in the infrared region have been examined by using the spherical SiO2 particles of 0.5, 1.0, and 1.5 mm in diameter. We compare the experimental results with three different theoretical calculations (Mie, T-matrix, and DDA) for aggregates of spherical silica grains.

Rotational Stability of Dynamic Planets with Lithospheres

Matsuyama, Isamu Manuel

We revisit the classic problem of the long-term rotational stability of planets in response to loading using a new, generalized theoretical development based on the fluid limit of viscoelastic Love number theory. Willemann (1984) treated axisymmetric loads and concluded that the equilibrium pole location was governed by a balance, independent of elastic lithospheric thickness, between the load-induced true polar wander (TPW) and stabilization by the remnant bulge. Our new analysis extends Willemann's (1984) study in several essential ways. First, the generalized theory demonstrates that the equilibrium pole position is a function of the lithospheric strength, with a convergence to Willemann's (1984) results evident only at very high values of elastic thickness, and significantly larger predicted TPW for planets with thin lithospheres. Second, we derive equations governing the stability of the rotation pole in the case of non-axisymmetric surface mass loads and internal (convective) contributions to the non-hydrostatic inertia tensor. We find that such contributions, even when they are small relative to axisymmetric contributions, can profoundly influence the rotational stability. Indeed, we demonstrate the relatively permissive conditions under which non-axisymmetric forcing initiate a so-called inertial interchange TPW (IITPW) event. These results suggest that Willemann's (1984) axisymmetric load analysis significantly underestimates the potential excursions of the planetary rotation vector. Finally, Willemann's (1984) analysis is often cited to argue for a small (<18deg) TPW of Mars driven by the development of a Tharsis-sized load. We demonstrat e that, even in the absence of the above-noted destabilizing effects of load asymmetry, the equations governing the rotational stability permit higher excursions of the Martian rotation vector than has previously been appreciated.

Two-Dimensional Numerical Simulations of the Shear Instability of the Dust Layer in a Protoplanetary Disk

Ishitsu, Naoki

Gas tends to revolve around with sub-Kepler velocity due to the pressure gradient. On the other hand, dust tends to revolve with Kepler velocity. If the gas and dust exert the drag force each other, their velocity depends on the dust to gas spatial density ratio. Thus shear arises in the dust layer if the dust aggregates settle down. Then the shear instability can occur in the dust layer. If so, there is the possibility that flow transits to turbulent. Turbulence stirs up the dust aggregates from the midplane. Thus, the planetesimal formation due to the gravitational instability can not occur.

It is important to investigate the vertical dust density distribution after the shear instability in order to know how the planetesimals are formed. In this work, we perform two- dimensional numerical simulations of shear flows in the dust layer. We confirmed that the dust is stirred from dust layer by turbulence due to the shear instability and then the dust density distributions reach quasi-static distributions.

Search for extrasolar planets in binary systems.

Toyota, Eri

Among 150 extrasolar planets discovered to date, about 20 planets exist in multiple star systems. This scarcity of the extrasolar planets in multiple star systems prevent us from discussing about the differences between planets found in single stars and in multiple star systems. For example, the probability of planetary occurrence,orbital characteristics, such as the mass-period and the eccentricity-period distribution. It is suggested that there are some differences in orbital characteri stics at the above distributions from observational results. As described in the beginning, the lack of samples prevent us from conducting statistical debate. It is important to increase the number of planets in binary systems. We have started a search for extrasolar planets in binary systems by precise Doppler shift measurements from 2003, using the HIgh Dispersion Echelle Spectrograph(HIDES) at Okayama Astrophysical Observatory. We here report the current status of the survey and future work.

The Rossiter-McLaughlin Effect for Extrasolar Ringed Planets

Ohta, Yasuhiro

A transiting extrasolar planet sequentially blocks off the light coming from the different parts of the disk of the host star. Because of the spin of the star, this produce a distortion in the line profiles of the stellar spectrum, leading to an apparent anomaly in the radial velocity curves, known as the Rossiter-McLaughlin effect. If the planet has a large ring, there are additional effects comes from the planetary ring. We discuss the detection and characterization of the ringed planets using the Rossiter- McLauglin effect.

Searching for planets accompany to Late G type giant stars

Liu, Yujuan

Searching for planets around stars heavier than the Sun (i.e., ~2-3 solar masses) has some special meaning, because the lifetime of surrounding disk of intermediate-mass may difference to solar-mass stars' (Haisch et al. 2001a, 2001b), and the existence of gas giant planets around such stars would constrain the timescale of formation of gas giant planet. Such survey will test the true value of the disk instability scenario, where planets can form in the time of thousands of years (Boss 1998).

Dr. Sato et al. began to search for planets around late- G giants using the High Dispersion Echelle Spectrograph (HIDES, Izumiura 1999) on the 1.88m telescope at Okayama Astronomical Observatory (OAO). And following we start a joint project with them. They help us install an iodine-cell filter for Xinglong 2.16m telescope, which has been used to detect planetary system from the end of 2004.

In this Kobe International School of planetary sciences I would like to give the preliminary result of the spectrum we took on October 2004.

Migration mechanism of Neptune

Takahashi, Keisuke

An outward orbital migration of Neptune in early solar system history provides an efficient mechanism for shortening the planet growth time as well as sweeping up large numbers of Trans-Neptunian objects into Neptune's mean-motion resonances. Though several works about migration of Neptune have been done, its hard to apply other planetary system because of their restricted initial condition. We investigate the basic mechanism of orbital migration in two situation. That are one giant planet and planetesimals (restricted 3-body calculation), and two giant planets and planetesimals (restricted 4-body calculation). They revolves around the Sun within a swarm of planetesimals. We numerically integrated the orbital evolution of planetesimals with various or bital elements and find net angular momentum exchange. In the 3-body calculations, because of the difference of the synodic period and having eccentrici ty, effe cts from inner planetesimals and outer planetesimals are different. In the 4-body calculations also has feature of 3-body calculations. And added pl anet works like 'remover'. Planetesimals around Neptune are scattered and stocha stically increase their eccentricities. Some of them are finally scattered by J upiter and remove from feeding zone of Neptune. This effect pushes the planet o utward. By comparing the results of these two simulations, we can extract the ef fects of added planet. In our presentation, we will show these results and outline of the fomulation method of angular momentum that Neptune obtains at unit time.

Basic development of a miniaturized X-ray tube for in-situ X-ray analysis of planetary surface material

Ogawa, Kazunori

Japan Aerospace Exploration Agency (JAXA) started to plan SELENE-2 lunar lander mission. We have planned a XRF/XRD (X-ray fluorescence Spectrometer / X-ray Diffractometer) X-ray probe analyzer to be carried on SELENE-2 to investigate mineralogical characteristics on the lunar surface materials. This instrument requires X-ray tubes as a X-ray probe source to be operation. However, X-ray tubes have never been carried on previous spacecraft because of its large mass and size. In this study, we search the possibility of the carbon nanotube (CNT) based field emission (FE) type miniaturized X-ray tube (CNT-FE X-ray tube) to be carried on the spacecraft as a probe source of the X-ray analyzer. The objective of this study is to validate possibility of CNT-FE X-ray tube to be carried on spacecraft by experimental methods.

Structure and Evolution of Nearby Stars with Planets

Takeda, Genya

The California and Carnegie Planet Search has obtained high-quality (R = 70000-90000, S/N = 3-500) echelle spectra of over 1200 nearby stars taken with the Hamilton spectrograph at Lick Observatory, the HIGHRES spectrograph at Keck, and UCLES at the Anglo-Australian Observatory. Combining various observations with spectral synthesis modeling permits precise determinations of Teff, v sin(i), log(g), and several metal abundances which allow us to derive the physical parameters of these stars. For the theoretical derivation of model stellar parameters, we use the Yale stellar evolution code (YREC). YREC evolves a star through a sequence of models of increasing age, solving the stellar evolution equations for interior profiles such as chemical composition, pressure, temperature, density and luminosity. Using YREC, we create an extensive collection of stellar evolutionary models, and we combine our fine grid of stellar evolutionary tracks with the spectroscopic observations and Hipparcos data to derive physical stellar parameters of interest, such as masses, radii, ages, and size of the convective envelope. Derived stellar parameters are then carefully analyzed using the Bayesian probability theory to avoid systematic biases and produce reliable probability distribution functions. We apply this method for more than 1000 observed stars to explore the physical properties of stars hosting planets.

Size Distribution of Disks in the Trapezium Cluster

Vicente, Silvia

In this poster I will present results on the size distribution of circumstellar disks in the Trapezium cluster as measured from HST/WFPC2 data. Direct diameter measurements of a sample of 135 bright proplyds and 14 silhouettes disks suggest that there is a single population of disks well characterized by a power-law distribution with an exponent of -1.9 +- 0.3 between disk diameters 100--400 AU. For the stellar mass sampled (from late G-- --to late M stars) we find no obvious correlation between disk diameter and stellar mass. We also find that there is no obvious correlation between disk diameter and the projected distance to the ionizing Trapezium OB stars.

We estimate that about 40\% of the disks in the Trapezium have radius larger than 50 AU. We suggest that the origin of the Solar system's (Kuiper belt) outer edge is likely to be due to the star formation environment and disk destruction processes (photoevaporation, collisions) present in the stellar cluster on which the Sun was probably formed.

Formation of a Comet Cloud -Scattering of Planetesimals by a Planet-

Higuchi, Arika

We investigated the first dynamical stage of comet cloud formation, scattering of planetesimals by a planet. The orbits of planetesimals were calculated using circular restricted three-body formalism. We obtained the probabilities of results of scattering as functions of orbital parameters of planets and planetesimals: (a)collision with the planet, (b)escape from the planetary system, and (c)candidacy for a member of the comet cloud (planetesimals with large semimajor axes). We also derived the simple empirical formulas of these probabilities, which are accurate enough for order of magnitude estimation. We found that a planetesimal with an initial eccentricity of $e\gtrsim0.4$ can escape from the planetary system or be a candidate for an element of the comet cloud due to scattering by a planet. As the energy range of the comet cloud is narrow, the probability of any planet producing escapers is always much higher than that of producing candidates. Using the probabilities and assuming the distribution of planetesimals, we obtained the efficiencies of collision, escape, and candidacy for the planet. We applied the results to the solar system and found that, among the four giant planets, Jupiter is the planet most responsible for producing candidates for elements of the Oort cloud among the four giant planets, as far as the inclination of planetesimals is constant or proportional to the reduced Hill radius of each planet.

Using Stellar Limb-darkening to Improve the Radius Estimate of HD209458b

Knutson, Heather

The transiting planet HD209458b has an unusually large radius relative to its mass. Current structural models of hot Jupiters cannot explain this radius without some form of external heating, either in the form of perturbations by a second smaller planet, tidal forces produced by the inclination of the planet's orbit relative the equatorial plane of its host star, or the conversion of incident stellar radiation into kinetic energy in the form of winds. In order to resolve this uncertainty, it is important to have a precise measurement of the radius of HD209458b. In this work we use data obtained with the STIS spectrometer on the Hubble Space Telescope covering the 290-1030 nm wavelength range. We divide the spectrum into multiple bandpasses and fit a transit curve in each bandpass using theoretical limb-darkening coefficients from model stellar spectra. This allows us to break the degeneracy between stellar and planetary radii and obtain multiple independent estimates for the radius of the planet. We then combine these measurements to obtain a measurement of the planet's radius with a significantly lower error than previous measurements.

Co-authors: D. Charbonneau (Harvard-Smithsonian Center for Astrophysics), R. Noyes >(Harvard-Smithsonian Center for Astrophysics), T. Brown (National Center for Atmospheric Research), and R. Gilliland (Space Telescope Science Institute)

Numerical Simulations of Dust Circulation in Protoplanetary Disks

Fujiwara, Daisuke

The meter-sized particles rapidly fall into the central star due to the gas drag force, before planetesimal formation. Thus, some mechanisms moving the particles outward are required for planetesimal formation. We consider the stellar radiation pressure induced the dust outflow for a weak turbulent disk with a puffed-up inner rim, where the gas convection is induced because of a steep radial temperature gradient. Our main objective is to show the dust circulation in the protoplanetary disk. We find that in the shadowed region the outflow mass flux at the surface layer of the disk is comparable to the inflow mass flux at the disk interior, i.e. dust circulation is realized. Further, the outflow flux at the surface layer becomes a quasi-steady state on a short timescale. Therefore, we show that the steady surface density of the particles is enhanced in the inner shadowed region due to dust circulation. Their enhanced abundance may cause planetesimal formation.

Evidence of a Stellar Encounter on Edgeworth-Kuiper Belt

Kobayashi, Hiroshi

We investigate the influence of a stellar fly-by encounter on the Edgeworth-Kuiper belt objects through numerical orbital calculations, in order to explain both mass depletion and high orbital inclinations of the classical Edgeworth-Kuiper belt (CEKB) objects, which have semimajor axis of 42--48AU and perihelia beyond 35AU. The observationally inferred total mass of the CEKB is $\sim 1/10$ Earth masses, which is only $\sim 0.02$ of that extrapolated from the minimum-mass solar nebula model. The CEKB consists of bimodal population: ``hot population'' with inclinations $i \simeq 0.2$--0.6-- --radians and ``cold population'' with $i \simeq 0.1$. The observationally suggested difference in size and color of objects between the two populations may imply different origins of the two populations. We find that both the depletion of solid materials in the CEKB and the formation of the hot population are accounted for by a single close stellar encounter with pericenter distance of 80--100AU and inclination relative to the initial protoplanetary-- --disk $\simeq 50^{\circ}$-$70^{\circ}$. Such a stellar encounter highly pumps up eccentricities of most objects in the CEKB and then their perihelia migrate within 35AU. These objects would be removed by Neptune's perturbations after Neptune is formed at or migrates to the current position (30AU). Less than 10\% of the original objects remain in stable orbits with small eccentricities and perihelion distances larger than $35$AU, in the CEKB, which is consistent with the observation. We find that $i$ of the remaining objects are as large as that of the observed hot population. The only problem is how to stop Neptune's migration at $\sim 30$AU, which is addressed in a separate paper. The depletion by the stellar encounter extends deeply into $\sim 30$--35AU, which provides the basis of the formation model for the cold population through Neptune's outward migration by Levison and Morbidelli (2003, {\it Nature} {\bf 426}, 419-421). The combination of our model with Levison \& Morbidelli's model could consistently explain the mass depletion, truncation at 50AU, bimodal distribution in $i$, and differences in size and color between the hot and the cold populations in the CEKB.