bluuebunny/crossref_metadata_2025 huggingface dataset:
A Steady State Model of X-Ray Emitting Coronae around Accreting Non-Magnetic White Dwarfs in Cataclysmic Variables
Authors: Mahasena Putra , Osaki Yoji
Published: March 2014

The X-ray emission of non-magnetic cataclysmic variable stars is considered. It is well known that a nearly spherical hot corona is produced around accreting white dwarfs because of strong viscous heating, and of rather inefficient cooling of matter at the boundary layer if the accretion rate is below some critical value. A steady state model of X-ray emitting coronae, into which mass is steadily supplied from the boundary layer, is then constructed and the X-ray spectra are calculated as functions of the mass-supply rate Ṁs. Eclipses of such corona were simulated. It has been found that the thermal energy of the corona is transported downward by conduction to the denser area near to the surface of the white dwarf, where it is emitted as X-ray radiation. Around 5% of the matter supplied by the disk could leave the system as stellar wind. Most of the X-rays are radiated from regions near to the white dwarf surface within this model. Eclipse simulations of this model agree with recent observations of eclipsing system HT Cas.
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

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).
Optical Number Count Estimation of IRIS Far-Infrared Survey of Galaxies
Authors: Hirashita Hiroyuki , Takeuchi Tsutomu T. , Ohta Kouji , Shibai Hiroshi
Published: March 2014

Infrared Imaging Surveyor (IRIS) is a satellite which will be launched at the beginning of 2003. One of the main purposes of the IRIS mission is an all-sky survey in the far-infrared region with a flux limit much deeper than that of IRAS. The detection of a large number of galaxies ( ∼ several × 106 in the whole sky) is expected in this survey. We investigated the expected optical and near-infrared (NIR) number counts of galaxies detected by the far-infrared scanner (FIS) of IRIS (hereafter, IRIS galaxies) and the possibility of their optical and NIR follow-up. The spectral energy distribution and the luminosity function of the IRIS galaxies are modeled based on the properties of galaxies observed by IRAS. The IRIS galaxies are divided into two populations according to their infrared luminosities (LIR): normal spirals (LIR < 1010 L⊙) and starbursts (LIR > 1010L⊙). The expected number counts of IRIS galaxies for both of the populations are calculated in B and H bands. We show that about 60 normal galaxies and about 80 starburst galaxies are detected per square degree in both of the two bands, when galaxy evolution is not taken into account. All of the normal population of IRIS galaxies are located at the redshift z ≲ 0.1. As for the starburst population, we also calculated the number of galaxies with a simple model of evolution. The total number of starburst population predicted by the evolution model is larger by 20% than that expected from the non-evolution model. In the evolution model, the numbers of low-z (z < 1), intermediate-z (1 < z < 3), and high-z (z > 3) galaxies are 100, 20, and 0.2 per square degree, respectively.
Cluster Mass Estimate Using Strong Gravitational Lenses Revisited
Authors: Ono Takehiro , Masai Kuniaki , Sasaki Shin
Published: March 2014

To study clusters of galaxies, the cluster mass is one of the most important quantities. However, it has been recognized that there exists more than a factor of 2 difference between the mass determined from X-ray observations (X-ray mass) and that from strong lensing effects (lensing mass). Intending to solve the discrepancy, we examined the means of the mass derivation from strong lensing effects. We found that the conventional way could overestimate the mass by 10–30%. In this paper, we present an alternative way to estimate the lensing mass. By our re-analysis, the discrepancy between the lensing mass and the X-ray mass can be reduced. We also discuss the causes of the remaining discrepancy.
Determination of the Two-Body Relaxation Time of Galaxies in an Expanding Universe
Authors: Ardi Eliani , Tsuchiya Toshio , Inagaki Shogo
Published: March 2014

The two-body relaxation time of gravitationally interacting galaxies in the Einstein-de Sitter universe is studied. First, we reformulate the scattering problem so that the time change of the cross section due to cosmic expansion can be taken into account. Next we calculate numerically the orbits of encounters to various sets of orbital parameters while specifying the initial states of the encounters: initial separation, impact parameter, and initial relative velocity between two galaxies. By combining the results of these studies, we obtain the two-body relaxation time as a function of the relative velocity vo at the initial epoch and the number density n of galaxies within proto-clusters of galaxies. The relaxation time is roughly the free-fall time for a small relative velocity, VQ < 300 km s∼1(m/1011M®) [11/(1 + z)), while it is proportional to VQ>3 for a high relative velocity. The effects of the cosmic expansion make the relaxation time longer than that in non-expanding systems, especially for proto-clusters of galaxies with the number density n < 3 × 103 Mpc∼3 (1011 A4®/ra)[(1 + z)/llf, where m is the mass of a galaxy and z is its redshift.
The Enormous Outburst of the 7.9 km s-1 Water-Maser Feature in Orion KL
Authors: Omodaka Toshihiro , Maeda Toshihisa , Miyoshi Makoto , Okudaira Atuya , Nishio Masanori , Miyaji Takeshi , Motiduki Nanako , Morimoto Masaki , Kobayashi Hideyuki , Sasao Tetsuo
Published: March 2014

We report on a spectacular flare in the water-vapor maser emission from the KL nebula, which we found in 1997 December. The flare, at a velocity of 7.9 km s−1, continued to increase in intensity exponentially and had a flux density greater than 3.5×106 Jy. The central velocity of the flare component was 7.9 km s−1 and the line width was less than 40 kHz. We did not detect a “rapid„ time variation in the intensity. The flare component is currently increasing steadily. A preliminary VLBI observation was made using a Japanese domestic VLBI network, called J-Net, in order to determine the location of the flare. Its position is $\alpha= 05^\textrm h32^\textrm m 46^\textrm s.6, \delta=-5^\circ 24^\prime 27^{\prime \prime}_.{2} (1950.0) \pm 1^{\prime \prime}.$ In this region, strong outbursts were reported during the period from 1979 August to 1985 November (Matveenko et al. 1988, AAA 49.131.147). Both the central velocity and the position of the present flare seems to be the same as that of previous ones. This suggests a common origin of these phenomena.
A New Imaging System of the Corona at Norikura
Authors: Ichimoto Kiyoshi , Noguchi Motokazu , Tanaka Nobuyuki , Kumagai Kazuyoshi , Shinoda Kazuya , Nishino Tetsuo , Fukuda Takeo , Sakurai Takashi , Takeyama Norihide
Published: March 2014

A new imaging system of the coronal green line (Fe XIV 5303 Å) was constructed at the Norikura Solar Observatory. The system consists of a 10-cm coronagraph, a tunable Lyot filter, and a cooled CCD camera. The transmission curve of the Lyot filter can be modulated by two liquid-crystal variable retarders. This scheme provides quick wavelength tuning and efficient subtraction of sky background. Two-dimensional distributions of the intensity and Doppler shift of the coronal green line can be obtained within 30 seconds with accuracies of better than 10−6I⊙ and 1 km s−1. Regular operation was started in 1997 September. The aim of the new system is to investigate plasma motions associated with the magnetic field reconnection and waves in the solar corona.
Core-Halo Structure of a Chemically Homogeneous Massive Star and Bending of the Zero-Age Main Sequence
Authors: Ishii Mie , Ueno Munetaka , Kato Mariko
Published: March 2014

We have recalculated the interior structure of very massive stars of uniform chemical composition with the OPAL opacity. Very massive stars are found to develop a core-halo structure with an extended radiative-envelope. With the core-halo structure, because a more massive star has a more extended envelope, the track of the upper zero-age main-sequence (ZAMS) curves redward in the H-R diagram at > 100 M® (Z=0.02), >70 Af® (Z=0.05), and > 15 M® for helium ZAMS (X=0, Z=0.02). Therefore, the effective temperatures of very massive ZAMS stars are rather low: e.g., for a 200 M® star, log Teff=4.75 (Z=0.004), 4.60 (Z=0.02), 4.46 (Z=0.05), and 4.32 (Z=0.10). The effective temperatures of very luminous stars (> 120 M® ) found in the LMC, the SMC, and the Galaxy are discussed in relation to this metal dependence of a curving upper main-sequence.
Analysis of Mathematical Morphology for Quantifying Galaxy Distributions in AT-Body Simulations
Authors: Ueda Haruhiko
Published: March 2014

We used a counts-in-cells analysis for quantifying galaxy distributions in cosmological TV-body simulations. We adopted seven simulations which were evolved from different power-law initial conditions and CDM initial conditions with different density parameter. In our analyses, we focused on information of the galaxy distributions in two-dimensions, and adopted a mathematical morphology which is one of the most noticeable fields in image analysis. We propose new statistical measures which are based on the mathematical morphology. These measures relate to the area of the counts-in-cells or the pattern spectrum. Prom our analyses, the histogram of the area, the pattern spectrum, and these new measures are found to be useful to distinguish the difference of the galaxy distributions among power-law models as well as CDM models.
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

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.
Doppler-Boosting Effect on the Fluxes of Active Galactic Nuclei
Authors: Mei Dong-Cheng , Xie Guang-Zhong , Qin Yi-Ping , Bai Jin-Ming , Cheng Luo-En
Published: March 2014

A study of Doppler-boosting effect on the fluxes of active galactic nuclei (AGNs) with relativistic bulk motion is presented. Four AGNs samples (the BL Lacertae object sample, the core-dominated high-polarization quasar sample, the core-dominated low-polarization quasar sample, and the lobe-dominated quasar sample) presented by Ghisellini et al. (1993, AAA 57. 158. 207), are employed. All plots of radio flux versus optical flux, corrected by Doppler factors, for the four samples exhibit an obvious correlation between the two quantities, in agreement with what would be predicted by the synchrotron-emission mechanism. The results show that Doppler-boosting effect is indeed obvious for the AGNs with relativistic bulk motion.
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

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.
A Study of the Molecular Cloud toward the H II Regions S 35 and S 37 with NANTEN
Authors: Saito Hiro , Tachihara Kengo , Onishi Toshikazu , Yamaguchi Nobuyuki , Mizuno Norikazu , Mizuno Akira , Ogawa Hideo , Fukui Yasuo
Published: March 2014

We have made new observations of a large field of ∼ 10 square degrees toward the two southern H II regions S35 and S37. Observations were made in the 12CO, 13CO, and C18O J= 1−0 emission with the NANTEN telescope at Las Campanas, Chile. These observations have revealed a giant molecular cloud of ∼ 1.3 × 105M⊙ in 12CO, highly elongated with a size of ∼ 80 pc × ∼ 20 pc, where a previously known active site of star formations, including GGD 27IR and HH 80/81, is located. The cloud appears lifted up to z ∼ 100 pc from the galactic plane at an inclination angle of ∼ 70°, exhibiting indications of strong interactions with the H II regions. Star formation has been found to be very active in the cloud. We have discovered four molecular outflows driven by luminous far-infrared sources of ∼ 102−104L⊙ in addition to that previously known toward GGD 27 IRS. The activity is also demonstrated by the existence of several dense C18O clumps whose mass ranges from ∼ 3 × 102M⊙ to ∼ 4 × 103M⊙ . The five molecular outflows are embedded in these C18O clumps. In addition, a comparison with H I shows that the CO cloud is located at the edge of an H I hole of ∼ 55 pc radius. Since the H I gas surrounding the hole shows a signature of expansion at several km s-1, we suggest that the H I hole represents a supershell created by some explosive events, like supernova explosions, during the last ∼ 4 × 106 yr. This supershell may also provide an explanation for the origin of the molecular distribution.
Evolution of Clusters of Galaxies: Mass Stripping from Galaxies and Growth of Common Halos
Authors: Sensui Tomohiro , Funato Yoko , Makino Junichiro
Published: March 2014

We investigated the evolution of clusters of galaxies using self-consistent N-body simulations in which each galaxy was modeled by many particles. We carried out simulations for about 20 cases using different initial conditions. In all simulations, clusters were initially in virial equilibrium. We found that more than half of the total mass escaped from individual galaxies within a few crossing times of the cluster, and that a diffuse halo was formed. The growth rate of the common halo depended on the size of individual galaxies only weakly. The stripping of the mass from galaxies was mainly due to the interaction of galaxies, not due to the effect of the tidal field of the cluster potential. The amount of stripped mass was larger for galaxies in the central region than for those in the outer region, since the interactions were more frequent in the central region. As a result, a positive correlation between the distance from the center and the mass of the galaxy developed. The volume-density profile of the common halo is expressed as ρ ∞ r-1 in the central region. This mass distribution is consistent with the mass distribution in clusters estimated using X-ray observations.
A General Method for the Analysis of Observations
Authors: Unno Wasaburo , Yuasa Manabu
Published: March 2014

A general method for constructing the science of a complex system from observational data has been developed from the view point of mathematical epistemology. A complete description of an observed system is achieved by establishing a large number of addresses under which all of the data are systematically arranged and by adopting an embedding dimension (number of variables to describe the system) appropriately for the complexity of the system. The variables are then normalized, and descriptive principal-component analyses (DESPCA) are performed to describe the system. Then, the addition of time derivatives (or variables of describing law) to the set of PCA's of the previous DESPCA provides an extended data set to be applied to a dynamical principal-component analysis (DYNPCA) which follows. The advantage of DYNPCA lies, among others, in a systematic improvement of the system used for analysis and in a quantitative estimation of the uncertainty of the differential equation of the dynamical system (or of the law) determined from the minimum eigen-value of the DYNPCA. As a simple application of the DYNPCA, the distance determination of mass-losing super-giants considered in a previous study is re-discussed from the point of view of methodology. The traditional use of classification in empirical sciences is found to be well adaptable in cooperation with the DYNPCA.
Near-Infrared Emission-Line Galaxies in the Hubble Deep Field North
Authors: Iwamuro Fumihide , Motohara Kentaro , Maihara Toshinori , Iwai Jun'ichi , Tanabe Hirohisa , Taguchi Tomoyuki , Hata Ryuji , Terada Hiroshi , Goto Miwa , Oya Shin , Iye Masanori , Yoshida Michitoshi , Karoji Hiroshi , Ogasawara Ryusuke , Sekiguchi Kazuhiro
Published: March 2014

We present the 2.12 μm narrow-band image of the Hubble Deep Field North taken with the near-infrared camera (CISCO) on the Subaru telescope. Among five targets whose Hα or [OIII] emission lines are redshifted into our narrow-band range expected from their spectroscopic redshift, four of them have strong emission lines, especially for the two [OIII] emission-line objects. The remaining one target shows no Hα emission in spite of its bright rest-UV luminosity, indicating that this object is already under the post-starburst phase. The volume-averaged SFR derived from the detected two Hα emission is roughly consistent with that evaluated from the rest-UV continuum.
Near-Infrared Spectroscopy of the Cool Brown Dwarf, SDSS 1624+00
Authors: Nakajima Tadashi , Tsuji Takashi , Maihara Toshinori , Iwamuro Fumihide , Motohara Ken-taro , Taguchi Tomoyuki , Hata Ryuji , Tamura Motohide , Yamashita Takuya
Published: March 2014

Using the Subaru Telescope, we have obtained multiple near-infrared spectra of the cool brown dwarf, SDSS 1624 + 00 (J162414.37+002915.8), in search of spectral variability in an 80 minute time span. We have found the suspected variability of water vapor absorption throughout the observations, which requires a confirmation with a longer time baseline. After coadding the spectra, we have obtained a high-quality spectrum covering from 1.05 to 1.8 μm. There are three kinds of spectral indicators, the water vapor bands, methane band and KI lines at 1.243 and 1.252 μm, which can be used to study the temperature and the presence of dust. We compare the spectra of SDSS 1624+00 and Gliese 229B, while paying special attention to these indicators. The shallower water vapor absorption of SDSS 1624+00 indicates that it is warmer and/or dustier. The shallower methane absorption suggests that SDSS 1624+00 is warmer. We interpret the deeper KI lines in SDSS 1624+00 as being the result of its higher temperature. With the help of model spectra, we conclude that SDSS 1624+00 is warmer and dustier than Gliese 229B. For the first time in a cool brown dwarf, a finite flux is seen at the bottom of the water vapor band between 1.34 and 1.42 μm, which means that the 1.4 μm band of water can be completely observed from the ground.
Usability of the NFW Galaxy Profile as a Cosmological Tool Estimated from 2-Image Gravitational Lens Systems
Authors: Asano Katsuaki
Published: March 2014

The profile of Navarro, Frenk, and White (the NFW profile), which was derived from N-body simulations of cold dark-matter halos, is a strong candidate for a galaxy or cluster profile. In order to check the usability of the NFW profile as a first approximation of a galaxy model, we studied the characteristic overdensity and scale radius of galaxies by reproducing the image positions and flux ratios of 2-image gravitational lens systems, under the following simple assumptions: the galaxies are spherically symmetric, and stars and external shear do not contribute to the gravitational lens. The scale radii of the lensing galaxies are smaller, and the characteristic overdensities are larger than the predicted value in the N-body simulations. These results indicate that our assumptions are overly simplified. It may be impossible to simply adopt the NFW profile, which does not include stars, to probe the cosmological parameters or light propagation in an inhomogeneous universe and so on. If we adopt a softened isothermal profile to the lensing galaxies, the scale radii and the central matter densities agree with models which are derived from other observational results for early-type galaxies and which are independent of gravitational lensing. The isothermal sphere as a first approximation of a galaxy model has no serious problem.
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

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< 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<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

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.
Period Measurement of AGB Stars in the Outer Galactic Disk
Authors: Nakashima Jun-ichi , Jiang B. W. , Deguchi Shuji , Sadakane Kozo , Nakada Yoshikazu
Published: March 2014

The light variation of the 47 AGB star candidates in the outer galactic disk has been monitored at the I-band for 5 years. Periods were well determined for 18 of them, and less reliably for the other 25. The average period of the objects is then 500 days. According to the period-luminosity relation, the mean luminosity of the sample stars is 10000 L⊙. Based on the absolute luminosity, derived from the period-luminosity relation and the apparent luminosity from the observation, the distances to the objects were determined. The calculated distances are slightly greater than those obtained previously based on the assumption of a constant luminosity of 8000 L⊙. In addition, SiO maser emission was detected for most of the observed objects, so that their radial velocities were accurately known. With the assumption of circular rotation in galactic disk, the rotation curve and Oort's constants were derived.
Global Relationships among the Physical Properties of Galaxy Cluster Cores
Authors: Fujita Yutaka , Takahara Fumio
Published: March 2014

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.
Chemical Evolution in the Large Magellanic Cloud
Authors: Nagataki Shigehiro , Watanabe Gentaro
Published: March 2014

We present a new input parameter set of the Pagel model (Pagel, Tautvaišiene 1998, AAA 70.156.032) for the Large Magellanic Cloud (LMC) in order to reproduce the observations, including the star formation rate history. It is concluded that the probability for (3–8) M⊙ stars to explode as SNe Ia has to be quite high ( ∼ 0.17) in the LMC. As a result, a steep initial mass function slope and the existence of outflow are not needed in order to attain a low [O/Fe] ratio in the LMC. As for the current supernova ratio, a high ratio ( ∼ 1.3) is concluded by the new parameter set, which is consistent with recent X-ray observations.
Highly Polarized Burst of a Water Maser in Orion-KL
Authors: Horiuchi Shinji , Kameya Osamu
Published: March 2014

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.
Multi-Stage Drive of Astrophysical Jets
Authors: Fukue Jun
Published: March 2014

Because of radiation drag (Compton drag), it is difficult to produce highly relativistic jets driven by radiation pressure or magnetic force. Namely, under the present paradigm of uniform steady jets, disk radiation fields as well as magnetic fields easily drive mildly relativistic jets. However, the jet terminal speed can approach the speed of light in such very extreme cases as a point source, since radiation drag suppresses any acceleration. In order to break down this situation, we should abandon some of the basic assumptions, such as the uniformity or steadiness, or both. We propose multi-stage-rocket type jets, which are accelerated by radiation fields of successive radiators, taking account of the spatial non-uniformity. A few stages of emission layers are sufficient for the jets to become highly relativistic.
ASCA Observations of a Near-by Cluster in Antlia
Authors: Nakazawa Kazuhiro , Makishima Kazuo , Fukazawa Yasushi , Tamura Takayuki
Published: March 2014

The Antlia cluster is a near-by poor cluster which has a redshift of z = 0.0087. X-ray observations with ASCA have revealed that the cluster is almost isothermal in the X-ray with a temperature of kT ∼ 2.0 keV. The metal abundance is Z ∼ 0.35 Z⊙, and the 0.5–10.0 keV cluster luminosity is $\sim 3.4 \times 10^{42} h^{-2}_{75} \textrm {erg s}^{-1}$ within r < 250 h-175 kpc. There was no X-ray central excess brightness and little central cool component, which are frequently seen in near-by poor clusters. The Antlia cluster is the nearest poor cluster without these central features.
GRAPE-5: A Special-Purpose Computer for N-Body Simulations
Authors: Kawai Atsushi , Fukushige Toshiyuki , Makino Junichiro , Taiji Makoto
Published: March 2014

We have developed a special-purpose computer for gravitational many-body simulations, GRAPE-5. GRAPE-5 accelerates the force calculation which dominates the calculation cost of the simulation. All other calculations, such as the time integration of orbits, are performed on a general-purpose computer (host computer) connected to GRAPE-5. A GRAPE-5 board consists of eight custom pipeline chips (G5 chip) and its peak performance is 38.4 Gflops. GRAPE-5 is the successor of GRAPE-3. The differences between GRAPE-5 and GRAPE-3 are: (1) The newly developed G5 chip contains two pipelines operating at 80 MHz, while the GRAPE chip, which was used for GRAPE-3, had one at 20 MHz. The calculation speed of GRAPE-5 is 8-times faster than that of GRAPE-3. (2) The GRAPE-5 board adopted a PCI bus as the interface to the host computer instead of VME of GRAPE-3, resulting in a communication speed one order of magnitude faster. (3) In addition to the pure 1/r potential, the G5 chip can calculate forces with arbitrary cutoff functions, so that it can be applied to the Ewald or P3M methods. (4) The pairwise force calculated on GRAPE-5 is about 10-times more accurate than that on GRAPE-3. On one GRAPE-5 board, one timestep with a direct summation algorithm takes 14 (N/128 k)2 seconds. With the Barnes-Hut tree algorithm (θ = 0.75), one timestep can be done in 15 (N/106) seconds.
Sample Variance of the Higher-Order Cumulants of the Cosmic Velocity Divergence Field
Authors: Seto Naoki , Yokoyama Jun'ichi
Published: March 2014

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

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. >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

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

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

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

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

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.
Superdisks in Supersoft X-Ray Sources
Authors: Fukue Jun , Matsumoto Katsura
Published: March 2014

In supersoft X-ray sources the mass accretion rate is roughly equal to the Eddington rate, and traditional standard disks cannot be adequate. We thus propose a supercritical accretion disk (superdisk) for supersoft X-ray sources. We have found that superdisks exhibit various distinct features, compared with standard thin disks. The continuous spectra of superdisks generally become flat ($ \nu S_\nu \sim \nu^0$), which are greatly different from those of disk-blackbody spectra, as expected in the usual accretion disk systems. This flat nature is not so prominent in supersoft X-ray sources, compared with that in the superdisk around a black hole, since the radial extension of the disk is much smaller. Moreover, irradiation becomes important for a smaller accretion rate system. The superdisk picture was applied to RX J0019.8+2156, and reproduced its spectra and optical light curves well.
An Extremely Red Nucleus in an Absorbed QSO at z=0.65
Authors: Akiyama Masayuki , Ohta Kouji
Published: March 2014

The results of $ K$-band-imaging observations of a candidate of an absorbed QSO at $ z=0.653$, AX J131831+3341, are presented. The $ B-K$ color of the object is 4.85 mag, which is much redder than optically-selected QSOs. The $ K$-band image shows nuclear and extended components, the same as in the optical $ V$-, $ R$-, and $ I$-band images. The nuclear component ($ I-K = 4.29$ mag) is much redder than the power-law models with energy indices of 0 to $-1.0$, which well reproduce the $ V-R$ and $ R-I$ optical colors of the nuclear component. A heavily absorbed ($ A_V \sim 3$ mag) nucleus may emerge in the $ K$-band, while optical light may originate from scattered nuclear light. The $ I-K$ color of the extended component is 2.2 mag, which is consistent with the post-starburst nature of the host galaxy, which is also suggested from the $ V-R$ and $ R-I$ colors of the extended component.
Study of the Long-Term X-Ray Variability of a Possible Quasar RX J0957.9+6903 with ASCA
Authors: Ezoe Yu-ichiro , Iyomoto Naoko , Makishima Kazuo
Published: March 2014

The long-term variability and spectral properties of a possible quasar, RX J0957.9+6903, were studied utilizing 16 ASCA observations spanning 5.5 years. The average 0.7–10 keV spectrum of RX J0957.9+6903 is well represented by a power-law continuum having a photon index of $ 1.58 \pm 0.03$ and an absorption column of $ \sim 1 \times 10^{21}~\mathrm{cm}^{-2}$. The 2–10 keV flux of RX J0957.9+6903 varied by a factor of four over a period of six years, around a mean of $ \sim 8.8 \times 10^{-12}~\mathrm{erg}\,\mathrm{s}^{-1}\,\mathrm{cm}^{-2}$. Peak-to-peak variability within each observation was less than 25% on $ \sim 1$ day time scale. These properties support the classification of RX J0957.9+6903 as a quasar. The power spectrum density (PSD) was estimated in a “forward” manner over a frequency range of $ 10^{-8.2}$-$ 10^{-4.3}$ Hz by utilizing the structure function method and a Monte Carlo simulation assuming a broken power-law type PSD. Then, the break frequency $ f_\mathrm{b}$ of the PSD of RX J0957.9+6903 has been constrained as 1/$ f_\mathrm{b} = 1600^{+\infty}_{-1100}$ days, and the logarithmic slope of the high-frequency region of the PSD as $ \alpha =-1.55 \pm 0.2$ . A comparison of the estimated PSDs is made between RX J0957.9+6903 and the M81 nucleus, observed in the same field of view.
Nonlinear Stochastic Biasing of Peaks and Halos: Scale-Dependence, Time-Evolution, and Redshift-Space Distortion from Cosmological N-body Simulations
Authors: Taruya Atsushi , Magira Hiromitsu , Jing Yi Peng , Suto Yasushi
Published: March 2014

We have quantified the degree of nonlinearity and stochasticity of the clustering of biased objects using cosmological $N$-body simulations. Adopting the peaks and the halos as representative biasing models, we focused on the two-point correlation of the biased objects, dark matter and their cross-correlation. Especially, we took account of the effect of redshift-space distortion and attempted to clarify the scale dependence and the time dependence by analyzing the biasing factor and the cross-correlation factor. On small scales, stochasticity and nonlinearity become appreciable and strongly object-dependent, especially in redshift space due to the pair-wise velocity dispersion of the biased objects. Nevertheless, an approximation of deterministic linear biasing, $\delta_\mathrm{obj}\simeq b_\mathrm{obj} \delta_\mathrm{mass}$, works reasonably well even in the quasi-linear regime, $r \gtrsim 10\,h^{-1} \textrm{Mpc}$, and linear redshift-space distortion explains the clustering amplitudes in redshift space in this regime.
Polarization and Variations of BL Lacertae Objects
Authors: Fan J. H. , Cheng K. S. , Zhang L.
Published: March 2014

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

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

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.