bluuebunny/crossref_metadata_2025 huggingface dataset:
Japanese VLBI Network Observations of Radio-Loud Narrow-Line Seyfert 1 Galaxies
Authors: Doi Akihiro , Fujisawa Kenta , Inoue Makoto , Wajima Kiyoaki , Nagai Hiroshi , Harada Keiichiro , Suematsu Kousuke , Habe Asao , Honma Mareki , Kawaguchi Noriyuki , Kawai Eiji , Kobayashi Hideyuki , Koyama Yasuhiro , Kuboki Hiromitsu , Murata Yasuhiro , Omodaka Toshihiro , Sorai Kazuo , Sudou Hiroshi , Takaba Hiroshi , Takashima Kazuhiro , Takeda Koji , Tamura Sayaka , Wakamatsu Ken-ichi
Published: March 2014

We performed phase-reference very long baseline interferometry (VLBI) observations on five radio-loud narrow-line Seyfert 1 galaxies (NLS1s) at 8.4 GHz with the Japanese VLBI Network. Each of the five targets (RXS J08066$+$7248, RXS J16290$+$4007, RXS J16333$+$4718, RXS J16446$+$2619, and B3 1702$+$457) in milli-Jansky levels were detected and unresolved in milli-arcsecond resolutions, i.e., with brightness temperatures higher than $10^7$ K. The nonthermal processes of active galactic nucleus activity, rather than starbursts, are predominantly responsible for the radio emissions from these NLS1s. Out of the nine known radio-loud NLS1s, including those chosen for this study, we found that the four most radio-loud objects exclusively have inverted spectra. This suggests a possibility that these NLS1s are radio-loud due to Doppler beaming, which can apparently enhance both the radio power and the spectral frequency.
Dissipation of Magnetic Flux in Primordial Star Formation: From Run-away Phase to Mass-Accretion Phase
Authors: Maki Hideki , Susa Hajime
Published: March 2014

We investigate the dissipation of magnetic flux in primordial star-forming clouds throughout their collapse, including the run-away collapse phase as well as the accretion phase. We solve the energy equation and the non-equilibrium chemical reactions in the collapsing gas, in order to obtain the radial distribution of the ionized fraction during the collapse. As a result, we find that the ionized fraction is high enough for the magnetic field to couple with the gas throughout evolution of the cloud. This result suggests that the jet formation from protostars as well as the activation of magneto–rotational instability in the accretion disk are enabled in the presence of the cosmological seed magnetic flux proposed by Langer, Puget, and Aghanim (2003, Phys. Rev. D67, 43505).
Searching for a Companion Star of Tycho’s Type Ia Supernova with Optical Spectroscopic Observations
Authors: Ihara Yutaka , Ozaki Jin , Doi Mamoru , Shigeyama Toshikazu , Kashikawa Nobunari , Komiyama Yutaka , Hattori Takashi
Published: March 2014

We report on our first results of photometric and spectroscopic observations for Tycho’s supernova remnant (SNR Tycho) to search for the companion star of a type Ia supernova. From photometric observations using Suprime-Cam on the Subaru Telescope, we have picked up stars brighter than 22 mag (in $V$-band) for spectroscopy, which are located within a circular region with a radius of 30${}^{\prime\prime}$ around the center of SNR Tycho. If the ejecta of young supernova remnants, such as SNR Tycho, have a sufficient amount of Fe I, we should be able to detect absorption lines at 3720 Å and associated with transitions from the ground state of Fe I in the spectrum of the companion star. To identify the companion star of a SN Ia using these characteristic absorption lines of Fe I, we performed optical low-resolution spectroscopy of their targets using FOCAS on the Subaru Telescope. In our spectroscopic observations, we obtained spectra of 17 stars in the SNR Tycho region and compared them with template stellar spectra. We detect significant absorption lines from two stars at 3720 Å. In addition, spectra of four stars also have possible absorption lines. Since the widths of their absorption lines are broad, it is likely that the detected absorptions are due to Fe I in the expanding ejecta of SNR Tycho. However, none of stars exhibit a clear red wing in the observed profiles of the absorption, though a star in the background of the SNR should show it. Hence, we suggest another interpretation, that the detected absorption lines might be caused by the peculiarity of stars. Though Tycho(G) was raised as a candidate of the companion star of Tycho’s supernova in a previous study, we did not obtain evidence supporting the previous research. On the contrary, a star named Tycho(E) has an absorption line at 3720 Å, and its projected position is close to the center of SNR Tycho. Based on our observations, Tycho(E) is a new candidate as the companion star of Tycho’s supernova.
A New Model for the Structure of the DACs and SACs Regions in the Oe and Be Stellar Atmospheres
Authors: Danezis Emmanouel , Nikolaidis Dimitris , Lyratzi Evaggelia , Popovic Luka C. , Dimitrijevic Milan S. , Antoniou Antonis , Theodosiou Efstratios
Published: March 2014

We present a new mathematical model for the density regions where a specific spectral line and its SACs/DACs are created in the Oe and Be stellar atmospheres. In calculations of final spectral line function we consider that the main processes for the line broadening are the rotation of the density regions creating the spectral line and its DACs/SACs, as well as the random motions of the ions. This line function is able to reproduce the spectral feature, which enables us to calculate some important physical parameters, such as the rotational, radial, and random velocities, the full width at half maximum, the Gaussian deviation, the optical depth, the column density, and the absorbed or emitted energy. Additionally, we can calculate the percentage of the contribution of the rotational velocity and the ions’ random motions of the DACs/SACs regions to the line broadening. Finally, we present two tests and three short applications of the proposed model.
Infrared Spectroscopy of Short-Period Cataclysmic Variables
Authors: Ishioka Ryoko , Sekiguchi Kazuhiro , Maehara Hiroyuki
Published: March 2014

We present near-infrared spectra for five dwarf novae with short orbital periods. We performed fittings of the spectral energy distributions (SEDs) by assuming a power-law distribution for the accretion disk and using template spectra of late-type dwarfs for the secondary star. Two are WZ Sge–or WX Cet-type stars, whose spectra show water absorption features, and one of them shows K$\;$ I and Na$\;$ I absorption lines in the $J$-band. We find that the secondary contributions to the overall SED are larger in WZ Sge stars than in ER UMa stars. The SED fitting suggests M9 and L1 type dwarf companions for our WZ Sge systems, and an M2 dwarf for our ER UMa star. We discuss the direct relationship between the high temperatures of secondary stars and high mass-transfer rates in ER UMa stars. SDSS J013701.06–091234.9 is the only object showing a spectrum dominated by the secondary component. The spectrum strongly suggests that the evolutionary path of SDSS J013701.06–091234.9 is different from that of ordinary CVs, and this object is a candidate of EI Psc-like systems.
Near-Infrared Spectra of 29 Carbon Stars: Simple Estimates of Effective Temperature
Authors: Tanaka Masuo , Letip Ahmatjan , Nishimaki Yuichirou , Yamamuro Tomoyasu , Motohara Kentaro , Miyata Takashi , Aoki Wako
Published: March 2014

Near-infrared spectra of 29 carbon stars in the 0.9–2.4$\mu$m range were obtained by using a cross-dispersed echelle spectrograph. The target stars, which were classified into C-H, C-R, C-J, and C-N types, were selected from an atlas of Barnbaum, Stone, and Keenan (1996, ApJS, 105, 419). Because the stars are non long-period variables, the phase differences of the light curves do not strongly affect the spectra. The effective temperatures ($T_{\mathrm{eff}}$) of the carbon stars were estimated with errors of $\pm\;$200 K by fitting our spectra at wavelengths of 1.35, 1.74, and 2.29$\mu$m, with simple model spectra, while considering the H$^{-}$ opacity minimum to be around 1.6$\mu$m. At these wavelengths, molecular absorption due to CO, CN, and C$_{2}$ is not strong. The derived effective temperatures are distributed between 5100 K and 2600 K, and highly correlate with the temperature sequence in Barnbaum, Stone, and Keenan (ibid.), although the stars with temperature sequences beyond 4 have similar temperatures near $\sim$ 3000 K. We also compared our results with values derived by other methods in the literature: the aperture diameter method, the infrared flux method, and some model calculations.
Neutrino Emission from Type Ia Supernovae
Authors: Kunugise Takashi , Iwamoto Koichi
Published: March 2014

Type Ia supernovae (SNe Ia) produce a burst of neutrino emission due to electron captures on free protons and nuclei in the hot, dense matter synthesized by explosive nucleosynthesis. We calculated the luminosity and energy spectrum of the burst for a standard SN Ia model W7. We found a peak luminosity of the total three-flavor neutrinos of $\sim$10$^{50}$ergs$^{-1}$ and a neutrino emission duration of $\sim$1s. The average energy of the neutrinos was found to be $\sim$3 MeV. Electron neutrinos generated in the central region of SN Ia undergo flavor oscillations between $v_e, v_\mu$, and $v_\tau$. As a result, the fraction of electron neutrinos is reduced to $\sim$0.55. The detectability of these neutrinos and the implications for progenitor scenarios of SNe Ia are discussed.
Suzaku Observations of the Local and Distant Hot ISM
Authors: Smith Randall K. , Bautz Mark W. , Edgar Richard J. , Fujimoto Ryuichi , Hamaguchi Kenji , Hughes John P. , Ishida Manabu , Kelley Richard , Kilbourne Caroline A. , Kuntz K. D. , McCammon Dan , Miller Eric , Mitsuda Kazuhisa , Mukai Koji , Plucinsky Paul P. , Porter F. Scott , Snowden Steve L. , Takei Yoh , Terada Yukikatsu , Tsuboi Yohko , Yamasaki Noriko Y.
Published: March 2014

Suzaku observed the molecular cloud MBM 12 and a blank field less than $3^{\circ}$ away to separate the local and distant components of the diffuse soft X-ray background. Towards MBM 12, a local ($D \lesssim 275 \,\mathrm{pc}$) O VII emission line was clearly detected with an intensity of $3.5 \;\mathrm{photons} \;\mathrm{cm}^{-2} \,\mathrm{s}^{-1} \,\mathrm{sr}^{-1}$ (or line units, LU), and the O VIII flux was ${<0.34 \;\mathrm{LU}}$. The origin of this O VII emission could be hot gas in the Local Hot Bubble (LHB), charge exchange within the heliosphere with oxygen ions from the solar wind (SWCX), or both. If entirely from the LHB, the emission could be explained by a region with emission measure of $0.0075 \,\mathrm{cm}^{-6} \,\mathrm{pc}$ and a temperature of $1.2 \times 10^6 \,\mathrm{K}$. However, this temperature and emission measure implies $1/4 \;\mathrm{keV}$ emission in excess of observations. There is no evidence in the X-ray light curve or solar wind data for a significant contribution from geocoronal SWCX, although interplanetary SWCX is still possible. In any case, the observed O VII flux represents an upper limit to both the LHB emission and interplanetary SWCX in this direction. The blank field was observed immediately afterwards. The net off-cloud O VII and O VIII intensities were (respectively) $2.34 \pm 0.33$ and $0.77 \pm 0.16 \;\mathrm{LU}$, after subtracting the on-cloud foreground emission. If this more distant O VII and O VIII emission is from a thermal plasma in collisional equilibrium beyond the Galactic disk, we infer it has a temperature of $(2.1 \pm 0.1) \times 10^6 \,\mathrm{K}$ with an emission measure of $(4 \pm 0.6) \times 10^{-3} \,\mathrm{cm}^{-6} \,\mathrm{pc}$.
Suzaku Observations of HESS J1616—508: Evidence for a Dark Particle Accelerator
Authors: Matsumoto Hironori , Ueno Masaru , Bamba Aya , Hyodo Yoshiaki , Mori Hideyuki , Uchiyama Hideki , Tsuru Takeshi Go , Koyama Katsuji , Kataoka Jun , Katagiri Hideaki , Takahashi Tadayuki , Hiraga Junko , Yamauchi Shigeo , Hughes John P. , Senda Atsushi , Kokubun Motohide , Kohmura Takayoshi , Porter Frederick S.
Published: March 2014

We observed the bright unidentified TeV $\gamma$-ray source HESS J1616$-$508 with the X-ray Imaging Spectrometers onboard the Suzaku satellite. No X-ray counterpart was found to a limiting flux of $3.1 \times 10^{-13} \,\mathrm{erg} \,\mathrm{s}^{-1} \,\mathrm{cm}^{-2}$ in the 2–10 keV band, which is some 60-times below the $\gamma$-ray flux in the 1–10TeV band. This object is bright in TeV $\gamma$-rays, but very dim in the X-ray band, and thus is one of the best examples in the Galaxy of a “dark particle accelerator.” We also detected soft thermal emission with $kT \sim 0.3 \hbox{--} 0.6 \,\mathrm{keV}$ near the location of HESS J1616$-$508. This may be due to a dust-grain scattering halo from the nearby bright supernova remnant RCW 103.
Suzaku Observation of the Metallicity Distribution in the Intracluster Medium of the Fornax Cluster
Authors: Matsushita Kyoko , Fukazawa Yasushi , Hughes John P. , Kitaguchi Takao , Makishima Kazuo , Nakazawa Kazuhiro , Ohashi Takaya , Ota Naomi , Tamura Takayuki , Tozuka Miyako , Tsuru Takeshi Go , Urata Yuji , Yamasaki Noriko Y.
Published: March 2014

The metallicity distribution in the Fornax cluster was studied with the XIS instrument on board the Suzaku satellite. The K-shell lines of O and Mg were resolved clearly, and the abundances of O, Mg, Si, S, and Fe were measured with great accuracy. The region within a $4'$ radius of NGC 1399 shows approximately solar abundances of Fe, Si, and S, while the $\mathrm{O/Fe}$ and $\mathrm{Mg/Fe}$ abundance ratios are about 0.4–0.5 and 0.7 in solar units, respectively. In the outer region of the radius range $6' < r < 23'$, the Fe and Si abundances drop to 0.4–0.5 solar and show no significant gradient within this region. The abundance ratios, $\mathrm{O/Fe}$ and $\mathrm{Mg/Fe}$, are consistent with those in the central region. We also measured the Fe abundance around NGC 1404 to be approximately solar, and the O, Ne, and Mg abundances to be 0.5–0.7 times the Fe level. A significant relative enhancement of Fe within 130 kpc of NGC 1399 and in NGC 1404 indicates an origin in SN Ia, in contrast to the species O, Ne, and Mg, which reflect the stellar metallicity. The mass-to-light ratios for O and Fe within 130 kpc of NGC 1399 are over an order of magnitude lower than those in rich clusters, reflecting the metal enrichment history of this poor cluster.
In-Orbit Performance of the Hard X-Ray Detector on Board Suzaku
Authors: Kokubun Motohide , Makishima Kazuo , Takahashi Tadayuki , Murakami Toshio , Tashiro Makoto , Fukazawa Yasushi , Kamae Tuneyoshi , Madejski Greg M. , Nakazawa Kazuhiro , Yamaoka Kazutaka , Terada Yukikatsu , Yonetoku Daisuke , Watanabe Shin , Tamagawa Toru , Mizuno Tsunefumi , Kubota Aya , Isobe Naoki , Takahashi Isao , Sato Goro , Takahashi Hiromitsu , Hong Soojing , Kawaharada Madoka , Kawano Naomi , Mitani Takefumi , Murashima Mio , Suzuki Masaya , Abe Keiichi , Miyawaki Ryouhei , Ohno Masanori , Tanaka Takaaki , Yanagida Takayuki , Itoh Takeshi , Ohnuki Kousuke , Tamura Ken-ichi , Endo Yasuhiko , Hirakuri Shinya , Hiruta Tatsuro , Kitaguchi Takao , Kishishita Tetsuichi , Sugita Satoshi , Takahashi Takuya , Takeda Shin’ichiro , Enoto Teruaki , Hirasawa Ayumi , Katsuta Jun’ichiro , Matsumura Satoshi , Onda Kaori , Sato Mitsuhiro , Ushio Masayoshi , Ishikawa Shin-nosuke , Murase Koichi , Odaka Hirokazu , Suzuki Masanobu , Yaji Yuichi , Yamada Shinya , Yamasaki Tomonori , Yuasa Takayuki ,   the HXD team
Published: March 2014

The in-orbit performance and calibration of the Hard X-ray Detector (HXD) on board the X-ray astronomy satellite Suzaku are described. Its basic performances, including a wide energy bandpass of 10–600 keV, energy resolutions of $\sim 4 \,\mathrm{keV}$ (FWHM) at 40 keV and $\sim 11\%$ at 511 keV, and a high background rejection efficiency, have been confirmed by extensive in-orbit calibrations. The long-term gains of PIN-Si diodes have been stable within 1% for half a year, and those of scintillators have decreased by 5–20%. The residual non-X-ray background of the HXD is the lowest among past non-imaging hard X-ray instruments in energy ranges of 15–70 and 150–500 keV. We provide accurate calibrations of energy responses, angular responses, timing accuracy of the HXD, and relative normalizations to the X-ray CCD cameras using multiple observations of the Crab Nebula.
Fine-Scale Structures of the Evershed Effect Observed by the Solar Optical Telescope aboard Hinode
Authors: Ichimoto Kiyoshi , Shine Richard A. , Lites Bruce , Kubo Masahito , Shimizu Toshifumi , Suematsu Yoshinori , Tsuneta Saku , Katsukawa Yukio , Tarbell Theodore D. , Title Alan M. , Nagata Shin’ichi , Yokoyama Takaaki , Shimojo Masumi
Published: March 2014

The small-scale structure of the Evershed effect is being studied using data obtained by the Spectropolarimeter and the Broadband Filter Imager of the Solar Optical Telescope aboard Hinode. We find that the Evershed flow starts at the leading edge of inwardly migrating bright penumbral grains, and turns to nearly a horizontal flow preferentially in the dark lanes of the penumbra. A number of small elongated regions that have an upward motion of $\sim$1 km s$^{-1}$ are found in the deep photosphere distributed over the penumbra. They are cospatial with bright grains and have relatively horizontal magnetic fields. A number of patches having a strong downward motion associated with the opposite magnetic polarity from the sunspot are also found in the mid and outer penumbra. They could be identified as foot points of the Evershed flow channels, though the identification of individual pairs is not straightforward. Our results provide strong support for some recent findings from ground-based high-resolution observations, and are in general agreement with the well-known picture of the uncombed structure of the penumbra, in which the penumbrae consist of rising flux tubes carrying nearly horizontal Evershed flows embedded in more vertical background magnetic fields.
Formation of Moving Magnetic Features and Penumbral Magnetic Fields with Hinode/SOT
Authors: Kubo Masahito , Ichimoto Kiyoshi , Shimizu Toshifumi , Tsuneta Saku , Suematsu Yoshinori , Katsukawa Yukio , Nagata Shin’ichi , Tarbell Theodore D. , Shine Richard A. , Title Alan M. , Frank Zoe A. , Lites Bruce , Elmore David
Published: March 2014

Vector magnetic fields of moving magnetic features (MMFs) were well observed with the Solar Optical Telescope (SOT) aboard the Hinode satellite. We focused on the evolution of three MMFs with the SOT in this study. We found that an MMF having relatively vertical fields with the same polarity as the sunspot was detached from the penumbra around the granules appearing in the outer penumbra. This suggests that granular motions in the outer penumbra are responsible for disintegration of the sunspot. Two MMFs with polarity opposite to the sunspot are located around the outer edge of horizontal fields extending from the penumbra. This is evidence that the MMFs with polarity opposite to the sunspot are the prolongation of penumbral horizontal fields. Redshifts larger than the sonic velocity in the photosphere are detected for some of the MMFs with polarity opposite to the sunspot.
Small-Scale Magnetic-Flux Emergence Observed with Hinode Solar Optical Telescope
Authors: Otsuji Kenichi , Shibata Kazunari , Kitai Reizaburo , UeNo Satoru , Nagata Shin’ichi , Matsumoto Takuma , Nakamura Tahei , Watanabe Hiroko , Tsuneta Saku , Suematsu Yoshinori , Ichimoto Kiyoshi , Shimizu Toshifumi , Katsukawa Yukio , Tarbell Theodore D. , Lites Bruce , Shine Richard A. , Title Alan M.
Published: March 2014

We observed small-scale magnetic-flux emergence in a sunspot moat region by the Solar Optical Telescope (SOT) aboard the Hinode satellite. We analyzed filtergram images observed at wavelengths of Fe 6302 Å, G band, and Ca II H. In Stokes$I$ images of Fe 6302 Å, emerging magnetic flux was recognized as dark lanes. In the G band, they showed to be their shapes almost the same as in Stokes$I$ images. These magnetic fluxes appeared as dark filaments in Ca II H images. Stokes$V$ images of Fe 6302 Å showed pairs of opposite polarities at footpoints of each filament. These magnetic concentrations were identified to correspond to bright points in G band/Ca II H images. From an analysis of time-sliced diagrams, we derived the following properties of emerging flux, which are consistent with those of previous studies: (1) Two footpoints separate each other at a speed of 4.2 kms$^{-1}$ during the initial phase of evolution, and decrease to about 1 kms$^{-1}$ 10 minutes later. (2) Ca II H filaments appear almost simultaneously with the formation of dark lanes in Stokes$I$ in an observational cadence of 2 minutes. (3) The lifetime of the dark lanes in the Stokes $I$ and G band is 8 minutes, while that of Ca filament is 12 minutes. An interesting phenomena was observed, that an emerging flux tube expanded laterally in the photosphere with a speed of 3.8 kms$^{-1}$. A discussion on the horizontal expansion of the flux tube is given with refernce to previous simulation studies.
EUV Emission Lines and Diagnostics Observed with Hinode/EIS
Authors: Young Peter R. , Zanna Del Giulio , Mason Helen E. , Dere Ken P. , Landi Enrico , Landini Massimo , Doschek George A. , Brown Charles M. , Culhane Len , Harra Louise K. , Watanabe Tetsuya , Hara Hirohisa
Published: March 2014

Quiet Sun and active region spectra from the Hinode/EIS instrument are presented, and the strongest lines from different temperature regions discussed. A list of emission lines recommended to be included in EIS observation studies is presented based on analysis of blending and diagnostic potential using the CHIANTI atomic database. In addition we identify the most useful density diagnostics from the ions covered by EIS.
Probing the Physical Properties of the NGC 5548 Broad Line Region Using Balmer Lines
Authors: Popović Luka Č. , Shapovalova Alla I. , Chavushyan Vahram H. , Ilić Dragana , Burenkov Alexandr N. , Mercado Abelardo , Bochkarev Nikolay G.
Published: March 2014

We investigated the physical characteristics of the broad line region (BLR) of NGC 5548 using the Boltzmann plot (BP) method, which we applied to the Balmer lines observed from 1996 to 2004. We found that variability earlier detected in the lines is also present in the temperature parameter $A$, obtained from the BP method. Using the BP temperature parameter $A$ to calculate temperature, we found that the average temperature for the considered period was $T \approx$10000 K, and that it varies from 5000K (in 2002) to 15000K (in 1998). This variation correlates with the AGN-component of the optical continuum flux ($r=$ 0.85), and may indicate the existence of an accretion disk in the BLR of NGC 5548.
RT Leonis Minoris: Does It Belong to an A- or W-Type Overcontact Binary System?
Authors: Qian Sheng-Bang , He Jia-Jia , Xiang Fu-Yuan
Published: March 2014

New photometric observations and analyses of the W UMa-type binary system RT Leonis Minoris are presented. A period study with our four times of light minimum, including other eclipse times from the literature, suggests that the orbital period of the binary star is variable. The O – C curve can be explained as a cyclic variation with an amplitude of 0:d0049 and a period of 46.7 yr. Photometric solutions were derived by using the 2003 version of the Wilson–Devinney method (1971, ApJ, 166, 605), and absolute parameters of the system were determined. The results indicate that RT LMi is an ambiguous W UMa-type overcontact system for the following reasons: (i) the depths of both minima are nearly equal, which makes it very difficult to distinguish whether it belongs to an A- or W-type system; (ii) the primary minima in Hoffmann’s light curves are an occultation, indicating a W-type system, while the primary minimum in our light curve is a transit, suggesting an A-type light variation; and (iii) though our light curve shows an A-type variation, the photometric solutions indicate a higher secondary temperature of T2 = 6513 K (T1 = 6400 K), making the binary system, surprisingly, of W-type. These may indicate that Binnendijk’s classification based on the shape of the light curve cannot reveal the physical properties of W UMa-type binary stars of this kind.
Near-Infrared Coronagraphic Observations of a Classical T Tauri Star, DO Taurus
Authors: Itoh Yoichi , Hayashi Masahiko , Tamura Motohide , Oasa Yumiko , Hioki Tomonori , Fukagawa Misato , Kudo Tomoyuki
Published: March 2014

A high angular resolution near-infrared image of a classical T Tauri star, DO Tau, was obtained with Coronagraphic Imager with Adaptive Optics (CIAO) mounted on the Subaru Telescope. Circumstellar emission was detected at $\sim 1{\rlap{\hskip.75pt{^{\prime\prime}}}\hskip.75pt.\hskip1.75pt}7$ from the central star in the direction of the redshifted jet. No emission was found toward the opposite direction. We also found one faint point source 3${\rlap{\hskip.75pt{^{\prime\prime}}}\hskip.75pt.\hskip1.75pt}$46 away from the central star. The following observation will reveal whether it is an associated planetary mass object or a background object.
A New Surface Density Model of Jovian Trojans around Triangular Libration Points
Authors: Nakamura Tsuko , Yoshida Fumi
Published: March 2014

We constructed a new surface number density distribution model for Jovian Trojans around the L4 or L5 libration point of Jupiter. This is an empirical asymmetric model of the Maxwellian-Gaussian type, derived from numerical integrations of orbital motions for actual Trojan asteroids around the L4 point. With this model, in combination with the observed surface number densities obtained by Yoshida and Nakamura (2005, AJ, 130, 2900; 2008, PASJ, 60, 297), we estimate that the total populations of L4 and L5 Trojans with diameters $(D)>$ 2 km are (6.3$\pm$1.0) $\times$ 10$^{4}$ and (3.4$\pm$0.5) $\times$ 10$^{4}$, respectively. These results indicate that the L4 total populations ($D>$ 2 km) calculated previously by Jewitt, Trujillo, and Luu (2000, AJ, 120, 1140) and by Yoshida and Nakamura (2005, ibid.) using the former’s isotropic Gaussian model are overestimated by a factor of 3–4.
Subaru Weak Lensing Study of Seven Merging Clusters: Distributions of Mass and Baryons
Authors: Okabe Nobuhiro , Umetsu Keiichi
Published: March 2014

We present and compare projected distributions of mass, galaxies, and the intracluster medium (ICM) for a sample of merging clusters of galaxies based on a joint weak-lensing, optical photometric, and X-ray analysis. Our sample comprised seven nearby Abell clusters, for which we had conducted systematic, deep imaging observations with Suprime-Cam on the Subaru Telescope. Our seven target clusters, representing various merging stages and conditions, allowed us to investigate in detail the physical interplay between dark matter, ICM, and galaxies associated with cluster formation and evolution. A 1750 and A 1758 are binary systems consisting of two cluster-sized components; A 520, A 754, A 1758N, A 1758S, and A 1914 are on-going cluster mergers; and A 2034 and A 2142 are cold-front clusters. In the binary clusters, the projected mass, optical light, and X-ray distributions are overall similar and regular without significant substructures. On-going and cold-front merging clusters, on the other hand, reveal highly irregular mass distributions. Overall, the mass distribution appears to be similar to the galaxy luminosity distribution, whereas their distributions are quite different from the ICM distribution in a various ways. We also measured for individual targets global cluster parameters, such as the cluster mass, the mass-to-light ratio, and the ICM temperature. A comparison of the ICM and the virial temperatures of merging clusters from X-ray and weak-lensing analyses, respectively, shows that the ICM temperature of on-going and cold-front clusters is significantly higher than the cluster virial temperature by a factor of $\sim 2$. This temperature excess in the ICM could be explained by the effects of merger boosts.
Suzaku Results on Cygnus X-1 in the Low/Hard State
Authors: Makishima Kazuo , Takahashi Hiromitsu , Yamada Shin’ya , Done Chris , Kubota Aya , Dotani Tadayasu , Ebisawa Ken , Itoh Takeshi , Kitamoto Shunji , Negoro Hitoshi , Ueda Yoshihiro , Yamaoka Kazutaka
Published: March 2014

The black-hole binary Cygnus X-1 was observed for 17ks with the Suzaku X-ray observatory in 2005 October, while it was in a low/hard state with a 0.7-300keV luminosity of $4.6\times 10^{37}$ ergs $^{-1}$ . The XIS and HXD spectra, spanning 0.7-400keV, were reproduced successfully, incorporating a cool accretion disk and a hot Comptonizing corona. The corona is characterized by an electron temperature of $ \sim$ 100keV, and two optical depths of $ \sim$ 0.4 and $ \sim$ 1.5, which account for the softer and harder continua, respectively. The disk has an innermost temperature of $ \sim$ 0.2keV, and is thought to protrude half way into the corona. The disk not only provides seed photons to the Compton cloud, but also produces a soft spectral excess, a mild reflection hump, and a weakly broadened iron line. A comparison with the Suzaku data on GRO J1655 $-$ 40 reveals several interesting spectral differences, which can mostly be attributed to inclination effects, assuming that the disk has a flat geometry while the corona is grossly spherical. An intensity-sorted spectroscopy indicates that the continuum becomes less Comptonized when the source flares up on time scales of 1-200s, while the underlying disk remains unchanged.
Luminosity Dependence of the Electron Temperature in the Bright Hard
State of the Black Hole Candidate GX 339–4
Authors: Miyakawa Takehiro , Yamaoka Kazutaka , Homan Jeroen , Saito Koji , Dotani Tadayasu , Yoshida Atsumasa , Inoue Hajime
Published: March 2014

We have analyzed 200 Rossi X-ray Timing Explorer observations of the black hole candidate GX339 $-$ 4, all from bright hard state periods between 1996 and 2005. The purpose of our study is to investigate the radiation mechanisms in the hard state of GX 339 $-$ 4. The broadband 3-200keV spectra were successfully modeled by a simple analytic model, power-law with an exponential cut-off modified with a smeared edge. The obtained energy cut-off ( $E_{\rm {cut}}$ ) was distributed over 50-200keV, and the photon index over 1.4-1.7. We found a clear anti-correlation ( $E_{\rm {cut}} \propto L^{-0.70\pm0.06}$ ) between the X-ray luminosity ( $L$ ) in 2-200keV and $E_{\rm {cut}}$ , when $L$ is larger than $7 \times 10^{37}$ ergs $^{-1}$ (assuming a distance of 8kpc), while $E_{\rm {cut}}$ is roughly constant at around 200keV when $L$ is smaller than $7 \times 10^{37}$ ergs $^{-1}$ . This anti-correlation remained unchanged by adopting a more physical thermal Comptonization model, which resulted in an anti-correlation that can be expressed as $kT_{\rm {e}} \propto L^{-0.24\pm0.06}$ . These anti-correlations can be quantitatively explained by a picture in which the energy-flow rate from protons to electrons balances with inverse Compton cooling.
On Black Hole Mass Estimation from X-Ray Spectra of Ultraluminous X-Ray Sources
Authors: Vierdayanti Kiki , Watarai Ken-ya , Mineshige Shin
Published: March 2014

We propose a methodology to derive a black-hole mass for super-critical accretion flow. Here, we use the extended disk blackbody (extended DBB) model, a fitting model in which the effective temperature profile obeys the relation $T_{\rm eff} \propto r^{-p}$, with $r$ being the disk radius and $p$ being treated as a fitting parameter. We first numerically calculate the theoretical flow structure and its spectra for a given black-hole mass, $M$, and accretion rate, $\dot{M}$. Through fitting to the theoretical spectra by the extended DBB model, we can estimate the black-hole mass, $M_{\rm x}$, assuming that the innermost disk radius is $r_{\rm in}=3r_{\rm g} (\propto M_{\rm x})$, where $r_{\rm g}$ is the Schwarzschild radius. We find, however, that the estimated mass deviates from that adopted in the spectral calculations, $M$, even for low-$\dot{M}$ cases. We also find that the deviations can be eliminated by introducing a new correction for the innermost radius. Using this correction, we calculate mass correction factors, $M/M_{\rm x}$, in the super-critical regimes for some sets of $M$ and $\dot M$, finding that a mass correction factor ranges between $M/M_{\rm x} \sim$1.2-1.6. The higher is $\dot{M}$, the larger does the mass correction factor tend to be. Since the correction is relatively small, we can safely conclude that the black holes in ULXs, which Vierdayanti et al. (2006, PASJ, 58, 915) analyzed, are stellar-mass black holes with the mass being $<100M_{\odot}$.
Enrichment of Lead (Pb) in the Galactic Halo
Authors: Aoki Wako , Honda Satoshi
Published: March 2014

We determined lead (Pb) abundances for 12 red giants with the stellar metallicity [Fe$/$H] ranging between $-2.1$ and $-1.3$ and its upper limits for 2 lower-metallicity objects, as well as lanthanum (La) and europium (Eu) abundances. The averages of [Pb$/$Fe] and [Pb$/$Eu] were $-0.3$ and $-0.6$, respectively, and no clear increase of these ratios with increasing metallicity was found. The [La$/$Eu] values are only slightly higher than that of the $r$-process component in solar-system material. These results, together with the previous studies for globular clusters, suggest a small contribution of the $s$-process to the Pb abundance of the field stars studied here, supporting an estimate of Pb production by the $r$-process from the solar-system abundances.
Clustering of Emission-Line Stars in the W 5 E H ii Region
Authors: Nakano Makoto , Sugitani Koji , Niwa Takahiro , Itoh Yoichi , Watanabe Makoto
Published: March 2014

We have made a new survey of emission-line stars in the W 5 E H ii region to investigate the population of PMS stars near the OB stars by using the Wide Field Grism Spectrograph 2 (WFGS2). A total of 139 H$\alpha$ emission stars were detected and their $g'i'$-photometry was performed. Their spatial distribution shows three aggregates, i.e., two aggregates near the bright-rimmed clouds at the edge of the W 5 E H ii region (BRC 13 and BRC 14) and one near the exciting O7V star. The age and mass of each H$\alpha$ star were estimated from an extinction–corrected color-magnitude diagram and theoretical evolutionary tracks. We found, for the first time in this region, that the young stars near the exciting star are systematically older (4 Myr) than those near the edge of the H ii region (1 Myr). This result supports that the formation of stars proceeds sequentially from the center of H ii region to the eastern bright rim. We further suggest a possibility that the birth of low-mass stars near the exciting star of the H ii region precedes the production of massive OB stars in the pre-existing molecular cloud.
The FFX Correlator
Authors: Iguchi Satoru , Okuda Takeshi
Published: March 2014

We established a new algorithm for a correlation process in radio astronomy. This scheme consists of a 1st-stage Fourier transform as a filter and a 2nd-stage Fourier transform for spectroscopy. The “FFX” correlator stands for Filter and FX architecture, since the 1st-stage Fourier transform is performed as a digital filter, and the 2nd-stage Fourier transform is performed as a conventional FX scheme. We developed FFX correlator hardware not only for verifying the FFX scheme algorithm, but also for applying to the Atacama Submillimeter Telescope Experiment (ASTE) telescope toward high-dispersion and wideband radio observations at submillimeter wavelengths. In this paper, we present the principle of the FFX correlator and its properties, as well as evaluation results with the production version.
Multiple-Component Analysis of the Time-Resolved Spectra of GRB041006: A Clue to the Nature of the Underlying Soft Component of GRBs
Authors: Shirasaki Yuji , Yoshida Atsumasa , Kawai Nobuyuki , Tamagawa Toru , Sakamoto Takanori , Suzuki Motoko , Nakagawa Yujin , Kobayashi Akina , Sugita Satoshi , Takahashi Ichiro , Arimoto Makoto , Shimokawabe Takashi , Pazmino Nicolas Vasquez , Ishimura Takuto , Sato Rie , Matsuoka Masaru , Fenimore Edward E. , Galassi Mark , Lamb Donald Q. , Graziani Carlo , Donaghy Timothy Q. , Atteia Jean-Luc , Pelangeon Alexandre , Vanderspek Roland , Crew Geoffrey B. , Doty John P. , Villasenor Joel , Prigozhin Gregory , Butler Nat , Ricker George R. , Hurley Kevin , Woosley Stanford E. , Pizzichini Graziella
Published: March 2014

GRB041006 was detected by HETE-2 on 2004 October 06. The light curves in four different energy bands display different features. At higher energy bands several peaks are seen in the light curve, while at lower energy bands a single broader bump dominates. It is expected that these different features are the result of a mixture of several components, each of which has different energetics and variability. We analyzed the time-resolved spectra, which were resolved into several components. These components can be classified into two distinct classes. One is a component that has an exponential decay of $E_{\rm p}$ with a characteristic timescale shorter than $\sim\;$30 s; its spectrum is well represented by a broken power-law function, which is frequently observed in many prompt GRB emissions, so it should have an internal-shock origin. Another is a component whose $E_{\rm p}$ is almost unchanged with a characteristic timescale longer than $\sim\;$60 s, and shows a very soft emission and slower variability. The spectrum is characterized by either a broken power law or a black-body spectrum. By assuming that the soft component is a thermal emission, the radiation radius is initially $4.4 \times 10^{6}$km, which is a typical radius of a blue supergiant, and its expansion velocity is $2.4 \times 10^{5}$km s$^{-1}$ in the source frame.
Distance to VY Canis Majoris with VERA
Authors: Choi Yoon Kyung , Hirota Tomoya , Honma Mareki , Kobayashi Hideyuki , Bushimata Takeshi , Imai Hiroshi , Iwadate Kenzaburo , Jike Takaaki , Kameno Seiji , Kameya Osamu , Kamohara Ryuichi , Kan-Ya Yukitoshi , Kawaguchi Noriyuki , Kijima Masachika , Kim Mi Kyoung , Kuji Seisuke , Kurayama Tomoharu , Manabe Seiji , Maruyama Kenta , Matsui Makoto , Matsumoto Naoko , Miyaji Takeshi , Nagayama Takumi , Nakagawa Akiharu , Nakamura Kayoko , Oh Chung Sik , Omodaka Toshihiro , Oyama Tomoaki , Sakai Satoshi , Sasao Tetsuo , Sato Katsuhisa , Sato Mayumi , Shibata Katsunori M. , Tamura Yoshiaki , Tsushima Miyuki , Yamashita Kazuyoshi
Published: March 2014

We report on astrometric observations of H$_2$O masers around the red supergiant VY Canis Majoris carried out with VLBI Exploration of Radio Astrometry (VERA). Based on astrometric monitoring for 13 months, we successfully measured a trigonometric parallax of 0.88$\pm$0.08mas, corresponding to a distance of 1.14$^{+0.11} _{-0.09}$kpc. This is the most accurate determined distance to VY CMa and the first one based on an annual parallax measurement. The luminosity of VY CMa has been overestimated due to a previously accepted distance. With our result, we re-estimated the luminosity of VY CMa to be (3$\pm$0.5)$\times$10$^{5}L_{\odot}$ using the bolometric flux integrated over optical and IR wavelengths. This improved luminosity value makes the location of VY CMa on the Hertzsprung-Russell (HR) diagram much closer to the theoretically allowable zone (i.e. the left side of the Hayashi track) than previous ones, though the uncertainty in the effective temperature of the stellar surface still does not permit us to make a final conclusion.
Variable Asymmetry of the Circumstellar Envelope in IK Tauri Traced by SiO Maser Emission
Authors: Matsumoto Naoko , Omodaka Toshihiro , Imai Hiroshi , Shimizu Rie , Bushimata Takeshi , Choi Yoon Kyung , Hirota Tomoya , Honma Mareki , Inomata Noritomo , Iwadate Kenzaburo , Jike Takaaki , Kameno Seiji , Kameya Osamu , Kamohara Ryuichi , Kan-Ya Yukitoshi , Kawaguchi Noriyuki , Kobayashi Hideyuki , Kuji Seisuke , Kurayama Tomoharu , Maeda Toshihisa , Manabe Seiji , Miyaji Takeshi , Nakagawa Akiharu , Nagayama Takumi , Nakashima Koichiro , Oh Chung Sik , Oyama Tomoaki , Sakai Satoshi , Sakakibara Seiichiro , Sasao Tetsuo , Sato Katsuhisa , Shibata Katsunori M. , Shintani Motonobu , Sofue Yoshiaki , Sora Kasumi , Suda Hiroshi , Tamura Yoshiaki , Tsushima Miyuki , Yamashita Kazuyoshi
Published: March 2014

We observed the SiO ($v=1$ and $v=2$, $J=$ 1-0) maser emissions toward the Mira variable IK Tauri (IK Tau, NML Tau, IRC$+$10050) over nine epochs from 2003 November to 2005 April using the VLBI Exploration of Radio Astrometry (VERA) telescope array. We found that the SiO maser distributions around IK Tau are highly variable, depending on the stellar pulsation phase. The velocity structures were complex and also time-variable, and are inconsistent with a simply rotating shell that was suggested by previous observations. Based on fittings of the SiO maser distributions to elliptical ring models, we found that the ring size seems to vary in correlation with the pulsation phase, as previously found for TX Cam. Comparisons of the $v=1$ and $v=2$ maser distributions reveal that 42-50% of the maser pairs have a positional offset less than 0.5mas, suggesting that the maser pumping in these spots is likely to be dominated by line overlapping or collisional pumping, rather than pure radiative pumping. In order to model the velocity structure of the spoke-like features observed in IK Tau, we propose a ballistic-orbit model, in which a gas clump ejected from the stellar surface moves radially outward with a gravitational deceleration, and argue that the stellar mass can be deduced from that model.
Large-Scale NH3 Observations toward the Galactic Star-Forming Regions I. W 51 Molecular Cloud Complex
Authors: Sorai Kazuo , Habe Asao , Nishitani Hiroyuki , Hosaka Keita , Watanabe Yoshimasa , Miwa Shinichi , Ohishi Yukie , Motogi Kazuhito , Minamidani Tetsuhiro , Awano Johta , Sumida Sakurako , Fukuya Yoshiaki , Uchida Ryosuke , Kaneko Noboru , Fujimoto Masayuki Y. , Koyama Yasuhiro , Kimura Moritaka , Nakai Naomasa
Published: March 2014

Large-area observations of dense molecular gas were made in NH$_{3}$ ($J$, $K$) $=$ (1, 1), (2, 2), and (3, 3) inversion lines with 4'.5 resolution toward the molecular cloud complex of the W51 region. The observations were a part of a NH$_{3}$ survey of the Galactic star-forming regions using the Tomakomai 11-m radio telescope. NH$_{3}$ ($J$, $K$) $=$ (1, 1) and (2, 2) emission was detected in the W51 A and B complexes, while the detection of ($J$, $K$) $=$ (2, 2) emission was marginal in W51 B. The rotation temperature was $\sim$40K in the central part of the W51 A complex, while being $\sim$20K in the other positions. A weak correlation is found that the ortho-to-para ratio decreases with increasing the rotation temperature, the far-infrared luminosity and the index of the star-formation efficiency. This tendency is explained if star formation has continued for more than the time scale of the transformation between ortho- and para-NH$_{3}$: active star formation on a large scale, such as the interaction of molecular clouds with a spiral arm, has made the molecular gas warmer, even in a scale of $\sim$10pc, and the proceeding transformation has made the ortho-to-para ratio lower.
Catalogue of 12CO(J = 1−0) and 13CO(J = 1−0) Molecular Clouds in the Carina Flare Supershell
Authors: Dawson Joanne R. , Kawamura Akiko , Mizuno Norikazu , Onishi Toshikazu , Fukui Yasuo
Published: March 2014

We present a catalogue of $^{12}$CO($J=$ 1-0) and $^{13}$CO($J=$ 1-0) molecular clouds in the spatio-velocity range of the Carina Flare supershell, GSH287$+$04$-$17. The data cover a region of $\sim$66 square degrees and were taken with the NANTEN 4m telescope, at spatial and velocity resolutions of $\sim$2.6' and 0.1kms$^{-1}$. Decomposition of the emission results in the identification of 156 $^{12}$CO clouds and 60 $^{13}$CO clouds, for which we provide observational and physical parameters. Previous work suggests the majority of the detected mass forms part of a comoving molecular cloud complex that is physically associated with the expanding shell. The cloud internal velocity dispersions, degree of virialization and size-linewidth relations are found to be consistent with those of other Galactic samples. However, the vertical distribution is heavily skewed towards high-altitudes. The robust association of high-$z$ molecular clouds with a known supershell provides some observational backing for the theory that expanding shells contribute to the support of a high-altitude molecular layer.
Planetary Companions to Evolved Intermediate-Mass Stars: 14 Andromedae, 81 Ceti, 6 Lyncis, and HD167042
Authors: Sato Bun'ei , Toyota Eri , Omiya Masashi , Izumiura Hideyuki , Kambe Eiji , Masuda Seiji , Takeda Yoichi , Itoh Yoichi , Ando Hiroyasu , Yoshida Michitoshi , Kokubo Eiichiro , Ida Shigeru
Published: March 2014

We report on the detection of four extrasolar planets orbiting evolved intermediate-mass stars from a precise Doppler survey of G-K giants at Okayama Astrophysical Observatory. All of the host stars are considered to be formerly early F-type or A-type dwarfs when they were on the main sequence. 14 And (K0 III) is a clump giant with a mass of 2.2$M_{\odot}$ and has a planet of minimum mass $m_2$sin$i$$=$ 4.8$M_{\rm J}$ in a nearly circular orbit with a 186d period. This is one of the innermost planets around evolved intermediate-mass stars, and such planets have only been discovered in clump giants. 81 Cet (G5 III) is a clump giant with 2.4$M_{\odot}$ hosting a planet of $m_2$sin$i$$=$ 5.3$M_{\rm J}$ in a 953d orbit with an eccentricity of $e=$ 0.21. 6 Lyn (K0 IV) is a less-evolved subgiant with 1.7$M_{\odot}$, and has a planet of $m_2$sin$i$$=$ 2.4$M_{\rm J}$ in a 899d orbit with $e=$ 0.13. HD167042 (K1 IV) is also a less-evolved star with 1.5$M_{\odot}$ hosting a planet of $m_2$sin$i$$=$ 1.6$M_{\rm J}$ in a 418d orbit with $e=$ 0.10. This planet was independently announced by Johnson et al. (2008, ApJ, 675, 784). All of the host stars have solar or sub-solar metallicity, which supports the lack of a metal-rich tendency in planet-harboring giants in contrast to the case of dwarfs.
Multi-Object Infrared Camera and Spectrograph (MOIRCS) for the Subaru Telescope* I. Imaging
Authors: Suzuki Ryuji , Tokoku Chihiro , Ichikawa Takashi , Uchimoto Yuka Katsuno , Konishi Masahiro , Yoshikawa Tomohiro , Tanaka Ichi , Yamada Toru , Omata Koji , Nishimura Tetsuo
Published: March 2014

MOIRCS is a fully cryogenic near-infrared instrument for the 8.2 m Subaru Telescope. MOIRCS has two observation modes: a wide-field imaging mode and a multiobject spectroscopy mode. This paper describes the imaging mode, its specifications, and actual performances that we confirmed through laboratory tests and commissioning observations. The imaging mode provides a 4' $\times$ 7' field of view with a pixel scale of 0”.117pixel$^{-1}$ in the wavelength range of 0.85 to 2.5$\mu$ using cooled optics and two 2048 $\times$ 2048 HgCdTe HAWAII-2 focal plane arrays. Good-quality images are obtained over the entire field of view with practically no chromatic aberration. The limiting magnitudes for a point source estimated from observed background brightness and throughput are 23.7 in the $J$ band, 23.0 in the $H$ band, and 22.6 in the $K_{\rm s}$ band (Vega) with $S/N$$=$ 5, 0”.5 seeing, 1”.0 aperture, and 1hr exposure.
Abundance Inhomogeneity in the Northeastern Rim of the Cygnus Loop Revealed by the Suzaku Observatory
Authors: Katsuda Satoru , Tsunemi Hiroshi , Uchida Hiroyuki , Miyata Emi , Nemes Norbert , Miller Eric D. , Mori Koji , Hughes John. P.
Published: March 2014

We present the results of a spatially resolved spectral analysis from four Suzaku observations covering the northeastern rim of the Cygnus Loop. A two-$kT_\mathrm{e}$ non-ionization equilibrium (NEI) model fairly well represents our data, which confirms the NEI condition of the plasma there. The metal abundances are depleted relative to the solar values almost everywhere in our field of view. We find abundance inhomogeneities across the field: the northernmost region (Region A) has enhanced absolute abundances compared with other regions. In addition, the relative abundances of Mg$/$O and Fe$/$O in Region A are lower than the solar values, while those in the other regions are twice higher than the solar values. As far as we are concerned, neither a circumstellar medium, fragments of ejecta, nor abundance inhomogeneities of the local interstellar medium around the Cygnus Loop can explain the relatively enhanced abundance in Region A. This point is left as an open question for future work.