bluuebunny/crossref_metadata_2025_split huggingface dataset:
Near-Infrared Observations of S 255-2 : The Heart of a Massive YSO Cluster
Authors: Itoh Yoichi , Tamura Motohide , Suto Hiroshi , Hayashi Saeko S. , Murakawa Koji , Oasa Yumiko , Nakajima Yasushi , Kaifu Norio , Kosugi George , Usuda Tomonori , Doi Yoshiyuki 
Published: March 2014

Abstract
High-resolution near-infrared ($J$$H$$K$$L^\prime$$M^\prime$) images of a massive star-forming region, S 255-2, were obtained with the Subaru Telescope and an infrared camera, CIAO. These images clearly resolve two sets of bipolar nebulae illuminated by two independent massive YSOs. A number of cluster member YSOs have been detected, including 3 new sources. Seven early-B type stars have been identified within 10 pc of S 255-2; three are associated with extended optical H II regions. The variation in the appearance of these early-B type stars suggests an evolutionary sequence of massive stars in the S 255 region.
SiO Maser Survey in the Galactic Center Region with a Multi-Beam Receiver
Authors: Miyazaki Atsushi , Deguchi Shuji , Tsuboi Masato , Kasuga Takashi , Takano Shuro 
Published: March 2014

Abstract
We have made a wide-field survey of SiO masers in the $7'' \times 13''$ area around the Galactic center with the Nobeyama 45-m radio telescope using a $2 \times 3$ multi-beam SIS mixer receiver at 43 GHz. We detected 9 SiO maser sources (6 of them are new); newly detected 6 sources have been identified with Miras or OH 1612 MHz maser sources. The source surface number density, $\sim 360$ per square degree, found in this survey is slightly smaller than the number density of OH 1612 MHz sources in the same area. A least-squares analysis of the radial velocities of the detected sources has revealed a rapid rotation of the stars around the Galactic center. This implies that most of the objects detected in this survey belong to the nuclear disk near the Galactic center.
ASCA Observation of the Millisecond Pulsar PSR J2124$-$3358
Authors: Sakurai Ikuya , Kawai Nobuyuki , Torii Ken’ichi , Negoro Hitoshi , Nagase Fumiaki , Shibata Shinpei , Becker Werner 
Published: March 2014

Abstract
The isolated 4.9 ms pulsar PSR J2124$-$3358 was observed with ASCA on 1998 May 9, and the X-ray spectrum in the 0.5–10 keV band was obtained. The X-ray spectrum can be fitted with a single blackbody model with a temperature $kT = 0.31^{+0.08}_{-0.06}\,\mathrm{keV}$, although a simple power-law model with a relatively large photon index $\Gamma = 2.8^{+0.6}_{-0.5}$ cannot be rejected.
The r-Process Nucleosynthesis in Neutrino-/Magnetocentrifugally-Driven Winds
Authors: Nagataki Shigehiro , Kohri Kazunori 
Published: March 2014

Abstract
We consider the effects of the rotation and magnetic fields on the rapid neutron capture nucleosynthesis (r-process nucleosynthesis) in neutrino-driven winds. We examine the features of steady and subsonic wind solutions which extend the model of Weber and Davis (1967, Astron. Jahresber. 67.6776), which is a representative solar-wind model. Then, we find that the entropy per baryon becomes lower and the dynamical timescale becomes longer as the angular velocity becomes higher. The results are inappropriate for the production of r-process nuclei. Therefore, we conclude that it is difficult to realize a successful r-process nucleosynthesis in this framework.
Solar Models with Helioseismic Constraints and the Solar Neutrino Problem
Authors: Watanabe Satoru , Shibahashi Hiromoto 
Published: March 2014

Abstract
Imposing a constraint of the sound-speed profile determined from helioseismology and updating the microphysics, we have revised our seismic solar model, constructed with the assumption of a homogeneous metal abundance distribution, and have shown that the theoretically expected neutrino fluxes are still significantly more than the observations. With the same sound-speed profile constraint, we also constructed solar models with low metal abundance in the core, and evaluated the neutrino fluxes of these models to see if nonstandard solar models with a low metal core can solve the solar neutrino problem. Some of these models are in agreement with the Homestake data, the Super-Kamiokande data, and the sound-speed profile simultaneously, but none of these satisfy both the neutrino flux data, including GALLEX and SAGE, and the helioseismically determined density profile.
Specifying the Environments around GRB, Explaining the Fe Line in the X-Ray Afterglow of GRB 000214
Authors: Kotake Kei , Nagataki Shigehiro 
Published: March 2014

Abstract
We present a model for explaining the Fe K$\alpha$ line and the continuum in the afterglow of GRB 000214. In this paper, we pose the importance to seek the physically natural environment around GRB 000214. For reproducing the observation, we need a ring-like remnant around the progenitor, like that of SN 1987A produced by the mass-loss of the progenitor and the fireball spread over all directions. The observation of GRB 000214, in which the continuum power-law spectrum decreased faster than the line, motivated us to consider two independent systems for the line emission and the continuum spectrum. At first, the continuum spectrum can be fitted by the afterglow emission of the fireball pointing toward the observer, which does not collide with the ring because the emission of GRB and the afterglow are highly collimated to the observer by the relativistic beaming effect. Secondly, the line can be fitted by the fluorescence of the Fe atoms in the ring illuminated by the X-ray afterglow. The significance of this study is that our model may strongly constrain the GRB model.
Revisiting the Faint Blue Galaxy Problem
Authors: Mihara Kuniko 
Published: March 2014

Abstract
We have investigated whether the pure luminosity evolution (PLE) model in a flat universe with cosmological constant $\Lambda$ can explain the faint blue galaxy (FBG) problem in light of recent observations of a morphologically divided number count, redshift distribution, and color distribution. While the original FBG problem means an inconsistency between the total number count and redshift distribution at around $B &gt; 22\,\mathrm{mag}$, we consider here the FBG problem in a broader context. In particular, we pay attention to an evolution model of irregular galaxies, of which predictions from the standard model disagree with recent observations. In addition to the standard 'S model' with slow star formation, we introduce a non-standard 'R model' with rapid star formation for irregular galaxies, and investigate the properties of the sum of these models (S+R model). The observed total number count and redshift distribution in the $B$-band can be well reproduced by the PLE model in a $\Lambda$-dominated universe. As for irregular galaxies, while the S model underproduces the observed count, the S+R model can account for the observation. Considering that the observed color distribution of faint irregular galaxies is very broad, we propose a possibility that irregular galaxies are composed of at least two populations.
NIR Narrow- and Broad-Band Study of the SSA 22 Field
Authors: Tamura Naoyuki , Ohta Kouji , Maihara Toshinori , Iwamuro Fumihide , Motohara Kentaro , TAkata Tadafumi , Iye Masanori 
Published: March 2014

Abstract
Deep narrow- and broad-band near-infrared imaging observations of the central $ {2{}^{\mathrm {\prime }}} \times {2{}^{\mathrm {\prime }}}$ region of the SSA 22 field were made with the near-infrared camera (CISCO) attached to the Subaru Telescope. Using a narrow-band filter centered at $2.033\, {\mu \mathrm {m}}$, [O III] $\lambda~5007$ emitters at $z \sim 3.06 \pm 0.02$ were searched to examine star-forming activities in an over-density region where a clustering of Lyman Break Galaxies (LBGs) and Lyman $ \alpha$ emitter candidates around $ z = 3.09$ was reported, though the targeted redshift is slightly different from that of the peak of the over-density region. Although one emitter candidate at $ z = 3.06$ was detected, it is likely to be located at a redshift of between 1 and 2 judged based on multi-band photometry. Another emission-line object was detected in another narrow-band filter (“off band” filter) centered at $ 2.120\, {\mu \mathrm {m}}$, which is identified with a galaxy at $ z = 0.132$ (the emission line is Paschen $\alpha$). The $ K^{\prime}$-band imaging data revealed the presence of 12 Extremely Red Objects (EROs) with $I_{814}-K^{\prime} \geq4$. The distribution of the EROs does not seem to coincide with that of Lyman Break Galaxies or Lyman $\alpha $ emitters at $ z \sim3$. The magnitudes and colors of the EROs are not consistent with those of passively evolving massive elliptical galaxies at $ z \sim3$. Candidates for counterparts of the submm sources detected with SCUBA are found; no EROs around the submm sources are found in our magnitude limit.
Changing Supercycle of the ER UMa-Type Star V1159 Ori
Authors: Kato Taichi 
Published: March 2014

Abstract
We examined the VSNET light curve of the ER UMa-type star V1159 Ori. We detected a large variation of the supercycle (the interval between successive superoutbursts) between extremes of 44.6 and 53.3d. The outburst activity was also found to decrease when the supercycle was long. The observed variation of the supercycle corresponds to a variation of $ \sim 40\%$ of the mass-transfer rate from the secondary star, totally unexpected for this class of objects. We also detected a hint of $ \sim 1800 \,\mathrm{d}$ periodicity in the variation, whose period is close to what has been suggested for solar-type cycles for cataclysmic variables (CVs). If this periodicity is caused by the magnetic activity of the secondary star, this detection constitutes the first clear evidence of continuing magnetic activity in CV evolution, even after crossing the period gap. This activity may partly explain still poorly understood origins of the high mass-transfer rates in ER UMa-type stars.
A CO Outflow and a Molecular Cloud Core Associated with a Young Massive Star IRAS 22134$+$5834
Authors: Dobashi Kazuhito , Uehara Hayato 
Published: March 2014

Abstract
We present the results of the recent 12CO ($J=1$-0), 13CO ($J=1-0$), and C 18O ($J=1-0$) observations carried out toward a bright IRAS point source (22134$+$5834) using the 45 m telescope at Nobeyama Radio Observatory (NRO) equipped with the 4 multi-beam receiver system. The IRAS source exhibits a cold color spectrum in the far infrared wavelengths and has a high luminosity of $\simeq 1700 \,{{{L}_{\odot}}}$ at the adopted distance of 900 pc, indicating that the IRAS source is a good candidate for an embedded young massive star whose luminosity is equivalent to that of an early B-type star having $\simeq 8 \,{{{M}_{\odot}}}$. A bipolar outflow and a dense core associated with IRAS 22134$+$5834 were detected by the present observations. It is remarkable that the outflow has a very large total molecular mass of $26 \,{{{M}_{\odot}}}$, which makes this source one of the most massive outflows reported to date. We derived the dynamical time scale ($\simeq 7\times 10^4 \,\mathrm{yr}$), mechanical momentum ($\simeq 140 \,{{{M}_{\odot}}}\,\mathrm{km} \,\mathrm{s}^{-1}$), and kinetic energy ($\simeq 400 \,{{{M}_{\odot}}} \,\mathrm{km}^2 \,\mathrm{s}^{-2}$) of the outflow. The dense core traced in C18O is also massive ($206 \,{{{M}_{\odot}}}$) extending over $\simeq 1 \,\mathrm{pc}$. The core shows an elliptical shape with its major axis inclined by $-45 {{}^{\circ }}$ to the north. A velocity gradient of $0.9 \,\mathrm{km} \,\mathrm{s}^{-1} \,\mathrm{pc}^{-1}$ along the core major axis was observed, indicating a rotation of the core. We also detected blue and red velocity-shifted components in C18O along the core minor axis separated by $\simeq 0.7 \,\mathrm{km} \,\mathrm{s}^{-1}$ from the systemic velocity at $-18.2 \,\mathrm{km} \,\mathrm{s}^{-1}$, which are most likely to trace the mixture of the dense gas being swept up by the powerful outflow and the matter in the core infalling toward the central star.
ASCA Observations on Two Molecular Cloud Cores in the Perseus Complex
Authors: Yamauchi Shigeo , Tsuboi Yohko , Koyama Katsuji 
Published: March 2014

Abstract
We present ASCA results for two molecular cloud cores in the Perseus complex, Barnard 1 and a cloud core which contains a class 0 protostar, IRAS 03282$+$3035. Four X-ray sources are found, of which two have either a radio, infrared, or optical counterpart. The X-ray temperature and flux of an IRAS source, IRAS 03275$+$3020/AX J0330$+$3030, are similar to those of T Tauri stars. Thus, together with the infrared and optical data, this source can be classified as a T Tauri star. Two unidentified sources have a spectrum with moderate temperature and absorption, and are possibly new young stellar objects in the clouds. A radio source, BWE 0328$+$3054/AX J0331$+$3104, has a hard X-ray spectrum fitted with a power-law model of photon index $\sim 1.5$, and hence would be an active galactic nucleus. No X-ray emission is found from a class 0 protostar, IRAS 03282$+$3035, and a class 0 candidate, IRAS 03301$+$3057.
1998 Superoutburst of the Large-Amplitude SU UMa-Type Dwarf Nova WX Ceti
Authors: Kato Taichi , Matsumoto Katsura , Nogami Daisaku , Morikawa Koichi , Kiyota Seiichiro 
Published: March 2014

Abstract
We observed the 1998 November superoutburst of WX Cet, a dwarf nova originally proposed as a WZ Sge-like system. The observation established that WX Cet is an SU UMa-type dwarf nova with a mean superhump period of 0.05949(1)d, which is 2.1% longer than the reported orbital period. The lack of early superhumps at the earliest stage of the superoutburst, the rapid development of usual superhumps, and the possible rapid decay of late superhumps seem to support that WX Cet is a fairly normal large-amplitude SU UMa-type dwarf nova, rather than a WZ Sge-type dwarf nova with a number of peculiarities. However, a period increase of superhumps at a rate $\dot{P}/P = +8.5\pm 1.0 \times 10^{-5}$ was observed, which is one of the largest $\dot{P}/P$ ever observed in SU UMa-type dwarf novae. A linear decline of light, with a rate of $0.10 \,\mathrm{mag} \,\mathrm{d}^{-1}$, was observed in the post-superoutburst stage. This may be an exemplification of the decay of the viscosity in the accretion disk after the termination of a superoutburst, mechanism of which is proposed to explain a variety of post-superoutburst phenomena in some SU UMa-type dwarf novae.
Sunspot Magnetic Fields Observed with a Large-Format Infrared Array
Authors: Sakurai Takashi , Yanagisawa Kenshi , Kobiki Toshihiko , Kasahara Shouichi , Nakakubo Kayoko 
Published: March 2014

Abstract
Spectro-polarimetric observations of sunspots were carried out by using a PtSi near-infrared camera (KONIC) of Kiso Observatory, The University of Tokyo, in the period of 1999 November 3–5. The camera was attached to a spectrograph of the Domeless Solar Telescope at Hida Observatory, Kyoto University. We observed the absorption lines of Fe I at 15648.5${Å}$ (Landè factor $g_{\mathrm{L}} = 3$) and 15652.9${Å}$ ($g_{\mathrm{L~eff}} = 1.53$), and derived the distribution of the magnetic field strengths and inclination angles across the sunspots. The ratio of the Zeeman splitting of the two lines was derived to be $0.39 \pm 0.01$, while the ratio of the Landè factors is 0.51. Our data indicates that the effective Landè factor of the 15652.9${Å}$ line is $1.17 \pm 0.03$.
Study of Molecular Clouds and Star Formation in the Region of IC 2118
Authors: Kun Maria , Aoyama Hiroko , Yoshikawa Nao , Kawamura Akiko , Yonekura Yoshinori , Onishi Toshikazu , Fukui Yasuo 
Published: March 2014

Abstract
We carried out a 12CO survey of molecular clouds in the region of the reflection nebula IC 2118. Our observations covered the whole area of IC 2118 ($\sim 6 \,\mathrm{deg^2}$) with a 2.$^{\prime}$6 beam at a $4^{\prime}$ grid spacing. We identified six molecular clouds. Based on a literature search we found a distance value of 210 pc for the reflection nebula and its associated molecular clouds, indicating that the clouds are probably interacting with the Orion–Eridanus Bubble. Using this distance value, we determined the physical properties of the clouds. We also made an objective prism search for $\mathrm{H}\alpha$ emission stars in the region in order to find possible solar-type stars born in the clouds, and identified 46 candidate pre-main-sequence stars. Their spectroscopic follow-up is in progress. Seven of them have so far proved to be T Tauri stars.
Photospheric Abundances of Volatile and Refractory Elements in Planet-Harboring Stars
Authors: Takeda Yoichi , Sato Bun’ei , Kambe Eiji , Aoki Wako , Honda Satoshi , Kawanomoto Satoshi , Masuda Seiji , Izumiura Hideyuki , Watanabe Etsuji , Koyano Hisashi , Maehara Hideo , Norimoto Yuji , Okada Takafumi , Shimizu Yasuhiro , Uraguchi Fumihiro , Yanagisawa Kenshi , Yoshida Michitoshi , Miyama Shoken M. , Ando Hiroyasu 
Published: March 2014

Abstract
By using the high-dispersion spectra of 14 bright planet-harboring stars (along with 4 reference stars) observed with the new coudé echelle spectrograph at Okayama Astrophysical Observatory, we investigated the abundances of volatile elements (C, N, O, S, Zn; low condensation temperature $T_\mathrm{c}$) in order to examine whether these show any significant difference compared to the abundances of other refractory elements (Si, Ti, V, Fe, Co, Ni; high $T_\mathrm{c}$), which are known to be generally overabundant in those stars with planets, since a $T_\mathrm{c}$-dependence is expected if the cause of such a metal-richness is due to the accretion of solid planetesimals onto the host star. We found, however, that all elements which we studied behave themselves quite similarly to Fe (i.e., $[\mathrm{X} / \mathrm{Fe}] \simeq 0$), even for the case of volatile elements. This may suggest that the enhanced metallicity in those planet-bearing stars is not so much an acquired character (by accretion of rocky material) as rather primordial.
Collisional Evolution of Galaxy Clusters and the Growth of Common Halos
Authors: Takahashi Koji , Sensui Tomohiro , Funato Yoko , Makino Junichiro 
Published: March 2014

Abstract
We investigated the dynamical evolution of clusters of galaxies in virial equilibrium using Fokker–Planck models and self-consistent $N$-body models. In particular, we focused on the growth of a common halo, which is a cluster-wide halo formed by matter stripped from galaxies, and the development of a central density cusp. The Fokker–Planck models include the effects of two-body gravitational encounters both between galaxies and between galaxies and common halo particles. The effects of tidal mass stripping from the galaxies due to close galaxy–galaxy encounters and accompanying dissipation of the orbital kinetic energies of the galaxies were also taken into account in the Fokker–Planck models. We find that the results of the Fokker–Planck models are in excellent agreement with those of the $N$-body models regarding the growth of the common halo mass and the evolution of the cluster density profiles. In the central region of the cluster, a shallow density cusp, approximated by $\rho (r) \propto r^{-\alpha}$ ($\alpha \sim 1$), develops. This shallow cusp results from the combined effects of two-body relaxation and tidal stripping. The cusp steepness, $\alpha$, weakly depends on the relative importance of the tidal stripping. When the effect of stripping is important, the central velocity dispersion decreases as the central density increases and, consequently, a shallow ($\alpha &lt;2$) cusp is formed. In the limit of no stripping, usual gravothermal core collapse occurs, i.e. the central velocity dispersion increases as the central density increases with a steep ($\alpha \gt 2$) cusp left. We conclude from our consideration of the origin of the cusp demonstrated here that shallow cusps should develop in real galaxy clusters.
IR Com: Deeply Eclipsing Dwarf Nova Below the Period Gap —A Twin of HT Cas?
Authors: Kato Taichi , Baba Hajime , Nogami Daisaku 
Published: March 2014

Abstract
We observed an X-ray selected, deeply eclipsing cataclysmic variable IR Com ($=\mathrm{S}~10932$). We detected an outburst occurring on 1996 January 1. The light curve of the outburst closely resembled that of a normal outburst of an SU UMa-type dwarf nova, rather than that of an intermediate polar. Time-resolved photometry during the outburst showed that eclipses became systematically deeper and narrower as the outburst faded. Full-orbit light curves in quiescence showed little evidence of orbital humps or asymmetry of the eclipses. In addition to the presence of high–low transitions in quiescence, the overall behavior of the outbursts and the characteristics of the eclipse profiles suggest that IR Com can be best understood as a twin of HT Cas, a famous eclipsing SU UMa-type dwarf nova with a number of peculiarities.
Photometry of the 1991 Superoutburst of EF Pegasi: Super-Quasi-Periodic Oscillations with Rapidly Decaying Periods
Authors: Kato Taichi 
Published: March 2014

Abstract
We observed the 1991 October outburst of EF Peg. Prominent superhumps with a period of 0.08705(1)d were observed, qualifying EF Peg as being a long-period SU UMa-type dwarf nova. The superhump period showed a monotonic decrease during the superoutburst, which makes a contrast to the virtually zero period change observed during the 1997 superoutburst of the same object. Large-amplitude and highly coherent quasi-periodic oscillations (super–QPOs) were observed on October 18, when superhumps were still growing in amplitude. Most strikingly, the QPOs showed a rapid decrease in the period from 18 min to 6.8 min within the 3.2-hr observing run. Such a rapid change in the period has not been observed in any class of QPOs in cataclysmic variables. We propose a hypothesis that the rapid decrease of the QPO period reflects a rapid removal of the angular momentum from an orbiting blob in the accretion disk, via viscosity in a turbulent disk. A brief comparison is given with the QPOs in X-ray binaries, some of which are known to show a similar rapid decrease in the periods.
The Contribution of Warm Gas in Cluster Galaxies to the Soft X-Ray Emission of Clusters
Authors: Cheng Ling-Mei 
Published: March 2014

Abstract
We investigate the possible existence and X-ray emission of warm gas associated with the gravitational potential wells of individual galaxies in rich clusters in an attempt to account for the EUV and soft X-ray excess detected in some nearby clusters. The intrinsic properties of hot intracluster gas and warm galactic gas are specified by the assumption of isothermality and the equation of hydrostatic equilibrium, and the underlying gravitational potentials are described by the universal density profile. Moreover, the Schechter luminosity function and the King model are adopted for the number and spatial distributions of the cluster galaxies, respectively. We fix the gas fraction in different galaxies using Einstein Observatory and ROSAT observations. Our numerical calculation in conjunction with Monte Carlo technique shows that cluster galaxies consisting primarily of ellipticals can make a nonnegligible contribution to the EUV and soft X-ray emission seen in the central regions of clusters. For a rich cluster, like Coma, a small fraction (6%) of soft X-ray emission in the 0.1–1 keV band may come from galaxies, while a significant excess of up to 26% in the 0.01–0.1 keV band can be attributed to galaxies. The cosmological implications and observational consequence of this alternative scenario for the EUV and soft X-ray excess in clusters are addressed.