bluuebunny/crossref_metadata_2025_split huggingface dataset:
H2 Line Emission Associated with the Formation of the First Stars
Authors: Mizusawa Hiromi , Nishi Ryoichi , Omukai Kazuyuki 
Published: March 2014

Abstract
Molecular hydrogen ($\mathrm{H}_2$) line radiation emitted in the formation events of first-generation stars is evaluated in a discussion of its detectability by future observational facilities. $\mathrm{H}_2$ luminosity evolution from the onset of prestellar collapse until the formation of a $\sim 100 \,{{{M}_{\odot}}}$ protostar is followed. Calculations are extended not only to the early phase of the runaway collapse, but also to the later phase of accretion, whose observational features have not been studied before. Contrary to the runaway collapse phase, where the pure-rotational lines are always dominant, in the accretion phase rovibrational line emission becomes prominent. The maximum luminosity is also attained in the accretion phase for strong emission lines. The peak intensity of the strongest rovibrational line reaches $\sim 10^{-29} \,\mathrm{W} \,\mathrm{m}^{-2}$, corresponding to the flux density of $10^{-5} \,\mu\mathrm{Jy}$, for a source at the typical redshift of first-generation star formation, $1+z = 20$. Although the redshifted rovibrational $\mathrm{H}_2$ emission from such an epoch falls in the wavelength range of the next-generation infrared satellite, Space Infrared Telescope for Cosmology and Astrophysics, for exceeding the detection threshold, $10^7$ such protostars are required to reach the maximum luminosity simultaneously in a pregalactic cloud. It is improbable that this condition is satisfied in a realistic scenario of early structure formation.
Importance of Prolate Neutrino Radiation in Core-Collapse Supernovae: The Reason for the Prolate Geometry of SN1987A?
Authors: Madokoro Hideki , Shimizu Tetsuya , Motizuki Yuko 
Published: March 2014

Abstract
We have carried out 2-D simulations of core-collapse supernova explosions. The local neutrino radiation field was assumed to have its maximum value either at the symmetry (polar) axis or on the equatorial plane. These led to prolate and oblate explosions, respectively. We have found that the gain of the explosion energy in the prolate explosion evolves more predominately than that in the oblate one when the total neutrino luminosity is given. Namely, the prolate explosion is more energetic than the oblate one.
One of the authors (Shimizu et al. 2001) showed for the first time that globally anisotropic neutrino radiation produces a more powerful explosion than does spherical neutrino radiation. In our previous study (Madokoro et al. 2003), we improved the numerical code of Shimizu et al. (2001), and demonstrated that globally anisotropic neutrino radiation yields a more energetic explosion than does spatially-fluctuated neutrino radiation. Together with the result of this paper, we conclude that globally anisotropic (prolate) neutrino radiation is the most effective way to increase the explosion energy among various types of explosions investigated in these studies. We discuss the reason for this. Our result is suggestive of the fact that the expanding materials of SN1987A have been observed to have a prolate geometry.
Near-Infrared Unidentified-Line Morphology of the Planetary Nebula NGC 7027
Authors: Okumura Shin-ichiro , Mori Atsushi , Yanagisawa Kenshi 
Published: March 2014

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

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

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

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

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

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

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

Abstract
We present time-resolved CCD photometry of LL And during its 1993 outburst. The observation revealed the presence of superhumps with a period of 0.05697(3)d. This period is one of the smallest among the hydrogen-rich dwarf novae. Although LL And has been proposed to be a WZ Sge-type dwarf nova based on its low outburst frequency, our new analysis indicates that the outburst amplitude ($\sim 5 \,\mathrm{mag}$) and outburst duration ($9\pm 2 \,\mathrm{d}$) are much smaller and shorter than in typical WZ Sge-type dwarf novae. We suspect that the unusual outburst properties of LL And might be explained by assuming a “leaky disk” in quiescence, which was originally proposed to explain the prototypical WZ Sge-type outbursts. By combining with the recent suggestion of the orbital period, the fractional superhump excess is found to be 3.5(1)%, which is unusually large for this short-period system. LL And may be an object filling the gap in the evolutionary track, which has recently been proposed to explain the unusual ultracompact binaries with an evolved mass donor.
Optical Variations of XTE J1859+226 during the 1999 Outburst
Authors: Uemura Makoto , Kato Taichi , Pavlenko Elena , Shugarov Sergei , Mitskevich Marina , Fried Robert E. , Sano Yasuo 
Published: March 2014

Abstract
We report on our optical photometric observations of a black hole X-ray transient, XTE J1859$+$226 ($=$V406 Vul). We detected an optical reflare associated with an X-ray reflare about 50 d after the outburst maximum. The X-ray delay of the reflare was shorter than 2.3 d. We detected coherent modulations having a period of $0.38385 \pm 0.00073 \,\mathrm{d}$. The modulation appeared within 7 d after the outburst maximum. We propose two obvious interpretations for the nature of the modulations, that is, superhumps or orbital-period variations caused by an irradiated secondary star or an outer disk. The asymmetric profile of the modulations suggests the superhump scenario. The early appearance of superhumps indicates that the tidal dissipation had already grown before the reflare. The growing tidal dissipation is hence less likely to induce the reflare. In conjunction with the short X-ray delay of the reflare, the reflare may be triggered by the X-ray irradiation onto an outer cold disk. The appearance of humps may be earlier than the eccentricity growth time expected from the tidal instability model. It may imply a mass ratio larger than what could be inferred from the reported orbital period.
Photometric Observations of an SU UMa-type Dwarf Nova, VW Coronae Borealis, during Outbursts
Authors: Nogami Daisaku , Uemura Makoto , Ishioka Ryoko , Kato Taichi , Pietz Jochen 
Published: March 2014

Abstract
We report on photometric observations of an SU UMa-type dwarf nova, VW CrB, during two superoutbursts in 2001 and 2003 and a normal outburst in 2003. Superhumps with a period of 0.07287(1) d were observed during the 2003 superoutburst. The change rate of the superhump period was positive. During a normal outburst, there is some hint of modulation up to a 0.2-mag amplitude. However, no periodicity was found. The recurrence cycles of the normal outburst and the superoutburst, and the distance were estimated to be $\ge 50 \,\mathrm{d}$, $270 \sim 500 \,\mathrm{d}$, and $690^{+230}_{-170} \,\mathrm{pc}$, respectively. These recurrence cycles are the usual values for an SU UMa-type dwarf nova having this superhump period. The superhump period of VW CrB was the longest among those of SU UMa stars with positive derivatives of the superhump period. The coverage of our observations was, however, not sufficient, and the variation of the $P_\mathrm{SH}$ change rate of VW CrB is still unknown. A superhump regrowth and a brightening were seen near the end of the plateau phase. Measuring the deviation of the start timings of the brightening and the superhump regrowth ($ \gt 2$ days in VW CrB) will be a key to reveal the mechanism of these phenomena.
Optical Variability of the Afterglow of GRB 030329
Authors: Uemura Makoto , Kato Taichi , Ishioka Ryoko , Yamaoka Hitoshi , Monard Berto , Nogami Daisaku , Maehara Hiroyuki , Sugie Atsushi , Takahashi Susumu 
Published: March 2014

Abstract
We report on the optical light curve of the afterglow of GRB 030329. Our observation combined with publicly available data sets revealed that the light curve was rich in unexpectedly complicated structures throughout $\sim 6$ days after the burst. Our early observation indicates that the light curve can be described by a single power-law model with bumps until a supernova component became dominant. The bumps superimposed on a fading trend had roughly constant amplitudes and colors. The long-lived, large-amplitude variations indicate that additional energy was supplied for the shock region. The refreshed shock scenario is most plausible. The observed slopes of the bumps during early times, however, contradict the prediction of this model.
A New SU UMa-Type Dwarf Nova, QW Serpentis (= TmzV46)
Authors: Nogami Daisaku , Uemura Makoto , Ishioka Ryoko , Iwamatsu Hidetoshi , Kato Taichi , Pavlenko Elena P. , Baklanov Alex , NovÁk Rudolf , Kiyota Seiichiro , Tanabe Kenji , Masi Gianluca , Cook Lewis M. , Morikawa Koichi , Schmeer Patrick 
Published: March 2014

Abstract
We report on the results of the QW Ser campaign, which has been continued from 2000 to 2003 by the VSNET collaboration team. Four long outbursts and many short ones were caught during this period. Our intensive photometric observations revealed superhumps with a period of $0.07700(\pm 0.00004) \,\mathrm{d}$ during all four superoutbursts, proving the SU UMa nature of this star. The recurrence cycles of the normal outbursts and the superoutbursts were measured to be $\sim 50$ days and $240(\pm 30)$ days, respectively. The change rate of the superhump period was $-5.8 \times 10^{-5}$. The distance and the X-ray luminosity in the range of 0.5–2.4 keV are estimated to be $380(\pm60) \,\mathrm{pc}$ and $\log L_\mathrm{X} = 31.0 \pm 0.1 \,\mathrm{erg} \,\mathrm{s}^{-1}$. These properties have typical values for an SU UMa-type dwarf nova with this superhump period.
Forty Years of Spectroscopic Stellar Astrophysics in Japan
Authors: Sadakane Kozo , Hirata Ryuko , Tsuji Takashi 
Published: March 2014

Abstract
The development of Japanese spectroscopic stellar astrophysics in the recent 40 years is reviewed from an observational point of view. In this article, the research activities are provisionally divided into four fields: hot stars, hot emission-line (Be) stars, cool stars, and other stars. Historical developments of the observational facilities at Okayama Astrophysical Observatory (spectrographs and detectors) are also summarized in connection with the progress in scientific research activities.
Light-Curve and Period Changes in the W UMa-Type System TY Bootis
Authors: Li Lifang , Han Zhanwen , Zhang Fenghui 
Published: March 2014

Abstract
A detailed study of the period and the light curve of the eclipsing binary TY Bootis is presented. Based on a study of the $(\mathrm{O}-\mathrm{C})$ curve, we have found that two periodical variations superimpose on a continuous increase ($dP/dt = 6.283 \times 10^{-8} \,\mathrm{d} \,\mathrm{yr}^{-1}$) in its period. We compared light curves obtained by other groups, and found that the light curve of the system has changed considerably. We analyzed the physical mechanisms that underlie the variation in the period and light curve of the system, and obtained some new conclusions. The continuous increase of its orbital period is probably caused by mass transfer from the secondary to the primary, rather than an expansion of the primary due to its dynamical instability. Also, the two periodical components are probably caused by two different physical mechanisms, i.e., the light-time effect is one of the possible mechanisms, which might cause a periodical component with a longer timescale (31.5 yr), and the magnetic activity cycle is the other one, which might underlie the other periodical component with a shorter timescale (11.76 yr). The long-term variation in the light curve of the system is likely to be caused by a decrease in the light level of the primary due to starspot(s) on the primary or an expansion of the primary. Finally, the trends in the evolution of the system are discussed according to a theory of W UMa systems.
V1647 Orionis (IRAS 05436$-$0007): A New Look at McNeil’s Nebula
Authors: Ojha Devendra , Kusakabe Nobuhiko , Tamura Motohide , Nakajima Yasushi , Fukagawa Misato , Sugitani Koji , Baba Daisuke , Kato Daisuke , Kurita Mikio , Nagashima Chie , Nagayama Takahiro , Nagata Tetsuya , Sato Shuji 
Published: March 2014

Abstract
We present a study of the newly discovered McNeil’s nebula in Orion using simultaneous observations of the $JHK_{\mathrm{s}}$-bands with the near-infrared (NIR) camera SIRIUS on the IRSF 1.4m telescope. The cometary infrared nebula is clearly seen extending toward both north and south from the NIR source (V1647 Orionis), which illuminates McNeil’s nebula. The compact nebula has an apparent diameter of about $70 {}^{\prime \prime }$. The nebula is blue (bright in $J$) and has a cavity structure with two rims extending toward the north-east and the north-west. The north-east rim is brighter and sharp, while the north-west rim is diffuse. The north-east rim can be traced out to $\sim 40 {{}^{\prime \prime }}$ from the location of the NIR source. In contrast, no cavity structure can be seen toward the south, although the diffuse nebula is extended out to $\sim 20 {{}^{\prime \prime }}$. New NIR photometric data show a significant variation in the magnitudes ($\gt 0.15 \,\mathrm{mag} &gt; 0.15 \,\mathrm{mag}$) of the source of McNeil’s nebula within a period of one week, which is possibly under the phase of eruptive variables, like FUors or EXors.
Pre-Collimator of the Astro-E2 X-Ray Telescopes for Stray-Light Reduction
Authors: Mori Hideyuki , Iizuka Ryo , Shibata Ryo , Yoshito Haba , Hayakawa Akira , Hayashi Atsushi , Inoue Chiaki , Inoue Hirohiko , Ishida Manabu , Itoh Akiharu , Itoh Kei , Kunieda Hideyo , Maeda Yoshitomo , Misaki Kazutami , Naitou Masataka , Okada Shunsaku , Shimizu Tomoo , Yokoyama Yushi 
Published: March 2014

Abstract
We present the design and fabrication of the pre-collimator for the X-ray telescope onboard the X-ray astronomy satellite Astro-E2, and its effect on stray-light reduction. The pre-collimator was designed to efficiently reduce secondary reflection, which is the brightest component of stray light, giving rise to a ghost image in the field of view of the focal-plane detector. With the pre-collimator, composed of blades with an effective height of 30 mm, we confirmed from X-ray measurements that the intensity of the secondary reflection is reduced by roughly a few orders of magnitude on average in the off-axis angle range of $20' \hbox{--} 70'$. We also confirmed that the loss of the on-axis effective area due to installation of the pre-collimator is only $0.5 \pm 0.2\%$. The field of view becomes narrower, but the reduction factor amounts only to 8%. Ray-tracing simulations of in-flight observations also demonstrate that introduction of the pre-collimator is expected to be highly significant for improving data quality, due to a reduction of secondary reflection.