bluuebunny/crossref_metadata_2025_split huggingface dataset:
Restoring the Suzaku Source Position Accuracy and Point-Spread function
Authors: Uchiyama Yasunobu , Maeda Yoshitomo , Ebara Masatoshi , Fujimoto Ryuichi , Ishisaki Yoshitaka , Ishida Manabu , Iizuka Ryo , Ushio Masayoshi , Inoue Hirohiko , Okada Shunsaku , Mori Hideyuki , Ozaki Masanobu 
Published: March 2014

Abstract
We present an empirical correction of sky coordinates of X-ray photons obtained with the X-ray Imaging Spectrometer (XIS) aboard the Suzaku satellite to improve the source position accuracy and restore the point-spread function (PSF). The XIS images are known to have an uncertainty in position of up to $1′$, and to show considerable degradations of the PSF. These problems are caused by a drifting of the satellite attitude due to thermal distortion of the side panel #7, where the attitude control system is mounted. We found that the position error averaged over a pointing observation can be largely reduced by using the relation between the deviation of the source position in the DETX direction and the ecliptic latitude of the pointing target. We parameterized the wobbling of the source position synchronized with the 96-minute satellite orbital period with temperatures of onboard radiators and elapsed time since the night-day transition of the spacecraft. We developed software, aeattcor, to correct the image drift using these parameters, and applied it to 27 point-source images taken in the Suzaku initial science-operation phase. We show that the radius of the 90% error circle of the source position was reduced to $19′$ and the PSF was sharpened. These improvements have enhanced the scientific capability of the Suzaku XIS.
Identification of the Exciting Source of CO Outflow in the Star-Formation Region GGD 12-15
Authors: Sato Yaeko , Tamura Motohide , Kandori Ryo , Nakajima Yasushi , Kusakabe Nobuhiko , Hashimoto Jun , Kudo Tomoyuki , Saito Hiroo , Kitamura Yoshimi , Kawamura Akiko , Nishiyama Shogo , Sunada Kazuyoshi , Ueno Munetaka 
Published: March 2014

Abstract
We present results of near-infrared imaging polarimetry of the GGD 12-15 region with the IRSF 1.4m telescope and the SIRIUS camera/SIRPOL polarimeter and mid-infrared imaging with the AKARI telescope and the Infra-Red Camera (IRC). Two infrared sources, IRS 9E and IRS 9M near an H$_{\mathrm{2}}$O maser source situated on both sides around a VLA source (VLA 7), have been believed to be two bipolar lobes associated with a massive CO outflow. However, our polarimetric observations have revealed that IRS 9E is stellar-like, and not part of a reflection nebula. Furthermore, IRS 9M itself is not stellar, but a bipolar nebula, extending north-south. Both polarization vector maps and polarized intensity images show that the true illuminating source, IRS 9Mc, is not resolved, and is situated near the peak of the intensity image. Our astrometry also indicates that the position of IRS 9Mc does not coincide with the water maser position, but rather coincides with the VLA 7 position. We suggest that the unresolved illuminating source IRS 9Mc is the true exciting source of the CO outflow, corresponding to a mid-infrared source detected by AKARI with a lower spatial resolution. Fluxes of the newly identified source at 1 to 11$\mu$m were derived by separating contributions from nearby infrared sources; the spectral energy distribution is consistent with that of a class I/0 source.
Radial Velocity Search for Extrasolar Planets in Visual Binary Systems
Authors: Toyota Eri , Itoh Yoichi , Ishiguma Shinichiro , Urakawa Seitaro , Murata Daisuke , Oasa Yumiko , Matsuyama Hiroko , Funayama Hitoshi , Sato Bun’ei , Mukai Tadashi 
Published: March 2014

Abstract
We searched for extrasolar planets in visual binary systems using precise Doppler-shift measurements taken over a period of 4 yr. Using the HIgh Dispersion Echelle Spectrograph (HIDES) equipped on the Okayama Astrophysical Observatory (OAO) 188 cm reflector, we achieved a radial-velocity precision of about 10 ms$^{-1}$. We monitored both primary and secondary stars of six visual binary systems, and primary stars of three visual binaries. Among them, three objects show large radial-velocity variations. ADS 7311 A exhibits a decreasing trend in radial velocity with a best-fit slope of $-$30 ms$^{-1}$yr$^{-1}$, while 31 Dra A shows an increasing trend with a best-fit slope of $+$220 ms$^{-1}$yr$^{-1}$. These long-term trends in radial velocity may be attributable to unseen companions. BDS 10966 A shows a periodic variation in radial velocity with a period of 840 d and a semiamplitude of about 120 ms$^{-1}$, implying an association of a planetary-mass companion, rotational modulation, or nonradial oscillation of the photosphere. In any case, we should mention the nonassociation between BDS 10966 A and B, suggested by the different proper motions, radial velocities, and Hipparcos parallaxes.
Nobeyama Millimeter Array Observations of the Nuclear Starburst of M 83: A GMA Scale Correlation between Dense Gas Fraction and Star Formation Efficiency
Authors: Muraoka Kazuyuki , Kohno Kotaro , Tosaki Tomoka , Kuno Nario , Nakanishi Kouichiro , Handa Toshihiro , Sorai Kazuo , Ishizuki Sumio , Okuda Takeshi 
Published: March 2014

Abstract
We present aperture synthesis high-resolution ($\sim$7$^{\prime\prime}$$\times$ 3$^{\prime\prime}$) observations in CO ($J$$=$ 1–0), HCN ($J$$=$ 1–0), and 95 GHz continuum emission toward the central ($\sim$1.5 kpc) region of the nearby barred spiral galaxy M 83 with the Nobeyama Millimeter Array. Our high-resolution CO ($J$$=$ 1–0) mosaic map depicts the presence of molecular ridges along the leading sides of the stellar bar and a nuclear twin peak structure, whereas the distributions of the HCN ($J$$=$ 1–0) emission that traces dense molecular gas ($n_{\rm H_2}$$\gt$ a few $\times$ 10$^{4}$cm$^{-3}$) and the 95 GHz continuum emission that traces massive starburst show nuclear single-peak structures. The HCN ($J$$=$ 1–0) and the 95 GHz continuum peaks are not spatially coincident with the optical starburst regions traced by the HST $V$-band image, suggesting the existence of deeply buried ongoing starburst due to strong extinction ($A_{V}$$\sim$ 5 mag) near these peaks. We found that the HCN ($J$$=$ 1–0)$/$CO ($J$$=$ 1–0) intensity ratio, $R_{\rm HCN/CO}$, correlates well with the extinction-corrected star formation efficiency (SFE) in the central region of M 83 at a resolution of 7$^{\prime\prime}$.5 ($\sim$160 pc). This suggests that SFE is controlled by a dense gas fraction traced by $R_{\rm HCN/CO}$, even on a Giant Molecular cloud Association (GMA) scale. Moreover, the correlation between $R_{\rm HCN/CO}$ and SFE in M 83 seems to be almost coincident with that among the Gao and Solomon (2004 a, ApJ, 606, 271) sample. This suggests that the correlation between $R_{\rm HCN/CO}$ and the SFE on a GMA ($\sim$160 pc) scale found in M 83 is the origin of the global correlation on a few kpc scale shown by Gao and Solomon (2004a).
Time-Evolution of Peak Energy and Luminosity Relation within Pulses for GRB 061007: Probing Fireball Dynamics
Authors: Ohno Masanori , Ioka Kunihito , Yamaoka Kazutaka , Tashiro Makoto , Fukazawa Yasushi , Nakagawa Yujin E. 
Published: March 2014

Abstract
We performed a time-resolved spectral analysis of a bright, long gamma-ray burst GRB 061007 using Suzaku/WAM and Swift/BAT. Because of the large effective area of the WAM, we can investigate the time evolution of the spectral peak energy $E^{\rm t}_{ \rm peak}$ and the luminosity $L^{\rm t}_{\rm iso}$ with 1-s time resolution, and we find that the time-resolved pulses also satisfy the $E_{\rm peak}$–$L_{\rm iso}$ relation, which was found for the time-averaged spectra of other bursts, suggesting the same physical conditions in each pulse. Furthermore, the initial rising phase of each pulse could be an outlier of this relation with higher $E^{\rm t}_{ \rm peak}$ value by a factor of 2. This difference could suggest that the fireball radius expands by a factor of 2–4 and/or bulk Lorentz factor of the fireball is decelerated by a factor of $\sim$4 during the initial phase, providing a new probe of fireball dynamics in real time.
A Chain of Dark Clouds in Projection Against the Galactic Center
Authors: Nagayama Takahiro , Sato Shuji , Nishiyama Yuka , Murai Shogo , Nagata Tetsuya , Hatano Hirofumi , Kurita Mikio , Tamura Motohide , Nakajima Yasushi , Sugitani Koji , Oka Tomoharu , Sofue Yoshiaki 
Published: March 2014

Abstract
In a $J$, $H$, and $K_{\rm S}$ band survey of the Galactic center region over an area of 2${}^\circ$$\times$ 5${}^\circ$, we have found many dark clouds, among which a distinguished chain of dark clouds can be identified with a quiescent CO cloud. The distances of the clouds are estimated to be 3.2–4.2 kpc, corresponding to the Norma arm, by our new method for determining the distances to dark clouds using the cumulative number of stars against the $J-K_{\rm S}$ color. By adopting these estimated distances, the size and total mass of the cloud are estimated to be $\sim$70 pc in length and 6 $\times$ 10$^4$$M_\odot$, respectively. Three compact HII regions exist in the cloud, indicating that star-forming activities are going on at the cores of the quiescent CO cloud on the spiral arm.
Diffuse 18  $\mu$m Emission around TYC 3159-6-1 Discovered by the AKARI MIR All-Sky Survey
Authors: Takita Satoshi , Kitamura Yoshimi , Kataza Hirokazu , Ishihara Daisuke , Ueno Munetaka , Fujiwara Hideaki , Ikeda Norio , Kawamura Akiko , Murakami Hiroshi , Okamoto Yoshiko K. , Onaka Takashi , Oyabu Shinki , Sakon Itsuki , Takahashi Hidenori 
Published: March 2014

Abstract
We report on observations of the mysterious object TYC 3159-6-1 located toward the Cygnus X region. It shows interesting characteristics in the AKARI mid-infrared All-Sky Survey. The central star is clearly detected as a point source at 9 $\mu$m, while no point-like source, but a large shell-like structure is seen around the source at 18 $\mu$m. The optical spectrum indicates the presence of the weak H$\alpha$emission on the red smooth continuum, whereas the mid-infrared $N$band spectrum shows neither excess emission nor significant silicate absorption. Interferometric continuum observations at 104 GHz do not show any appreciable peak at the position of the star. On the basis of these observations, we investigate three possibilities of concerning the nature of TYC 3159-6-1: a nearby young stellar object, a heavily extincted high-mass star, and an asymptotic giant branch (AGB) star with a detached shell. We conclude that none of these cases can account for the observations consistently, and the nature of TYC 3159-6-1 remains a mystery.
Dependence of Spectral State Transition and Disk Truncation on Viscosity Parameter $\alpha $
Authors: Qiao Erlin , Liu Bi Fang 
Published: March 2014

Abstract
A wealth of Galactic accreting X-ray binaries has been observed in both the low/hard and high/soft states. The transition between these two states has often been detected. Observations show that the transition luminosity between these two states is different for different sources, ranging from 1% to 4% of the Eddington luminosity $L_{\rm Edd}$. Even for the same source, the transition luminosity at different outbursts can be different. The transition can occur at luminosities from 0.0069 to 0.15 $L_{\rm Edd}$. In order to investigate the underlying physics, we study the influence of viscosity parameter $\alpha $ on the transition luminosity on the basis of the disk-corona model for black holes. We calculate the mass-evaporation rate for a wide range of viscosity parameters such as 0.1 $\le$$\alpha $$\le$ 0.9. Fitting the numerical results, we obtain fitting formulae for both the transition accretion rate and the corresponding radius as a function of $\alpha $. We find that the transition luminosity is very sensitive to the value of $\alpha $, $L/L_{\rm Edd}\propto\alpha^{2.34}$. For 0.1 $\le$$\alpha $$\le$ 0.6, the transition luminosity varies by two orders of magnitude, from 0.001 to 0.2$L_{\rm Edd}$. Comparing with observations, we find that transition luminosity can be fitted by adjusting the value of $\alpha $, and the model-determined values of $\alpha $ are mostly in the range of observationally inferred values. We also investigate the truncation of the disk in the low/hard state for some luminous sources. Our results agree roughly with the observations.
Toward First-Principle Simulations of Galaxy Formation: II. Shock-Induced Starburst at a Collision Interface during the First Encounter of Interacting Galaxies
Authors: Saitoh Takayuki R. , Daisaka Hiroshi , Kokubo Eiichiro , Makino Junichiro , Okamoto Takashi , Tomisaka Kohji , Wada Keiichi , Yoshida Naoki 
Published: March 2014

Abstract
We investigated the evolution of interacting disk galaxies using high-resolution $N$-body/SPH simulations, while taking into account the multiphase nature of the interstellar medium. In our high-resolution simulations, a large-scale starburst occurred naturally at the collision interface between two gas disks at the first encounter, resulting in the formation of star clusters. This is consistent with observations of interacting galaxies. The probability distribution function (PDF) of the gas density showed a clear change during the galaxy–galaxy encounter. The compression of gas at the collision interface between the gas disks first appears as an excess at $n_{\rm H}$$\sim$ 10 cm$^{-3}$ in the PDF, and then it moves to higher densities ($n_{\rm H}$$\gtrsim$ 100 cm$^{-3}$) in a few times 10$^7$ years, where starburst takes place. After the starburst, the PDF goes back to a quasi-steady state. These results give a simple picture of starburst phenomena in galaxy–galaxy encounters.
Abundance Inhomogeneity in the Northern Rim of the Cygnus Loop
Authors: Uchida Hiroyuki , Tsunemi Hiroshi , Katsuda Satoru , Kimura Masashi , Kosugi Hiroko , Takahashi Hiroaki 
Published: March 2014

Abstract
We observed the northern rim of the Cygnus Loop with the Suzaku observatory in 5 pointings (P21–P25). From a spatially resolved analysis, all of the spectra were well fitted by a single component of the non-equilibrium ionization plasma model. From the best-fit parameters, we found that the abundances of the heavy elements are significantly lower than the solar values, except for those at the outermost edge in P21 and P22. The origin of the depleted metal abundances is still unclear, while such deficiencies have been reported from many other rim observations of the Loop. To explain these depletions at the rim regions, we considered several possibilities. The effects of resonance-line-scattering and grain condensation lower the values of the abundances. However, these are not sufficient to account for the observed abundance depletion.
Search for Remnant Clouds Associated with the TW Hya Association
Authors: Tachihara Kengo , Neuhäuser Ralph , Fukui Yasuo 
Published: March 2014

Abstract
We report on a search for the parental molecular clouds of the TW Hya association (TWA), using CO emission and NaI absorption lines. TWA is the nearest young ($\sim$50 pc; $\sim$10 Myr) stellar association; yet in spite of its youth there has been no detection of any associated natal molecular gas, as is the case with other typical young clusters. Using infrared maps as a guide, we conducted a CO cloud survey toward a region with a dust extinction of $E$($B-V$) $\gt$ 0.2 mag, or $A_{V}$$\gt$ 0.6 mag. CO emission was detected in the direction of three IR dust clouds, and we rejected one cloud out of the TWA, because no interstellar Na absorption was detected in the nearby Hipparcos stars, implying that it is too distant to relate to the TWA. The two other clouds exhibit only faint and small-scale CO emission. Interstellar NaI absorptions of Hipparcos targets (HIP 57809, HIP 64837, and HIP 64925, at distances of 133, 81, and 101 pc, respectively) by these clouds were also detected. We conclude that only a small fraction of the interstellar matter (ISM) toward the infrared (IR) dust cloud is located at a distance less than 100 pc, which may be all that is left out of the remnant clouds of TWA; the remaining remnant cloud dissipated within the last $\sim$1 Myr. Such a short-dissipation timescale may be due to an external perturbation or kinematic segregation that has a large stellar proper motion relative to the natal cloud.
Modified Slim-Disk Model Based on Radiation-Hydrodynamic Simulation Data: The Conflict between Outflow and Photon Trapping
Authors: Takeuchi Shun , Mineshige Shin , Ohsuga Ken 
Published: March 2014

Abstract
Photon trapping and outflow are two key physics issues associated with supercritical accretion flow. We investigated the conflict between these two processes based on two-dimensional radiation-hydrodynamic (RHD) simulation data, and constructed a simplified (radially) one-dimensional model. Mass loss due to outflow, which is not considered in the slim-disk model, reduces the surface density of the flow, and if very significantly, it can totally suppress the photon-trapping effects. If photon trapping is very significant, conversely, outflow can be suppressed because the radiation-pressure force is reduced. To see what actually occurs, we examined the RHD simulation data and evaluated the accretion and outflow rates as functions of the radius. We have found that the accretion rate monotonically decreases, while the outflow rate increases, as the radius decreases. However, the accretion remains constant at small radii, inside several Schwarzschild radii, since the outflow is suppressed by photon trapping effects. To understand the conflict between the photon trapping and outflow in a simpler way, we modeled the radial distribution of the accretion rate from our simulation data, and built up a new (radially) one-dimensional model, which is similar to the slim-disk model, but incorporates mass loss effects due to the outflow. We find that the surface density (and, hence, the optical depth) is greatly reduced even inside the trapping radius, compared to the case without outflow, whereas the effective temperature distribution hardly changes. That is, the emergent spectra do not sensitively depend on the amount of mass outflow. We conclude that the slim-disk approach is valid for interpreting observations, even if the outflow is taken into account. The observational implications of our findings are briefly discussed in relation to ultra-luminous X-ray sources.
Eruptions of Magnetic Ropes in Two Homologous Solar Events of 2002 June 1 and 2: a Key to Understanding an Enigmatic Flare
Authors: Meshalkina Nataliya S. , Uralov Arkadiy M. , Grechnev Victor V. , Altyntsev Alexander T. , Kashapova Larisa K. 
Published: March 2014

Abstract
The goal of this paper is to understand the drivers, configurations, and scenarios of two similar eruptive events, which occurred in the same solar active region 9973 on 2002 June 1 and 2. The June 2 event was previously studied by Sui, Holman, and Dennis (2006, ApJ, 646, 605; 2008, Adv. Space Res., 41, 976), who concluded that it was challenging for popular flare models. Using multi-spectral data, we analyzed a combination of the two events. Each of the events exhibited an evolving cusp-like feature. We have revealed that these apparent “cusps” were most likely mimicked by twisted magnetic flux ropes, but unlikely to be related to the inverted Y-like magnetic configuration in the standard flare model. The ropes originated inside a funnel-like magnetic domain whose base was bounded by an EUV ring structure, and the top was associated with a coronal null point. The ropes appear to be the major drivers for the events, but their rise was not triggered by reconnection in the coronal null point. We propose a scenario and a three-dimensional scheme for these events in which the filament eruptions and flares were caused by interaction of the ropes.
A Massive Substellar Companion to the Massive Giant HD 119445
Authors: Omiya Masashi , Izumiura Hideyuki , Han Inwoo , Lee Byeong-Cheol , Sato Bun’ei , Kambe Eiji , Kim Kang-Min , Yoon Tae Seog , Yoshida Michitoshi , Masuda Seiji , Toyota Eri , Urakawa Seitaro , Takada-Hidai Masahide 
Published: March 2014

Abstract
We detected a brown dwarf-mass companion around the intermediate-mass giant star HD 119445 (G6III) using the Doppler technique. This discovery is the first result from a Korean$-$Japanese planet search program based on precise radial velocity measurements. The radial velocity of this star exhibits a periodic Keplerian variation with a period, semiamplitude, and eccentricity of 410.2 d, 413.5 ms$^{-1}$, and 0.082, respectively. Adopting a stellar mass of 3.9$M_{\odot}$, we were able to confirm the presence of a massive substellar companion with a semimajor axis of 1.71AU and a minimum mass of 37.6$M_{\mathrm{J}}$, which falls in the middle of the brown dwarf-mass region. This substellar companion is the most massive ever discovered within 3AU of a central intermediate-mass star. The host star also ranks among the most massive stars with substellar companions ever detected by the Doppler technique. This result supports the current view of substellar systems that more massive substellar companions tend to exist around more massive stars, and may further constrain substellar system formation mechanisms.
A Study of Combining Technique of Single-Dish and Interferometer Data: Imaging Simulations and Analysis
Authors: Kurono, Yasutaka , Morita Koh-Ichiro , Kamazaki Takeshi 
Published: March 2014

Abstract
We have investigated a technique of combining single-dish data and interferometer data in the spatial frequency domain, using imaging simulations and analytical considerations. Our study shows that there is an optimum of the relative weights between the visibility data of a single-dish and an interferometer. The quality of the reconstructed combined image achieves the highest values at relative weights where the mean of the difference between the synthesized beam and the CLEAN beam is close to zero. We also examined the ($u$,$v$)-range that can be effectively used for the data combining by considering a blurring effect due to a pointing error. The error in single-dish deconvolution caused by the beam approximation is small with a large diameter of the single-dish aperture. The diameter should be at least 1.7-times larger than the minimum baseline of the interferometer for an amplitude accuracy better than 10%. Furthermore, we derived an estimate of the noise variance in the combined image, which agrees with our simulation results. The noise-added simulations demonstrate that there is a threshold of the noise level of the single-dish image, beyond which a large-scale error is emphasized in the combined image. We should take observation times to make at least the same noise level at the border of the spatial frequency between the single-dish and the interferometer. Although our examinations were assumed to use the 45 m telescope and NMA, our results concerning the required conditions for observations and data processes can be used in a general case of heterogeneous array imaging.
The Origin of an Extended X-Ray Emission Apparently Associated with the Globular Cluster 47 Tucanae
Authors: Yuasa Takayuki , Nakazawa Kazuhiro , Makishima Kazuo 
Published: March 2014

Abstract
Using the Suzaku X-ray Imaging Spectrometer, we performed a 130 ks observation of an extended X-ray emission, which was shown by ROSAT and Chandra observations to apparently associate with the globular cluster 47 Tucanae. The obtained 0.5–6 keV spectrum was successfully fitted with a redshifted thin thermal plasma emission model whose temperature and redshift are 2.2$^{+0.2}_{-0.3} $keV (at the rest frame) and 0.34$ \pm $0.02, respectively. The derived parameters, including the temperature, redshift, and luminosity, indicate that the extended X-ray source is a background cluster of galaxies, and its projected location falls, by chance, on the direction of the proper motion of 47 Tucanae.