bluuebunny/crossref_metadata_2025_split huggingface dataset:
Statistical Study of Solar X-Ray Jets Observed with the Yohkoh Soft X-Ray Telescope
Authors: Shimojo Masumi , Hashimoto Shizuyo , Shibata Kazunari , Hirayama Tadashi , Hudson Hugh S. , Acton Loren W. 
Published: March 2014

Abstract
We have found 100 X-ray jets in the database of full Sun images taken with the Soft X-ray Telescope (SXT) aboard Yohkoh during the period from 1991 November through 1992 April. A statistical study for these jets results in the following characteristics: 1) Most are associated with small flares (microflaressubflares) at their footpoints. 2) The lengths lie in the range of a few × 104−4 × 105 km. 3) The widths are 5 × 103–105 km. 4) The apparent velocities are 10–1000 km s−1 with an average velocity of about 200 km s−1 . 5) The lifetime of the jet extends to ˜ 10 hours and the distribution of the observed lifetime is a power law with an index of ˜ 1.2. 6) 76% of the jets show constant or converging shapes; the width of the jet is constant or decreases with distance from the foot point. The converging type tends to be generated with an energetic foot point event and the constant type by a wide energy range of the footpoint event. 7) Many jets (˜ 68%) appear in or near to active regions (AR). Among the jets ejected from bright-point like features in ARs, most (˜ 86%) are observed to the west of the active region. 8) 27% of the jets show a gap ( &gt; 104 km) between the exact footpoint of the jet and the brightest part of the associated flare. 9) The X-ray intensity distribution along an X-ray jet often shows an exponential decrease with distance from the footpoint. This exponential intensity distribution holds from the early phase to the decay phase.
Disk Instability-Induced Hard-Soft Transition in Soft X-Ray Transients
Authors: Mineshige Shin 
Published: March 2014

Abstract
Soft X-ray transients that are black-hole candidates (BHCs) exhibit hysteretic spectral transitions during outbursts; hard X-ray peaks generally precede soft X-ray peaks. To account for such behavior we propose a new model, in which the disk behavior is distinct across a critical radius. The outer portions suffer a thermal limit-cycle instability owing to partial ionization of hydrogen and helium, thereby modulating mass flow into the inner portions. In order to produce weak X-rays during the quiescence, however, the instability should be suppressed in the inner portions, probably due to small optical depths. Instead, the inner portions undergo forced bimodal transitions between the optically thick and thin branches in response to variable mass input from the outer portions. The inner part is on the optically thin, advection-dominated branch in the quiescence and rise phases, thus producing hard power-law radiation, while it is on the optically thick branch in the early decay phase, predominantly emitting soft radiation. Our model can basically account for the observations of black-hole transients.
Non-Local Effects of Turbulence on the Excitation of Trapped Oscillations in Dwarf-Nova Accretion Disks
Authors: Yamasaki Tatsuya , Kato Shoji 
Published: March 2014

Abstract
In a previous paper we showed, in order to suggest one possible mechanism of quasi-periodic oscillations (QPOs), that some axially symmetric radial oscillations can be trapped and excited in dwarf-nova accretion disks. This study was done by using a diffusion-type turbulent stress tensor. The adoption of a diffusiontype stress tensor is, however, not suitable, since the relaxation time of turbulence in Keplerian disks is comparable with the timescale of the oscillations, and the delay of the time response of the turbulence to the oscillations has non-negligible effects on the excitation of oscillations. In this paper we reexamine the excitation of trapped oscillations on dwarf-nova disks by taking the effects of the above-mentioned time delay of the stress tensor into account. The results show that although the growth rate of trapped oscillations decreases by a factor of 2-3, the oscillations are still excited, except for cases when the temperature dependence of the opacity is weak and the viscosity is small.
Soft X-Ray Coronal Structure Surrounding High-Latitude Dark Filaments Observed by Yohkoh
Authors: Uchida Yutaka , Fujisaki Kozo , Morita Satoshi , Torii Masaya , Hirose Shigenobu , Cable Samuel 
Published: March 2014

Abstract
The faint coronal structure existing prior to high-latitude X-ray arcade formation oberved by the Yohkoh Soft X-ray Telescope has turned out to be “overlapped dual arcades” whose inside legs cross with one another, rather than being a simple bipolar arcade whose top part is sagging due to loading of the dark filament material, as considered in previous models of dark filament suspension. The photospheric magnetic field under the crossed legs is found to be a belt of mixed polarity, extending tens of thousand kilometers, rather than a clean border of the two extended unipolar regions. The magnetic field distribution, as well as the coronal structure above it, are very different from the previously assumed situation for dark filaments based on the assumption of a bipolar photospheric magnetic field distribution. The coronal structure found in the region, the “overlapped dual arcades” structure, is most likely to be the “separatrix surfaces” in the quadruple photospheric magnetic source model for the magnetic configuration surrounding a dark-filament, as proposed by one of the present authors in his previous work (Uchida 1980, AAA 28.073.129).
Metallic Abundances in the Planet-Harboring G Type Star HD 217107
Authors: Sadakane Kozo , Honda Satoshi , Kawanomoto Satoshi , Takeda Yoichi , Takada-Hidai Masahide 
Published: March 2014

Abstract
The G8 dwarf star HD 217107 has been announced to have a planetary companion with an orbital period of 7.1 d. A detailed abundance analysis of this star was carried out using high-dispersion spectra in the visual and near IR regions, using a model atmosphere with Teff = 5500 ± 100 K, \ogg = 4.25 ± 0.1, and £t = 1-0 ± 0.3 km s−1. We derived the abundances of 13 elements and found that 11 of these elements (except for C and O) are enhanced with respect to the Sun. The abundance of iron is [Fe/H] = +0.31 ± 0.10. The mean abundance of lighter elements (Mg, Al, Si, and S) is systematically higher than that of iron peak elements (Cr, Fe, Co, and Ni) by about 0.2 dex. Combining with the published results, we found that all parent stars of planetary systems with a period shorter than 20 d are metal-rich.
An Astronomical Data Archive System with a Java-Based User Interface
Authors: Horaguchi Toshihiro , Nishihara Eiji , Yoshida Michitoshi , Aoki Kentaro , Ito Takashi , Watanabe Masaru , Ichikawa Shin'ichi , Takata Tadafumi , Yoshida Shigeomi , Hamabe Masaru 
Published: March 2014

Abstract
We have developed a data archive system for the optical telescopes of Okayama Astrophysical Observatory and Kiso Observatory. The archive system has a Java-based user interface and is accessible through the World Wide Web. Using this interface, users are able to search and preview observational data and also to refer to an environmental database of meteorological data and night-sky images. Most of the user interface, including an image previewer and environmental data viewers, has been developed as Java applets. The previewer has many functions, such as plotting a profile of a spectral image with its wavelength scale. The environmental viewers are useful to know the weather condition during an observation and to evaluate the quality of observational data. The applets have good performance running on client platforms, realizing interoperability of the system, and reducing network traffic. This system is also a prototype of the data-archive system of Subaru Telescope.
CO (J = 1–0) Observation of the cD Galaxy of AWM 7: Constraints on the Evaporation of Molecular Gas
Authors: Fujita Yutaka , Tosaki Tomoka , Nakamichi Akika , Kuno Nario 
Published: March 2014

Abstract
We have searched for molecular gas in the cD galaxy of a poor cluster of galaxies, AWM 7, using the Nobeyama 45 m telescope. We did not detect CO emission in the galaxy. Our limit of molecular gas in the inner 7.5 kpc is MH2&lt; 4× 108 M⊙ . We estimate the total mass of molecular gas left in the cD galaxy when the gas deposited by a cooling flow once becomes molecular gas and the molecular gas is continuously evaporated by the ambient hot gas. The observational limit of molecular gas requires f≳ 10-3, where f is the ratio of the heat conduction rate to that of Spitzer. However, this contradicts recent X-ray observations showing f&lt;10-5. Thus, the non-detection of CO cannot be explained by evaporation, and most of the cooled gas predicted by a cooling flow model may not change into molecular gas in the cD galaxy. Moreover, we estimate the evaporation time of molecular clouds brought to a cD galaxy through the capture of gas-rich galaxies and find that these clouds should not be evaporated if f≲ 10-3–10-4. Therefore, the non-detection of CO in a cD galaxy could constrain the total mass of the molecular clouds brought into it.
Light-Cone Effect on Clustering Statistics in Cosmological Redshift Space
Authors: Suto Yasushi , Magira Hiromitsu , Yamamoto Kazuhiro 
Published: March 2014

Abstract
We present a theoretical formalism to predict two-point clustering statistics (the power spectrum and the two-point correlation function), which simultaneously takes account of the linear velocity distortion, the nonlinear velocity distortion (finger-of-god), the cosmological redshift-space distortion, and the light-cone effect. To demonstrate the importance of these effects in exploring the clustering of objects at high redshifts, we show several model predictions for magnitude-limited surveys of galaxies and quasars. This methodology provides a quantitative tool to test various theoretical models against the upcoming precision data on clustering in the universe.
Global Relationships among the Physical Properties of Galaxy Cluster Cores
Authors: Fujita Yutaka , Takahara Fumio 
Published: March 2014

Abstract
Using X-ray data, we investigate the interrelations between gas density, ρ0 , virial density, ρvir , core radius, R, temperature, T, entropy, Sgas, and metal abundance, Z, in the core region of clusters of galaxies. First, we confirm that fundamental relations among ρ0 , R, and T found by Fujita and Takahara are reproduced by another data catalogue. Second, we find that, when clusters have two components in their surface brightness distribution, the inner components also satisfy the same fundamental relations on the assumption that the average temperature of the inner component is the same as that of the outer component. These results strengthen our interpretation that clusters form a two-parameter family in terms of the mass and ρvir ; a larger ρvir corresponds to an earlier formation epoch. We argue that the inner components represent distinct dark-matter components which collapsed ahead of the outer components. Third, we also find a tight relation between Sgas and ρvir , both for the outer and inner components; Sgas is smaller for a larger ρvir , but is larger than that produced through gravitational collapse alone for a larger ρvir . Although radiative cooling affects the thermal evolution, the tight relationship discovered suggests the existence of stable heating sources or stable energy transmission mechanisms. Finally, we find that the iron abundance at the centers of clusters is correlated with ρvir for the inner components. This implies that the iron produced by Type Ia supernovae has more accumulated for clusters formed earlier. We briefly discuss the implications of these findings.
Highly Polarized Burst of a Water Maser in Orion-KL
Authors: Horiuchi Shinji , Kameya Osamu 
Published: March 2014

Abstract
It has been reported that the 22 GHz water maser in the star-forming region Orion-KL has started an outburst (Omodaka et al. 1998, IAU Circ. 6893). We measured the linear polarization of the maser after the burst, during a phase of rapid flux density decrease. We found that the total flux density of 2.4 × 106 Jy (1998 December) exhibits about 46% linear polarization. Over the next six months we found that the total intensity decrease by about two orders of magnitude, while the fractional linear polarization gradually fell to 30%. These results suggest that the present bursting phenomenon has an origin similar to the super-maser event starting in 1979, and that the phenomenon of the extremely bright masers in this region is geometric in nature and related to a strong magnetic field.
Sample Variance of the Higher-Order Cumulants of the Cosmic Velocity Divergence Field
Authors: Seto Naoki , Yokoyama Jun'ichi 
Published: March 2014

Abstract
If primordial fluctuations follow Gaussian distribution, higher-order cumulants of cosmic fields could reflect nonlinear mode coupling, and would provide useful information about the gravitational instability picture of structure formation. We show that, in the usual case that the observed sample has a limited volume, their expected deviation (sample variance) from their universal values is nonvanishing, even in linear theory. As a result, we find that the relative sample variance of the skewness of the velocity divergence field can be as large as ∼ 30% in current velocity surveys.
CO Observations of Luminous IR Galaxies at Intermediate Redshift
Authors: Tutui Yoshinori , Sofue Yoshiaki , Honma Mareki , Ichikawa Takashi , Wakamatsu Ken-ichi 
Published: March 2014

Abstract
We present new measurements of the 12CO (J = 1-0) emission from 16 luminous infrared galaxies (LIGs) at intermediate redshift (cz ∼ 10000-50000 km s−1). These new data were selected by isolated and normal morphology. Although there already exist measurements of CO emission from LIGs in the literature, they are mostly strongly interacting/merging systems. The new CO data represent an important new addition to the literature in that they both expand the relatively small number of samples of LIGs measured in CO, and they include an interesting subset of LIGs that were selected based on isolated and normal morphology. The CO observations were performed using the NRO 45-m telescope. &gt;From measurements of the CO emission and the IRAS database, we discuss the molecular gas and dust properties of late-type galaxies at intermediate redshift. Comparisons of the CO and dust properties of the new result with those from other CO measurements have revealed the characteristics of this sample: (1) It shows the deepest CO observations of IRAS galaxies at intermediate redshift without any strong interaction features. (2) It has typical properties of normal IRAS galaxies in terms of star-formation efficiency, color-color diagrams and galactic nuclear activity. (3) It has a smaller gas-to-dust ratio than normal IRAS galaxies. This can be explained by a two-component dust model; our sample consists of mostly warm dust.
Profiles and Polarization Properties of Emission Lines from Relativistic Disks
Authors: Ogura Jun , Ohuo Nobuyori , Kojima Yasufumi 
Published: March 2014

Abstract
We examined the profiles and polarization properties of emission lines originating from the extremely relativistic region of Kepler disks. Because the emission region is more localized to the inner part, e.g., a few times the black hole radius, the profiles, and polarization properties are remarkably modified. The black hole spin significantly affects the properties through the inner edge. This observation, in spite of the technical difficulties, provides an important diagnostic of the relativistic region.
Discovery of a New Supernova Remnant in the Direction of G69.7+1.0
Authors: Yoshita Kumi , Miyata Emi , Tsunemi Hiroshi 
Published: March 2014

Abstract
We discovered a middle-aged supernova remnant (SNR) in the vicinity of G69.7+1.0 using the ASCA satellite. G69.7+1.0 was identified in the 2.7 GHz survey and classified as a shell-type SNR with a diameter of 16′. During the ROSAT all-sky survey, the X-ray emission was detected in the direction of G69.7+1.0. However, it extends beyond the radio shell, and an X-ray bright region was located outside of the radio shell. A spectral study with the ASCA and ROSAT shows a thin thermal plasma with an electron temperature of ∼ 0.4 keV. There is no significant variation of the spectral parameters over the field of view, except for the lower column density of the eastern part. We also found a large shell structure which surrounds the X-ray bright region in both optical and radio images. We suggest that the observed X-ray emission is associated with the large optical and radio shell, and that they are part of a new SNR, different from the radio SNR G69.7+1.0, which we have named AX J2001+3235 or G69.4+1.2. The large shell and the electron temperature of ∼ 0.4 keV indicate that AX J2001+3235 is an evolved SNR. From a comparison with the column density of CTB 80 (G69.0+2.7), we estimate that the distance of the SNR is about 2.5 kpc.
ASCA Observations of the Crab-Like Supernova Remnant 3C 58
Authors: Torii Ken'ichi , Slane Patrick O. , Kinugasa Kenzo , Hashimotodani Kiyoshi , Tsunemi Hiroshi 
Published: March 2014

Abstract
We present here X-ray observation of a Crab-like supernova remnant (SNR) 3C 58 with ASCA. We find that the integrated energy spectrum over the nebula is consistent with previous results, showing a power-law spectrum with the photon index of γ = 2.2–2.4, modified by interstellar absorption of about (3–4)' 1021 cm−2. The inclusion of a blackbody component, which is attributable to the central compact source, significantly improves the spectral fit. Stringent upper limits for any line emitting thin hot plasma are established. We find for the first time that the nebular spectrum is harder in the central part of the SNR, becoming softer toward the periphery, while the absorption column is uniform across the nebula. Correspondingly, the nebular size decreases with increasing photon energy, which is a steeper function of the radius than that of the Crab nebula. The results are compared with synchrotron energy-loss models, and the nature of the putative pulsar is discussed. A timing analysis was performed to search for pulsed X-ray emission from the central compact source. No significant pulsations were observed; and we present the upper limit for the pulsed fraction.
Oscillations of Static Discs around Schwarzschild Black Holes: Effect of Self-Gravitation
Authors: Semerák Oldřich , Žáček Miroslav 
Published: March 2014

Abstract
The oscillations of accretion-disc matter about roughly circular motion may produce a quasi-periodic variation in the observed signal (Ipser 1996, AAA 65.067.047). They were studied theoretically on non-gravitating, test discs, in a pseudo-Newtonian manner as well as in general relativity, both in static and in stationary fields. The present paper shows how the radial profiles of oscillation frequencies can be modified by the self-gravity of the disc. Exact superpositions of a Schwarzschild black hole with the Lemos and Letelier (1994, AAA 61.067.077) annular discs (static thin discs obtained by inversion of the first Morgan-Morgan solution) are considered to be simple (static) models of an accretion system. Both the epicyclic and perpendicular frequencies are plotted against the Schwarzschild radius, the circumferential radius, and the proper distance from the horizon. The curves indicate that in the innermost parts more massive discs are more stable with respect to horizontal perturbations, whereas they are less stable with respect to vertical perturbations. In the case of a sequence of discs interpretable as counter-rotating particles on stable time-like circular geodesics and having their inner rims just on marginally stable circular orbits, oscillations of the inner parts get faster with increasing disc mass; the maximum of the epicyclic frequency, important for trapping of the low-frequency modes near the inner radius, moves to smaller radii and becomes somewhat higher.
Observations of Ammonia in External Galaxies II. Maffei 2
Authors: Takano Shuro , Nakai Naomasa , Kawaguchi Kentarou , Takano Toshiaki 
Published: March 2014

Abstract
The ammonia (J,K) = (1,1), (2,2), (3,3), and (4,4) transitions in the 23.7−24.1 GHz region were searched in a nearby galaxy, Maffei 2, to study the relation between the molecular abundances and the physical conditions in galaxies. The (1,1), (2,2), and (3,3) emission lines were clearly detected. The obtained rotational temperatures and ortho-to-para abundance ratios are about 30 K and about 2.6, respectively. The abundance of NH3 relative to H2 in Maffei 2 was found to be the largest among galaxies where NH3 has already been detected, and the abundance in Maffei 2 is more than an order of magnitude larger than the already reported upper limit in M 82. Hence, we further confirmed the systematically peculiar molecular abundance regarding the formation mechanisms of molecules already reported in M 82.
Polarization and Variations of BL Lacertae Objects
Authors: Fan J. H. , Cheng K. S. , Zhang L. 
Published: March 2014

Abstract
BL Lacertae objects are an extreme subclass of AGNs showing rapid and large-amplitude variability, high and variable polarization, and core-dominated radio emissions. If a strong beaming effect is the cause of the extreme observation properties, one would expect that these properties would be correlated with each other. Based on the relativistic beaming model, relationships between the polarization and the magnitude variation in brightness, as well as the core-dominance parameter are derived and used statistically to compare with the observational data of a BL Lacertae object sample. The statistical results are consistent with these correlations, which suggests that the polarization, the variation, and the core-dominance parameter are possible indications of the beaming effect.
Metallic Abundances in the Planet-Harboring G-Type Star HD 38529
Authors: Sadakane Kozo , Ohkubo Michiko , Sato Shizuka , Osada Kyoichi , Takada-Hidai Masahide , Masuda Seiji , Izumiura Hideyuki , Koyano Hisashi , Maehara Hideo , Norimoto Yuji , Okada Takafumi , Shimizu Yasuhiro , Uraguchi Fumihiro , Watanabe Etsuji , Yanagisawa Kenshi , Yoshida Michitoshi 
Published: March 2014

Abstract
The abundances of 16 elements (C through Y) in the recently detected planet-harboring G4 IV star HD 38529 are presented. A spectroscopic analysis was carried out differentially relative to the Sun. The adopted atmospheric parameters of the star are $T_\mathrm{eff} = 5500\pm100~\mathrm{K}, \log g = 3.6\pm0.1, \xi_{\mathrm{t}}= 1.0\pm0.3~\mathrm{km}~\mathrm{s}^{-1}$, and [M/H]$= +0.3$. Iron is definitely overabundant with respect to the Sun, [Fe/H]$= +0.40\pm0.06$, and all other elements are also found to be enhanced. The enhancements of iron peak elements (Ti through Ni) are coincident with that of Fe within $\pm 0.1~$dex, while C and O are slightly less enhanced than Fe.
Twin Jets as a Potential Distance Detector
Authors: Qin Yi-Ping , Xie Guang-Zhong 
Published: March 2014

Abstract
A preview study of using observational data of the proper motions and Doppler-shifted velocities of twin jets to determine the distance of sources inside and outside our Galaxy is made. We investigate the feasibility of this method by studying the uncertainty of the distance caused by the uncertainties of the measured quantities. It shows that, when the motion of components of the jet is relativistic, the uncertainty of the distance is within the same order of the uncertainties of the measured values of the proper motions and Doppler-shifted velocities. In particular, when assuming that the pattern speed equals the flow speed in the jet, for 10% uncertainties of the measured quantities, the uncertainty of the distance caused by them would be well within 13%. With the current technique, this method is realizable. For the convenience of choosing the sources to observe, some sources as potential targets are also listed in this paper.