bluuebunny/crossref_metadata_2025 huggingface dataset:
Helical Tomography of an Accretion Disk by Superhump Light Curves of the 2001 Outburst of WZ Sagittae
Authors: Osaki Yoji
Published: March 2014

A new method for analyzing complex superhump light curves for the 2001 outburst of WZ Sagittae is proposed. The complexity arises because intrinsically time-varying and non-axisymmetric distributions of superhump light sources are coupled with the aspect effects around the binary orbital phase because of its high orbital inclination. The new method can disentangle these complexities by separating the non-axisymmetric spatial distribution in the disk from the time variation with the superhump period. It may be called a helical tomography of an accretion disk because it can reconstruct a series of disk images (i.e., disk’s azimuthal structures) at different superhump phases. The power spectral data of superhump light curves of the 2001 outburst of WZ Sge by Patterson et al. (2002, PASP, 114, 721) are now interpreted under a new light based on the concept of helical tomography, and the azimuthal wave numbers of various frequency modes are identified. In particular, a frequency component, $n\omega_0-\Omega$, where $\omega_0$ and $\Omega$ are the orbital frequency and a low frequency of the apsidal precession of the eccentric disk, is understood as an $(n-1)$-armed traveling wave in the disk. A vigorous excitation of a wave component of $\cos(2\Theta-3\omega_0 t)$ in the first week of the superhump era of WZ Sge, where $\Theta$ is the azimuthal angle, supports Lubow’s (1991, AAA 54.064.175) theory of non-linear wave coupling of the eccentric Lindblad resonance for the superhump phenomenon. This method can in principle be applied to other SU UMa stars with high orbital inclination if light curves are fully covered over the beat cycle.
Possibility of the Presence of S, SO2, and CO2 at the Poles of the Moon
Authors: Berezhnoy Alexey A. , Hasebe Nobuyuki , Hiramoto Takuji , Klumov Boris A.
Published: March 2014

The presence of volatiles near the lunar poles is considered. The chemical composition of a lunar atmosphere temporarily produced by comet impact is analyzed during the day and night. C-rich and long-period comets are insufficient sources of water ice on the Moon. O-rich short-period comets deliver significant amounts of $\mathrm{H}_{2} \mathrm{O}$, $\mathrm{CO}_{2}$, $\mathrm{SO}_{2}$, and S to the Moon. An observable amount of polar hydrogen can be delivered to the Moon by a single impact of an O-rich short-period comet with diameter of 5 km in the form of water ice. The areas where $\mathrm{CO}_{2}$ and $\mathrm{SO}_{2}$ ices are stable against a thermal sublimation are estimated to be 300 and $1500 \,\mathrm{km}^{2}$, respectively. If water ice exists in the 2 cm top regolith layer, $\mathrm{CO}_{2}$ and $\mathrm{SO}_{2}$ ices can be stable in the coldest parts of permanently shaded craters. The delivery rate of elemental sulfur near the poles is estimated to be $10^{6} \,\mathrm{g} \,\mathrm{yr}^{-1}$. The sulfur content is estimated to be as high as 1 wt% in the polar regions. The SELENE gamma-ray spectrometer can detect sulfur polar caps on the Moon if the sulfur content is higher than 1 wt%. This instrument can check the presence of hydrogen and minerals with the unusual chemical composition at the lunar poles.
The First Radioastronomical Observation with Photonic Local Oscillator
Authors: Shuro Takano , Ueda Akitoshi , Yamamoto Takashi , Asayama Shinichiro , Sekimoto Yutaro , Noguchi Takashi , Ishiguro Masato , Takara Hidehiko , Kawanishi Satoki , Ito Hiroshi , Hirata Akihiko , Nagatsuma Tadao
Published: March 2014

We present the results of experimental radioastronomical observations of an interstellar molecular spectral line with an SIS (superconductor–insulator–superconductor) receiver pumped by a photonic local oscillator (LO). A millimeter-wave LO signal was generated by feeding an optical comb signal into a W-band (75–110 GHz) photomixer using a uni-traveling-carrier photodiode (UTC-PD). A CS $J = 2 \hbox{--} 1$ line at 98 GHz was observed toward a high-mass star-forming region W 51 ($\mathrm{H}_2 \mathrm{O}$). We compared the obtained spectra with those obtained with a conventional Gunn oscillator as an LO. As a result, the line parameters, such as the width, intensity, and frequency, were consistent with each other. The results presented here show that the photonic LO is a very promising source for heterodyne receivers in millimeter–and submillimeter-wave astronomy.
Detectability of the Warm/Hot Intergalactic Medium through Emission Lines of O VII and O VIII
Authors: Yoshikawa Kohji , Yamasaki Noriko Y. , Suto Yasushi , Ohashi Takaya , Mitsuda Kazuhisa , Tawara Yuzuru , Furuzawa Akihiro
Published: March 2014

Most of the cosmic baryons predicted by the big-bang nucleosynthesis have evaded direct detection. Recent numerical simulations indicate that approximately 30 to 50 percent of the total baryons in the present universe are supposed to take the form of warm/hot intergalactic medium (WHIM) whose X-ray continuum emission is very weak. To identify those missing baryons, we consider in detail the detectability of WHIM directly through the emission lines of O VII (561, 568, 574, 665 eV) and O VIII (653 eV). For this purpose, we create mock spectra of the emission lines of WHIM using a light-cone output of cosmological hydrodynamic simulations. While the predicted fluxes are generally below the current detection limit, an unambiguous detection will be feasible with a dedicated X-ray satellite mission, which we also discuss in detail. Our proposed mission is especially sensitive to a WHIM with gas temperature of $T = 10^{6 \hbox{--} 7} \,\mathrm{K}$ and overdensity of $\delta = 10 \hbox{--} 100$ up to a redshift of 0.3 without being significantly contaminated by the cosmic X-ray background and the Galactic emissions. Thus, such a mission provides a unique and important tool to identify a large fraction of otherwise elusive baryons in the universe.
Hydrodynamic Modeling of a Flare Loop Connecting the Accretion Disk and Central Core of Young Stellar Objects
Authors: Isobe Hiroaki , Shibata Kazunari , Yokoyama Takaaki , Imanishi Kensuke
Published: March 2014

Many young stellar objects, such as protostars and T-Tauri stars, show strong flare activity. In this paper we present a hydrodynamic simulation of a flare loop that connects the central star and the accretion disk, and discuss the evaporation of the chromosphere of the central star and the disk. We assumed a long ($ \gt 10 \,{{{R}_{\odot}}}$$ \gt 10 \,{{{R}_{\odot}}}$) loop length, and that the flare energy is deposited near the half-way point between the disk and the stellar surface. We found that in some cases all of the plasma in the accretion disk is heated to the flare temperature and spreads over the flare loop. The condition for this “disk disappearance” was examined. The X-ray spectrum expected when we observe the simulation result was synthesized by taking into account the instrumental response of ASCA/GIS. However, we could not find any clear observational signature of the existence of the disk, because the bulk properties of a flare loop are determined by the flare heating flux and loop length, and not by the involvement of the disk. We found that the synthesized spectrum is reasonably fitted with a two-temperature model, and that the temperature of the hotter component is several factors lower than the maximum temperature of the simulation result.
Discovery of Interacting Molecular Gas toward the TeV Gamma-Ray Peak of the SNR G 347.3–0.5
Authors: Fukui Yasuo , Moriguchi Yoshiaki , Tamura Keisuke , Yamamoto Hiroaki , Tawara Yuzuru , Mizuno Norikazu , Onishi Toshikazu , Mizuno Akira , Uchiyama Yasunobu , Hiraga Junko , Takahashi Tadayuki , Yamashita Koujin , Ikeuchi Satoru
Published: March 2014

Supernova remnants ($=$ SNR) are suggested to be sites of cosmic-ray acceleration. In particular, it has been an issue of keen interest whether cosmic ray protons are being accelerated in a SNR which emits TeV $\gamma$-rays. A crucial observational test for this is to find dense molecular gas towards the SNR, because such molecular gas can best verify the existence of cosmic-ray protons via pion decay to $\gamma$-rays. Here, we show that new high-resolution mm-wave observations of interstellar CO molecule have revealed molecular gas at 1 kpc distance interacting with the TeV $\gamma$-ray SNR G 347.3$-$0.5, and that a molecular cloud of $\sim 200$ solar masses is clearly associated with the TeV $\gamma$-ray peak, providing strong evidence for proton acceleration. We have estimated the total energy of accelerated protons to be $\sim 1048 \,\mathrm{erg}$, which corresponds to an acceleration efficiency of $\sim 0.001$, posing an observational constraint on the proton acceleration.
One Approach to the Star-Formation History Inferred from the GRB Lag–Luminosity Relation
Authors: Toshio Murakami , Yonetoku Daisuke , Izawa Hisayo , Ioka Kunihito
Published: March 2014

The distances of about thirty gamma-ray bursts (GRBs) are known. The most remote one is at $z \sim 4.5$, and the remaining more dimmer GRBs are supposed to be more remote. If we can estimate the distances for the dimmer GRBs, their distances should be much beyond $z \sim 4.5$. Two independent studies to estimate their distances were previously conducted. One was based on the variability–luminosity relation, and the other was based on the lag–luminosity relation. However, these relations can apply only for a very limited range of luminosity. In this paper, we introduce the viewing angles and use a new lag-luminosity relation by Ioka and Nakamura (2001, ApJ, 554, L163), which is capable of explaining the luminosity of the nearest GRBs. By applying the new relation, we infer the star-formation history out to $z \sim 4$. Our result shows an increasing trend of star-formation out to $z \sim 4$. However, the lag–luminosity relation itself is still a matter of debate, and thus this work is a tentative approach. For example, we have used only eight known GRB distances. Our result should be checked and calibrated by future data with Swift, observing more distant GRBs.
Cloudy Accretion Disks
Authors: Kitabatake Etsuko , Fukue Jun
Published: March 2014

Gas and dust surrounding an accretion disk suffer from the influence of the strong radiation of the disk, to make cloud layers above and below the disk in some cases. We examined a stable configuration of such cloud layers formed around the standard accretion disk. The cloud configuration is drastically changed as the disk effective luminosity $\Gamma_\mathrm{eff}$ increases, where $\Gamma_\mathrm{eff}$ is defined as $\Gamma_\mathrm{eff} = (\sigma / \sigma_\mathrm{T}) (m_\mathrm{p}/m) (L_\mathrm{d} / L_\mathrm{E}), \sigma$ and $m$ being the particle cross-section and mass, respectively, $\sigma_\mathrm{T}$ and $m_\mathrm{p}$ the Thomson cross-section and proton mass, respectively, and $L_\mathrm{d}$ and $L_\mathrm{E}$ the disk and Eddington luminosities, respectively. When $\Gamma_\mathrm{eff}$ is smaller than 0.8, the cloud configuration is almost parallel to the disk plane, except for the innermost region, where the configuration is inclined to reach the inner edge of the disk. When $\Gamma_\mathrm{eff}$ exceeds about 0.8, on the other hand, the cloud layer is split at a middle region, where the stable cloud layer disappears. We also calculated the temperature distribution and continuous spectra of the cloud layer. For small $\Gamma_\mathrm{eff}$, the temperature distribution of the cloud resembles the standard disk. As $\Gamma_\mathrm{eff}$ increases, however, the temperature of the inner cloud decreases and that of the outer cloud somewhat increases, due to the irradiation and shadowing effects. As a result, the continuous spectra become softer with $\Gamma_\mathrm{eff}$.
Light-Curve Diagnosis of a Hot Spot for Accretion-Disk Models
Authors: Fukue Jun
Published: March 2014

Light curves of a hot spot rotating in a relativistic Keplerian disk were found to be periodic with typically two peaks, originating from a gravitational focusing effect and a Doppler boost. On the other hand, we found that light curves of a hot spot spirally infalling in a sub-Keplerian advective disk are aperiodic with typically a single peak, originating from a gravitational focusing effect or a Doppler boost. Such a difference in the light curves of a hot spot can discriminate background disk models.
Monte Carlo Modeling of Non-Gravitational Heating Processes in Galaxy Clusters
Authors: Shimizu Mamoru , Kitayama Tetsu , Sasaki Shin , Suto Yasushi
Published: March 2014

We consider non-gravitational heating effects on galaxy clusters based on the Monte Carlo modeling of merging trees of dark matter halos combined with the thermal evolution of gas inside each halo. Under the assumption of hydrostatic equilibrium and isothermal gas profiles, our model takes account of the metallicity evolution, metallicity-dependent cooling of gas, supernova energy feedback, and heating due to jets of radio galaxies in a consistent manner. The observed properties of galaxy clusters can be explained in models with higher non-gravitational heating efficiency than that in the conventional model. The possibilities include jet heating by the Fanaroff–Riley Type II radio galaxies, and the enhanced star formation efficiency and/or supernova energy feedback, especially at high redshifts.
Discovery of a Peculiar Pulsar in the Small Magellanic Cloud
Authors: Ueno Masaru , Yamaguchi Hiroya , Takagi Shin-ichiro , Yokogawa Jun , Koyama Katsuji
Published: March 2014

We report on a peculiar X-ray binary pulsar, IKT 1 $=$ RX J0047.3$-$7312, observed with XMM-Newton in 2000 October. The X-ray spectrum is described by a two-component spectrum. The hard component has a broken power-law with respective photon indices of 0.2 and 1.8, below and above the break energy at 5.8 keV. The soft component can be modeled by a blackbody of $kT = 0.6 \,\mathrm{keV}$. The X-ray flux shows a gradual decrease and periodic variations of about 4000 s. The averaged flux in 0.7–10.0 keV is $2.9 \times 10^{-12} \,\mathrm{erg} \,\mathrm{cm}^{-2} \,\mathrm{s}^{-1}$, which is $\sim 10$-times brighter than that in a ROSAT observation in 1999 November. In addition to the 4000-s variation, we found coherent pulsations of $263 \pm 1 \,\mathrm{s}$. These discoveries strengthen the Be/X-ray binary scenario proposed by the ROSAT and ASCA observations on this source, and confirm that most of the hard sources in the Small Magellanic Cloud are X-ray binary pulsars. A peculiar property of this XBP is that the coherent pulsations are found only in the soft component, and the folded light curve shows a flat top shape with a sharp dip. We discuss the nature of this XBP focusing on the peculiar soft component.
Study of the Bipolar Nebula IRAS 19312+1950. I. Mapping Observations
Authors: Nakashima Jun-ichi , Deguchi Shuji , Kuno Nario
Published: March 2014

IRAS 19312$+$1950 is an SiO maser source that exhibits a prominent bipolar nebulosity. Mapping observations of this object were made in the CO $J = 1 \hbox{--} 0$,${{13\atop} \mathrm{CO}} J = 1 \hbox{--} 0$, C${{18\atop} \mathrm{O}} J = 1 \hbox{--} 0$, CS $J= 2 \hbox{--} 1$, and HCN $J = 1 \hbox{--} 0$ lines and in the 150 GHz continuum band. Near-infrared imaging observations were also made in the $J, H$, and $K$-bands. The line profiles of the ${{12\atop} \mathrm{CO}}$ and HCN spectra consist of a weak component with the width of $50 \,\mathrm{km} \,\mathrm{s}^{-1}$ and a strong component of the width of $3 \,\mathrm{km} \,\mathrm{s}^{-1}$. The profiles of the ${{13\atop} \mathrm{CO}}$, C${{18\atop} \mathrm{O}}$, and CS lines have only the narrow component. Both of the components have an intensity peak at the IRAS position. The narrow component was clearly resolved with a $15^{\prime\prime}$ telescope beam. The spectral energy distribution of this object exhibits a doubly peaked profile between 1 and 25$\, {\mu \mathrm {m}}$. The 150 GHz continuum flux density was found to be 0.07 Jy, which is consistent with the flux density predicted by the expanding envelope model with a mass loss rate of $\sim 10^{-4} \,{{{M}_{\odot}}} \,\mathrm{yr}^{-1}$ at a distance of 2.5 kpc. We argue that the broad component originates from the expanding envelope of this object, and that the hot dust cloud, the source of the narrow component, is physically associated with this object. Though the present observations do not preclude the possibility of a young stellar object, we argue that it is less plausible. We conclude that IRAS 19312$+$1950 is an AGB/post-AGB star that evolved from a massive progenitor.
Three-Dimensional Magnetohydrodynamic Numerical Simulations of Coronal Loop Oscillations Associated with Flares
Authors: Miyagoshi Takehiro , Yokoyama Takaaki , Shimojo Masumi
Published: March 2014

We performed three-dimensional MHD numerical simulations for solar coronal magnetic loop oscillations and found: (1) The loop oscillation period is determined by its Alfvén time. (2) The amplitude of oscillation decreases exponentially in time. This is explained as energy transport by fast-mode MHD waves. The damping rate, $\omega _\mathrm{damp}$, is described as $\omega _\mathrm{damp} \propto V_\mathrm{a}/R$, where $V_\mathrm{a}$ is the Alfvén speed around loops and $R$ is the radius of the loop. Because of computer resources limitations, the plasma $\beta$ value is much larger than that of the real corona. We thus applied a scaling law derived from numerical simulation results to the real corona parameter ranges and analyzed the results.
A 8.8–50 GHz Complete Spectral Line Survey toward TMC-1 I. Survey Data
Authors: Kaifu Norio , Ohishi Masatoshi , Kawaguchi Kentarou , Saito Shuji , Yamamoto Satoshi , Miyaji Takeshi , Miyazawa Keisuke , Ishikawa Shin-ichi , Noumaru Chiaki , Harasawa Sumiko , Okuda Michiko , Suzuki Hiroko
Published: March 2014

We completed the first spectral line survey toward a cold, dark cloud TMC-1 (cyanopolyyne peak) in a frequency range between 8.8 and 50.0 GHz by the 45-m radio telescope of Nobeyama Radio Observatory. We detected 414 lines of 38 molecular species including 11 new molecules, such as $\mathrm{C_6H}$, CCO, $\mathrm{C_3O}$, CCS, $\mathrm{C_3S}$, HNCCC, HCCNC, $\mathrm{HC_3NH^{+}}$, HCCCHO, $\mathrm{CH_2CN}$, and cyclic $\mathrm{C_3H}$ ($c\hbox{-}\mathrm{C_3H}$), which were previously reported; only one significant line, U49536, remains unidentified. 177 out of 414 lines are reported for the first time. Some half of the detected molecules are linear carbon-chain species and their derivatives. We also discovered three new rarer isotopomers: CC${{34\atop} \mathrm{S}}, \mathrm{C_3}$${{34\atop} \mathrm{S}}$, and HDCS. Spectral charts are presented together with the observed line parameters of all detected lines. Improved molecular constants of several carbon-chain molecules obtained during the course of identification are also presented.
A High-Resolution Very Large Array Observation of a Protostar in OMC-3: Shock-Induced X-Ray Emission by a Protostellar Jet
Authors: Tsujimoto Masahiro , Koyama Katsuji , Kobayashi Naoto , Saito Masao , Tsuboi Yohko , Chandler Claire J.
Published: March 2014

Using the Very Large Array (VLA) in the A-configuration, we obtained a high-resolution 3.6 cm map of a hard X-ray source detected by the Chandra X-ray Observatory in a protostellar clump in Orion molecular cloud 3. Two radio continuum sources were detected in the vicinity of the X-ray source, both of which have NIR counterparts. We conclude that these VLA sources are free–free emission produced by shocks in protostellar jets from the NIR class I protostars. Using the centimeter data, we determined the power and orientation of the protostellar jets. The center position of the X-ray emission was found to be $\sim 1 {{}^{\prime \prime }} \hbox{--} 2 {{}^{\prime \prime }}$ offset from the exciting sources of the jets, and the displacement is in the direction of the jets and molecular outflows. We discuss the nature of the X-ray emission as the shock-excited plasma at the shock front where the jet propagates through the interstellar medium at a speed of $\sim 1000 \,\mathrm{km} \,\mathrm{s}^{-1}$.
Current Performance and On-Going Improvements of the 8.2 m Subaru Telescope
Authors: Iye Masanori , Karoji Hiroshi , Ando Hiroyasu , Kaifu Norio , Kodaira Keiichi , Aoki Kentaro , Aoki Wako , Chikada Yoshihiro , Doi Yoshiyuki , Ebizuka Noboru , Elms Brian , Fujihara Gary , Furusawa Hisanori , Fuse Tetsuharu , Gaessler Wolfgang , Harasawa Sumiko , Hayano Yutaka , Hayashi Masahiko , Hayashi Saeko , Ichikawa Shinichi , Imanishi Masatoshi , Ishida Catherine , Kamata Yukiko , Kanzawa Tomio , Kashikawa Nobunari , Kawabata Koji , Kobayashi Naoto , Komiyama Yutaka , Kosugi George , Kurakami Tomio , Letawsky Michael , Mikami Yoshitaka , Miyashita Akihiko , Miyazaki Satoshi , Mizumoto Yoshihiko , Morino Junichi , Motohara Kentaro , Murakawa Koji , Nakagiri Masao , Nakamura Kyoko , Nakaya Hidehiko , Nariai Kyoji , Nishimura Tetsuo , Noguchi Kunio , Noguchi Takeshi , Noumaru Junichi , Ogasawara Ryusuke , Ohshima Norio , Ohyama Yoichi , Okita Kiichi , Omata Koji , Otsubo Masashi , Oya Shin , Potter Robert , Saito Yoshihiko , Sasaki Toshiyuki , Sato Shuji , Scarla Dennis , Schubert Kiaina , Sekiguchi Kazuhiro , Sekiguchi Maki , Shelton Ian , Simpson Chris , Suto Hiroshi , Tajitsu Akito , Takami Hideki , Takata Tadafumi , Takato Naruhisa , Tamae Richard , Tamura Motohide , Tanaka Wataru , Terada Hiroshi , Torii Yasuo , Uraguchi Fumihiko , Usuda Tomonori , Weber Mark , Winegar Tom , Yagi Masafumi , Yamada Toru , Yamashita Takuya , Yamashita Yasumasa , Yasuda Naoki , Yoshida Michitoshi , Yutani Masami
Published: March 2014

An overview of the current status of the 8.2 m Subaru Telescope constructed and operated at Mauna Kea, Hawaii, by the National Astronomical Observatory of Japan is presented. The basic design concept and the verified performance of the telescope system are described. Also given are the status of the instrument package offered to the astronomical community, the status of operation, and some of the future plans. The status of the telescope reported in a number of SPIE papers as of the summer of 2002 are incorporated with some updates included as of 2004 February. However, readers are encouraged to check the most updated status of the telescope through the home page, http://subarutelescope.org/index.html, and/or the direct contact with the observatory staff.
X-Ray Expanding Features Associated with a Moreton Wave
Authors: Noriyuki Narukage , Morimoto Taro , Kadota Miwako , Kitai Reizaburo , Kurokawa Hiroki , Shibata Kazunari
Published: March 2014

We report on the simultaneous observation of a Moreton wave in $\mathrm{H}\alpha$ and two kinds of coronal expanding features in soft X-rays near the solar limb. We consider the faster X-ray feature and the slower one as being an “X-ray wave” and “ejecta”, respectively. The chromospheric Moreton wave propagated on the solar disk at a speed of $1040 \pm 100 \,\mathrm{km} \,\mathrm{s}^{-1}$, whereas the coronal X-ray wave propagated outside of the disk toward the outer corona at $1400 \pm 250 \,\mathrm{km} \,\mathrm{s}^{-1}$. We identified the X-ray wave as MHD fast-mode shock. The fast-mode Mach number ($M_{\mathrm{f}}$) of the X-ray wave was also estimated to be about 1.13–1.31, which decreases during propagation. The timing when the $M_{\mathrm{f}}$ became “1” is consistent with that of the disappearance of the Moreton wave. Moreover, we discuss the 3-dimensional structure of the shock wave and the relation between the shock wave and the ejecta (and $\mathrm{H}\alpha$ filament eruptions).
Observations of Cyclopropenylidene (Cyclic-C3H2) in the External Galaxies NGC 253 and M 82
Authors: Oike Tomoko , Kawaguchi Kentarou , Takano Shuro , Nakai Naomasa
Published: March 2014

Several transitions of the cyclopropenylidene (cyclic-$\mathrm{C}_3\mathrm{H}_2$) molecule have been observed in the 83–218 GHz region toward NGC 253 and M 82. Assuming local thermodynamic equilibrium, the rotational temperatures were determined to be $10.8 \pm 2.4 \,\mathrm{K}$ and $11.5 \pm 3.0 \,\mathrm{K}$ for NGC 253 and M 82, respectively, where the errors indicate three standard deviations ($3 \,\sigma$). The column densities of cyclic-$\mathrm{C}_3\mathrm{H}_2$ were determined to be ${N\mathrm{(NGC~253)} = (2.7 \pm 1.1) \times 10^{13} \,\mathrm{cm}^{-2}}$ and $N\mathrm{(M~82)} = (1.9 \pm 0.9) \times 10^{13} \,\mathrm{cm}^{-2}$. Large velocity gradient calculations were applied to estimate kinetic temperatures of around 60 K for NGC 253 and M 82. Considering the present result and recent observations of $\mathrm{NH}_3$ in both galaxies, molecular production mechanisms are discussed.
First mm-VLBI Observations between the TRAO 14-m and the NRO 45-m Telescopes: Observations of 86 GHz SiO Masers in VY Canis Majoris
Authors: Shibata Katsunori M. , Chung Hyung-Soo , Kameno Seiji , Roh Duk-Gyoo , Umemoto Tomofumi , Kim Kwang-Dong , Asada Keiichi , Han Seog-Tae , Mochizuki Nanako , Cho Se-Hyung , Sawada-Satoh Satoko , Kim Hyun-Goo , Bushimata Takeshi , Minh Young Chol , Miyaji Takeshi , Kuno Nario , Mikoshiba Hiroshi , Sunada Kazuyoshi , Inoue Makoto , Kobayashi Hideyuki
Published: March 2014

We have made VLBI observations at 86 GHz using a 1000-km baseline between Korea and Japan with successful detections of SiO $v = 1, J = 2$ -$1$ maser emissions from VY CMa and Orion KL in 2001 June. This was the first VLBI result for this baseline and the first astronomical VLBI observation for the Korean telescope. Since then, we observed SiO $v = 1, J = 2$ -$1$ maser emission in VY CMa in 2002 January and 2003 February and derived the distributions of the maser emissions. Our results show that the maser emissions extend over 2–4 stellar radii, and were within the inner radius of the dust shell. We observed other SiO maser sources and continuum sources, and 86-GHz continuum emissions were detected from three continuum sources. It was verified that this baseline has a performance comparable to the most sensitive baseline in the VLBA and the CMVA, and is capable of investigating the proper motions of maser features in circumstellar envelopes using monitoring observations.
Line-Profile Variations during an Eclipse of a Dwarf Nova, IP Pegasi
Authors: Ishioka Ryoko , Mineshige Shin , Kato Taichi , Nogami Daisaku , Uemura Makoto
Published: March 2014

Accretion disks are rotating disks formed by accreting matter onto compact objects, and are thought to be the source of various active phenomena. Dwarf novae, the best-studied disk systems, composed of a white dwarf with a surrounding disk and a red-dwarf companion star, exhibit double-peaked emission-line profiles because of disk rotation. When a disk is eclipsed by the companion star, the emission-line profiles vary with time, since a different portion of the disk having a different line-of-sight velocity is successively obscured. We report on spectacular variations of the line profiles during an eclipse that we obtained for the first time through Subaru spectroscopy of an eclipsing dwarf nova, IP Peg. Our fine data are useful for investigating detailed velocity profiles as well as the non-axisymmetric emissivity distribution. The observed variations are basically consistent with Keplerian rotation, but are more complex than those predicted by a simple axisymmetric model.
H2 Line Emission Associated with the Formation of the First Stars
Authors: Mizusawa Hiromi , Nishi Ryoichi , Omukai Kazuyuki
Published: March 2014

Molecular hydrogen ($\mathrm{H}_2$) line radiation emitted in the formation events of first-generation stars is evaluated in a discussion of its detectability by future observational facilities. $\mathrm{H}_2$ luminosity evolution from the onset of prestellar collapse until the formation of a $\sim 100 \,{{{M}_{\odot}}}$ protostar is followed. Calculations are extended not only to the early phase of the runaway collapse, but also to the later phase of accretion, whose observational features have not been studied before. Contrary to the runaway collapse phase, where the pure-rotational lines are always dominant, in the accretion phase rovibrational line emission becomes prominent. The maximum luminosity is also attained in the accretion phase for strong emission lines. The peak intensity of the strongest rovibrational line reaches $\sim 10^{-29} \,\mathrm{W} \,\mathrm{m}^{-2}$, corresponding to the flux density of $10^{-5} \,\mu\mathrm{Jy}$, for a source at the typical redshift of first-generation star formation, $1+z = 20$. Although the redshifted rovibrational $\mathrm{H}_2$ emission from such an epoch falls in the wavelength range of the next-generation infrared satellite, Space Infrared Telescope for Cosmology and Astrophysics, for exceeding the detection threshold, $10^7$ such protostars are required to reach the maximum luminosity simultaneously in a pregalactic cloud. It is improbable that this condition is satisfied in a realistic scenario of early structure formation.
Multiresolution Analysis of Cosmological N-Body Simulations and Comparison with Two-Dimensional Galaxy Distributions for Estimating Large-Scale Structure
Authors: Ueda Haruhiko , Takeuchi Tsutomu T.
Published: March 2014

A multiresolution analysis was performed to estimate the large-scale structure of cosmological $N$-body simulations. To explore relations between the multiresolution analysis and the galaxy distributions, a method that is familiar to image processing engineering was utilized. We proposed a new technique for quantifying the large-scale structures, and found that this is useful to discriminate differences in galaxy distributions among power-law simulations. We next applied the multiresolution analysis to CDM simulations, and also obtained a confirmation of the usefulness of this analysis; our new technique had advantages in clearly distinguishing differences in galaxy distributions in CDM models. We finally compared the galaxy distributions in the two-dimensional observational data (LEDA2 d subsample) with those in CDM mock samples, and found that the standard CDM model does not reproduce the galaxy distributions in our universe.
Importance of Prolate Neutrino Radiation in Core-Collapse Supernovae: The Reason for the Prolate Geometry of SN1987A?
Authors: Madokoro Hideki , Shimizu Tetsuya , Motizuki Yuko
Published: March 2014

We have carried out 2-D simulations of core-collapse supernova explosions. The local neutrino radiation field was assumed to have its maximum value either at the symmetry (polar) axis or on the equatorial plane. These led to prolate and oblate explosions, respectively. We have found that the gain of the explosion energy in the prolate explosion evolves more predominately than that in the oblate one when the total neutrino luminosity is given. Namely, the prolate explosion is more energetic than the oblate one.

One of the authors (Shimizu et al. 2001) showed for the first time that globally anisotropic neutrino radiation produces a more powerful explosion than does spherical neutrino radiation. In our previous study (Madokoro et al. 2003), we improved the numerical code of Shimizu et al. (2001), and demonstrated that globally anisotropic neutrino radiation yields a more energetic explosion than does spatially-fluctuated neutrino radiation. Together with the result of this paper, we conclude that globally anisotropic (prolate) neutrino radiation is the most effective way to increase the explosion energy among various types of explosions investigated in these studies. We discuss the reason for this. Our result is suggestive of the fact that the expanding materials of SN1987A have been observed to have a prolate geometry.
Near-Infrared Unidentified-Line Morphology of the Planetary Nebula NGC 7027
Authors: Okumura Shin-ichiro , Mori Atsushi , Yanagisawa Kenshi
Published: March 2014

Medium-resolution ($R \sim 500$), $K$-band two-dimensional spectra are presented for the planetary nebula NGC 7027. The spatial distributions for the two bright unidentified lines near 2.199 and 2.287$\, {\mu \mathrm {m}}$ were revealed and examined compared to those of other emission lines. It was spatially confirmed that the unidentified lines do not arise from neutral molecules, but ionized species. The ionization potentials of their parent ions are lower than that of He II, and comparable to or higher than that of $\mathrm{Br}\gamma$. Our results support the previous studies of identification of parent species, on the condition that the carriers of the unidentified lines are partly excited by collisions.
Inhomogeneity in the Hot Intracluster Medium of Abell 1060 Observed with Chandra
Authors: Hayakawa Akira , Furusho Tae , Yamasaki Noriko Y. , Ishida Manabu , Ohashi Takaya
Published: March 2014

A Chandra observation of the non-cooling flow cluster A 1060 has confirmed that the hot intracluster medium has fairly uniform distributions of temperature and metal abundance from a radius of about 230 kpc to the central 5 kpc region ($H_0 = 75 \,\mathrm{km} \,\mathrm{s}^{-1} \,\mathrm{Mpc}^{-1}$). The radial temperature profile shows a broad peak at 30–40 kpc from the center at a level $\sim 20\%$ higher than that in the outer region. Assuming spatially uniform temperature and abundance distributions, we derived a 3-dimensional density structure by iteratively correcting the $\beta$ model, and obtained the central gas density to be $8.2^{+1.8}_{-1.0} \times 10^{-3} \,\mathrm{cm}^{-3}$. The distribution of gravitational mass was estimated from the density profile, and a central concentration of mass within a radius of 50 kpc was indicated. The data also suggest several high-abundance regions. The most significant blob adjacent to the central galaxy NGC 3311 has a radius of about 9 kpc, which indicates a metallicity of $\sim 1.5$ solar. We consider that this blob may be produced by the gas stripped off from NGC 3311.
Chandra Observation of a Group of Galaxies HCG 80: Does the Spiral-Only Group Have Hot Intragroup Gas?
Authors: Ota Naomi , Morita Umeyo , Kitayama Tetsu , Ohashi Takaya
Published: March 2014

We present an analysis of Chandra X-ray observations of a compact group of galaxies, HCG 80 ($z=0.03$). The system is a spiral-only group composed of four late-type galaxies, and has a high-velocity dispersion of $309 \,\mathrm{km} \,\mathrm{s}^{-1}$. With high-sensitivity Chandra observations, we searched for diffuse X-ray emission from the intragroup medium (IGM); however, no significant emission was detected. We place a severe upper limit on the luminosity of the diffuse gas as $L_\mathrm{X} < 6 \times 10^{40} \,\mathrm{erg} \,\mathrm{s}^{-1}$. On the other hand, significant emission from three of the four members were detected. In particular, we discovered huge halo emission from HCG 80a that extends on a scale of $\sim 30 \,\mathrm{kpc}$ perpendicular to the galactic disk, whose X-ray temperature and luminosity were measured to be $\sim 0.6 \,\mathrm{keV}$ and $\sim 4 \times10^{40} \,\mathrm{erg} \,\mathrm{s}^{-1}$ in the 0.5–2 keV band, respectively. It is most likely to be an outflow powered by intense starburst activity. Based on the results, we discuss possible reasons for the absence of diffuse X-ray emission in the HCG 80 group, suggesting that the system is subject to galaxy interactions, and is possibly at an early stage of IGM evolution.
An Ultrasoft Transient X-Ray Source near the Galactic Bulge Region
Authors: Yamauchi Shigeo , Nakamura Emi
Published: March 2014

Further analysis of an ultrasoft transient X-ray source near the Galactic bulge region is reported. This source was discovered in scanning observations with Ginga, and was at first designated as GS 1734$-$275 (Makino 1988). The source position was re-determined using revised satellite attitude data, and then this source was named GS 1732$-$273. The revised position is in agreement with those of the transient sources, KS 1732$-$273, discovered with Mir-Kvant in 1989, and 1RXS J173602.0$-$272541, discovered with the ROSAT all-sky survey in 1990. The X-ray spectrum, constructed by a scan-fit technique, is well represented by a multicolor disk model with a temperature at the inner disk radius of 0.7–0.8 keV. The spectral properties and the transient behavior suggest that GS 1732$-$273 is a candidate source of black hole binaries.
X-Ray Flares from a Late B-Type Star, HD 38563S, in NGC 2068 Observed with Chandra X-Ray Observatory
Authors: Yanagida Takayuki , Ezoe Yu-ichiro , Makishima Kazuo
Published: March 2014

A report is made on the Chandra archival data analysis of NGC 2068, which is one of the nearest ($\sim 400 \,\mathrm{pc}$) and X-ray active star-forming regions, with an estimated age of $10^{5-6} \,\mathrm{yr}$. The observation was made for 100 ks. Using the wavdetect tool, 152 X-ray sources were detected, of which 52 had counterparts in the 2MASS survey. One of the brightest X-ray sources is apparently identified with a $V = 10.42$ late B-type main-sequence star, HD 38563S. During the observation, it exhibited two X-ray flares, with the 0.5–8.0 keV luminosity reaching $\sim 10^{31.6} \,\mathrm{erg} \,\mathrm{s}^{-1}$. The flare X-rays evolved on a time scale of several hours, and showed a thermal spectrum of temperature of $\sim 5 \,\mathrm{keV}$. These results suggests that this star forms an active binary, although contamination by a T Tauri star also remains an alternative possibility.
A Solar Eclipse Versified in the Shijing
Authors: Kawabata Kin-aki , Tanikawa Kiyotaka , Sôma Mitsuru
Published: March 2014

A solar eclipse versified in an ode called ‘At the conjunction in the 10th month’ in the Shijing 詩経 has been analyzed under the light of the present astronomy. We have shown that the solar eclipse on 735 BC November 30 is a unique candidate of the eclipse in 801–720 BC satisfying the following three requirements: (1) the sexagenary cyclic day of the eclipse was xin-mao, (2) the sun became faint in the capital, and (3) the moon was eclipsed not long before the solar eclipse. The eclipse was at least very close to annular in Hao 鎬 (the Capital of Western Zhou). The maximum magnitude of every eclipse between 794 BC and 764 BC was too small to say ‘the sun became faint’ like in the ode. These results strongly support the dating of the eclipse by Hirayama and Ogura (1915, Tokyo Sugaku-Buturigakkwai Kizi, Ser.2, 8, 2) and reject any dating in 794–764 BC.
$\Delta T$
and the Tidal Acceleration of the Lunar Motion from Eclipses Observed at Plural Sites
Authors: Tanikawa Kiyotaka , Sôma Mitsuru
Published: March 2014

An eclipse on 188 BC July 17 was observed and recorded both at Chang’an (China) and Rome (Italy). An eclipse on AD 873 July 28 was observed and recorded both at Nishapur (Iran) and Kyoto (Japan). The eclipse was annular at Nishapur. These plural records of deep eclipses are rare in history, and are useful for determining the clock correction, $\Delta T$, and the lunar tidal acceleration, $\dot{n}$. We have tried to determine as precisely as possible the ranges of these two parameters. If we fix the tidal acceleration to $- {25\rlap {.}{}^{\mathrm {\prime \prime }}83} \,\mathrm{cy}^{-2}$, we get, as a best estimate, $12581 \,\mathrm{s} < \Delta T < 12741 \,\mathrm{s}$ from the 188 BC eclipse and contemporary eclipses, and $3327 \,\mathrm{s} < \Delta T < 3498 \,\mathrm{s}$ from the AD 873 eclipse and contemporary eclipses.
Mass and Spin of GRS 1915 $+$ 105 Based on a Resonance Model of QPOs
Authors: Kato Shoji
Published: March 2014

We demonstrate that the four high-frequency QPOs observed in GRS 1915$+$105 can be interpreted as the oscillation modes on disks that non-linearly and resonantly interact with a warp. The warp is assumed to be a low-frequency global pattern on the disk. This identification suggests that the relevant mass, $M$, and spin parameter, $a$, are $M=13 \hbox{--} 14 \,{{{M}_{\odot}}}$ and $a=0 \hbox{--} 0.15$.
XMM-Newton Observations of G32.45+0.1 and G38.55+0.0: Diffuse Hard X-Ray Sources Found by the ASCA Galactic Plane Survey
Authors: Yamaguchi Hiroya , Ueno Masaru , Koyama Katsuji , Bamba Aya , Yamauchi Shigeo
Published: March 2014

We report on XMM-Newton observations of G32.45$+$0.1 and G38.55$+$0.0. These were discovered as diffuse hard X-ray sources by the ASCA Galactic Plane Survey, but the limited spatial resolution of ASCA could not conclude whether these are truly diffuse or a group of unresolved point-sources. XMM-Newton, with higher spatial resolution than ASCA, confirmed that G32.45$+$0.1 has a diffuse shell-like structure with a radius of $\sim {4{}^{\mathrm {\prime }}}$. The spectrum shows a featureless continuum, and can thus be fitted by a power-law model of $\Gamma \sim 2.2$ with an absorption of $N_{\mathrm{H}} \sim 5.2 \times 10^{22} \,\mathrm{cm}^{-2}$. From this $N_{\mathrm{H}}$ value, we estimated the distance to G32.45$+$0.1 to be $\sim 17 \,\mathrm{kpc}$. Thus, the luminosity (in the 0.5–10.0 keV band) and radius of the shell are $\sim 9.5 \times 10^{34} \,\mathrm{ergs} \,\mathrm{s}^{-1}$ and $\sim 20 \,\mathrm{pc}$, respectively. The radio complex sources in the NRAO/VLA Sky Survey (NVSS; 1.4 GHz) are globally associated with the X-ray shell of G32.45$+$0.1. Therefore, G32.45$+$0.1 is likely to be a synchrotron-dominant shell-like SNR. No significant diffuse structure was found in the XMM-Newton image of another ASCA diffuse source, G38.55$+$0.0. The upper limit of the observed flux (0.5–10.0 keV) is estimated to be $9.0 \times 10^{-13} \,\mathrm{ergs} \,\mathrm{cm}^{-2} \,\mathrm{s}^{-1}$, which is consistent with the ASCA result.
On the Shape of Superbubbles Evolving in the Galactic Plane
Authors: Zaninetti Lorenzo
Published: March 2014

The galactic supershells are cavities in the interstellar medium. These shells can be explained by introducing the concept of superbubbles, the theoretical result of multiple supernova. The superbubbles can be analytically described if the ambient medium has a constant density both in the so-called bursting phase and in the subsequent adiabatic expansion. In order to solve the expansion of superbubbles in the ISM, which is a non-homogeneous medium, a numerical technique is used that divides the sphere into many sectors. By varying the time of the bursting phenomenon and the time over which the phenomenon is followed, elliptical and hour-glass shapes or vertical walls can be obtained. Application of the developed theory/code to the super-shell associated with GW 46.4$+$5 and with GSH238 allows us to say that the suggested physical parameters are consistent with our theory. The map of the expanding superbubble’s velocity can be tentatively traced by generating random points on the expanding surface. The structure of the galactic plane as a result of the evolution of many super-bubbles was simulated by adopting the percolation theory in order to generate new OB associations.
Study of the Bipolar Nebula IRAS 19312+1950. II. Circumstellar Chemistry
Authors: Deguchi Shuji , Nakashima Jun-ichi , Takano Shuro
Published: March 2014

The bipolar nebula IRAS 19312$+$1950 is a unique SiO maser source exhibiting both properties of young and evolved objects. To clarify the nature of this object, we made molecular line observations with the Nobeyama 45-m radio telescope. We detected emission from O-bearing ($\mathrm{HCO}^{{+}}\mkern-2.0mu$, SiO, SO, and $\mathrm{SO}_2$), C–and N-bearing molecules (CN, CS, HCN, HNC, $\mathrm{NH}_{3}$, $\mathrm{N}_{2}\mathrm{H}^{+}\mkern-2.0mu$, $\mathrm{HC}_{3}\mathrm{N}$, $\mathrm{H}_2\mathrm{CS}$, and $\mathrm{CH}_3\mathrm{OH}$), and their isotopic species (C${{17\atop} \mathrm{O}}, {{13\atop} \mathrm{C}}$${{18\atop} \mathrm{O}}$, and C${{34\atop} \mathrm{S}}$). The line profiles consist of weak broad ($\Delta v \sim 30 \,\mathrm{km} \,\mathrm{s}^{-1}$) and/or strong narrow ($\Delta v \lesssim 5 \,\mathrm{km} \,\mathrm{s}^{-1}$) components, depending on the molecular species. Strong time variations of $\mathrm{H}_2\mathrm{O}$ and SiO masers were also observed. Numerical modeling of the envelope with the LVG-code resulted in a good fit of the model with a mass loss rate of $2.6 \times10^{-4} \,{{{M}_{\odot}}} \,\mathrm{yr}^{-1}$ to the observed intensities for the broad-component lines. On the other hand, non-O-bearing molecules, which only have narrow profiles, were found to have abundances typical of those in cool dust clouds. No isotopic enrichment was found, indicating little evidence of the narrow cool component being ejecta of the central AGB star or a possible companion. These facts compelled us to conclude that IRAS 19312$+$1950 is an exotic mass-losing evolved star embedded in a low-mass ($\sim 20 \; \,{{{M}_{\odot}}}$) dark cloud.
Cartridge-Type 800 GHz Receiver for the Atacama Submillimeter Telescope Experiment (ASTE)
Authors: Sugimoto Masahiro , Sekimoto Yutaro , Tatematsu Ken’ichi , Kamba Toshiaki , Toba Hiroyuki , Yokogawa Sozo , Okuda Takeshi , Kohno Kotaro , Noguchi Takashi , Yamaguchi Nobuyuki , Kandori Ryo , Muraoka Kazuyuki
Published: March 2014

We have developed a cartridge-type 800 GHz receiver for the ASTE telescope in Atacama, Chile. The receiver has been assembled with a cooled receiver optics, a Nb-based SIS mixer, a local oscillator (LO) optics, and IF components in a 170 mm diameter column-type cartridge. The cooled optics is composed of a single ellipsoidal mirror to couple between the feed horn and the subreflector of the antenna, and an LO coupler with 10% efficiency. Owing to its cartridge and cryostat structure, the mechanical vibrations of the GM cryocooler are significantly reduced, and therefore the receiver is highly stable on the telescope. The receiver noise temperature, using a Nb-based SIS mixer and a 4–8 GHz HEMT amplifier, was attained to 1300 K in DSB at an LO frequency of 815 GHz. The system noise temperature, $T_{\mathrm{sys}}$, was typically 4000–8000 K in DSB at an LO frequency of 812 GHz during operations, which depended on the atmospheric opacity. The typical zenith opacity at an LO frequency of 812 GHz was $\sim 1$. The half-power beam width (HPBW) of the main beam was measured by total power scanning across the Moon, and was consistent with the diffraction limit. A spectrum of the CO $J=7 \hbox{--} 6$ line (806.6518 GHz) toward Orion KL was successfully detected.
1993 Superoutburst of LL Andromedae
Authors: Kato Taichi
Published: March 2014

We present time-resolved CCD photometry of LL And during its 1993 outburst. The observation revealed the presence of superhumps with a period of 0.05697(3)d. This period is one of the smallest among the hydrogen-rich dwarf novae. Although LL And has been proposed to be a WZ Sge-type dwarf nova based on its low outburst frequency, our new analysis indicates that the outburst amplitude ($\sim 5 \,\mathrm{mag}$) and outburst duration ($9\pm 2 \,\mathrm{d}$) are much smaller and shorter than in typical WZ Sge-type dwarf novae. We suspect that the unusual outburst properties of LL And might be explained by assuming a “leaky disk” in quiescence, which was originally proposed to explain the prototypical WZ Sge-type outbursts. By combining with the recent suggestion of the orbital period, the fractional superhump excess is found to be 3.5(1)%, which is unusually large for this short-period system. LL And may be an object filling the gap in the evolutionary track, which has recently been proposed to explain the unusual ultracompact binaries with an evolved mass donor.