bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Photometric Study for the Weak-Contact Binary V700 Cygni
Authors: Yang Yuan-Gui , Dai Hai-Feng 
Published: March 2014

Abstract
We present a new charge-coupled device (CCD) photometry for the weak-contact binary V700 Cygni. From our light curves in the VR bands, a photometric solution was deduced by the 2003 version of the W – D program. The results show that V700 Cyg is a W-subtype binary with $q$$=$ 0.5437($\pm$0.0018) and $f$$=$ 15.1%($\pm$0.3%). The contributions of the third light to the total light are $l_{3V}$$=$ 2.59%($\pm$0.10%) and $l_{3R}$$=$ 2.64%($\pm$0.10%) for the VR bands, respectively. Based on all available light-minimum times from 1946 to 2008, a detailed period analysis reveals that there exists a long-term period increase with a periodic oscillation. This cyclic variation, with $P_3$$=$ 54.0($\pm$2.0)yr, $A$$=$ 0.$^{\rm d}$0185 ($\pm$0.$^{\rm d}$0012 d), and $e{}^\prime$$=$ 0.2117($\pm$0.0059) from equation (3), may result from a light-time effect via the third body, identified by the third light in the photometric solution. If an additional body exists, V700 Cyg may be a triple star system. This kind of tertiary component may remove angular momentum from the central system, which may play an important role in the formation and evolution of the binary. A continuous period increase at a rate of $dP/dt$$=$$+$0.33($\pm$0.08) $\times$ 10$^{-7}$dyr$^{-1}$ can be interpreted as being mass transfer from the less-massive component to the more-massive one. With mass transferring, the orbital period increases and the separation between both components becomes wider. Finally, the contact configuration will break, as predicted by TRO theory. Therefore, this kind of weak-contact binary with a secular period increase will evolve into a broken-contact configuration.
Photometry of Three Superoutbursts of the SU UMa-Type Dwarf Nova, SW Ursae Majoris
Authors: Soejima Yuichi , Nogami Daisaku , Kato Taichi , Uemura Makoto , Imada Akira , Sugiyasu Kei , Maehara Hiroyuki , Torii Ken’ichi , Tanabe Kenji , Oksanen Arto , Nakajima Kazuhiro , Novák Rudolf , Masi Gianluca , Hynek Tomáš , Martin Brian , Buczynski Denis , Pavlenko Elena P. , Shugarov Sergei Yu. , Cook Lewis M. 
Published: March 2014

Abstract
We investigated superhump evolution, analysing optical photometric observations of the 2000 February–March, the 2002 October–November, and the 2006 September superoutbursts of SW UMa. The superhumps evolved in the same way after their appearance during the 2000 and 2002 superoutbursts, and probably during the 2006 one. This indicates that superhump evolution may be governed by invariable binary parameters. We detected a periodicity in the light curve after the end of the 2000 superoutburst without any phase shift, which seems to be the remains of the superhumps. We found QPOs at the end stage of the 2000 and 2002 superoutbursts, but failed to find extraordinarily large-amplitude QPOs, called ‘super-QPOs’, which previously had been observed in SW UMa.
Effects of Hardness of Primordial Binaries on the Evolution of Star Clusters
Authors: Tanikawa Ataru , Fukushige Toshiyuki 
Published: March 2014

Abstract
We have investigated the effects of the hardness of primordial binaries on the whole evolution of star clusters by means of $N$-body simulations. Using a newly developed code, GORILLA, we simulated eleven $N$$=$ 16384 clusters with primordial binaries whose binding energies are equal in each cluster in the range of 1−300$kT_0$, where 1.5$kT_0$ is the average stellar kinetic energy at the initial time. We found that, in both the soft ($\le$3$kT_0$) and hard ($\ge$300$kT_0$) limits, clusters experience deep core collapse. For intermediate hardness (10−100$kT_0$), the core collapses halt halfway due to an energy releases of the primordial binaries. The core radii at the halt can be explained by their energy budget.
An X-Ray Face-On View of the Sagittarius B Molecular Clouds Observed with Suzaku
Authors: Ryu Syukyo G. , Koyama Katsuji , Nobukawa Masayoshi , Fukuoka Ryosuke , Tsuru Takeshi Go 
Published: March 2014

Abstract
We present a new methodology to derive the positions of the Sagittarius (Sgr) B molecular clouds (MCs) along the line of sight, as an application study of the Galactic center diffuse X-rays (GCDX). The GCDX are composed of hot plasma emission of about 7 keV and 1 keV temperatures, and non-thermal continuum emission including the 6.4 keV line from neutral irons. The former, the Galactic center plasma emission (GCPE), is uniformly distributed over 1$^\circ$ in longitude, while the latter is clumpy emission produced by Thomson scattering and fluorescence from MCs irradiated by external X-rays (the X-ray reflection nebula emission: XRNE). We examined the Suzaku X-ray spectra of the GCPE and XRNE near to the Sgr B MC complex, and found that the spectra suffer from two different absorptions of $N_{\rm H}$ (Abs1) $\geq$10$^{23}$H cm$^{-2}$ and $N_{\rm H}$ (Abs2) $\simeq$6 $\times$ 10$^{22}$H cm$^{-2}$. Abs1 is proportional to the 6.4 keV-line flux, and hence is due to the MCs, while Abs2 is typical of interstellar absorption toward the Galactic center. Assuming that the GCPE plasma is spherically-extended around Sgr A$^\ast$ with a uniform density and the same angular distribution of the two temperature components, we quantitatively estimated the line-of-sight positions of the MCs from the flux ratio the GCPE spectrum suffered by Abs1 and that with no Abs1. The results suggest that the Sgr B MCs are located at the near side of Sgr A$^\ast$ in the GCPE.
New Spectral State of Supercritical Accretion Flow with Comptonizing Outflow
Authors: Kawashima Tomohisa , Ohsuga Ken , Mineshige Shin , Heinzeller Dominikus , Takabe Hideaki , Matsumoto Ryoji 
Published: March 2014

Abstract
Supercritical accretion flows inevitably produce radiation-pressure driven outflows, which Compton up-scatter soft photons from the underlying accretion flow, thereby making hard emission. We performed two-dimensional radiation hydrodynamic simulations of supercritical accretion flows and outflows, while incorporating such Compton scattering effects, and demonstrated that there appears a new hard spectral state at higher photon luminosities than that of the slim-disk state. In this state, as the photon luminosity increases, the photon index decreases and the fraction of the hard emission increases. The Compton $y$-parameter is on the order of unity (and thus the photon index will be $\sim$2) when the apparent photon luminosity is ${\sim}$ 30$L_{\rm E}$ (with $L_{\rm E}$ being the Eddington luminosity) for nearly face-on sources. This explains the observed spectral hardening of the ULX NGC 1313 X-2 in its brightening phase, and thus supports the model of supercritical accretion onto stellar-mass black holes in this ULX.
Origin of 6.4 keV Line Emission from Molecular Clouds in the Galactic Center
Authors: Dogiel Vladimir , Cheng Kwong-Sang , Chernyshov Dmitrii , Bamba Aya , Ichimura Atsushi , Inoue Hajime , Ko Chung-Ming , Kokubun Motohide , Maeda Yoshitomo , Mitsuda Kazuhisa , Yamasaki Noriko Y. 
Published: March 2014

Abstract
We analyze the 6.4 keV line and continuum emission from the molecular cloud Sgr B2 and the source HESS J1745$-$303, which is supposed to be a complex of molecular gas. From the HESS results it follows that Sgr A$^\ast$ is a source of high energy protons, which penetrate into molecular clouds producing there a TeV gamma-ray flux. We present arguments that Sgr A$^\ast$ may also produce a flux of subrelativistic protons which generate the 6.4 keV line and bremsstrahlung continuum emission from the clouds.
Suzaku X-Ray Study of an Anomalous Source XSS J12270–4859
Authors: Saitou Kei , Tsujimoto Masahiro , Ebisawa Ken , Ishida Manabu 
Published: March 2014

Abstract
We report on the results of a Suzaku X-ray observation of XSS J12270$-$4859, one of the hard X-ray sources in the INTEGRAL catalogue. This object has been classified as an intermediate polar (IP) by its optical spectra, and a putative X-ray period of $\sim$860 s. With a 30 ks exposure by Suzaku, we obtained a well-exposed spectrum in the 0.2–70 keV band. We conclude against a previous IP classification based on a lack of Fe K$\alpha$ emission features in the spectrum and a failure to confirm the previously reported X-ray period. Instead, the X-ray light curve is filled with exotic phenomena, including repetitive flares lasting for $\sim$100 s, occasional dips with no apparent periodicities, spectral hardening after some flares, and bimodal changes pivoting between quiet and active phases. The rapid flux changes, the dips, and the power-law spectrum point toward an interpretation that this is a low-mass X-ray binary. Some temporal characteristics are similar to those in the Rapid Burster and GROJ1744$-$28, making XSS J12270$-$4859 a very rare object.
Similarity between the Molecular Loops in the Galactic Center and the Solar Chromospheric Arch Filaments
Authors: Takahashi Kunio , Nozawa Satoshi , Matsumoto Ryoji , Machida Mami , Fukui Yasuo , Kudo Natsuko , Torii Kazufumi , Yamamoto Hiroaki , Fujishita Motosuji 
Published: March 2014

Abstract
We carried out two-dimensional magnetohydrodynamic simulations of the Galactic gas disk to show that the dense loop-like structures discovered by the Galactic center molecular cloud survey using the NANTEN 4-m telescope can be formed by a buoyant rise of magnetic loops due to the Parker instability. At the initial state, we assumed a gravitationally stratified disk consisting of a cool layer ($T$$\sim$ 10$^{3} $K), a warm layer ($T$$\sim$ 10$^{4} $K), and a hot layer ($T$$\sim$ 10$^{5} $K). The simulation box was a local part of the disk containing the equatorial plane. The gravitational field was approximated by that of a point mass at the Galactic center. The self-gravity, and the effects of the Galactic rotation were ignored. Numerical results indicate that the length of the magnetic loops emerging from the disk is determined by the scale height of the hot layer ($\sim$ 100 pc at 1 kpc from the Galactic center). The loop length, velocity gradient along the loops, and large velocity dispersions at their foot points are consistent with the NANTEN observations. We also show that the loops become top-heavy when the curvature of the loop is sufficiently small, so that the rising loop accumulates the overlying gas faster than sliding it down along the loop. This mechanism is similar to that in the formation of solar chromospheric arch filaments. The molecular loops emerge from the low-temperature layer just like the dark filaments observed in the H$\alpha$ image of the emerging flux region of the Sun.
Improved Measurement of the Rossiter–McLaughlin Effect in the Exoplanetary System HD 17156
Authors: Narita Norio , Hirano Teruyuki , Sato Bun’ei , Winn Joshua N. , Suto Yasushi , Turner Edwin L. , Aoki Wako , Tamura Motohide , Yamada Toru 
Published: March 2014

Abstract
We present an improved measurement of the Rossiter–McLaughlin effect for the exoplanetary system HD 17156, based on radial-velocity data gathered with the Subaru 8.2-m telescope throughout the planetary transit of UT 2008 November 7. The data allow for a precise and independent determination of the projected spin-orbit angle of this system: $\lambda $$=$ 10${\rlap{^\circ}\hskip.5pt.\hskip1pt}$0 $ \pm $5${\rlap{^\circ}\hskip.5pt.\hskip1pt}$1. This result supersedes the previous claim of $\lambda $$=$ 62${}^\circ$$ \pm $25${}^\circ$ by Narita et al. (2008, PASJ, 60, L1), which was based on lower-precision data with poor statistics. Thus the stellar spin and planetary orbital axes of the HD 17156 system are likely to be well-aligned, despite the planet’s large orbital eccentricity suggesting a history of strong dynamical interactions.
The MAXI Mission on the ISS: Science and Instruments for Monitoring All-Sky X-Ray Images
Authors: Matsuoka Masaru , Kawasaki Kazuyoshi , Ueno Shiro , Tomida Hiroshi , Kohama Mitsuhiro , Suzuki Motoko , Adachi Yasuki , Ishikawa Masaki , Mihara Tatehiro , Sugizaki Mutsumi , Isobe Naoki , Nakagawa Yujin , Tsunemi Hiroshi , Miyata Emi , Kawai Nobuyuki , Kataoka Jun , Morii Mikio , Yoshida Atsumasa , Negoro Hitoshi , Nakajima Motoki , Ueda Yoshihiro , Chujo Hirotaka , Yamaoka Kazutaka , Yamazaki Osamu , Nakahira Satoshi , You Tetsuya , Ishiwata Ryoji , Miyoshi Sho , Eguchi Satoshi , Hiroi Kazuo , Katayama Haruyoshi , Ebisawa Ken 
Published: March 2014

Abstract
The Monitor of All-sky X-ray Image (MAXI) mission is the first astronomical payload to be installed on the Japanese Experiment Module — Exposed Facility (JEM-EF or Kibo-EF) on the International Space Station. It has two types of X-ray slit cameras with wide FOVs and two kinds of X-ray detectors consisting of gas proportional counters covering the energy range of 2 to 30 keV and X-ray CCDs covering the energy range of 0.5 to 12 keV. MAXI will be more powerful than any previous X-ray All Sky Monitor payloads, being able to monitor hundreds of Active Galactic Nuclei. A realistic simulation under optimal observation conditions suggests that MAXI will provide all-sky images of X-ray sources of $\sim $20 mCrab ($\sim $7 $\times$ 10$^{-10} $erg cm$^{-2} $s$^{-1}$ in the energy band of 2–30 keV) from observations during one ISS orbit (90 min), $\sim $4.5 mCrab for one day, and $\sim $2 mCrab for one week. The final detectability of MAXI could be $\sim $0.2 mCrab for two years, which is comparable to the source confusion limit of the MAXI field of view (FOV). The MAXI objectives are: (1) to alert the community to X-ray novae and transient X-ray sources, (2) to monitor long-term variabilities of X-ray sources, (3) to stimulate multi-wavelength observations of variable objects, (4) to create unbiased X-ray source cataloges, and (5) to observe diffuse cosmic X-ray emissions, especially with better energy resolution for soft X-rays down to 0.5 keV.
Multifrequency Study of Giant Radio Pulses from the Crab Pulsar with the K5 VLBI Recording Terminal
Authors: Popov Mikhail , Soglasnov Vladimir , Kondratiev Vladislav , Bilous Anna , Moshkina Olga , Oreshko Vasily , Ilyasov Yury , Sekido Mamoru , Kondo Tetsuro 
Published: March 2014

Abstract
Simultaneous multifrequency observations of Crab pulsar giant pulses (GPs) were performed with the 64-m Kalyazin radio telescope at four frequency ($\nu$$=$ 0.6, 1.4, 2.2, and 8.3 GHz) using the K5 VLBI recording terminal. The K5 terminal provided continuous recording in 16 $\times$ 4-MHz wide frequency channels distributed over 4 frequency bands. Several thousand GPs were detected during about 6 hours of observations on two successive days in 2005 July. The radio spectra of single GPs were analyzed at separate frequencies and over the whole frequency range. These spectra manifest notable modulation over the frequency ranges, $\Delta\nu$, both on large ($\Delta\nu/\nu$$\approx$ 0.5) and small ($\Delta\nu/$$\nu$$\approx$ 0.01) frequency scales. A cross-correlation analysis of GPs at 2.2 GHz showed that their pulse shapes can be interpreted as being an ensemble of unresolved bursts grouped together on time scales of $\approx$1$ \mu$s, being well-correlated over a 60-MHz band. The corresponding GP cross-correlation functions do not obey the predictions of the amplitude-modulated noise model of Rickett (1975), thus indicating that unresolved components represent a small number of elementary emitters.
Suzaku Observation of Diffuse X-Ray Emission from the Open Cluster Westerlund 2: a Hypernova Remnant?
Authors: Fujita Yutaka , Hayashida Kiyoshi , Takahashi Hiroaki , Takahara Fumio 
Published: March 2014

Abstract
We present an analysis of Suzaku observations of the young open cluster Westerlund 2, which is filled with diffuse X-ray emission. We found that the emission consists of three thermal components, or two thermal and one non-thermal components. The upper limit of the energy flux of the non-thermal component is smaller than that in the TeV band observed with H.E.S.S. This may indicate that active particle acceleration has stopped in this cluster, and that the accelerated electrons have already cooled. The gamma-ray emission observed with H.E.S.S. is likely to come from high-energy protons, which hardly cool, in contrast with electrons. The metal abundances of the diffuse X-ray gas may indicate the explosion of a massive star in the past.
Relativistic Spectra of Hot Black-Hole Winds
Authors: Sumitomo Naoko , Saito Hideki , Fukue Jun , Watarai Kenya 
Published: March 2014

Abstract
We examine hybrid thermal-nonthermal synchrotron spectra from a spherically symmetric, optically-thin wind, taking into account the relativistic effect. In relativistic flow from the central object, due to the relativistic beaming effect, the observed spectra often shift towards high frequency and high intensity directions. In optically thin outflows, however, we find that the intensity of the observed spectra decreases compared with that of the emitted ones, although the peak frequency shifts towards the high-frequency direction. This is because in the optically thin outflows we can see the far-side flows that go away from the observer. We thus carefully consider optically thin relativistic flows around a black hole, such as Sgr A$^\ast$.
Suzaku Observation of the Radio Halo Cluster Abell 2319: Gas Dynamics and Hard X-Ray Properties
Authors: Sugawara Chika , Takizawa Motokazu , Nakazawa Kazuhiro 
Published: March 2014

Abstract
We present the results of a Suzaku observation of the radio halo cluster Abell 2319 (A 2319). The metal abundance in the central cool region is found to be higher than the surrounding region, which was not resolved in former studies. We confirm that the line-of-sight velocities of the intracluster medium in the observed region are consistent with those of the member galaxies of the entire A 2319 and A 2319A subgroup for the first time, though no velocity difference within the region has been detected. On the other hand, we have not found any signs of gas motion relevant to the A 2319B subgroup. Hard X-ray emission from the cluster has clearly been detected, but its spectrum is likely to be thermal. Assuming a simple single-temperature model for the thermal component, we find that the upper limit of the non-thermal inverse Compton component becomes 2.6 $\times$ 10$^{-11} $erg s$^{-1} $cm$^{-2}$ in the 10–40 keV band, which means that the lower limit of the magnetic field is 0.19 $\mu$G with a radio spectral index of 0.92. Although the results slightly depend on the detailed spectral modeling, it is robust that the upper limit of the power-law component flux and lower limit of the magnetic field strength become $\sim $3 $\times$ 10$^{-11} $erg s$^{-1} $cm$^{-2}$ and $\sim $0.2$\mu$G, respectively. Considering the lack of a significant amount of very hot ($\sim $20 keV) gas and the strong bulk flow motion, it is more likely that the relativistic non-thermal electrons responsible for the radio halo are accelerated through intracluster turbulence rather than shocks.
VLBI Detections of Parsec-Scale Nonthermal Jets in Radio-Loud Broad Absorption Line Quasars
Authors: Doi Akihiro , Kawaguchi Noriyuki , Kono Yusuke , Oyama Tomoaki , Fujisawa Kenta , Takaba Hiroshi , Sudou Hiroshi , Wakamatsu Ken-ichi , Yamauchi Aya , Murata Yasuhiro , Mochizuki Nanako , Wajima Kiyoaki , Omodaka Toshihiro , Nagayama Takumi , Nakai Naomasa , Sorai Kazuo , Kawai Eiji , Sekido Mamoru , Koyama Yasuhiro ,   the VLBI group at Geographical Survey Institute, Asano Shoichiro , Uose Hisao 
Published: March 2014

Abstract
We conducted radio detection observations at 8.4 GHz for 22 radio-loud broad absorption line (BAL) quasars, selected from the Sloan Digital Sky Survey Third Data Release, by a very-long-baseline interferometry (VLBI) technique. The VLBI instrument we used was developed by the Optically ConnecTed Array for VLBI Exploration project (OCTAVE), which is operated as a subarray of the Japanese VLBI Network. We aimed to select BAL quasars with nonthermal jets suitable for measuring their orientation angles and ages by subsequent detailed VLBI imaging studies to evaluate two controversial issues of whether BAL quasars are viewed nearly edge-on, and of whether BAL quasars are in a short-lived evolutionary phase of the quasar population. We detected 20 out of 22 sources using the OCTAVE baselines, implying brightness temperatures greater than 10$^{5}$ K, which presumably come from nonthermal jets. Hence, BAL outflows and nonthermal jets can be generated simultaneously in these central engines. We also found four inverted-spectrum sources, which are interpreted as Doppler-beamed, pole-on-viewed relativistic jet sources, or young radio sources: single edge-on geometry cannot describe all BAL quasars. We discuss the implications of the OCTAVE observations for investigations for the orientation and evolutionary stage of BAL quasars.
Frequency Separation Variations of the Solar Low-Degree p-Modes
Authors: Yang Wuming , Meng Xiangcun 
Published: March 2014

Abstract
Variations of frequency separations of low-degree p-modes have been studied over the solar-activity cycle. The studied separations were obtained from the frequencies of low-degree p-modes of the Global Oscillation Network Group (GONG). The 10.7 cm radio flux was used as an index of solar activity. Small separations of the p-mode frequencies are considered to be mainly dependent on the conditions in stellar interiors. Thus, they could be applied to a diagnosis of the changes in the stellar interior. Our calculation results show that the magnitudes of the variations of the mean large separations are less than 1$ \sigma$ over the solar-activity cycle. Small separations show different behaviors in the ascending and descending phases of activity. In the ascending phase, variations of the small separations are less than 1$ \sigma$. However, the small separations had systematic shifts during the period from 2004 to 2007. These shifts were roughly 1$ \sigma$ or more. The variations in the ratios of the small-to-large separations with time were similar to the changes of the small separations. The effects of the changes in the large separations on the ratios were negligible. The variations of the separations may be a consequence of influence from the surface activity, or systematic errors in measurements, or some processes taking place in the solar interior.
Suzaku Observations of Thermal and Non-Thermal X-Ray Emission from the Middle-Aged Supernova Remnant G156.2$+$5.7
Authors: Katsuda Satoru , Petre Robert , Hwang Una , Yamaguchi Hiroya , Mori Koji , Tsunemi Hiroshi 
Published: March 2014

Abstract
We present results from an X-ray analysis of a Galactic middle-aged supernova remnant (SNR), G156.2$+$5.7, which is bright and largely extended in X-ray wavelengths, showing a clear circular shape (radius $\sim$ 50$^\prime$). Using the Suzaku satellite, we observed this SNR in three pointings: partially covering the northwestern rim, the eastern rim, and the central portion of this SNR. In the northwestern rim and the central portion, we confirmed that the X-ray spectra consist of soft and hard-tail emissions, while in the eastern rim we found no significant hard-tail emission. The soft emission was well-fitted by a non-equilibrium ionization (NEI) model. In the central portion, a two-component (the interstellar medium and the metal-rich ejecta) NEI model was used to fit the soft emission better than a one-component NEI model from a statistical point of view. The relative abundances in the ejecta component suggest that G156.2$+$5.7 is a remnant from a core-collapse SN explosion whose progenitor mass is less than 15$M_\odot$. The origin of the hard-tail emission is highly likely to be non-thermal synchrotron emission from relativistic electrons. In the northwestern rim, the relativistic electrons seem to be accelerated by a forward shock with a slow velocity of $\sim$ 500 kms$^{-1}$.