bluuebunny/crossref_metadata_2025_split huggingface dataset:
Discovery of the Slowest X-Ray Pulsar in the SMC, AX J0049.5–7323, with ASCA
Authors: Yokogawa Jun , Imanishi Kensuke , Ueno Masaru , Koyama Katsuji 
Published: March 2014

Abstract
The discovery of coherent pulsations with ASCA from an X-ray source, AX J0049.5−7323, is reported. The barycentric period was determined to be 755.5 ± 0.6 s, which is the longest among X-ray pulsators in the SMC. The X-ray spectrum has been found to be unchanged through ASCA observations, with a photon index of ∼ 0.8 and a luminosity of ∼ 5 × 1035 erg s−1 (0.7−10 keV). Archival data of the Einstein and the ROSAT satellites indicate that the flux has been ≲ 10−12 erg s−1 cm−2 (≲ 5 × 1035 erg s−1) for over 20 years and exhibits a variability with a factor of ≳ 10. We argue that AX J0049.5−7323 is an X-ray pulsar with a Be star companion.
Water-Vapor Maser Emission from the Seyfert 2 Galaxy IC 2560: Evidence for a Super-Massive Black Hole
Authors: Ishihara Yuko , Nakai Naomasa , Iyomoto Naoko , Makishima Kazuo , Diamond Philip , Hall Peter 
Published: March 2014

Abstract
We present an H$_2$O maser emission study of the Seyfert galaxy IC 2560 based on single-dish and VLBI observations. The maser emission was detected in multiple velocity ranges: one around the systemic velocity, one blue-shifted from the systemic velocity by $\sim220$-$420~$km$~$s$^{-1}$, and one red-shifted by $\sim210$-$350~$km$~$s$^{-1}$. This was the first detection of high-velocity features in this galaxy. The velocity of the systemic features drifts at a mean rate of $2.62\pm0.09~$km$~$s$^{-1}~$yr$^{-1}$. Assuming a compact Keplerian disk at the nucleus, the inner and outer radii of this disk are 0.07 and 0.26 pc, respectively. The central mass confined within the disk inner radius is $2.8\times10^6~M_{\odot}$, and its density is at least $2.1\times10^9~M_{\odot}~\mbox{pc}^{-3}$. Such a high density strongly suggests the existence of a black hole at the nucleus. The maser spots of the systemic features are distributed over $\lt 0.3~$mas (0.04 pc). The continuum source at the same position as the maser source is $\lt 1.0~$mas (0.13 pc) in size, and its brightness temperature of $2.7\times10^{11}~$K confirms IC 2560 to be an AGN. The 2-10 keV luminosity based on ASCA data is $1.0\times10^{41}~$erg$~$s$^{-1}$, which makes IC 2560 one of the low-luminosity AGNs. Adopting the standard accretion model, the mass-accretion rate needs to be $2\times10^{-5}~M_{\odot}~\mbox{yr}^{-1}$ in order to explain the X-ray luminosity.
Bondi Accretion onto a Luminous Object
Authors: Fukue Jun 
Published: March 2014

Abstract
Spherical accretion of ionized gas onto a gravitating object is examined under the influence of central radiation. In classical Bondi accretion onto a non-luminous source with mass $ M$, the accretion rate $ \dot{M}_\mathrm{B}$ is expressed as $ \dot{M}_\mathrm{B}= \lambda(\gamma) \times 4\pi G^2 M^2\rho_\infty c_{\mathrm{s}\infty}^{-3}$, where $ \rho_\infty$ is the density at infinity and $ c_{\mathrm{s}\infty}$ the sound speed at infinity. We first found that the normalized accretion rate $ \lambda(\gamma)$ is approximated by $ \lambda(\gamma) = -(5/4)\gamma+ (19/8)$, instead of a rigorous expression. When the central object is a “spherical” source, the accretion rate $ \dot{M}$ reduces to $ \dot{M}_\mathrm{B} (1-\Gamma)^2$, where $ \Gamma$ is the central luminosity normalized by the Eddington one. If the central luminosity is produced by the accretion energy, the steady canonical luminosity is determined and the normalized luminosity does not exceed unity, as expected. On the other hand, when the central object is a “disk” source, such as an accretion disk, the accretion rate becomes $ \dot{M}/\dot{M}_\mathrm{B} = 1 -2\Gamma_\mathrm{d} + (4/3)\Gamma_\mathrm{d}^2$ for $ \Gamma_\mathrm{d} \leq 1/2$, and $ \dot{M}/\dot{M}_\mathrm{B} = 1 /(6\Gamma_\mathrm{d})$ for $ \Gamma_\mathrm{d} &gt; 1/2$, where $ \Gamma_\mathrm{d}$ is the normalized disk luminosity. We also found steady canonical solutions, where the normalized luminosity can exceed unity for sufficiently large accretion rates. The anisotropic radiation field of accretion disks greatly modifies the accretion nature.
A Molecular Cloud and an Expanding Cavity Adjacent to the Nonthermal Filaments of the Galactic Center Radio Arc
Authors: Oka Tomoharu , Hasegawa Tetsuo , Sato Fumio , Tsuboi Masato , Miyazaki Atsushi 
Published: March 2014

Abstract
Large-scale CO images taken with the $2 \times 2$ focal-plane array receiver on the 45 m telescope of Nobeyama Radio Observatory reveal parsec-scale structure of molecular gas around the Galactic center radio arc. The LVG analysis shows that the gas kinetic temperature is considerably enhanced ($T_\mathrm{k} \geq 70 \,\mathrm{K}$) in CO 0.13–0.13, a cloud which seems to be in contact with the nonthermal filaments of the Galactic center radio arc. This lends support for an interaction between CO 0.13–0.13 and the nonthermal filaments. The interaction with the strong magnetic field in and around the nonthermal filaments may heat up the molecular gas in CO 0.13–0.13 through shock dissipation and/or magnetic viscosity.
We also find an expanding cavity adjacent to the nonthermal filaments. The shell has a radius of $\sim 5 \,\mathrm{pc}$ and an expansion velocity of $25 \,\mathrm{km} \,\mathrm{s}^{-1}$. This expanding cavity might have been formed by several hundred supernovae or a single hypernova within $3 \times 10^5 \,\mathrm{yr}$. Magnetic tubes in this region could have been swept up by the expanding cavity, and compressed by interactions with CO 0.13–0.13. An interaction between the cloud and magnetic field may accelerate electrons to relativistic energies through shock acceleration or magnetic field reconnection.
Subaru Deep Near-Infrared Imaging of the Field of a Possible Proto-Cluster Near the Radio Galaxy 53W002 at $z=2.4$
Authors: Yamada Toru , Motohara Kentaro , Iwamuro Fumihide , Maihara Toshinori , Kajisawa Masaru , Tanaka Ichi , Kodama Tadayuki , Terada Hiroshi , Goto Miwa , Tanabe Hirohisa , Taguchi Tomoyuki , Hata Ryuji , Takata Tadafumi , Sekiguchi Kazuhiro , Iye Masanori , Sasaki Toshiyuki , Usuda Tomonori , Kosugi George , Simpson Chris 
Published: March 2014

Abstract
We present the results of deep $K^\prime$ - and $J$-band imaging of the field of a proto-cluster region near the radio galaxy 53W002 at $z=2.390$ with the Subaru Telescope. The data were analyzed together with deep optical and near-infrared (NIR) images taken with the Hubble Space Telescope to investigate the properties of ten optically compact emission-line galaxies and candidates. Excluding the three objects which may contain active galactic nuclei, many are faint or undetected at $K^\prime$ ($\lambda_\mathrm{rest} \approx 6000 \,{Å}$), and are therefore revealed to be intrinsically small starbursting objects. On the other hand, we detect few objects with colors and magnitudes expected for quiescent massive galaxies at $z=2.4$ in the field.
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
Observations of Ammonia in External Galaxies I. NGC 253 and M 82
Authors: Takano Shuro , Nakai Naomasa , Kawaguchi Kentarou 
Published: March 2014

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.