bluuebunny/crossref_metadata_2025_split huggingface dataset:
ASCA Observation of the Lyman-Limit Quasar PKS 2145+067
Authors: Yamasaki Noriko Y. , Ishikawa Teru , Ohashi Takaya 
Published: March 2014

Abstract
An X-ray observation of a famous Lyman-limit quasar PKS 2145+067 at zem= 0.990 was carried out with ASCA. The source showed a 2–10 keV flux of 1.3 × 10−11 erg cm−2 s−1 (LX = 2.5 ' 1046 erg s−1 for H0= 50 km s−1 Mpc−1) described by a power-law spectrum with a photon index of the Γ = 1.63 ± 0.04. In the ASCA energy band, no excess absorption was detected, implying that absorption column density at zab = 0.791 was less than 1.6 ' 1021 cm−2 if the absorbing medium had a metal abundance of 0.5 solar. A comparison with previous Einstein Observatory and ROSAT observations shows that PKS 2145+067 has increased in luminosity by a factor of 2–3 between 1991 and 1998.
Distribution and Kinematics of Molecular Gas in Barred Spiral Galaxies. II. NGC 253
Authors: Sorai Kazuo , Nakai Naomasa , Kuno Nario , Nishiyama Kohta , Hasegawa Tetsuo 
Published: March 2014

Abstract
The large scale mapping of the disk of a nearby barred galaxy, NGC 253 in CO (J = 1–0), was made with an angular resolution of 16″. Molecular gas concentrates in the nuclear region and the large-scale bar seen in near-infrared images. The radial distribution of molecular gas indicates a secondary peak, whose radius agrees with that of the Hα ring and the ends of the bar, as well as a central strong peak. The radial distribution is well fitted by an exponential function or a power law outside the secondary peak. A rotation curve is rising in the inner region and changes to flat at the ring. These facts suggest that molecular gas infalls from the outer disk by losing angular momentum due to gaseous viscosity in the region of the differential rotation, and accumulates at the ring. In the bar region (and within the corotation radius), molecular gas again loses its angular momentum due to the bar potential, and is infalling toward the nuclear region. The upper limit of the noncircular motion along the major axis of the bar in the leading edge of the bar is ≈ 70–130 km s−1 in the rest frame of the bar.
Basic Properties of Supercritical Accretion Disks
Authors: Fukue Jun 
Published: March 2014

Abstract
At the turn of the millennium, supercritical accretion disks (superdisks), where the mass-accretion rate highly exceeds the Eddington's one, are being resurrected under recent observational and theoretical progress. We examined the effects and properties of the self-irradiation, self-occultation, continuous and line spectra of superdisks, and found various distinct features of superdisks. Due to self-irradiation, the effective flux is enhanced by a factor of 1.1 to 1.8 all over the disk, depending on the relative disk thickness. For a superdisk with finite thickness, the flux at infinity is enhanced in the poleward direction, while it is zero in the equatorial direction. The continuous spectra are generally flat (vSv ∼ v0), as long as we see the disk pole-on. It, however, strongly depends on the inclination angle: for a larger inclination angle the central part of the disk is self-occulted and the flat nature of the continuum disappears. The line spectra are also greatly modified from those of the standard disk. In the non-relativistic standard model the line spectra have symmetrical double peaks. In the superdisk, however, the line spectra become asymmetric with strong blue peaks and weak red peaks, even for the non-relativistic case. This is due to the projection effect. The relations between the observables and model parameters are derived.
Some Features of Manifestations of Coronal Holes in Microwave Emission
Authors: Krissinel Boris B. , Kuznetsova Svetlana M. , Maksimov Vladimir P. , Prosovetsky Dmitry V. , Grechnev Victor V. , Stepanov Alexandr P. , Shishko Ludmila F. 
Published: March 2014

Abstract
Using observational data from the SSRT, we have investigated the behavior of four mid- and low-latitude coronal holes. The coronal holes under study appeared as regions of decreased emission intensity relative to the quiet Sun level totally or partially coincident with holes in EUV emission. Difference in the electron density and temperature in different holes or different parts of a hole can account for the diversity of manifestations of coronal holes. Estimates showed that the influence of these parameters is strongest in the wavelength range of 2–5 cm. Depending on particular values of the coronal electron density and temperature, coronal holes are either indistinguishable from the background of the quiet Sun, or show up as regions of decreased or increased microwave emission.
Solar Radio Radiation Bursts on 1998 April 15
Authors: Ning Zongjun , Fu Qijun , Lu Quankang 
Published: March 2014

Abstract
We present two remarkable “decimetric pulsation” events (DCIM) around the time 1998 0415 0800, detected by spectrometers (1.00–2.00 GHz and 2.60–3.80 GHz) at Beijing Astronomical Observatory (BAO). High-resolution dynamic spectra reveal various fine structures, such as spike groups, pulsations, type-III bursts, patches, and zebra patterns or evolving emission lines on the rising phase of the second DCIM around 3 GHz. It is the first time that such a wealth of fine features have been detected in a same type IV-DCIM event; it is also the first time that blips pairs simultaneously drifting towards the same frequency have been recorded; it is the second time to observe an evolving emission line, and the first above 1 GHz.
Moderate Dispersion Spectra of NH2 in Comet Hale-Bopp: Analysis of Population Distribution in $\widetilde X^{2} \textrm B_{1}(0,0,0)$
State of NH
2
Authors: Kawakita Hideyo , Ayani Kazuya , Kawabata Tetsuya 
Published: March 2014

Abstract
We carried out moderate-dispersion spectroscopic observations of comet Hale-Bopp (C/1995O1) on 1997 February 25, in order to study the fine structure of two NH 2 emission bands, $\widetilde A(0,9,0)-\widetilde X(0,0,0)$ and $\widetilde A(0,8,0)-\widetilde X(0,0,0)$ , which was resolved in our spectra. We compared the observed fine structure with that of the modeled spectra, which were computed based on the transition probabilities of NH 2 between the $\widetilde A(0,v^{\prime}_{2},0)$ and $\widetilde X(0,0,0)$ states determined by ourselves. From a comparison between the observation and the calculations we concluded that the population distribution of the NH 2 in the $\widetilde X(0,0,0)$ ground state can be approximated by the Boltzmann distribution at a temperature of 60 K.
Detections of SiO and H2O Masers in the Bipolar Nebula IRAS 19312+1950
Authors: Nakashima Jun-ichi , Deguchi Shuji 
Published: March 2014

Abstract
We report on the detection of SiO and H2O masers toward a newly found bipolar nebula, IRAS 19312+1950. This object exhibits extreme red IRAS color [log (F25/F12) = 0.5 and log (F60/F25) = 0.7] and a nebulosity having a size of about 30″ extended to the south-west in the 2MASS near-infrared image. Toward this object, we have detected emission from the H2O 6(1,6)–5(2,3) transition, the SiO J = 1–0, v = 1 and 2, and J = 2–1, v = 1 transitions, and the SO 2(2)–1(1) and H13CN J = 1–0 transitions. The thermal lines of SO and H13CN are shifted by about 12 km s−1 in radial velocity with respect to the maser lines, indicating that thermal emission comes from the background molecular cloud. However, the SiO J = 2−1, v = 2 spectrum shows another component of SiO emission separated by 26 km s−1 from the main component, that might be formed in a rotating or expanding shell.
Discovery of Non-Thermal X-Rays from the Shell of RCW 86
Authors: Bamba Aya , Koyama Katsuji , Tomida Hiroshi 
Published: March 2014

Abstract
We report the ASCA (Advanced Satellite for Cosmology and Astrophysics) results of RCW 86, a shell-like supernova remnant (SNR). The bright region in the X-ray band traces the radio clumpy shell, although details of the structure are different. The X-ray spectrum from each part of the shell can not be fitted to a thin thermal plasma model, but requires at least three components: a low-temperature plasma of 0.3 keV, a high-temperature plasma of ≥ several keV, and a power-law component with a photon index of ∼ 3. The abundances of O, Ne, Mg, and Si are significantly higher than that of Fe, indicating that RCW 86 is a type II SNR. The absorption column of ∼ 3×1021 H cm-2 indicates the distance to the SNR to be several kpc. The power-law component can be interpreted to be synchrotron radiation of high-energy electrons. Assuming an energy density equipartition between the magnetic field and the electrons, and using the radio and X-ray spectra, we argue that high-energy electrons are accelerated up to 20 TeV. The acceleration efficiency is, however, different from shell to shell.
The VLBI Space Observatory Programme and the Radio-Astronomical Satellite HALCA
Authors: Hirabayashi Hisashi , Hirosawa Haruto , Kobayashi Hideyuki , Murata Yasuhiro , Asaki Yoshiharu , Avruch Ian M. , Edwards Philip G. , Fomalont Edward B. , Ichikawa Tsutomu , Kii Tsuneo , Okayasu Rikako , Wajima Kiyoaki , Inoue Makoto , Kawaguchi Noriyuki , Chikada Yoshihiro , Bushimata Takeshi , Fujisawa Kenta , Horiuchi Shinji , Kameno Seiji , Miyaji Takeshi , Shibata Kazunori M. , Shen Zhi-Qiang , Umemoto Tomofumi , Kasuga Takashi , Nakajima Jun'ichi , Takahashi Yukio , Enome Shinzou , Morimoto Masaki , Ellis Jordan , Meier David L. , Murphy David W. , Preston Robert A. , Smith Joel G. , Wietfeldt Rick D. , Benson John M. , Claussen Mark J. , Flatters Chris , Moellenbrock George A. , Romney Jonathan D. , Ulvestad James S. , Langston Glen I. , Minter Anthony H. , D'Addario Larry R. , Dewdney Peter E. , Dougherty Sean M. , Jauncey David L. , Lovell James E. J. , Tingay Steven J. , Tzioumis Anastasios K. , Taylor A. Russell , Cannon Wayne H. , Gurvits Leonid I. , Schilizzi Richard T. , Booth Roy S. , Popov Misha V. 
Published: March 2014

Abstract
The radio astronomy satellite HALCA was launched by the Institute of Space and Astronautical Science in 1997 February to participate in Very Long Baseline Interferometry (VLBI) observations with arrays of ground radio telescopes. HALCA is the main element of the VLBI Space Observatory Programme (VSOP), a complex international endeavor involving over 25 ground radio telescopes, five tracking stations and three correlators. Simultaneous observations with HALCA's 8 meter diameter radio telescope and ground radio telescopes synthesize a radio telescope over twice the size of the Earth, enabling the highest resolution 1.6 GHz and 5 GHz images to be made.
HALCA's Onboard VLBI Observing System
Authors: Kobayashi Hideyuki , Wajima Kiyoaki , Hirabayashi Hisashi , Murata Yasuhiro , Kawaguchi Noriyuki , Kameno Seiji , Shibata Katsunori M. , Fujisawa Kenta , Inoue Makoto , Hirosawa Haruto 
Published: March 2014

Abstract
The first space VLBI satellite, HALCA, was launched on 1997 February 12. We report the characteristics of HALCA as an orbiting VLBI station with 8-m deployment antenna. It is required the high system gain, low system noise, and high stability of phase transfer. And the stabilities of system gain and system noise are needed for imaging of VLBI. HALCA achieved the requirement as a VLBI stations and has made almost 3 times longer baselines than ground global VLBI networks. It means observations with 3 times higher angular resolution have been carried out. We have measured aperture efficiencies of the deployment antenna, system noise temperatures, stability of onboard local oscillators, and stability of phase link. HALCA's onboard radio astronomy system has 1.60–1.73 GHz, 4.7–5.0 GHz, and 21.9–22.3 GHz receivers and two-channel high-rate samplers. Typical values of system noise temperature in orbit are 70 K and 90 K at 1.6 and 5 GHz respectively. At 22 GHz, the apparent system noise temperature is 400 K; however, this is mostly due to attenuation between the main antenna and the 22 GHz low noise amplifier. A reference tone signal is transmitted from a ground tracking station which is locked on a ground hydrogen maser oscillator. The internal phase stability of local oscillators is around 5° r.m.s. at 5 GHz. The total gain of the receiving system and the bit distribution of the high-rate samplers have also been checked. With the exception of the 22 GHz attenuation, the in-orbit performance of the VLBI observing system matches the ground-test results very well.
Viscous Transonic Decretion in Disks of Be Stars
Authors: Okazaki Atsuo T. 
Published: March 2014

Abstract
We consider the characteristics of the outflow in disks of Be stars, based on the viscous decretion disk scenario. In this scenario, the matter ejected from the equatorial surface of a star drifts outward because of the effect of viscosity, and forms the disk. For simplicity, we adopt the $ \alpha$-prescription for the viscous stress, and assume the disk to be isothermal. Solving the resulting wind equations, we find that a transonic solution exists for any value of $ \alpha$. The sonic point is located at $r \gt 100\;R$$ r \gt 100\;R$ for the plausible values of parameters, where $ R$ is the stellar radius. The sonic radius is smaller for a higher temperature and/or a larger radiative force. We also find that the topology of the sonic point is nodal for $ \alpha \gtrsim 0.95$, while it is of the saddle type for $ \alpha \lesssim 0.9$. We expect that the sonic point in the former case is unstable, whereas that in the latter case is stable. The outflow is highly subsonic in the inner part of the disk. Roughly, the outflow velocity increases linearly with $ r$ and the surface density decreases as $ r^{-2}$. Interestingly, the disk is near-Keplerian in the inner subsonic region, while it is angular-momentum conserving in the outer subsonic region and in the supersonic region. Our results, together with the observed range of the base density for Be star disks, suggest that the mass-loss rate in the equatorial region is at most comparable with that in the polar region.
Amplification of Magnetic Fields in an Accretion Disk with a Starburst Torus
Authors: Kamaya Hideyuki 
Published: March 2014

Abstract
It is widely believed that a black hole is surrounded by an accretion disk. Such an accretion disk should have magnetic fields whose evolution is important to understand the disk dynamics, since the viscosity in the disk must originate from magnetic turbulence. In the case of the accretion disk of AGN (active galactic nuclei) with a circum-disk star-burst region, we point out that the so-called $ \alpha $-dynamo effect via radiation drag due to an exterior radiation field around the disk works well. This is possible since the drag time-scale is longer than the dynamical time-scale. Importantly, we find that the starburst AGN satisfies this criterion. Thus, the magnetic field of the accretion disk of the starburst AGN is amplified by the dynamo effect owing to the radiation drag. This results in enhancing the mass-accretion rate to the massive black-hole of AGN within the star-burst region.
Intracluster Supernova as a Possible Extra Energy Source of Clusters
Authors: Sasaki Shin 
Published: March 2014

Abstract
The observed luminosity–temperature relation of clusters is considerably steeper than that expected from a simple scaling relation. Although extra energy input is a likely solution, its source has not been identified. We propose intracluster supernova as a possible source, and also predict the supernova rate in intracluster space as a critical test.
The Most Luminous Protostars in Molecular Clouds: A Hint to Understand the Stellar Initial Mass Function
Authors: Dobashi Kazuhito , Yonekura Yoshinori , Matsumoto Tomoaki , Momose Munetake , Sato Fumio , Bernard Jean-Philippe , Ogawa Hideo 
Published: March 2014

Abstract
The maximum luminosity of protostars forming in molecular clouds has been investigated as a function of the parent cloud mass on the basis of a rich cloud sample searched for in the literature. In total, we gathered 499 molecular clouds among the published data, out of which 243 clouds were found to be associated with protostellar candidates selected from the IRAS point-source catalog. A diagram of the maximum stellar luminosity in each cloud and the parent cloud mass shows that the protostars in the clouds associated with H II regions are apparently more luminous than those in clouds away from H II regions over the entire cloud mass range investigated ($ 1 \lt M_\mathrm{CL}/M_{{\odot }} \lt 10^6$). In addition, we found that there are well-defined upper and lower limits in the maximum stellar luminosity distribution with the lower limit having a steeper dependence on the cloud mass ($ L_\mathrm{MAX} \propto M_\mathrm{CL}^{1.5}$) than the upper one ($ L_\mathrm{MAX}\propto M_\mathrm{CL}^{0.8}$). All of these features can be naturally accounted for if we assume that the luminosity function of protostars is controlled by the cloud mass and the external pressure imposed on the cloud surface. We introduce a simple model for the stellar luminosity function as a function of these quantities, which should be closely related to the stellar initial mass function.
The Ortho-to-Para Ratio and the Chemical Properties of C3 H2 in Dark Cloud Cores
Authors: Takakuwa Shigehisa , Kawaguchi Kentarou , Mikami Hitomi , Saito Masao 
Published: March 2014

Abstract
We have observed cyclic C$_3$H$_2$ ($J_{K_{a}K_{c}}= 2_{12}$–$1_{01}, 2_{02}$–$1_{11}, 3_{12}$–$3_{03}$) lines at the 3 mm wavelength region toward the starless TMC-1C cloud and the protostellar core of L 1527 with the 45 m telescope at Nobeyama Radio Observatory. In both clouds, the $2_{12}$–$1_{01}$ and $2_{02}$–$1_{11}$ lines are strongly detected, while the $3_{12}$–$3_{03}$ line is only detected toward the center of the protostellar core L 1527. From our statistical equilibrium analyses of the ortho-C$_3$H$_2$ ($2_{12}$–$1_{01}$) and the para-C$_3$H$_2$ ($2_{02}$–$1_{11}$) lines, the ortho-to-para ratios of C$_3$H$_2$ are determined to be $2.4\pm0.1$ and $2.5\pm0.5$ in TMC-1C and L 1527, respectively. These values are lower than the statistical value of 3, although the error of the ratio in L 1527 is large. Since thermal equilibrium with a dust temperature of 10 K still gives a ratio of 3 in c-C$_3$H$_2$, this result should suggest the lower ortho-to-para ratio of the precursor molecule, c-C$_3$H$_{3}^{+}$, which is thought to be mainly produced by C$_3$H$^{+} +$ H$_2$. Thus, we conclude that the lower ortho-to-para ratio of c-C$_3$H$_2$ is due to a lower ortho-to-para ratio of H$_{2}$ than the statistical value.
OHS: OH-Airglow Suppressor for the Subaru Telescope
Authors: Iwamuro Fumihide , Motohara Kentaro , Maihara Toshinori , Hata Ryuji , Harashima Takashi 
Published: March 2014

Abstract
This paper describes an OH-airglow Suppressor (OHS) for the infrared Nasmyth focus of the Subaru telescope. OHS has the capability of eliminating 224 airglow-lines in the J- and H-bands, which are major sources of background radiation at near-infrared wavelengths up to 2 ${\mu \mathrm {m}}$. Specifically, it is a pre-optics system installed between the telescope and an infrared camera/spectrograph (CISCO). The suppressor reduces sky background emissions to 1/25 and its throughput is 40%. As a result, the S/N gain achieved with OHS is more than 1 mag compared to the typical spectroscopic approach. The limiting magnitude measured during a test observing run was found to be H = 21.1 mag ($\lambda/\Delta\lambda = 210, S/N = 5$) in the standard 4000 s exposure sequence.
ASCA Deep Survey in the Lockman Hole Field
Authors: Ishisaki Yoshitaka , Ueda Yoshihiro , Yamashita Akiko , Ohashi Takaya , Lehmann Ingo , Hasinger Günther 
Published: March 2014

Abstract
We present the results of deep observations of the Lockman Hole field with the ASCA SIS, covering $926\,\mathrm{arcmin}^2$ in the 1–7 keV energy range, with a sensitivity 3–5 times deeper than the previous ASCA larger area surveys. Utilizing the results of the ROSAT Ultra Deep survey, we have detected 32, 25, and 15 sources in the 1–7, 1–2, and 2–7 keV bands, and only 4, 4, and 1 sources remain unidentified, respectively. The average hardness of the sources detected in the 1–7 keV band with fluxes of between $10^{-14}$ and $10^{-13}\,\mathrm{erg}\,\mathrm{cm}^{-2}\,\mathrm{s}^{-1}$ corresponds to a photon index of $1.65\pm 0.10$. Type-2 AGNs show significantly harder spectra than type-1s, which can be explained by absorption column densities of $N_{\mathrm{H}} \simeq 10^{22-23}\,\mathrm{cm}^{-2}$ at the source redshifts. Fifteen sources are detected in the hard-band (2–7 keV), consisting of six type-1 AGNs, six type-2 AGNs, one star, one cluster of galaxies, and one unidentified source. Type-2 AGNs make up a major part of hard X-ray populations in the 2–7 keV band at a flux level of $3\times 10^{-14}\,\mathrm{erg}\,\mathrm{cm}^{-2}\,\mathrm{s}^{-1}$ (2–7 keV). The redshift distributions of type-1 and type-2 AGNs suggest a lack of high luminosity (optically-defined) type-2 AGNs with intrinsic $N_{\mathrm{H}} \lt 10^{23}\,\mathrm{cm}^{-2}$, in the redshift range $z\simeq 1$–$2$ and/or with intrinsic luminosities larger than $3\times 10^{44}\,\mathrm{erg}\,\mathrm{s}^{-1}$ (2–10 keV at source frame).
Water Maser Survey in the Andromeda Galaxy
Authors: Imai Hiroshi , Ishihara Yuko , Kameya Osamu , Nakai Naomasa 
Published: March 2014

Abstract
We report on a water maser survey in the Andromeda galaxy (M 31). The surveyed H II regions with $^{12}$CO clouds are expected to be regions of ongoing star formation with water maser activity. Nevertheless, we could not detect any water maser emission with an upper limit of around 0.35 Jy or $4.9\times 10^{-3}\,L_{ {\odot }}$ in isotropic luminosity. These results indicate a low activity of the present star formation in M 31.
Photometric Observation of a New in-the-Gap SU UMa-Type Dwarf Nova V 725 Aquilae during the 1999 Superoutburst
Authors: Uemura Makoto , Kato Taichi , Pavlenko Elena , Baklanov Alex , Pietz Jochen 
Published: March 2014

Abstract
We report our photometric observation of the 1999 September outburst of a dwarf nova, V725 Aql. Our detection of superhumps established that it belongs to SUUMa stars. By performing a period analysis of the superhumps, we revealed a long superhump period of $0.09909 \pm 0.00015\,\mathrm{d}$, which implies that its orbital period is well over 2 hr. The outburst light curve is typical for a superoutburst, though, after the superoutburst, the object experienced a re-brightening which can be seen in some SUUMa stars with short orbital periods. The 1999 superoutburst occurred about 1650 d after the last possible superoutburst in 1995. This indicates the supercycle of V725 Aql to be long, over 1000 d. This long supercycle implies a low mass-transfer rate of this star.
ASCA Observations of the Temperature Structure and Metal Distribution in the Perseus Cluster of Galaxies
Authors: Ezawa Hajime , Yamasaki Noriko Y. , Ohashi Takaya , Fukazawa Yasushi , Hirayama Masaharu , Honda Hirohiko , Kamae Tuneyoshi , Kikuchi Ken’ichi , Shibata Ryo 
Published: March 2014

Abstract
Large-scale distributions of hot-gas temperature and Fe abundance in the Perseus cluster have been studied with multi-pointing observations by the GIS instrument onboard ASCA. Within a radius of $ {20{}^{\mathrm {\prime }}}$ from the cluster center, the energy spectra requires two temperature components, in which the cool component indicates $ kT \sim 2\;\mathrm{keV}$ and the hot-component temperature shows a significant decline from about 8 keV to 6 keV toward the center. In the outer region of the cluster, the temperature shows a fluctuation with an amplitude of about 2 keV, which suggest that a western region at $ \sim {16{}^{\mathrm {\prime }}}$ from the cluster center is relatively hotter. As for the Fe abundance, a significant decline with radius is detected from 0.44 solar at the center to $ \sim 0.1$ solar at a $ {50{}^{\mathrm {\prime }}}$ offset region. If the observed Fe-K line intensity within $ {4{}^{\mathrm {\prime }}}$ from the center is suppressed by a factor of 2 due to the resonance scattering effect, the corrected Fe mass density follows the galaxy distribution. Finally, our results do not support the large-scale velocity gradients previously reported from the same GIS data.