bluuebunny/crossref_metadata_2025 huggingface dataset:
VLBI Monitoring Observations of Water Masers around the Semi-Regular Variable Star R Crateris
Authors: Ishitsuka José K. , Imai Hiroshi , Omodaka Toshihiro , Ueno Munetaka , Kameya Osamu , Sasao Tetsuo , Morimoto Masaki , Miyaji Takeshi , Nakajima Jun-ichi , Watanabe Teruhiko
Published: March 2014

We monitored water-vapor masers around the semi-regular variable star R Crateris with the Japanese VLBI Network (J-Net) at the 22 GHz band during four epochs with intervals of one month. The relative proper motions and Doppler-velocity drifts of twelve maser features were measured. Most of them existed for longer than 80 days. The 3-D kinematics of the features indicates a bipolar expanding flow. The major axis of the asymmetric flow was estimated to be at P.A.$= 136^{\circ}$. The existence of a bipolar outflow suggests that a Mira variable star had already formed a bipolar outflow. The water masers are in a region of apparent minimum radii of $1.3 \times 10^{12} \,\mathrm{m}$ and maximum radii of $2.6 \times 10^{12} \,\mathrm{m}$, between which the expansion velocity ranges from 4.3 to $7.4 \,\mathrm{km} \,\mathrm{s}^{-1}$. These values suggest that the water masers are radially accelerated, but still gravitationally bound, in the water-maser region. The most positive and negative velocity-drifting features were found relatively close to the systemic velocity of the star. We found that the blue-shifted features are apparently accelerated and the red-shifted apparently decelerated. The acceleration of only the blue-shifted features seems to be consistent with that of the expanding flow from the star.
Sensitive CO Observations of the LMC Supergiant Shells with NANTEN: Their Effects on the Formation of Molecular Clouds and Stellar Clusters
Authors: Yamaguchi Reiko , Mizuno Norikazu , Onishi Toshikazu , Mizuno Akira , Fukui Yasuo
Published: March 2014

A statistical study of the effects of supergiant shells (SGSs) on the formation of stars and molecular clouds was made based on sensitive CO ($J=1 \hbox{--} 0$) observations of the molecular clouds in the LMC with NANTEN. The sensitive observations have detected 168 CO clouds whose mass ranges from $\sim 4 \times 10^4 \,{{{M}_{\odot}}}$ to $3 \times 10^6 \,{{{M}_{\odot}}}$. Out of the 168 clouds, 63 are associated with the SGSs, accounting for $\gtrsim 35\%$. The surface number and mass densities of the CO clouds are higher by a factor of 1.5–2 at the edge of the SGSs than elsewhere. This suggests the formation of CO clouds under the dynamical effects of the SGSs, such as the accumulation of interstellar medium. Young stellar clusters are more actively formed on the side of the CO clouds facing to the center of the SGSs, particularly where the $\mathrm{H}\alpha$ filaments are adjacent to the CO clouds. The number of clusters is increased by a factor of 2 on the side facing to the center of the SGSs with respect to the CO peaks compared with on the side far from the center. These results strongly suggest that cluster formation is triggered by dynamical effects of the SGSs. We find that $\sim 60\%$ of the young clusters are located within the boundary of the SGSs, and propose that a few 10% of the young clusters of $\tau \lt 10 \,\mathrm{Myr}$ have likely been formed due to dynamical effects of the SGSs.
A CO Survey of the LMC with NANTEN: II. Catalog of Molecular Clouds
Authors: Mizuno Norikazu , Yamaguchi Reiko , Mizuno Akira , Rubio Mónica , Abe Rihei , Saito Hiro , Onishi Toshikazu , Yonekura Yoshinori , Yamaguchi Nobuyuki , Ogawa Hideo , Fukui Yasuo
Published: March 2014

From a 12CO ($J=1 \hbox{--} 0$) survey with the NANTEN telescope, we present a complete catalog of giant molecular clouds (GMCs) in the Large Magellanic Cloud. In total, 107 CO clouds have been identified, 55 of which were detected at more than 3 observed positions. For the 55 clouds, the physical properties, such as size, line-width, virial mass, and CO luminosity, are cataloged. From a statistical analysis of these quantities, we show that GMCs in the LMC are close to gravitational equilibrium. A comparison with H i data indicates that most of the CO clouds are distributed in dense parts of H i gas, whose H i column density is greater than $10^{21} \,\mathrm{cm}^{-2}$. It is notable that the mass ratio of the molecular-to-atomic hydrogen of the lower radial velocity component of gas is $\sim 0.2$, which is a factor of 2 higher than that of the gaseous-disk component, $\sim 0.1$. Molecular clouds are apparently formed efficiently in the parent atomic clouds in the lower velocity component. The CO Arc, which is a few kpc scale ordered structure of CO clouds along the southern optical edge of the galaxy, corresponds well to the the lower velocity component of H i gas.
A CO Survey of the LMC with NANTEN: III. Formation of Stellar Clusters and Evolution of Molecular Clouds
Authors: Yamaguchi Reiko , Mizuno Norikazu , Mizuno Akira , Rubio Mónica , Abe Rihei , Saito Hiro , Moriguchi Yoshiaki , Matsunaga Ken’ichi , Onishi Toshikazu , Yonekura Yoshinori , Fukui Yasuo
Published: March 2014

In order to elucidate star formation in the LMC, we made a complete study of CO clouds with NANTEN. In the present paper, we compare 55 giant molecular clouds (GMCs), whose physical quantities were well determined, with young objects, such as young stellar clusters and H ii regions. We find that the GMCs are actively forming stars and clusters; 23 and 40 are found to be associated with the clusters and the H ii regions, respectively. The clusters associated with the GMCs are significantly young; $\sim 85\%$ of them are younger than $\sim 10 \,\mathrm{Myr}$. In addition, compact groups of the young clusters are often found at the peak position of the GMCs, e.g., N 159 and N 44, while much looser groups are away from the GMCs. This suggests that the clusters are formed in groups and disperse as they become old. The distributions of the CO, [C ii], and UV indicate that the GMCs are likely to be rapidly dissipated within several Myr due to UV photons from the clusters. We also estimate the evolutionary time scale of the GMCs; they form stars in a few Myr after their birth, and form clusters during the next few Myr, and are dissipated in the subsequent few Myr.
Discovery of a New ER UMa-Type Dwarf Nova IX Draconis
Authors: Ishioka Ryoko , Kato Taichi , Uemura Makoto , Iwamatsu Hidetoshi , Matsumoto Katsura , Martin Brian E. , Billings Gary W. , Novak Rudolf
Published: March 2014

We observed a new dwarf nova, IX Dra, for 46 days between 2000 November 10 and 2001 June 17, and revealed that IX Dra is the fifth member of a peculiar group of SU UMa stars, called ER UMa stars. The light curve is almost perfectly identical to that of V1159 Ori: supercycle, 53 d; interval of normal outbursts, 3–4 d; duty cycle, $\sim 30\%$; and the outburst amplitude, 2.5 mag. From a time-series observation during the superoutbursts, we obtained a presumable superhump period of 0.067 d. We note that some clustering may exist in the period distribution of ER UMa stars. It is needed to confirm this clustering by a larger number of examples.
Effect of a Magneto-Rotational Instability on Jets from Accretion Disks
Authors: Kudoh Takahiro , Matsumoto Ryoji , Shibata Kazunari
Published: March 2014

We present the results of 2.5-dimensional MHD simulations of jet formation from accretion disks that are unstable for a magneto-rotational instability. Numerical simulations show that magnetically driven jets are ejected from magneto-rotationally-unstable disks. The velocities of the jets are of the order of the Keplerian velocities of the disks. In this paper, we mainly focus on the effect of the magneto-rotational instability on magnetically driven jets from thick disks. For that purpose, we initially impose a sinusoidal perturbation with finite amplitude on a rotating disk that is threaded by a vertical uniform magnetic field. The perturbation grows by the magneto-rotational instability, and the nonlinear development of the instability leads to a channel flow which causes violent accretion. As the accretion continues, the accretion flow is partially turned outward to the outflow that is accelerated by the magnetic force along the poloidal magnetic field line, i.e., a magnetically driven jet is produced. Models with initial finite amplitude perturbation (i.e., $\vert\delta v\vert/V_\mathrm{s} = 0.1$ where $\delta v$ is the velocity perturbation and $V_\mathrm{s}$ is the sound velocity) are compared with those without any perturbation that we previously studied. The mass-accretion rate, mass-ejection rate, and jet velocity are larger when the perturbation is imposed on in the disk. However, the jet velocity is of the order of the Keplerian velocity of the disk, almost independent of the perturbation.
Ram-Pressure Effects on Dense Molecular Arms in the Central Regions of Spiral Galaxies by Intracluster Medium
Authors: Hidaka Makoto , Sofue Yoshiaki
Published: March 2014

We investigated ram-pressure effects by an intracluster wind on an inner disk of spiral galaxies by a hydrodynamical simulation. Even if the wind is mild and not strong enough to strip the gas disk, the ram pressure disturbs orbits of the inter-arm gas significantly. This results in asymmetric dense molecular arms in the inner few kpc region of a galaxy. This mechanism would explain the asymmetric CO gas distributions in the central regions often observed in Virgo spirals.
Observations of Ammonia in External Galaxies I. NGC 253 and M 82
Authors: Takano Shuro , Nakai Naomasa , Kawaguchi Kentarou
Published: March 2014

The ammonia $ (J,K) = (1,1)$, $ (2,2)$, $ (3,3)$, and $ (4,4)$ transitions in the 23.7–24.1 GHz region were searched for in nearby galaxies, NGC 253 and M 82, to study the relation between the molecular abundances and physical conditions. The $ (1,1)$, $ (2,2)$, and $ (3,3)$ emission lines were clearly detected in NGC 253, but no lines were found in M 82. In NGC 253 the shapes of the three emission lines were different from one another. The rotational temperatures obtained in NGC 253 were $ \lesssim 17 \hbox{--} 50 \,\mathrm{K}$, depending on the velocity components. There are two main results: (1) The ortho-to-para abundance ratio was obtained in NGC 253 and found to be different depending on the velocity components. The ratio was about 1 for the velocity component where the $ (2,2)$ line is detected. On the other hand, the ratio was more than 6 for another velocity component where the $ (2,2)$ line is barely detected. This high ratio corresponds to an equilibration temperature of less than 8 K between ortho and para. (2) The abundance of $ \mathrm{NH}_3$ in NGC 253 was found to be about an order of magnitude larger than the upper limit in M 82. This result is an additional evidence for the different molecular abundances which were already reported between NGC 253 and M 82. In addition, the molecular abundances including $ \mathrm{NH}_3$ in nearby galaxies with rich molecular gas were compared, and we found that the molecular abundance in M 82 is systematically peculiar concerning the formation mechanisms of molecules. We discussed factors which cause such a peculiarity in M 82.
On the Abundance of Potassium in Metal-Poor Stars
Authors: Takeda Yoichi , Zhao Gang , Chen Yu-Qin , Qiu Hong-Mei , Takada-Hidai Masahide
Published: March 2014

Based on extensive statistical-equilibrium calculations, we performed a non-LTE analysis of the K i 7699 equivalent-width data of metal-deficient stars for the purpose of clarifying the behavior of the photospheric potassium abundance in disk/halo stars. While the resulting non-LTE abundance corrections turned out to be considerably large, amounting to 0.2–0.7 dex, their effect on the [K/Fe] vs. [Fe/H] relation is not very important, since these corrections do not show any significant dependence on the metallicity. Hence, we again confirmed the results of previous LTE studies, that [K/Fe] shows a gradual systematic increase toward a lowered metallicity up to [K/Fe] $sim$ 0.3–0.5 at [Fe/H] $sim$-1 to -2, such as in the case of $ \alpha$ elements.
CCD Photometry of the MUSES-C Mission Target: Asteroid (25143) 1998 SF36
Authors: Dermawan Budi , Nakamura Tsuko , Fukushima Hideo , Sato Hideo , Yoshida Fumi , Sato Yusuke
Published: March 2014

Near-Earth asteroid (25143) 1998 SF36 is now planned as the target for the Japanese MUSES-C sample return mission. We conducted extensive photometric observations at NAO-Mitaka from 2001 February 15 until March 19 to obtain its physical properties, such as asteroid’s colors, rotation period, phase curve, and light curves. The colors of this asteroid were found to be S-type and in agreement with the spectroscopic result by Binzel et al. (2001, Meteor. Planet. Sci., 36, 1167). From the phase curve of this object, the visual absolute magnitude is obtained to be 18.61 $\pm$ 0.18; we suggest that the albedo may be higher than that for typical S-type asteroids, after applying a known empirical relation between phase curve slope and geometric albedo. We also reveal that the synodic rotation period of this asteroid is $12.13 \pm 0.02 \,\mathrm{hr}$ and the peak-to-peak light variation amplitude at zero phase angle has been shown to be $\sim 0.49 \,\mathrm{mag}$, which implies the ratio of the longest and intermediate ellipsoidal axes for the asteroid $\gtrsim 1.6$.
A New Empirical Method for Estimating the Far-Infrared Flux of Galaxies
Authors: Nagata Hirohisa , Shibai Hiroshi , Takeuchi Tsutomu T. , Onaka Takashi
Published: March 2014

We propose a new empirical method to estimate the total far-infrared flux of galaxies from the spectral energy distribution (SED) at wavelengths of $ \lambda \leq 100 \, {\mu \mathrm {m}}$. It is difficult to derive the total far-infrared luminosity from only the IRAS data, though it is one of the most important properties of galaxies. Observations by Infrared Telescope in Space (IRTS) indicate that the SED of the diffuse emission from the Galactic plane in this wavelength region can be derived from the $ 60 \, {\mu \mathrm {m}}$ to $ 100 \, {\mu \mathrm {m}}$ color. This empirical SED relation was improved in order to obtain a better fit to the Galactic plane data for $ I_\nu(60 \, {\mu \mathrm {m}}) / I_\nu(100 \, {\mu \mathrm {m}}) \gt 0.6$, and applied to 96 IRAS galaxies for which ISOPHOT and KAO data are available at $ \lambda \gt 100 \, {\mu \mathrm {m}}$. As a result, the empirical relation well describes the far-infrared (FIR) SED for a majority of galaxies. Additionally, the total FIR flux for $ \lambda \geq 40 \, {\mu \mathrm {m}}$ was derived from the flux densities at 60 and $ 100 \, {\mu \mathrm {m}}$ by using this model. For the 96 IRAS galaxies, the uncertainty in the total far-infrared flux of the present method is 26%. The present method is more accurate than the previous one widely used to derive the total infrared flux from the IRAS 60 and $ 100 \, {\mu \mathrm {m}}$ data.
Development of Iodine Cells for the Subaru HDS and the Okayama HIDES: I. Instrumentation and Performance of the Spectrographs
Authors: Kambe Eiji , Sato Bun’ei , Takeda Yoichi , Ando Hiroyasu , Noguchi Kunio , Aoki Wako , Izumiura Hideyuki , Wada Setsuko , Masuda Seiji , Okada Norio , Shimizu Yasuhiro , Watanabe Etsuji , Yoshida Michitoshi , Honda Satoshi , Kawanomoto Satoshi
Published: March 2014

We have developed iodine ($\mathrm{I}_2$) cells for the High Dispersion Spectrograph (HDS) on the Subaru telescope and for the HIgh Dispersion Echelle Spectrograph (HIDES) on the Okayama 1.88m reflector. The cell is put into a compact vacuum vessel, which fits into a small space behind the entrance slit of the HDS. The cell assembly is designed to minimize heat losses from the cell, which is heated during observations, to keep $\mathrm{I}_2$ vapor from condensation. The amount of $\mathrm{I}_2$ in the cell is determined to be best suited for radial-velocity measurements of solar-type stars. We also report on some performances of the HDS and HIDES as well as their instrumental profiles based on tests of our $\mathrm{I}_2$ cells. Lastly, we discuss future improvements of our instruments and data-analysis softwares for $\mathrm{I}_2$ observations, and also describe the scientific goals of our project.
Absorption Line Survey of H3+ toward the Galactic Center Sources I. GCS 3-2 and GC IRS3
Authors: Goto Miwa , McCall Benjamin J. , Geballe Thomas R. , Usuda Tomonori , Kobayashi Naoto , Terada Hiroshi , Oka Takeshi
Published: March 2014

We present high-resolution ($R = 20000$) spectroscopy of $\mathrm{H}_3^{+}$ absorption toward the luminous Galactic center sources GCS 3-2 and GC IRS 3. With the efficient wavelength coverage afforded by Subaru IRCS, six absorption lines of $\mathrm{H}_3^{+}$ have been detected in each source from 3.5 to 4.0$\, {\mu \mathrm {m}}$, three of which are new. In particular the 3.543$\, {\mu \mathrm {m}}$ absorption line of the $R(3, 3)^l$ transition arising from the metastable $(J, K) = (3, 3)$ state has been tentatively detected for the first time in the interstellar medium, where previous observations of $\mathrm{H}_3^{+}$ had been limited to absorption lines from the lowest levels: $(J, K) = (1, 0)$ of ortho-$\mathrm{H}_3^{+}$ and $(1, 1)$ of para-$\mathrm{H}_3^{+}$.

The $\mathrm{H}_3^{+}$ absorption toward the Galactic center takes place in dense and diffuse clouds along the line of sight as well as the molecular complex close to the Galactic nucleus. At least four kinematic components are found in the $\mathrm{H}_3^{+}$ absorption lines. We suggest identifications of the velocity components with those of H I, CO, and H$_2$CO previously reported from radio and infrared observations. $\mathrm{H}_3^{+}$ components with velocities that match those of weak and sharp CO and $\mathrm{H_{2}CO}$ lines are attributed to diffuse clouds. Our observation has revealed a striking difference between the absorption profiles of $\mathrm{H}_3^{+}$ and CO, demonstrating that the spectroscopy of $\mathrm{H}_3^{+}$ provides information complementary to that obtained from CO spectroscopy.

The tentative detection of the $R(3, 3)^l$ line and the non-detection of spectral lines from other $J \gt 1$ levels provide observational evidence for the metastability of the $(3, 3)$ level, which is theoretically expected. This suggests that other metastable $J = K$ levels with higher $J$ may also be populated.
Relations between Galaxy Formation and the Environments of Quasars
Authors: Enoki Motohiro , Nagashima Masahiro , Gouda Naoteru
Published: March 2014

We investigate the environments of quasars using a semi-analytic model which includes both galaxy and quasar formations based on a hierarchical clustering scenario. We assume that a supermassive black hole is formed and fueled by the accretion of cold gas during a major merger of galaxies. Our model can reproduce not only the general form of the galaxy luminosity functions in the local Universe, but also the observed relation between a supermassive black hole mass and a spheroid luminosity, the present black hole mass function and the quasar luminosity functions at different redshifts. Using this model, we predict the mean number of quasars per halo, the bias parameter of quasars and the probability distribution of the number of galaxies around quasars. The results of our model show that the spatial distribution of galaxies is different from that of quasars. Furthermore, we found that at $0.2 \lesssim z \lesssim 0.5$ most quasars are likely to reside in galaxy groups. On the other hand, at $1 \lesssim z \lesssim 2$ most quasars seem to reside in environments ranging from small groups of galaxies to clusters of galaxies. Comparing these predictions with observations in the future will enable us to constrain our model of quasar formation.
The Virgo High-Resolution CO Survey: I. CO Atlas
Authors: Sofue Yoshiaki , Koda Jin , Nakanishi Hiroyuki , Onodera Sachiko , Kohno Kotaro , Tomita Akihiko , Okumura Sachiko K.
Published: March 2014

We present the results of the Virgo high-resolution CO survey (ViCS) obtained with the Nobeyama Millimeter-wave Array (NMA). This survey was made during the course of a long-term project at Nobeyama from 1999 December through 2002 April. The objects were selected from Virgo cluster members, while considering the CO richness from the single-dish flux, mild inclination, and a lack of strong tidal perturbations. The central ${1{}^{\mathrm {\prime }}}$ regions ($\sim 4.7 \,\mathrm{kpc}$) of 15 spiral galaxies were observed with resolutions of ${2{}^{\mathrm {\prime \prime }}} \hbox{-} {5{}^{\mathrm {\prime \prime }}}$ and $10 \hbox{-} 20 \,\mathrm{km} \,\mathrm{s}^{-1}$, and sensitivities of $\sim 20 \,\mathrm{mJy} \,\mathrm{beam}^{-1}$ for a $10 \,\mathrm{km} \,\mathrm{s}^{-1}$ channel. The objects lie at the same distance of the Virgo cluster (16.1 Mpc), which is advantageous for comparisons among individual galaxies. We describe the details of observations and data reduction, and present an atlas of integrated CO intensity maps, velocity fields and position–velocity diagrams along the major axes. The molecular gas morphology in the Virgo galaxies shows a wealth of variety, not specifically depending on the Hubble types. Several galaxies show a strong concentration of gas in the central few kpc region, where the CO morphology shows either a “single-peak” or a “twin-peaks”. The morphology of more extended CO components can be classified into “arm-type”, “bar-type”, and “amorphous-type”.
SiO Maser Survey toward the Inner Galactic Disk: ${40{}^{\mathrm {\circ }}} \leq l \leq {70{}^{\mathrm {\circ }}}$ and $\vert b\vert \leq {10{}^{\mathrm {\circ }}}$
Authors: Nakashima Jun-ichi , Deguchi Shuji
Published: March 2014

We present the results of an SiO maser survey for color-selected IRAS sources in the area ${40{}^{\mathrm {\circ }}} < l < {70{}^{\mathrm {\circ }}}$ and $\vert b\vert < {10{}^{\mathrm {\circ }}}$ in the SiO $J = 1\hbox{--}0$, $v = 1$ and 2 transitions ($\sim 43 \,\mathrm{GHz}$). We detected 134 out of 272 observed sources in SiO masers; 127 were new detections. A systematic difference in the detection rates between SiO and OH maser searches was found. Especially, in the color ranges with $\log (F_{25}/F_{12})$ smaller than $-0.1$, the detection rate of the SiO masers is significantly higher than that of OH masers. We found a possible kinematic influence of the Galactic arm on the distribution of SiO maser sources. It was found that the velocity dispersion of SiO maser sources tends to decrease with the galactocentric distance. Using the present and previous data of SiO maser surveys, we found that the local velocity gradient of the rotational velocity of the Galaxy is consistent with the values obtained from other kinds of disk population stars within a statistical uncertainty. The Oort’s constants, A and B, were computed from the gradient of the rotation curve for the present data, and were consistent with the IAU standard values. In addition, in order to check the reliability of IRAS positions, we observed toward the MSX positions for 5 MSX counterparts, which are located more than ${20{}^{\mathrm {\prime \prime }}}$ away (but within ${60{}^{\mathrm {\prime \prime }}}$) from IRAS positions. We detected all of these 5 sources in SiO masers.
Galactic Center Shells and a Recurrent Starburst Model
Authors: Sofue Yoshiaki
Published: March 2014

By applying filtering techniques to remove straight filaments in the 20-cm VLA radio image of the Galactic Center Arc region, we have shown that numerous concentric radio shells of radii 5 to 20 pc are surrounding the Pistol and Sickle region, which we call Galactic Center Shells (GCS). Each shell has thermal energy of the order of $10^{49 \mbox{--} 50} \,\mathrm{erg}$. Several CO-line shells are associated, whose kinetic energies are of the order of $10^{49 \mbox{--} 50} \,\mathrm{erg}$. Summing up the energies of recognized GCSs, the total energy amounts to $\sim 10^{51} \,\mathrm{erg}$. The GCSs show an excellent correlation with the FIR shells observed at 16–26${\mu \mathrm {m}}$ with the MSX. We propose a model in which GCSs were produced by recurrent and/or intermittent starbursts in the Pistol area during the last million years. The most recent burst occurred some $10^5$ years ago, producing an inner round-shaped shell (GCS I); earlier ones a million years ago produced outer shells (GCS II and III), which are more deformed by interactions with the surrounding ISM and Sgr A halo. We argue that recurrent starbursts had also occurred in the past, which produced larger scale hyper-shell structures as well. A burst some million years ago produced the Galactic Center Lobe, and a much stronger one 15 million years ago produced the North Polar Spur.
Chandra X-Ray Spectral Analysis of Cooling Flow Clusters, 2A 0335 $+$ and Abell 2199
Authors: Kawano Naomi , Ohto Akimitsu , Fukazawa Yasushi
Published: March 2014

We report on a spatially resolved analysis of Chandra X-ray data on a nearby typical cooling flow cluster of galaxies 2A 0335$+$096, together with A2199 for a comparison. As recently found in the cores of other clusters, the temperature around the central part of 2A 0335$+$096 is 1.3–1.5 keV, which is higher than that inferred from the cooling flow picture. Furthermore, the absorption column density is almost constant against the radius in 2A 0335$+$096; there is no evidence of excess absorption up to 200–250 kpc. This indicates that no significant amount of cold material, which has cooled down, is present. These properties are similar to those of A2199. Since the cooling time in the central part is much shorter than the age of the clusters, a heating mechanism, which weakens the effect of radiative cooling, is expected to be present in the central part of both clusters of galaxies. Both 2A 0335$+$096 and A 2199 have radio jets associated with their cD galaxy. We discuss the possibility of heating processes caused by these radio jets by considering the thermal conduction and the sound velocity together with the observed disturbance of the ICM temperature and density. We conclude that the observed radio jets can produce local heating and/or cooling, but do not sufficiently reduce the overall radiative cooling. This implies that much more violent jets, whose emission has now decayed, heated up the cooling gas $ \gt 10^9$ years ago.
Near-Infrared Observations of MUSES-C Mission Target
Authors: Ishiguro Masateru , Abe Masanao , Ohba Youhei , Fujiwara Akira , Fuse Tetsuharu , Terada Hiroshi , Goto Miwa , Kobayashi Naoto , Tokunaga Alan T. , Hasegawa Sunao
Published: March 2014

We present near-infrared photometric and spectroscopic observations of the MUSES-C Japanese asteroid sample return mission target (25143) 1998 $\mathrm{SF}_{36}$, which were obtained with the 8-m SUBARU telescope. The near-infrared colors were found to be $J-H = 0.49 \pm 0.04$ and $H-K = 0.02 \pm 0.04$, where $J$, $H$, and $K$ are the magnitudes at the center wavelength of 1.25, 1.63, and 2.12$\, {\mu \mathrm {m}}$, respectively. Comparing these colors to those of known taxonomic type asteroids, we find this asteroid to be S-type. We combined our $M'$-band (4.68$\, {\mu \mathrm {m}}$) photometric data with $N$-band photometric data obtained at the mid-IR wavelength. Using the free beaming parameter thermal model (FBM), the derived size of 1998 $\mathrm{SF}_{36}$, assuming the shape of an ellipsoid, are $a = 620 \pm 140 \,\mathrm{m}$, $b= 280 \pm 60 \,\mathrm{m}$, and $c = 160 \pm 30 \,\mathrm{m}$, and geometric albedo in the $V$-band (0.55$\, {\mu \mathrm {m}}$) is $0.35 \pm 0.11$. The beaming parameter from FBM is found to be 1.1. Our results show that the albedo of 1998 $\mathrm{SF}_{36}$ is high among S-type asteroids, and that the thermal inertia seems to be higher than that of average asteroids. From this we can say that the regolith thickness of this small asteroid is thin, and/or the surface is covered with bare rocks. We also obtained photometric and spectroscopic data in the $L$-band (3.77$\, {\mu \mathrm {m}}$). Since there is no clear absorption band seen around 3$\, {\mu \mathrm {m}}$, we estimate that the water abundance of the surface material is less than 1% in weight.
Meteoroid Clusters in Leonids: Evidence of Fragmentation in Space
Authors: Watanabe Jun-ichi , Tabe Isshi , Hasegawa Hitoshi , Hashimoto Takema , Fuse Tetsuharu , Yoshikawa Makoto , Abe Shinsuke , Suzuki Bunji
Published: March 2014

Three short-duration “outbursts”, in which more than 20–40 meteors appeared in a few seconds, have been reported during a recent Leonid storm. The meteors in these events were extremely localized within a few hundred km, which should be caused by clusters of meteoroids. The existence of such clusters indicates the fragmentation of meteoroids during orbital motion in interplanetary space. Considering the extent of the spatial distribution, the fragmentation should have occurred at around the perihelion passage of the meteoroids just before encountering the Earth. This may cause a possible enhancement of smaller meteoroids, even in old dust trails. A possible example of similar clusters in the past meteor storm of Giacobinids is also noted.
Chandra Observation of the Anomalous X-Ray Pulsar 1E 1841−045
Authors: Morii Mikio , Sato Rie , Kataoka Jun , Kawai Nobuyuki
Published: March 2014

We present the results from a Chandra ACIS CC mode observation of an anomalous X-ray pulsar (AXP) 1E 1841$-$045. This was the first observation in which the pulsar spectrum over a wide energy range was spatially discriminated from the surrounding SNR, Kes 73. Like other AXPs, the phase-integrated spectrum was fitted well with a power-law plus blackbody model. The spectral parameters are $\Gamma = 2.0 \pm 0.3$, $kT_\mathrm{BB} = 0.44 \pm 0.02 \,\mathrm{keV}$, and $N_\mathrm{H} = 2.54^{+0.15}_{-0.13} \times 10^{22} \,\mathrm{cm}^{-2}$. This photon index is the flattest among AXPs, and resembles soft gamma-ray repeaters (SGRs) in a quiescent state. The pulse profile is double-peaked, and we found that the second peak has a significantly hard spectrum. The spectra of all phases are consistent with a power-law plus blackbody model with a constant temperature and photon index. When fitted with a two-blackbody model, we obtained a similarly good fit. These results can be interpreted by saying that there are two emission regions with different energy spectra.
Morphological Butcher–Oemler Effect in the SDSS “Cut and Enhance” Galaxy Cluster Catalog
Authors: Goto Tomotsugu , Okamura Sadanori , Yagi Masafumi , Sheth Ravi K. , Bahcall Neta A. , Zabel Shane A. , Crouch Michael S. , Sekiguchi Maki , Annis James , Bernardi Mariangela , Chong Shang-Shan , GÓmez Percy L. , Hansen Sarah , Kim Rita S. J. , Knudson Adam , Mckay Timothy A. , Miller Christopher J.
Published: March 2014

We investigated the evolution of the fractions of late-type cluster galaxies as a function of redshift using one of the largest, most uniform cluster samples available. The sample consisted of 514 clusters of galaxies in the range of $0.02 \leq z\leq 0.3$ from the Sloan Digital Sky Survey “Cut and Enhance” galaxy cluster catalog. This catalog was created using a single automated cluster-finding algorithm applied to uniform data from a single telescope, with accurate CCD photometry, thus minimizing the selection biases. We used four independent methods to analyze the evolution of the late-type galaxy fraction. Specifically, we selected late-type galaxies based on each of the rest-frame $g-r$ color, the $u-r$ color, galaxy profile fitting, and the concentration index. The first criterion corresponds to that used in classical Butcher–Oemler analyses. The last two criteria are more sensitive to the morphological type of galaxies. In all four cases, we find an increase in the fraction of late-type galaxies with increasing redshift, significant at the 99.9% level. The results confirm that cluster galaxies do change colors with redshift (the Butcher–Oemler effect) and, in addition, they change their morphology to later-type toward a higher redshift — indicating a morphological equivalence of the Butcher–Oemler effect. We also found a tendency of richer clusters to have lower fractions of late-type galaxies. This trend is consistent with a ram-pressure stripping model, where galaxies in richer clusters are affected by stronger ram pressure due to the higher temperature of clusters.
Evolution of Dust-to-Metal Ratio in Galaxies
Authors: Inoue Akio K.
Published: March 2014

This paper investigates the evolution of the dust-to-metal ratio in galaxies based on a simple evolution model for the amount of metal and dust with infall. We take into account grain formation in stellar mass-loss gas, grain growth by the accretion of metallic atoms in a cold dense cloud, and grain destruction by SN shocks. Especially, we propose that the accretion efficiency is independent of the star-formation history. This predicts various evolutionary tracks in the metallicity ($Z$)–dust-to-gas ratio ($\mathcal{D}$) plane depending on the star-formation history. In this framework, the observed linear $Z \hbox{--} \mathcal{D}$ relation of nearby spiral galaxies can be interpreted as a sequence of a constant galactic age. We emphasize that an observational study of the $Z \hbox{--} \mathcal{D}$ relation of galaxies at $z\sim 1$ is very useful to constrain the efficiencies of dust growth and destruction. We also suggest that the Lyman break galaxies at $z\sim 3$ have a very low dust-to-metal ratio, typically $\lesssim 0.1$. Although the effect of infall on the evolutionary tracks in the $Z \hbox{--} \mathcal{D}$ plane is quite small, the dispersion of the infall rate can disturb the $Z \hbox{--} \mathcal{D}$ relation with a constant galactic age.
Where is a Marginally Stable Last Circular Orbit in Super-Critical Accretion Flow?
Authors: Watarai Ken-ya , Mineshige Shin
Published: March 2014

Impressed by a widespread misunderstanding of the issue, we return to the old question concerning the location of the inner edge of the accretion disk around a black hole. We recall the fundamental results obtained in the 1970’s and 1980’s by Warsaw and Kyoto research groups that proved, in particular, that the inner edge does not coincide with the location of the innermost stable Keplerian circular orbit. We give some novel illustrations of this particular point and of some other fundamental results obtained before. To investigate the flow dynamics of the inner edge of an accretion disk, we carefully solved the structure of the transonic flow and plotted the effective potential profile based on the angular-momentum distribution calculated numerically. We showed that the flow does not have a potential minimum for accretion rates, $\dot{M} \gtrsim 10 L_\mathrm{E} / c^2$ (with $L_\mathrm{E}$ being the Eddington luminosity and $c$ being the speed of light). This property is realized even for relatively small viscosity parameters (i.e., $\alpha \sim 0.01$), because of the effect of the pressure gradient. In conclusion, an argument based on the last circular orbit of a test particle cannot give a correct inner boundary of the super-critical flow, and the inner edge should be determined in connection with radiation efficiency. The same argument can apply to optically thin ADAF. The interpretation of the observed QPO frequencies should be re-considered, since the assumption of a Keplerian rotation velocity can grossly over–or underestimate the disk rotation velocity, depending on the magnitude of the viscosity.
Quasar Mesolensing—Direct Probe to Substructures around Galaxies
Authors: Yonehara Atsunori , Umemura Masayuki , Susa Hajime
Published: March 2014

Recently, a “CDM crisis” is being discussed. The main point of this crisis is that the number of substructures presented by cosmological $N$-body simulations based on the CDM scenario for structure formation is much larger than the observed substructures. Therefore, it is crucial for this crisis to discriminate whether the expected number of CDM substructures really exist without detectable radiation, or do not exist. In this paper, we present a new idea to detect such invisible substructures by utilizing gravitational lensing. Here, we consider quasars that are gravitationally lensed by a foreground galaxy. A substructure around a lensing galaxy may superposed on one of the lensed images of such quasars. In this situation, additional image splitting should occur in the image behind the substructure, and additional multiple images are created. From our estimations, the separation and time delay between the additional multiple images are expected to be $1 \hbox{--} 30$ milli-arcsecond and $1 \hbox{--} 10^3$ second, respectively. Furthermore, we evaluate that the optical depth for such events is $\sim 0.1$. Consequently, future fine-resolution imaging and/or high-speed monitoring will unable us to find invisible substructures in one of a few multiple quasars.
Magnetically Arrested Disk: an Energetically Efficient Accretion Flow
Authors: Narayan Ramesh , Igumenshchev Igor V. , Abramowicz Marek A.
Published: March 2014

We consider an accretion flow model originally proposed by Bisnovatyi-Kogan and Ruzmaikin (1974), which has been confirmed in recent 3D MHD simulations. In the model, the accreting gas drags in a strong poloidal magnetic field to the center such that the accumulated field disrupts the axisymmetric accretion flow at a relatively large radius. Inside the disruption radius, the gas accretes as discrete blobs or streams with a velocity much less than the free-fall velocity. Almost the entire rest mass energy of the gas is released as heat, radiation and mechanical/magnetic energy. Even for a non-rotating black hole, the efficiency of converting mass to energy is of order 50% or higher. The model is thus a practical analog of an idealized engine proposed by Geroch and Bekenstein.
Detection of Molecular Hydrogen Emission Associated with LkH$\alpha$ 264
Authors: Itoh Yoichi , Sugitani Koji , Ogura Katsuo , Tamura Motohide
Published: March 2014

We have detected the emission of molecular hydrogen from a classical T Tauri star, LkH$\alpha$ 264 in the $v= 1 \hbox{--} 0$ S(1) line at 2.122$\, {\mu \mathrm {m}}$. The line velocity is coincident with the rest velocity of the star. The line profile is well reproduced by a model in which the line emanates from material in a Keplerian rotating circumstellar disk. Fluorescence by X-ray ionization and shock excitation due to accretion or a low-velocity wind are considered for the emission mechanism of molecular hydrogen.
A Giant Flare on a T Tauri Star Observed at Millimeter Wavelengths
Authors: Furuya Ray S. , Shinnaga Hiroko , Nakanishi Kouichiro , Momose Munetake , Saito Masao
Published: March 2014

We have conducted multi-epoch synthesis imaging of $\lambda = 2$ and 3 millimeter (mm) continuum emission and near-infrared $K$-band (2.2$\, {\mu \mathrm {m}}$) imaging of a flare event in 2003 January that occurred on the young stellar object GMR-A, which is suggested to be a weak-line T Tauri star in the Orion cluster. Our mm data showed that the flare activity lasted for at least over 13 days, whereas the $K$-band magnitude did not change during this event. In addition, we have succeeded in detecting short time variations of flux on time scales of 15 minutes. The total energy of the flare is estimated to be $\sim 10^{35 \hbox{--} 36} \,\mathrm{erg}$, which makes it one of the most energetic flares reported to date. Comparing the mm continuum luminosities with reported X-ray luminosities, we conclude that the mm flare was similar in nature to solar and other stellar flares. Our results will be a crucial step toward understanding magnetically induced stellar surface activities in T Tauri stars.
Exploring Cluster Physics with High-Resolution Sunyaev-Zel’dovich Effect Images and X-Ray Data: The Case of the Most X-Ray-Luminous Galaxy Cluster RX J1347—1145
Authors: Kitayama Tetsu , Komatsu Eiichiro , Ota Naomi , Kuwabara Takeshi , Suto Yasushi , Yoshikawa Kohji , Hattori Makoto , Matsuo Hiroshi
Published: March 2014

Foreseeing the era of high spatial resolution measurements of the Sunyaev–Zel’dovich effect (SZE) in clusters of galaxies, we present a prototype analysis of this sort combined with Chandra X-ray data. It is applied specifically to RX J1347$-$1145 at $z=0.451$, the most X-ray-luminous galaxy cluster known, for which the highest resolution SZE and X-ray images are currently available. We demonstrate that the combined analysis yields a unique probe of complex structures in the intracluster medium, offering determinations of their temperature, density, and line-of-sight extent. For a subclump in RX J1347$-$1145, previously discovered in our SZE map, the temperature inferred after removing the foreground and background components is well in excess of 20 keV, indicating that the cluster has recently undergone a violent merger. Excluding the region around this subclump, the SZE signals in submillimeter to centimeter bands (350, 150, and 21 GHz) are all consistent with those expected from Chandra X-ray observations. We further present a temperature deprojection technique based on the SZE and X-ray images, without any knowledge of spatially resolved X-ray spectroscopy. The methodology presented here will be applicable to a statistical sample of clusters available in the future SZE surveys.
Three-Point Correlation Functions of SDSS Galaxies in Redshift Space: Morphology, Color, and Luminosity Dependence
Authors: Kayo Issha , Suto Yasushi , Nichol Robert C. , Pan Jun , Szapudi István , Connolly Andrew J. , Gardner Jeff , Jain Bhuvnesh , Kulkarni Gauri , Matsubara Takahiko , Sheth Ravi , Szalay Alexander S. , Brinkmann Jon
Published: March 2014

We present measurements of the redshift-space three-point correlation function of galaxies in the Sloan Digital Sky Survey (SDSS). For the first time, we analyze the dependence of this statistic on galaxy morphology, color, and luminosity. In order to control systematics due to selection effects, we used $r$-band, volume-limited samples of galaxies, constructed from magnitude-limited SDSS data ($14.5 < r < 17.5$), and further divided the samples into two morphological types (early and late) or two color populations (red and blue). The three-point correlation function of SDSS galaxies follows the hierarchical relation well, and the reduced three-point amplitudes in redshift-space are almost scale-independent ($Q_z = 0.5 \sim 1.0$). In addition, their dependence on the morphology, color, and luminosity is not statistically significant. Given the robust morphological, color, and luminosity dependences of the two-point correlation function, this implies that galaxy biasing is complex on weakly non-linear to non-linear scales. We show that a simple deterministic linear relation with the underlying mass could not explain our measurements on these scales.
ASCA Observations of the Two Nearest Globular Clusters, M 4 and NGC 6397
Authors: Ishikawa Teru , Ishida Manabu , Ishisaki Yoshitaka , Ohashi Takaya , Yamasaki Noriko Y.
Published: March 2014

We report on ASCA observations of the two nearby globular clusters, M 4 and NGC 6397. Although 14 and 8 sources were detected at more than the $5\,\sigma$ confidence level from each cluster field, respectively, the majority of them, except for the cores of both clusters, were found unlikely to be associated with the clusters. The core of NGC 6397 shows optically thin thermal plasma emission with a temperature of $kT \gtrsim 12 \,\mathrm{keV}$. This result supports the results of HST, ROSAT, and Chandra, indicating that the main constituent of the NGC 6397 core is cataclysmic variables (CVs). The high temperature suggests it to be magnetic CVs, which supports the result of the HST spectroscopy. The core of M 4 was unambiguously detected at a $\gtrsim 5\,\sigma$ confidence level for the first time. Although we cannot carry out a detailed spectral analysis on the M 4 core due to a statistical limitation, the hardness ratio of the detected photons is also consistent with CVs. We compared the ASCA fluxes of the core sources to those from other X-ray observations. The absorption-corrected 0.5–10keV flux of the NGC 6397 core with ASCA was obtained to be $2.5 \times 10^{-12} \,\mathrm{erg} \,\mathrm{cm}^{-2} \,\mathrm{s}^{-1}$, and had been constant within a factor of $\sim 2$ during 1993–2001. The M 4 core flux obtained under the same condition is $2.6 \times 10^{-13} \,\mathrm{erg} \,\mathrm{cm}^{-2} \,\mathrm{s}^{-1}$, which seems to be $\sim 4$ times as high as the ROSAT HRI flux, although the possibility of a constant flux between the ASCA and HRI observations cannot be excluded due to a statistical limitation. Spectral and temporal properties of other out-of-core sources, including the radio galaxy PKS 1620$-$260 and the G0V star V972 Sco, are also described.
On the Period Variation of the Neglected W UMa-type Binary System V714 Monocerotis
Authors: Sheng-Bang Qian , Boonrucksar Soonthornthum , Fu-Yuan Xiang , Li-Ying Zhu , Jia-Jia He
Published: March 2014

Some new CCD times of the light minimum for a neglected W UMa-type binary star, V714 Monocerotis, observed in 2002 and 2003, are presented. By considering the general trend of the $\mathrm{O}- \mathrm{C}$ variation, a plausible $\mathrm{O}- \mathrm{C}$ curve was formed and a mean linear ephemeris was obtained. It was found that the period of the binary star shows a continuous decrease with rate of $dP/dt =-1.48 \times 10^{-7} \;\mathrm{d} \;\mathrm{yr}^{-1}$. In order to understand the evolutionary state of the binary system, new photometric and spectroscopic observations and a careful investigation on those data are required.
A Fast Parallel Treecode with GRAPE
Authors: Makino Junichiro
Published: March 2014

In this paper, we describe an implementation of the Barnes–Hut treecode on a cluster of PCs (Beowulf-class machines) equipped with GRAPE hardware. Our implementation is designed to achieve good performance on clusters of GRAPE with a relatively slow network, such as the standard Gigabit Ethernet. With 12 processors, the speedup over single-processor code reaches around 10. Our code is available on the web.
VERA Observation of the W49NH2O Maser Outburst in 2003 October
Authors: Mareki Honma , Choi Yoon Kyung , Bushimata Takeshi , Fujii Takahiro , Hirota Tomoya , Horiai Koji , Imai Hiroshi , Inomata Noritomo , Ishitsuka Jose , Iwadate Kenzaburo , Jike Takaaki , Kameya Osamu , Kamohara Ryuichi , Kan-ya Yukitoshi , Kawaguchi Noriyuki , Kobayashi Hideyuki , Kuji Seisuke , Kurayama Tomoharu , Manabe Seiji , Miyaji Takeshi , Nakagawa Akiharu , Nakashima Kouichirou , Nagayoshi Riiko , Omodaka Toshihiro , Oyama Tomoaki , Rioja Maria , Sakai Satoshi , Sakakibara Sei-ichiro , Sato Katsuhisa , Sasao Tetsuo , Shibata Katsunori M. , Shimizu Rie , Sora Kasumi , Suda Hiroshi , Tamura Yoshiaki , Yamashita Kazuyoshi
Published: March 2014

We report on a strong outburst of the W 49N $\mathrm{H}_2 \mathrm{O}$ maser observed with VERA. Single-dish monitoring with VERA 20m telescopes detected a strong outburst of the maser feature at $V_\mathrm{LSR} =-30.7 \,\mathrm{km} \,\mathrm{s}^{-1}$ in 2003 October. The outburst had a duration of $\sim 100$ days and a peak intensity of $7.9 \times 10^4 \,\mathrm{Jy}$, being one of the strongest outbursts in W 49N observed so far. VLBI observations with the VERA array were also carried out near to the maximum phase of the outburst, and the outburst spot was identified in the VLBI map. While the map was in good agreement with previous studies, showing three major concentrations of maser spots, we found a newly formed arc-like structure in the central maser concentration, which may be a shock front powered by a forming star or a star cluster. The outburst spot was found to be located on the arc-like structure, indicating a possible connection of the present outburst to a shock phenomenon.