bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of Hard X-Rays from the Compton-Thick Seyfert 2 Galaxy NGC 2273 with Suzaku
Authors: Awaki Hisamitsu , Terashima Yuichi , Higaki Yuusuke , Fukazawa Yasushi
Published: March 2014

We have obtained a broad-band spectrum of the Compton-thick Seyfert 2 galaxy NGC 2273 with Suzaku. The spectrum reveals the first detection of hard X-rays above $\sim$10 keV from NGC 2273. The broad-band spectrum is well represented by a three component model, accompanied by both a strong iron K$\alpha$ line with an equivalent width of $\sim$1.8 keV and several weak lines. The three component model consists of a soft component, a reflection component from cold matter, and an absorbed power law component. The soft component can be represented by thin thermal emission with $kT$$\sim$ 0.56 keV or by a scattered component with a scattering fraction of 0.4%. Fixing the photon indices of the power law and reflection components at 1.9, we found that the power law component, heavily absorbed by gas with a column density of $\sim$1.5 $\times$ 10$^{24}$cm$^{-2}$, has an intrinsic 2–10 keV luminosity of $\sim$1.7 $\times$ 10$^{42}$ergs$^{-1}$. We also applied a reflection model based on a Monte Carlo simulation, assuming a simple torus geometry. We found that the model fits the broad band spectrum well, and we placed some tentative constraints on the geometry of the putative torus in NGC 2273.
Proper Motions with Subaru II. A Sample in the Subaru/XMM-Newton Deep Survey Field
Authors: Richmond Michael W. , Morokuma Tomoki , Doi Mamoru , Komiyama Yutaka , Yasuda Naoki , Okamura Sadanori
Published: March 2014

We search for stars with proper motions in a set of deep Subaru images, covering about 0.48 square degrees to a depth of $i^{\prime} \simeq$ 26, taken over a span of five and a half years. We follow the methods described in Richmond et al. (2009, PASJ, 61, 97) to reduce and analyze this dataset. We present a sample of 69 stars with motions of high significance, and discuss briefly the populations from which they are likely drawn. Based on photometry and motions alone, we expect that 14 of the candidates may be white dwarfs. Our candidate with the largest proper motion is surprisingly faint and likely to prove interesting: its colors and motions suggest that it might be an M dwarf moving at over 500 km s$^{-1}$ or an L dwarf in the halo.
Milne–Eddington Solutions for Relativistic Spherical Flows
Authors: Fukue Jun
Published: March 2014

Relativistic radiative transfer in a relativistic spherical flow is examined using a fully special relativistic treatment. Under the assumption of a constant flow speed, we obtain analytical solutions of radiative moment equations in the case of a constant comoving luminosity, and in the streaming limit. In the case of a constant comoving luminosity, in the non-relativistic regime the luminosity in the inertial frame is constant, whereas in the relativistic regime there appears a term proportional to the velocity and the optical depth. The spherical pressure in the relativistic regime is also enhanced compared with that in the non-relativistic regime. In the case of the streaming limit, we can also integrate moment equations analytically to obtain the luminosity and the spherical pressure in the inertial frame. In this case the inertial luminosity increases with the optical depth, but the comoving one reduces. On the other hand, the spherical pressure in the inertial frame, which is proportional to the optical depth in the non-relativistic regime, reduces as the flow speed increases. These properties are similar to the plane-parallel case, if the luminosity and the spherical pressure are exchanged by the flux and the usual pressure, respectively.
AKARI Near- to Mid-Infrared Imaging and Spectroscopic Observations of the Small Magellanic Cloud. I Bright Point Source List
Authors: Ita Yoshifusa , Onaka Takashi , Tanabé Toshihiko , Matsunaga Noriyuki , Matsuura Mikako , Yamamura Issei , Nakada Yoshikazu , Izumiura Hideyuki , Ueta Toshiya , Mito Hiroyuki , Fukushi Hinako , Kato Daisuke
Published: March 2014

We carried out near- to mid-infrared imaging and spectroscopic observations of patchy areas in the Small Magellanic Cloud using the Infrared Camera aboard AKARI. Two 100 arcmin$^2$ areas were imaged in 3.2, 4.1, 7, 11, 15, and 24$ \mu$m, and also spectroscopically observed in the wavelength range continuously from 2.5 to 13.4$ \mu$m. The spectral resolving power, $\lambda/ \Delta \lambda$, values were about 20, 50, and 50 at 3.5, 6.6, and 10.6$ \mu$m, respectively. Other than the two 100 arcmin$^2$ areas, some patchy areas were imaged and/or spectroscopically observed as well. In this paper, we overview the observations and present a list of near- to mid-infrared photometric results, which lists $\sim $12000 near-infrared and $\sim $1800 mid-infrared bright point sources detected in the observed areas. The 10$ \sigma$ limits are 16.50, 16.12, 13.28, 11.26, 9.62, and 8.76 in Vega magnitudes at 3.2, 4.1, 7, 11, 15, and 24$ \mu$m bands, respectively.
Analytical Calculation of the Mergers of Black Hole–Neutron Star Binaries
Authors: Cho Hee-Suk , Lee Chang-Hwan
Published: March 2014

Black hole (BH)–neutron star (NS) mergers have been studied as one of the primary sources of gravitational wave radiation and a strong candidate for the sources of short-hard gamma-ray bursts (SHBs). In this work, we investigated the criterion for a tidal disruption to occur outside the innermost stable circular orbit with various initial conditions of BH and NS. We studied the merger processes due to Roche-lobe overflow by an analytical method with Newtonian orbital functions. By using the polytropic equation of state for the NS, we calculated the time scale of merger for both irrotating (IR) and corotationg (CR) configurations. The resulting time scale is $\sim $10$^{-3} $s for the IR case, which agrees well with that of hydrodynamic simulations. We present a simple comparison with the most recent simulation result. The connection to the SHBs is also discussed.
Subaru Near-Infrared Imaging of Herbig Ae Stars*
Authors: Fukagawa Misato , Tamura Motohide , Itoh Yoichi , Oasa Yumiko , Kudo Tomoyuki , Hayashi Saeko S. , Kato Eri , Ootsubo Takafumi , Itoh Yusuke , Shibai Hiroshi , Hayashi Masahiko
Published: March 2014

We report results of $H$-band ($\lambda =$ 1.65$ \mu$m) imaging observations of young intermediate-mass stars using the Subaru 8.2-m Telescope with the adaptive optics AO36 and the infrared coronagraph CIAO. The targets consist of 16 Herbig Ae/Be stars (15 Herbig Ae stars and one Herbig Be star) and four additional main-sequence stars with infrared excesses. Five protoplanetary disks have been spatially resolved around the Herbig Ae stars with ages of 2–8 Myr. The resolved disks have outer radii of several 100 AU, and their surface brightnesses range from 10 mag arcsec$^{-2}$ to 18 mag arcsec$^{-2}$. The images reveal various morphologies in optically thick disks: spiral arms around AB Aur, a banana-split structure with an outer arm for HD 142527, a compact circumprimary disk of HD 150193, a faint discontinuous ring around HD 163296, and an unstructured face-on disk of HD 169142. The detection of an optically thick disk in scattered light implies that it is vertically flared, and intercepts stellar light at least in the outer region where those images were obtained. However, the surface brightness distribution, the resolved structure, and other observational characteristics suggest that the disks are unlikely to be continuously flared young disks with small grains well mixed with gas. The detection rate and the disk brightness do not correlate with the stellar age and the disk mass, but there is a tendency that the brightest disks are still surrounded by long-lived envelopes (AB Aur, HD 100546, HD 142527). The significant diversity of the disk structure can be attributed to the multiplicity and the initial condition of the local star-forming environments. The detections of companion candidates around our targeted stars are also reported.
DM Delphini: A Progenitor of a Contact Binary with a Compact Tertiary Companion
Authors: Jia-Jia He , Sheng-Bang Qian
Published: March 2014

The orbital period of the short-period eclipsing binary DM Del was analyzed by using two newly determined eclipse times together with the others compiled from the literature. It has been discovered that the period shows a long-time continuous decrease at a rate of $dP/dt = -$2.27 $\times$ 10$^{-7}$ d yr$^{-1}$, while it undergoes a cyclic variation with a period of 31.73 years. Meanwhile, photometric light curves of a close binary in the $B$ and $V$ bands, published by Güdür et al., were analyzed with the 2003 version of the W–D code. It was found that the system is a semi-detached binary with a lobe-filling primary and a mass ratio of $q =$ 0.55. The long-time period decrease can be explained by mass transfer from the primary to the secondary. This is consistent with the semi-detached configuration. The geometrical structure of the binary and the long-term period decrease suggest that DM Del may be a progenitor of an overcontact binary or just in a broken-contact stage predicted by thermal relaxation oscillations. A cyclic period change reveals the presence of a tertiary unseen companion that may play an important role in the formation of the close binary by removing angular momentum from the central system.
Thermal and Magnetic Parameters in Solar Flares Derived from GOES X-Ray Light Curves
Authors: Yamamoto Tetsuya T. , Sakurai Takashi
Published: March 2014

The purpose of this study is to reproduce the GOES X-ray (1–8 ${Å}$) light curves of the impulsive phase of 20 solar flares and to estimate the thermal and magnetic parameters in flare loops. The expected X-ray light curves are calculated from the values of the coronal field strength and inflow velocity under some assumptions. We used the magnetic reconnection heating model of Shibata and Yokoyama (2002, ApJ, 577, 422), photospheric vector magnetic field data, and a simple 1-D flare loop model. It is found the maximum inflow velocities are $\sim $10$^{7} $cm s$^{-1}$, and that the maximum magnetic reconnection rates are 0.006–0.9, and further that the characteristic coronal field strengths are 6–100 G. Using the thermal and magnetic parameters derived, we found that geometrically our calculated flare loops are higher than the potential fields that model the postflare loops, and are also higher than the preflare loops containing magnetic free energy that is large enough to provide the thermal energy of a flare. Hence, we conclude that the plasma $\beta $ value would be near unity in the flare loops we studied, and the magnetic field lines shrunk during the decay phase. The downward velocities of the field-line shrinkage are estimated to be 10$^{6}$–10$^{7} $cm s$^{-1}$ except one event. The height of the reconnection point was roughly estimated to be from 10$^{10} $cm to 4 $\times$ 10$^{10} $cm. We propose a new interpretation of the Neupert effect, and also discuss a temporal relationship between the X-ray flux and the flare loop heating.
Stellar Parameters and Abundance Analysis of 58 Late G Giants
Authors: Liu Yujuan , Sato Bun’ei , Takeda Yoichi , Ando Hiroyasu , Zhao Gang
Published: March 2014

We present stellar atmospheric parameters, and kinematic parameters for a part of Xinglong Planet Search Program sample – 58 late G-type giants, obtained at Okayama Astrophysical Observatory. Additionally, we determined the chemical abundances, especially for the elements C, O, and Na. The metallicity distribution of our sample ranges covered from $-$0.6 to 0.2 in [Fe$/$H], which supports the previous results, suggesting a lack of super metal-rich giants with [Fe$/$H] $\gt +$0.2. The abundance of C is depleted by 0.13 dex, and [Na$/$Fe] shows an overabundance of 0.1 dex compared to a dwarf with the same spectral type, while the O abundance was not altered after the first dredge up. These results are consistent with theoretical predictions of stellar evolution. The behaviors of Si, Ca, Ti, Cr, Ni, Mn, ScII, YII, and CeII in our giants follow the same trends as in dwarfs.
Orbital Period Changes and Their Explanations in Two Algol Binaries: WY Per and RW Leo
Authors: Wen-Ping Liao , Sheng-Bang Qian
Published: March 2014

WY Per and RW Leo are two Algol-type binaries. Based on our new CCD observations and the almost century-long historical record of the times of primary eclipses for WY Per and RW Leo, the orbital period changes and their explanations were reanalyzed and rediscussed in detail. It has been found that the orbital period of WY Per shows a cyclic oscillation with a period of $P_{3} =$ 71.5 yr and a semiamplitude of $A_{3} =$ 0$^{\rm d}\!\!\!.$0739. The period variation can be interpreted by the light-travel time effect (LTTE) via the presence of a third body in an eccentric orbit with an eccentricity of $e_{3} \simeq$ 0.602 in the system. For RW Leo, its orbital period shows complex variations. Two cyclic variations (i.e., $P_{3} =$ 77.8 yr and $A_{3} =$ 0$^{\rm d}\!\!\!.$033, and $P_{4} =$ 39.1 yr and $A_{4} =$ 0$^{\rm d}\!\!\!.$022) were discovered. The cyclic variations of $P_{3} =$ 77.8 yr and $A_{3} =$ 0$^{\rm d}\!\!\!.$033 can be attributed to the LTTE via the presence of a third body in an eccentric orbit with an eccentricity of $e_{3} \simeq$ 0.732.
Mass Estimation of Merging Galaxy Clusters
Authors: Takizawa Motokazu , Nagino Ryo , Matsushita Kyoko
Published: March 2014

We investigate the impact of mergers on the mass estimation of galaxy clusters using $N$-body $+$ hydrodynamical simulation data. We estimate the virial mass from these data and compare it with the real mass. When a smaller subcluster’s mass is larger than a quarter of that of the larger one, the virial mass can be larger than twice the real mass. The results strongly depend on the observational directions, because of an anisotropic velocity distribution of the member galaxies. We have also made X-ray surface brightness and spectroscopic-like temperature maps from the simulation data. The mass profile is estimated from these data on the assumption of hydrostatic equilibrium. In general, a mass estimation with X-ray data gives us better results than a virial mass estimation. The dependence upon observational directions is weaker than in the case of a virial mass estimation. When the system is observed along the collision axis, the projected mass tends to be underestimated. This fact should be noted, especially when the virial and/or X-ray mass is compared with gravitational lensing results.
Orbital Period Analysis of Eclipsing Z Cam-Type Dwarf Nova EM Cygni: Evidence of Magnetic Braking and a Third Body
Authors: Dai Zhibin , Qian Sheng-Bang
Published: March 2014

Combining with our newest CCD times of light minimum of EM Cygni, all 45 available times of light minimum, including 7 data with large scatters, were compiled and an updated $O-C$ analysis was made. The best-fit for the $O-C$ diagram of EM Cygni was a quadratic-plus-sinusoidal fit. The secular orbital period decrease rate ($-$2.5 $\pm$ 0.3) $\times$ 10$^{-11}\ $s s$^{-1}$ means that a magnetic braking effect in EM Cygni with a mass-loss rate caused by stellar wind, 2.3 $\times$ 10$^{-10}\ M_{\odot}\ $yr$^{-1}$, is needed for explaining the observed orbital period decrease. Moreover, for explaining the significant cyclical period change with a period of $\sim\ $17.74 $\pm$ 0.01 yr, shown in the $O-C$ diagram, magnetic activity cycles and a light travel-time effect were considered in detail. The $O-C$ diagram of EM Cygni cannot totally rule out the possibility of multi-periodic modulation due to gaps present after 25000 cycles. Based on the hypothesis of a K-type third star in the literature, a light trave-time effect may be a more plausible explanation. However, the low orbital inclination of the third body ($\sim\ $7$^\circ\!\!\!.$4) suggests that the hypothetic K-type third star may be captured by EM Cygni. But, by assuming the spectral contamination from a block of circumbinary material instead of a K-type third star, the third star may be a brown dwarf in the case of a coplanar orbit with a parent binary.
Fibre Multi-Object Spectrograph (FMOS) for the Subaru Telescope
Authors: Kimura Masahiko , Maihara Toshinori , Iwamuro Fumihide , Akiyama Masayuki , Tamura Naoyuki , Dalton Gavin B. , Takato Naruhisa , Tait Philip , Ohta Kouji , Eto Shigeru , Mochida Daisaku , Elms Brin , Kawate Kaori , Kurakami Tomio , Moritani Yuuki , Noumaru Junichi , Ohshima Norio , Sumiyoshi Masanao , Yabe Kiyoto , Brzeski Jurek , Farrell Tony , Frost Gabriella , Gillingham Peter R. , Haynes Roger , Moore Anna M. , Muller Rolf , Smedley Scott , Smith Greg , Bonfield David G. , Brooks Charles B. , Holmes Alan R. , Lake Emma Curtis , Lee Hanshin , Lewis Ian J. , Froud Tim R. , Tosh Ian A. , Woodhouse Guy F. , Blackburn Colin , Content Robert , Dipper Nigel , Murray Graham , Sharples Ray , Robertson David J.
Published: March 2014

Fibre Multi-Object Spectrograph (FMOS) is the first near-infrared instrument with a wide field of view capable of acquiring spectra simultaneously from up to 400 objects. It has been developed as a common-use instrument for the F$/$2 prime-focus of the Subaru Telescope. The field coverage of 30$^\prime$ diameter is achieved using a new 3-element corrector optimized in the near-infrared (0.9–1.8$\ \mu$m) wavelength range. Due to limited space at the prime-focus, we have had to develop a novel fibre positioner, called “Echidna”, together with two OH-airglow suppressed spectrographs. FMOS consists of three subsystems: the prime focus unit for IR, the fibre positioning system/connector units, and the two spectrographs. After full systems integration, FMOS was installed on the telescope in late 2007. Many aspects of the performance were checked through various test and engineering observations. In this paper, we present the optical and mechanical components of FMOS, and show the results of our on-sky engineering observations to date.
Optical Spectroscopy of Candidates of Young Stellar Objects in NGC 1333
Authors: Itoh Yoichi , Gupta Ranjan , Oasa Yumiko , Sen A. K. , Tanaka Munechika , Terai Tsuyoshi , Nakaoka Seina
Published: March 2014

We carried out low-resolution optical spectroscopy of 14 low-luminosity young stellar object (YSO) candidates in the NGC 1333 cluster. These objects were previously identified by a near-infrared imaging survey. Eleven objects were confirmed to be YSOs by the H$\alpha$ line emission. The strengths of the H$\alpha$ emission are correlated with the near-infrared excesses of the objects. The spectral types of all YSOs are estimated to be M-type, indicative of low mass. Comparisons of the results of our spectroscopic observations and previous photometric observations with evolutionary tracks on the HR diagram suggest two objects to be young brown dwarfs.
What Kinds of Accretion Disks Are There in the Nuclei of Radio Galaxies?
Authors: Kaburaki Osamu , Nankou Takanobu , Tamura Naoya , Wajima Kiyoaki
Published: March 2014

It seems to be a widely accepted opinion that the types of accretion disks (or flows) generally realized in the nuclei of radio galaxies and in further lower mass-accretion rate nuclei are inner, hot, optically thin, radiatively inefficient accretion flows (RIAFs) surrounded by outer, cool, optically thick, standard-type accretion disks. However, observational evidence for the existence of such outer cool disks in these nuclei is rather poor. Instead, recent observations sometime suggest the existence of inner cool disks of the non-standard type, which develop in a region very close to their central black holes. Taking NGC 4261 as a typical example of such light-eating nuclei, for which both flux data ranging from radio to X-ray and data for the counterjet occultation are available, we examine the plausibility of such a picture for the accretion states, as mentioned above, based on model predictions. It is shown that the explanation of the gap seen in the counterjet emission in terms of the free–free absorption by an outer standard disk is unrealistic and, moreover, the existence itself of such an outer standard disk seems to be very implausible. Instead, the model of RIAF in an ordered magnetic field (so-called resistive RIAF model) can well serve to explain the emission gap in terms of the synchrotron absorption, as well as to reproduce the observed features of the overall spectral energy distribution (SED). This model also predicts that the RIAF state starts directly from an interstellar hot gas phase at around the Bondi radius, and terminates at the inner edge, whose radius is about 100-times the Schwartzschild radii. Therefore, there is a good possibility for a cool disk to develop within this innermost region.
Broad Balmer-Line Absorption in SDSS J172341.10+555340.5
Authors: Aoki Kentaro
Published: March 2014

We present the discovery of Balmer-line absorption from H$\alpha$ to H9 in an iron low-ionizaton broad absorption line (FeLoBAL) quasar, SDSS J172341.10$+$555340.5, by near-infrared spectroscopy with the Cooled Infrared Spectrograph and Camera for OHS (CISCO) attached to the Subaru Telescope. The redshift of the Balmer-line absorption troughs is 2.0530$\ \pm\ $0.0003, and it is blueshifted by 5370 km s$^{-1}$ from the Balmer emission lines. It is more than 4000 km s$^{-1}$ blueshifted from the previously known UV absorption lines. We detected relatively strong (EW$_{\rm rest} =$ 20 Å) [O III] emission lines that are similar to those found in other broad absorption line quasars with Balmer-line absorption. We also derived the column density of neutral hydrogen of 5.2 $\times$ 10$^{17}\ $cm$^{-2}$ by using the curve of growth and taking account of Ly$\alpha$ trapping. We searched for UV absorption lines that had the same redshift with Balmer-line absorption, and found Al III and Fe III absorption lines at $z =$ 2.053 that correspond to previously unidentified absorption lines, and the presence of other blended troughs that were difficult to identify.
Mass Function of Binary Massive Black Holes in Active Galactic Nuclei
Authors: Hayasaki Kimitake , Ueda Yoshihiro , Isobe Naoki
Published: March 2014

If the activity of active galactic nuclei (AGNs) is predominantly induced by major galaxy mergers, then a significant fraction of AGNs should harbor binary massive black holes in their centers. We have studied the mass function of binary massive black holes in nearby AGNs based on the observed AGN black-hole mass function and the theory of evolution of binary massive black holes interacting with a massive circumbinary disk within the framework of the coevolution of massive black holes and their host galaxies. The circumbinary disk is assumed to be steady, axisymmetric, geometrically thin, self-regulated, self-gravitating but nonfragmenting with a fixed fraction of the Eddington accretion rate, which is typically one tenth of the Eddington value. The timescale of orbital decay is then estimated to be $\sim\ $10$^{8}\ $yr for equal mass black holes, being independent of the black-hole mass, semimajor axis, and viscosity parameter, but dependent on the black-hole mass ratio, Eddington ratio, and mass-to-energy conversion efficiency. This makes it possible for any binary massive black holes to merge within the Hubble time under the binary–disk interaction. We find that (1.5%$\ \pm\ $0.6%) of the total number of nearby AGNs for the equal-mass ratio and (1.3%$\ \pm\ $0.5%) for the one-to-ten mass ratio have close binary massive black holes with an orbital period of less than 10 yr in their centers, detectable with ongoing highly sensitive X-ray monitors, such as Monitor of All-sky X-ray Image and/or Swift/Burst Alert Telescope. Assuming that all binary massive black holes have the equal-mass ratio, about 10% of AGNs with black-hole masses of 10$^{6.5-7}\ M_{\odot}$ have close binaries, and thus provide the best chance to detect them.
Trapped, Two-Armed, Nearly Vertical Oscillations in Disks with Toroidal Magnetic Fields
Authors: Kato Shoji
Published: March 2014

We have examined the trapping of two-armed ($m$$=$ 2) nearly vertical oscillations (vertical p-mode) in vertically isothermal ($c_{\rm s}$$=$ const.) relativistic disks with toroidal magnetic fields. The magnetic fields are stratified so that the Alfvén speed, $c_{\rm A}$, is constant in the vertical direction. The ratio $c_{\rm A}^2/c_{\rm s}^2$ in the vertical direction is taken to be a parameter that examines the effects of magnetic fields on wave trapping. We find that the two-armed nearly vertical oscillations are trapped in the inner region of the disks, and their frequencies decrease with an increase of $c_{\rm A}^2/c_{\rm s}^2$. The trapped regions of the fundamental ($n$$=$ 1) and the first-overtone ($n$$=$ 2) are narrow (less than the length of the Schwarzschild radius, $r_{\rm g}$), and their frequencies are relatively high (on the order of the angular frequency of disk rotation in the inner region). In contrast to this, the second overtone ($n$$=$ 3) is trapped in a wide region (a few times $r_{\rm g}$), and the frequencies are low and tend to zero in the limit of $c_{\rm A}^2/c_{\rm s}^2$$=$ 2.0.
Astrometry of Galactic Star-Forming Region Onsala 1 with VERA: Estimation of Angular Velocity of Galactic Rotation at the Sun
Authors: Nagayama Takumi , Omodaka Toshihiro , Nakagawa Akiharu , Handa Toshihiro , Honma Mareki , Kobayashi Hideyuki , Kawaguchi Noriyuki , Miyaji Takeshi
Published: March 2014

We conducted the astrometry of H$_2$O masers in the Galactic star-forming region Onsala 1 (ON 1) with the VLBI Exploration of Radio Astrometry (VERA). We measured a trigonometric parallax of 0.404$\ \pm\ $0.017 mas, corresponding to a distance of 2.47$\ \pm\ $0.11 kpc. ON 1 appears to be located near the tangent point at a Galactic longitude of 69$^\circ\!\!\!.$54. We estimated the angular velocity of the Galactic rotation at the Sun (the ratio of the Galactic rotation velocity at the Sun to the distance from the Sun to the Galactic center) to be $\Omega_0$$=$$\Theta_0 / R_0$$=$ 28.7$\ \pm\ $1.3 km s$^{-1}\ $kpc$^{-1}\ $ using the measured distance and proper motion of ON 1. This value is larger than the IAU recommended value of (220 km s$^{-1}/$8.5 kpc) $=$ 25.9 km s$^{-1}\ $ kpc$^{-1}\ $, but consistent with other results recently obtained with the VLBI technique.
Internal Proper Motions of Methanol Masers at 6.7 GHz in Massive Star-Forming Region Onsala 1
Authors: Sugiyama Koichiro , Fujisawa Kenta , Doi Akihiro , Honma Mareki , Isono Yasuko , Kobayashi Hideyuki , Mochizuki Nanako , Murata Yasuhiro , Sawada-Satoh Satoko , Wajima Kiyoaki
Published: March 2014

We present the internal proper motions of 6.7 GHz methanol masers in a massive star-forming region, Onsala 1 (ON 1), measured using the Japanese very long baseline interferometry network (JVN) at three epochs spanning 778 days. The methanol masers were clearly distinct from water masers. The methanol masers surrounded an ultra-compact (UC) H II region, and their distribution was similar to that of hydroxyl masers. The internal motions of the methanol masers were clearly detected; they show outward motions in roughly the north–south direction with a relative velocity of $\sim\ $5 km s$^{-1}$. Their motion is similar to that of hydroxyl masers, which showed expansion at $\sim\ $5 km s$^{-1}$, and these two types of masers seem to trace the expanding UC H II region. Another possibility is that the methanol masers are associated with a molecular outflow observed by H$^{13}$CO$^{+}$ and SiO lines, because the direction and velocity of the methanol masers were similar to those of the molecular lines. Regarding the relative phases of water and methanol masers in the evolutionary stage of massive young stellar objects, we found that the former was earlier than the latter in ON 1 by comparing the sites associated with the masers. The water masers were associated with dust emission at submillimeter wavelengths, whereas the methanol masers were associated with an UC H II region at centimeter wavelengths, which appears at a later evolutionary phase than the dust core.
Measurement of the Distance and Proper Motions of the H2O Masers in the Young Planetary Nebula K 3−35
Authors: Tafoya Daniel , Imai Hiroshi , GÓmez Yolanda , Torrelles José M. , Patel Nimesh A. , Anglada Guillem , Miranda Luis F. , Honma Mareki , Hirota Tomoya , Miyaji Takeshi
Published: March 2014

In this paper we present the results of very long baseline interferometry (VLBI) observations carried out with the VLBI Exploration of Radio Astrometry (VERA) array and the Very Long Baseline Array (VLBA) toward H$_{2}$O masers in a young planetary nebula K 3$-$35. From the VERA observations we measured the annual parallax and proper motion of a bright water maser spot in K 3$-$35. The resulting distance is $D$$=$ 3.9$^{+0.7}_{\hskip1.11pt-0.5}$ kpc. This is the first time that the parallax of a planetary nebula is obtained by observations of its maser emission. On the other hand, the proper motion of K 3$-$35 as a whole was estimated to be $\mu_{\alpha}$$=$$-$3.34 $\pm$ 0.10 mas yr$^{-1}$, $\mu_{\delta}$$=$$-$5.93 $\pm$ 0.07 mas yr$^{-1}$. From these results we determined the position and velocity of K 3$-$35 in Galactic cylindrical coordinates: ($R,\theta,\textsl{z}$) $=$ (7.11$^{+0.08}_{\hskip1.11pt-0.06}$ kpc, 27$^{\circ}$$\pm$ 5$^{\circ}$, 140$^{+25}_{\hskip1.11pt-18}$ pc) and ($V_{R}, V_{\theta}, V_{{\sl z}}$) $=$ (33 $\pm$ 16, 233 $\pm$ 11, 11 $\pm$ 2) km s$^{-1}$. Additionally, from our VLBA observations we measured the relative proper motions among the water maser spots located in the central region of the nebula, which have been proposed to be tracing a toroidal structure. The distribution and relative proper motions of the masers, compared with previous reported observed epochs, suggest that such structure could be totally destroyed within a few years, due to the action of high-velocity winds and the expansion of the ionization front in the nebula.
Deep CO Observations and the CO-to-H2 Conversion Factor in DDO 154, a Low Metallicity Dwarf Irregular Galaxy
Authors: Komugi Shinya , Yasui Chikako , Kobayashi Naoto , Hatsukade Bunyo , Kohno Kotaro , Sofue Yoshiaki , Kyu Shiori
Published: March 2014

We present a deep spectroscopic search for CO emission in the dwarf irregular galaxy DDO 154, which has an Oxygen abundance of only 1$/$20 of the solar value. The observations were conducted in order to constrain the CO-to-H$_2$ conversion factor at low metallicity. No CO was detected, however, despite being one of the sensitive observations done towards galaxies of this type. We succeed in putting a strong lower limit on the conversion factor, at least 10-times the Galactic value. Our result supports previous studies that argue for a high conversion factor at low metallicity.
Size Distribution of Main-Belt Asteroids with High Inclination
Authors: Terai Tsuyoshi , Itoh Yoichi
Published: March 2014

We investigated the size distribution of high-inclination main-belt asteroids (MBAs) so as to explore asteroid collisional evolution under hypervelocity collisions of around 10 km s$^{-1}$. We performed a wide-field survey for high-inclination sub-km MBAs using the 8.2-m Subaru Telescope with the Subaru Prime Focus Camera (Suprime-Cam). Suprime-Cam archival data were also used. A total of 616 MBA candidates were detected in an area of 9.0 deg$^2$ with a limiting magnitude of 24.0 mag in the SDSS $r$ filter. Most of the candidate diameters were estimated to be smaller than 1 km. We found a scarcity of sub-km MBAs with high inclination. Cumulative size distributions (CSDs) were constructed using Subaru data and published asteroid catalogs. The power-law indexes of the CSDs were 2.17$\ \pm\ $0.02 for low-inclination ($\lt\ $15$^{\circ}$) MBAs and 2.02$\ \pm\ $0.03 for high-inclination ($\gt\ $15$^{\circ}$) MBAs in the 0.7–50 km diameter range. The high-inclination MBAs had a shallower CSD. We also found that the CSD of S-like MBAs had a small slope with high inclination, whereas the slope did not vary with the inclination in the C-like group. The most probable cause of the shallow CSD of the high-inclination S-like MBAs is the large power-law index in the diameter–impact strength curve in hypervelocity collisions. The collisional evolution of MBAs may have advanced with oligopolistic survival during the dynamical excitation phase in the final stage of planet formation.
Monte Carlo Simulations of Radio Emitting Secondaries in-Ray Binaries
Authors: Bosch-Ramon Valenti , Khangulyan Dmitry
Published: March 2014

Several binary systems that contain a massive star have been detected in both the radio band and at very high energies. In the dense stellar photon field of these sources, gamma-ray absorption and pair creation are expected to occur, and the radiation from these pairs may contribute significantly to the observed radio emission. We aim at going deeper in studying the properties, and in particular the morphology, of the pair radio emission in gamma-ray binaries. We applied a Monte Carlo code that computes the creation location, the spatial trajectory and the energy evolution of the pairs produced in the binary system and its surroundings. The radio emission produced by these pairs, with its spectral, variability and spatial characteristics, was calculated as it would be seen from a certain direction. A generic case was studied first, and then the specific case of LS 5039 was also considered. We found that, confirming previous results, the secondary radio emission should appear as an extended radio structure of a few milliarcseconds size. This radiation would be relatively hard, with fluxes of up to $\sim$ 10 mJy. Modulation is expected, depending on the gamma-ray production luminosity, system eccentricity, and wind ionization fraction, and to a lesser extent on the magnetic-field structure. In gamma-ray binaries in general, the pairs created due to photon-photon interactions can contribute significantly to the core, and generate an extended structure. In the case of LS 5039, the secondary radio emission is likely to be a significant fraction of the detected core flux, with a marginal extension.
Asteroid Catalog Using AKARI: AKARI/IRC Mid-Infrared Asteroid Survey
Authors: Usui Fumihiko , Kuroda Daisuke , MÜLler Thomas G. , Hasegawa Sunao , Ishiguro Masateru , Ootsubo Takafumi , Ishihara Daisuke , Kataza Hirokazu , Takita Satoshi , Oyabu Shinki , Ueno Munetaka , Matsuhara Hideo , Onaka Takashi
Published: March 2014

We present the results of an unbiased asteroid survey in the mid-infrared wavelength region with the Infrared Camera (IRC) on board the Japanese infrared satellite AKARI. About 20% of the point source events recorded in the AKARI All-Sky Survey observations are not used for the IRC Point Source Catalog (IRC-PSC) in its production process because of a lack of multiple detection by position. Asteroids, which are moving objects on the celestial sphere, remain in these ``residual events''. We identify asteroids out of the residual events by matching them with the positions of known asteroids. For the identified asteroids, we calculate the size and albedo based on the Standard Thermal Model. Finally we have a new brand of asteroid catalog, named the Asteroid Catalog Using AKARI (AcuA), which contains 5120 objects, about twice as many as the IRAS asteroid catalog. The catalog objects comprise 4953 main belt asteroids, 58 near-Earth asteroids, and 109 Jovian Trojan asteroids. The catalog is publicly available via the Internet.
Experimental Search for the HAYABUSA Re-Entry Module on the Ground by Using a Remote-Sensing Instrument onboard Formosat-2 Satellite
Authors: Nakamura Ryosuke , Chen Bo , Matsuoka Masashi , Yamamoto Hirokazu , Kamei Akihide , Nakamura Kazuki , Yano Hajime
Published: March 2014

HAYABUSA was the first asteroid sample return mission launched from Uchinoura, Japan in 2003. The sample capsule re-entered the Earth's atmosphere at approximately 13:50 (UT) on 2010 June 13th, and safely landed on the Woomera Prohibited Area (WPA) in Australia. The capsule had to be found and retrieved as soon as possible to reduce any contamination risk. On the morning of the June 13th and 14th, the landing area was imaged by using Remote Sensing Instrument (RSI) onboard the Formosat-2 satellite to locate the HAYABUSA re-entry module, consisting of a capsule and a parachute. In spite of an accurate geometric registration and radiance comparison of the image pair, no statistically significant radiance variation was found on the landing site. It was demonstrated through this experiment, however, that satellite imagery could be a promising backup tool for the prompt discovery and retrieval of the sampling capsule of the HAYABUSA follow-on mission if we can utilize space-borne imagers with sub-meter spatial resolution and short revisit capability.
Star Formation in the Cometary Tails Associated with Cluster Galaxies
Authors: Yamagami Takahiro , Fujita Yutaka
Published: March 2014

We investigate the star-formation in cometary tails of galaxies in clusters. In particular, we focus on the evolution of molecular clouds in the tails that generate the stars. Assuming that the gas tails had been derived from the galaxies through ram-pressure stripping, we found that the gas must have been stripped mostly not in the form of molecular clouds, but in the form of H I gas or molecular gas that is not in clouds. Moreover, the molecular clouds are condensed in the tails, even away from the host galaxies. We also found that magnetic fields may be required to suppress the Kelvin–Helmholtz (KH) instability on the surface of molecular clouds, because otherwise the KH instability may destroy the molecular clouds before stars are formed in them.
Astrometry of 6.7 GHz Methanol Maser toward W 3(OH) with Japanese VLBI Network
Authors: Matsumoto Naoko , Honma Mareki , Isono Yasuko , Ujihara Hideki , Kimura Kimihiro , Matsumoto Kouhei , Sawada-Satoh Satoko , Doi Akihiro , Fujisawa Kenta , Ueno Yuji
Published: March 2014

We present the results of multiepoch VLBI observations for a 6.7 GHz methanol maser toward the UC H II region of W 3(OH) with Japanese VLBI Network (JVN). Based on phase-referencing VLBI astrometry, we derived the trigonometric annual parallax to be 0.598$\ \pm\ $0.067 mas, corresponding to a distance of 1.67$^{+0.21}_{-0.17}$ kpc. This is the first detection of parallax for a 6.7 GHz methanol maser with JVN, and demonstrates that JVN/VERA is capable of conducting VLBI astrometry for 6.7 GHz methanol maser sources within few kpc from the Sun. Based on in-beam mapping of the W 3(OH) methanol maser, we also measured the internal proper motions of its 6.7 GHz methanol maser for the first time. The internal proper motions basically show north–south expansion with a velocity of few km s$^{-1}$, being similar to OH masers. The spatial distribution and the internal proper motions of 6.7 GHz methanol masers suggest a rotating and expanding torus structure surrounding the UC H II region.
Long-Term Monitoring of the Black Hole Binary GX 339−4 in the High/Soft State during the 2010 Outburst with MAXI/GSC
Authors: Shidatsu Megumi , Ueda Yoshihiro , Nakahira Satoshi , Negoro Hitoshi , Yamaoka Kazutaka , Sugizaki Mutsumi , Hiroi Kazuo , Kawai Nobuyuki , Mihara Tatehiro , Matsuoka Masaru , Kimura Masashi , Ishikawa Masaki , Isobe Naoki , Kitayama Hiroki , Kohama Mitsuhiro , Matsumura Takanori , Morii Mikio , Nakagawa Yujin E. , Nakajima Motoki , Serino Motoko , Sootome Tetsuya , Sugimori Kousuke , Suwa Fumitoshi , Toizumi Takahiro , Tomida Hiroshi , Tsuboi Yohko , Tsunemi Hiroshi , Ueno Shiro , Usui Ryuichi , Yamamoto Takayuki , Yamazaki Kyohei , Yoshida Atsumasa
Published: March 2014

We present the results of monitoring the galactic black hole candidate GX 339 $-$ 4 with the Monitor of All-sky X-ray Image (MAXI) / Gas Slit Camera in the high/soft state during an outburst in 2010. All of the spectra throughout the 8-month period were well reproduced with a model consisting of multi-color disk emission and its Comptonization component, whose fraction is $\leq\ $ 25% in the total flux. In spite of the flux variability over a factor of 3, the innermost disk radius is constant at $R_{\rm in}$  $=$ 61 $\ \pm\ $ 2 km for an inclination angle of $i$  $=$ 46 $^\circ$ and a distance of $d$  $=$ 8 kpc. This $R_{\rm in}$ value is consistent with those of past measurements with Tenma in the high/soft state. Assuming that the disk extends to the innermost stable circular orbit of a non-spinning black hole, we estimate the black hole mass to be $M$  $=$ 6.8 $\ \pm\ $ 0.2 $\ M_{\odot}$ for $i$  $=$ 46 $^\circ$ and $d$  $=$ 8 kpc, which is consistent with that estimated from the Suzaku observation of the previous low/hard state. Further combined with the mass function, we obtained a mass constraint of 4.3 $\ M_\odot$  $<$  $M$  $<$ 13.3 $\ M_\odot$ for the allowed range of $d$  $=$ 6–15 kpc and $i$  $<$ 60 $^\circ$ . We also discuss the spin parameter of the black hole in GX 339 $-$ 4 by applying relativistic accretion disk models to the Swift/XRT data.
Bursting Activity in a High-Mass Star-Forming Region G33.640.21 Observed with the 6.7 GHz Methanol Maser
Authors: Fujisawa Kenta , Sugiyama Koichiro , Aoki Nozomu , Hirota Tomoya , Mochizuki Nanako , Doi Akihiro , Honma Mareki , Kobayashi Hideyuki , Kawaguchi Noriyuki , Ogawa Hideo , Omodaka Toshihiro , Yonekura Yoshinori
Published: March 2014

We report on the detection of bursts of 6.7 GHz methanol maser emission in a high-mass star-forming region, G33.64$-$0.21. One of the spectral components of the maser in this source changed its flux density by 7 times that of the previous day, and it decayed with a timescale of 5 days. The burst occurred repeatedly in the spectral component, and no other components showed such variability. A VLBI observation with the Japanese VLBI Network (JVN) showed that the burst location was at the southwest edge of a spatial distribution, and the bursting phenomenon occurred in a region much smaller than 70 AU. We suggest an impulsive energy release, like a stellar flare, as a possible mechanism for the burst. These results imply that 6.7 GHz methanol masers could be a useful new probe for studying bursting activity in the process of the star formation of high-mass YSOs with a high-resolution of AU scale.
Search for X-Ray Emission Associated with the Shapley Supercluster with Suzaku
Authors: Mitsuishi Ikuyuki , Gupta Anjali , Yamasaki Noriko Y. , Takei Yoh , Ohashi Takaya , Sato Kosuke , Galeazzi Massimiliano , Henry J. Patrick , Kelley Richard L.
Published: March 2014

Suzaku performed observations of 3 regions in and around the Shapley supercluster, a region located between A 3558 and A 3556, at $\sim\ $0.9 times the virial radii of both clusters, and two other regions at 1$^\circ$ and 4$^\circ$ away from the first pointing. The 4$^\circ$-offset observation was used to evaluate the Galactic foreground emission. We did not detect significant redshifted Oxygen emission lines (O VII and O VIII) in the spectra of all three pointings, after subtracting the contribution of foreground and background emission. The upper limit for the redshifted O VIII K$\alpha$ line intensity of the warm-hot intergalactic medium (WHIM) is 1.5 $\times$ 10$^{-7}$ photons s$^{-1}$ cm$^{-2}$ arcmin$^{-2}$, which corresponds to an overdensity of $\sim\ $380 ($Z/$0.1$\ Z_{\odot}$)$^{-1/2}$ ($L/$3 Mpc)$^{-1/2}$, assuming $T$  $=$ 3 $\times$ 10$^{6}$ K. We found excess continuum emission in the 1$^\circ$-offset and on-filament regions, represented by thermal models with $ kT\sim 1$ keV and $\sim\ $2 keV, respectively. The redshifts of both 0 and that of the supercluster (0.048) are consistent with the observed spectra. The $\sim\ $1 keV emission can also be fitted with Ne-rich Galactic (zero redshift) thin thermal emission. The radial intensity profile of the 2 keV component suggests contributions from A 3558 and A 3556, but with significant steepening of the intensity slope in the outer region of A 3558. Finally, we summarized the previous Suzaku search for the WHIM, and discussed the feasibility of constraining the WHIM. An overdensity of $\lt\ $400 could be detectable using O VII and O VIII emission lines in a range of 1.4 $\times$ 10$^{6}$ K $\lt\ $  $T$  $\lt\ $ 5 $\times$ 10$^{6}$ K or a continuum emission in a relatively high-temperature range of $T$  $\gt$ 5 $\times$ 10$^{6}$ K with the Suzaku XIS. The non-detection with Suzaku suggests that a typical line-of-sight average overdensity is $\lt\ $400.
Spectral Evolutions in Gamma-Ray Burst Exponential Decays Observed with Suzaku WAM
Authors: Tashiro Makoto S. , Onda Kaori , Yamaoka Kazutaka , Ohno Masahiro , Sugita Satoshi , Uehara Takeshi , Seta Hiromi
Published: March 2014

This paper presents a study on the spectral evolution of gamma-ray burst (GRB) prompt emissions observed with the Suzaku Wide-band All-sky Monitor (WAM). By making use of the WAM data archive, 6 bright GRBs exhibiting 7 well-separated fast-rise-exponential-decay (FRED) shaped light curves are presented, and the evaluated exponential decay time constants of the energy-resolved light curves from these FRED peak light curves are shown to indicate significant spectral evolution. The energy dependence of the time constants is well described with a power-law function, $\tau$($E$) $\propto$$E^\gamma$, where $\gamma$$\sim$$-$(0.34$ \pm $0.12) on average, although 5 FRED peaks show a consistent value of $\gamma$$=$$-$1$/$2, which is expected in synchrotron or inverse-Compton cooling models. In particular, 2 of the GRBs were located with accuracy sufficient to evaluate the time-resolved spectra with precise energy response matrices. Their behavior in spectral evolution suggests two different origins of emissions. In the case of GRB 081224, the derived 1-s time-resolved spectra are well described by a blackbody radiation model with a power-law component. The derived behavior of cooling is consistent with that expected from radiative cooling or expansion of the emission region. On the other hand, the other 1-s time-resolved spectra from GRB 100707A is well described by a Band GRB model as well as with the thermal model. Although relative poor statistics prevent us to conclude, the energy dependence in the decaying light curve is consistent with that expected in the former emission mechanism model.
Near-Infrared High-Dispersion Spectroscopic Observations of Water in Comet 81P/Wild 2 with Subaru/IRCS
Authors: Hashimoto Mio , Kobayashi Hitomi , Kawakita Hideyo
Published: March 2014

Near-infrared high-dispersion spectroscopic observations of comet 81P/Wild 2 were carried out on 2010 January 31 and February 1 by the Subaru telescope with IRCS. We detected two hot-band emission lines of H$_{2}$O: X(1,0,1) 2$_{02}$–X(1,0,0) 3$_{03}$ at 3526.5 cm$^{-1}$ and X(1,0,1) 2$_{11}$–X(1,0,0) 3$_{12}$ at 3514.4 cm$^{-1}$. The water production rate (${Q_{\rm H_{2}O}}$) was determined as (1.21 $\pm$ 0.05) ${\times}$ 10$^{28}$ molecules s$^{-1}$ based on the spherical coma model assuming the rotational temperature of 30 K on February 1. We found that water production rates determined by de Val-Borro et al. (2010, A&A, 521, L50) with Herschel/HIFI were consistent with ours within 3 $\sigma$ error-levels. Furthermore, our result is consistent with previous water production rates determined in the 1997 apparition.