bluuebunny/crossref_metadata_2025_split huggingface dataset:
N2H+ and HC3N Observations of the Orion A Cloud
Authors: Tatematsu Ken’ichi , Kandori Ryo , Umemoto Tomofumi , Sekimoto Yutaro 
Published: March 2014

Abstract
The “$\int$-shaped filament” of the Orion A giant molecular cloud was mapped in N$_2$H$^+$, and its northern end, the OMC-2/3 region, was also observed in HC$_3$N and CCS. The results were compared with maps of other molecular lines and the dust continuum emission. The N$_2$H$^+$ distribution is similar to the dust continuum distribution, except for the central part of the Orion Nebula. The distribution of H$^{13}$CO$^+$ holds a resemblance to that of the dust continuum, but the N$_2$H$^+$ distribution looks more similar to the dust continuum distribution. The N-bearing molecules, N$_2$H$^+$ and NH$_3$, seem to be more intense in OMC-2, compared with the H$^{13}$CO$^+$ and CS distribution. This suggests that OMC-2 has a higher abundance of N-bearing molecules, or a higher filling factor of the quiescent gas. We identified 34 cloud cores from N$_2$H$^+$ data. Over the Orion Nebula region, the N$_2$H$^+$ linewidth is large (1.1-2.1kms$^{-1}$). In the OMC-2/3 region, it becomes moderate (0.5-1.3kms$^{-1}$), and it is smaller (0.3-1.1kms$^{-1}$) in the south of the Orion Nebula. On the other hand, the gas kinetic temperature of the quiescent cores observed in N$_2$H$^+$ is rather constant ($\sim$20K) over the $\int$-shaped filament. We detected no CCS emission in the OMC-2/3 region. In general, the N$_2$H$^+$ and HC$_3$N distribution is quite similar in the OMC-2/3 region, but we observed a displacement between N$_2$H$^+$ and HC$_3$N over a 2$\prime$ scale in OMC-3, which has a chain of Class 0-I protostars (candidates).
A New 100-GHz Band Front-End System with a Waveguide-Type Dual-Polarization Sideband-Separating SIS Receiver for the NRO 45-m Radio Telescope
Authors: Nakajima Taku , Sakai Takeshi , Asayama Shin’ichiro , Kimura Kimihiro , Kawamura Masayuki , Yonekura Yoshinori , Ogawa Hideo , Kuno Nario , Noguchi Takashi , Tsuboi Masato , Kawabe Ryohei 
Published: March 2014

Abstract
We developed a waveguide-type dual-polarization sideband-separating SIS receiver system of the 100-GHz band for the 45-m radio telescope at the Nobeyama Radio Observatory, Japan. This receiver is composed of an ortho-mode transducer and two sideband-separating SIS mixers, which are both based on a waveguide technique. The receiver has four intermediate frequency (IF) bands of 4.0–8.0 GHz. Over the radio frequency range of 80–120 GHz, the single-sideband receiver noise temperatures are 50–100 K, and the image rejection ratios (IRRs) are greater than 10 dB. We developed new matching optics for the telescope beam as well as new IF chains for the four IF signals. The new receiver system was installed in the telescope, and we successfully observed the12CO,13CO, and C18O emission lines simultaneously toward the Sagittarius B2 region to confirm the performance of the receiver system. The SSB noise temperature of the system, including the atmosphere, became approximately half of that of the previous receiver system. The IRRs of the two 2SB mixers were estimated from the12CO and HCO+ spectra from the W 51 giant molecular cloud, resulting in &gt;20 dB for one polarization and &gt;12 dB for the other polarization.
On-The-Fly Observing System of the Nobeyama 45-m and ASTE 10-m Telescopes
Authors: Sawada Tsuyoshi , Ikeda Norio , Sunada Kazuyoshi , Kuno Nario , Kamazaki Takeshi , Morita Koh-Ichiro , Kurono Yasutaka , Koura Norikazu , Abe Katsumi , Kawase Sachiko , Maekawa Jun , Horigome Osamu , Yanagisawa Kiyohiko 
Published: March 2014

Abstract
We have developed a spectral line On-The-Fly (OTF) observing mode for the Nobeyama Radio Observatory 45-m and the Atacama Submillimeter Telescope Experiment 10-m telescopes. Sets of digital autocorrelation spectrometers are available for OTF with heterodyne receivers mounted on the telescopes, including the focal-plane 5$\times$5 array receiver, BEARS, on the 45-m. During OTF observations, the antenna is continuously driven to cover the mapped region rapidly, resulting in a high observing efficiency and accuracy. Pointing of the antenna and readouts from the spectrometer are recorded as fast as 0.1s. In this paper we report on improvements made to the software and instruments, requirements and optimization of observing parameters, the data-reduction process, and verification of the system. It is confirmed that, using optimal parameters, the OTF is about twice as efficient as the conventional position-switch observing method.
Implication for Super-Critical Accretion Flow in the Narrow-Line Seyfert 1 Galaxy PKS 0558–504
Authors: Haba Yoshito , Terashima Yuichi , Kunieda Hideyo , Ohsuga Ken 
Published: March 2014

Abstract
We present results from XMM-Newton observations of the narrow-line Seyfert 1 galaxy PKS 0558$-$504. The 2-12keV X-ray spectra can be well-reproduced by a single power law with a photon index of $\sim$2.2. The extrapolation of this power law continuum into the lower energy band reveals the existence of a strong soft excess component. When we applied a multicolor disk blackbody (MCD) model to the soft excess component, we found that the observed disk temperature, $kT_{\rm in}$, is much higher than that predicted from a standard Shakura-Sunyaev accretion disk. Furthermore, when the luminosity of the soft excess component, $L_{\rm disk}$, exceeds about 5$\times$10$^{44}$ergs$^{-1}$, $kT_{\rm in}$ seems to decrease in spite of the increase of luminosity. This trend is inconsistent with the standard accretion disk. Therefore, these results strongly suggest that the standard accretion-disk picture is no longer appropriate in the nucleus of PKS 0558$-$504. From the estimated bolometric luminosity ($\sim$10$^{46}$ergs$^{-1}$) and the central mass (5$\times$10$^7M_\odot$) of the black hole, PKS 0558$-$504 may be shining at the super-Eddington luminosity. We discuss a possible origin of the soft excess component, and suggest that significant photon trapping in the disk could explain the observational results.
Planetary Companions around Three Intermediate-Mass G and K Giants: 18 Delphini, ξ Aquilae, and HD 81688
Authors: Sato Bun’ei , Izumiura Hideyuki , Toyota Eri , Kambe Eiji , Ikoma Masahiro , Omiya Masashi , Masuda Seiji , Takeda Yoichi , Murata Daisuke , Itoh Yoichi , Ando Hiroyasu , Yoshida Michitoshi , Kokubo Eiichiro , Ida Shigeru 
Published: March 2014

Abstract
We report on the detection of 3 new extrasolar planets from a precise Doppler survey of G and K giants at Okayama Astrophysical Observatory. The host stars, 18 Del (G6 III), $\xi $Aql (K0 III) and HD81688 (K0 III-IV), are located in the clump region on the HR diagram with estimated masses of 2.1-2.3$M_{\odot}$. 18Del b has a minimum mass of $10.3 M_{\rm J}$ and resides in a nearly circular orbit with period of 993d, which is the longest one around evolved stars. $\xi $ Aql b and HD81688 b have minimum masses of 2.8 and 2.7$M_{\rm J}$, and reside in nearly circular orbits with periods of 137 and 184d, respectively, which are the shortest ones around evolved stars. All of the substellar companions ever discovered around intermediate-mass (1.7-3.9$M_{\odot}$) clump giants have semimajor axes larger than 0.68AU, suggesting a lack of short-period planets. Our numerical calculations suggest that Jupiter-mass planets within about 0.5AU (even up to 1AU, depending on the metallicity and adopted models) around 2-3$M_{\odot}$ stars could be engulfed by the central stars at the tip of RGB due to tidal torque from the central stars. Assuming that most of the clump giants are post-RGB stars, we can not distinguish whether the lack of short-period planets is primordial, or due to engulfment by central stars.
Incidence of High-Amplitude δ Scuti-Type Variable Stars
Authors: Lee Yong-Hwa , Kim Sungsoo S. , Shin Jihye , Lee Jiwon , Jin Ho 
Published: March 2014

Abstract
An order-of-magnitude estimate for the incidence of high-amplitude $\delta$ Scuti-type variable stars (HADS) in the $\delta$Scuti area of the H-R diagram was calculated. Using a model for the stellar distribution in the Milky Way, we calculated the number of stars that are expected to fall in the $\delta$Scuti area of the H-R diagram within the magnitude range and sky coverage of the ROTSE Survey for Variables I (RSV1). The incidence of the HADS phenomenon was then obtained by comparing the number of stars calculated by the model with the actual, observed number of HADS in the RSV1. We find that $\sim$0.24% of the stars that lie in the $\delta$Scuti area of the H-R diagram within the RSV1 observational limits exhibit the HADS phenomenon. This number is much lower than the incidence of low-amplitude $\delta$Scuti stars (LADS), $\gtrsim 1/3$, implying that the HADS phenomenon takes place in a very small fraction of stars and/or its duration is very short, compared to the LADS.
V802 Aquilae: A Short-Period Eclipsing Binary with Magnetic Activity
Authors: Yang Yuan-Gui , Qian Sheng-Bang , Zhu Li-Ying , Liu Liang , Nakajima Kazuhiro 
Published: March 2014

Abstract
New CCD observations for V802 Aql were observed from 2004 to 2007, and seven light minimum timings were obtained. Using the Wilson–Devinney code, the photometric solution was deduced from $R$-band observations. The results show that the mass-ratio and the contact degree are $q=$ 0.1443$\pm$0.0059 and $f=$ 34.9%$\pm$7.6%, respectively. Comparing the parameters of the dark spot from our results with those from Samec et al., it is found that the magnetic activity of the primary component may have been migrating towards its equator from 2002 to 2005. An orbital period analysis weakly suggests that the orbital period may undergo a cyclic variation with a period of $P_{3}=$ 8.32 yr and an amplitude of $A=$ 0$^{\rm d}$.0196. The periodic oscillation of this binary may be more plausibly explained as being the result of magnetic activity cycles. Therefore, the eclipsing star V802 Aql may be coalescing via magnetic breaking.
Note on an Inversion Formula to Determine Binary Elements by Astrometry
Authors: Asada Hideki 
Published: March 2014

Abstract
Simplified solutions to determine binary elements by astrometry were obtained in terms of elementary functions (Asada et al. 2004, PASJ, 56, L35), and therefore require neither iterative nor numerical methods. In the framework of the simplified solution, this paper discusses the remaining two parameters of the time of periastron passage and the longitude of the ascending node in order to complete the solution. We thus clarify a difference between the simplified solution and other analytical methods.
Long-Time Simulations of Astrophysical Jets: Energy Structure and Quasi-Periodic Ejection
Authors: Ibrahim Ahmed , Shibata Kazunari 
Published: March 2014

Abstract
We have performed self-consistent 2.5-dimensional nonsteady MHD numerical simulations of jet formation as long as possible, including the dynamics of accretion disks. Previous simulations showed that, in the case where the calculation time of the simulations is very short as compared with the time scale of observed jets, there is no significant difference between the characteristics of the nonsteady and steady MHD simulations. Thus, we have investigated long-time evolutions of the mass-accretion rate, mass-outflow rate, jet velocity, and various energy fluxes. We found that the ejection of a jet is quasi-periodic. The period of the ejection, $T_{\rm ejection}$, is related to the time needed for the initial magnetic field, $B_0$, to be twisted to generate a toroidal filed, $T_{\rm ejection} \propto {V_{\rm A}}^{-1} \propto {B_0}^{-1} \propto {E_{\rm mg}}^{-1/2}$, where $V_{\rm A}$ is the Alfvén velocity and $E_{\rm mg}$ the initial magnetic energy. We compared our results with both the steady-state theory and the previous 2.5-dimensional nonsteady MHD simulations. We found that the time-averaged velocity of the jet, $V_{{\rm jet}, \mathrm{avg}}$, is $\sim 0.1V_{\mathrm{K}}$ and $\sim 0.1V_{{\rm jet}, \mathrm{max}}$, where $V_{\mathrm{K}}$ is the Keplerian velocity at $(r,{z})=(1,0)$ and $V_{{\rm jet},\mathrm{max}}$ the maximum velocity of the jet. Nevertheless, the characteristics of our simulations are consistent with those of the steady solution and previous short-time simulations. We found that the dependences of the time-averaged velocity and the mass-outflow rate, $\dot{M}_{{\rm w},\mathrm{avg}}$, on the initial magnetic field are approximately $V_{{\rm jet},\mathrm{avg}} \propto {B_0}^{0.3}$ and $\dot{M}_{{\rm w},\mathrm{avg}} \propto {B_0}^{0.32}$, respectively.
Late Superhumps in WZ Sge-Type Dwarf Novae
Authors: Kato Taichi , Maehara Hiroyuki , Monard Berto 
Published: March 2014

Abstract
We report on the detection of very stable modulations with periods unexpectedly ($\sim\;$0.5%) longer than the superhump periods during the slowly fading stage of WZ Sge-type superoutbursts in three systems: GW Lib, V455 And, and WZ Sge. The periods are naturally explained by assuming that these modulations are superhumps arising from matter near the tidal truncation radius. This finding provides additional support for the hypothetical idea concerning expansion of the accretion disk well beyond the 3:1 orbital resonance in some low mass-ratio systems. Combined with the effect of a 2:1 resonance, we explain the origin of positive period derivatives in certain short-period SU UMa-type dwarf novae.
Japanese VLBI Network Observations of SiO Masers in the M-Type Giant IRC −10414
Authors: Ueda Kosuke , Imai Hiroshi , Deguchi Shuji , Kamohara Ryuichi , Maeda Toshihisa , Matsumoto Naoko , Omodaka Toshihiro 
Published: March 2014

Abstract
We present two-epoch maps of SiO masers ($v=$ 1 and $v=$ 2, $J=$ 1-0) associated with the M-type star IRC$-$10414, which were obtained with the Japanese VLBI Network (JVN). The spatial and Doppler velocity distributions, and the intensity ratio of the $v=$ 1 to $v=$ 2 ($J=$ 1-0) lines have significantly changed for eight years since our previous Very Long Baseline Array (VLBA) observation. The maser proper motions revealed by these two-epoch observations with an interval of one month are quite random and too fast to be explained by ballistic motions of the maser clumps. The maser distributions seen in the present observations cannot be explained by a rotating-infalling ring model implied in the previous work. We discuss the kinematical relation between the SiO and H$_{2}$O masers in IRC$-$10414. In the present observations, the scale sizes of SiO $v=$ 1 and $v=$ 2 masers in IRC$-$10414 were roughly equal, as observed in typical Mira variables.
Statistical Properties of Stellar HO Masers− Results of Three−Year Single−Dish Observations with the VERA Iriki Telescope
Authors: Shintani Motonobu , Imai Hiroshi , Ando Kazuma , Nakashima Kouichiro , Hirota Tomoya , Inomata Noritomo , Kai Takayuki , Kameno Seiji , Kijima Masachika , Kobayashi Hideyuki , Kuroki Mina , Maeda Toshihisa , Maruyama Kenta , Matsumoto Naoko , Miyaji Takeshi , Nagayama Takumi , Nagayoshi Riiko , Nakamura Kayoko , Nakagawa Akiharu , Namikawa Daichi , Omodaka Toshihiro , Oyama Tomoaki , Sakakibara Seiichiro , Shimizu Rie , Sora Kasumi , Tsushima Miyuki , Ueda Kosuke , Ueda Yuya , Yamashita Kazuyoshi 
Published: March 2014

Abstract
We report on the results of monitoring observations of 242 stellar H$_2$O masers, which have been made with the Iriki 20m telescope of the VLBI Exploration of Radio Astrometry (VERA) from 2003 July to 2006 November. The present paper mainly focuses on 85 stellar H$_2$O masers that have been tightly observed with a time spacing of typically 1−2 months. In particular, 46 masers out of them have been recognized concerning their periodic flux variation and have light−curve data of stellar visual light. Thus, the present paper shows some statistical views of the observed time variability properties of stellar H$_2$O masers. We found a good correlation between a time delay of the variation in the H$_2$O maser flux with respect to that in the stellar visual light and the stellar pulsation period. The corresponding phase lags are mildly scattered, but are mainly concentrated in the range, $0.7\leq\Delta \phi\leq\;$1.5. We also measured line−of−sight velocity drifts of the individual spectral peaks of H$_2$O maser emission, which indicate radial acceleration of mass−loss outflows from the evolved stars. We discuss possible pulsation−driven shock waves that are enhanced near the stellar surface, and are propagating outwards in the circumstellar envelope.
Suzaku Observation of the Ophiuchus Galaxy Cluster: One of the Hottest Cool Core Clusters
Authors: Fujita Yutaka , Hayashida Kiyoshi , Nagai Masaaki , Inoue Susumu , Matsumoto Hironori , Okabe Nobuhiro , Reiprich Thomas H. , Sarazin Craig L. , Takizawa Motokazu 
Published: March 2014

Abstract
We present the analysis of a Suzaku observation of the Ophiuchus galaxy cluster. We confirmed that the cluster has a cool core. While the temperature of the intracluster medium (ICM) decreases toward the center, the metal abundance increases. Except for the core ($r\lesssim\;$50kpc), the cluster is hot ($\sim\;$9-10keV) and is almost isothermal for $r\lesssim 1$Mpc; the latter contradicts a previous study. We do not detect any variation of the redshift of the ICM in the cluster; the upper limit of the velocity difference is 3000kms$^{-1}$. The iron-line ratios in X-ray spectra indicate that the ICM has reached the ionization equilibrium state. From these results, we conclude that the Ophiuchus cluster is not a major merger cluster, but one of the hottest clusters with a cool core. We obtain the upper limit of non-thermal emission from the cluster, which is consistent with both the recent claimed detection with INTEGRAL and the recent upper limits with the Swift/BAT. If the cluster has bright non-thermal emission, as suggested by the INTEGRAL measurement, it is probably not due to a recent major cluster merger.
Tropospheric Delay Calibrations for VERA
Authors: Honma Mareki , Tamura Yoshiaki , Reid Mark J. 
Published: March 2014

Abstract
We present techniques for the tropospheric delay calibration, which is the key to increasing the accuracy of the phase-referencing astrometry with Very Long Baseline Interferometry (VLBI). We study three methods, and make a comparison of these methods to discuss the accuracy in calibration. Our results show that all three methods can calibrate the tropospheric zenith delay within accuracy of $\sim$2cm. We also present simulations of positional errors in VLBI Exploration of Radio Astrometry (VERA) at the presence of an error in the tropospheric zenith delay, showing that parallax measurements with accuracy of 10$\mu$as can be readily achieved for sources at high declination and with small separation angles between the target Galactic maser and extragalactic position references.
Note on Artificial Deformation in Object Shapes Due to Pixelization
Authors: Hamana Takashi , Miyazaki Satoshi 
Published: March 2014

Abstract
We qualitatively examine the properties of artificial deformation in the shapes of objects (galaxies and stars) induced by pixelization effects (also called aliasing effects) using toy mock simulation images. Two causes of these effects have been recognized. One is a consequence of observing the continuous sky with discrete pixels, which is called “first pixelization”. The other, called “second pixelization”, is a consequence of resampling a pixelized image onto another pixel grid whose coordinates are not perfectly adjusted to the input grid. We pay special attention to the latter, because it might be a potential source of a systematic noise in weak-lensing analysis. In particular, it is found that resampling with rotation induces artificial ellipticities in object shapes having a periodic concentric-circle-shaped pattern. Our major findings are as follows: (1) The root-mean-square (RMS) of artificial ellipticities in object shapes induced by the first pixelization effect can be as large as RMS $\gtrsim$ 10$^{-2}$ if the characteristic size of the objects (e.g., the FWHM) is smaller than twice of the pixel size. However, for larger objects, it quickly becomes very small (RMS $\lesssim$ 10$^{-5}$). (2) The amplitude of shape deformation induced by the second pixelization effect depends on the object size. It also depends strongly on the interpolation scheme adopted to carry out resampling and on the grid size of the output pixels. The RMS of ellipticities in object shapes induced by the second pixelization effect can be suppressed to well below $10^{-2}$ if one adopts a proper interpolation scheme (implemented in popular image processing softwares). We also discuss the impact of pixelization effects on a weak-lensing analysis.
Suzaku Wide-Band Observations of SN 1006
Authors: Bamba Aya , Fukazawa Yasushi , Hiraga Junko S. , Hughes John P. , Katagiri Hideaki , Kokubun Motohide , Koyama Katsuji , Miyata Emi , Mizuno Tsunefumi , Mori Koji , Nakajima Hiroshi , Ozaki Masanobu , Petre Rob , Takahashi Hiromitsu , Takahashi Tadayuki , Tanaka Takaaki , Terada Yukikatsu , Uchiyama Yasunobu , Watanabe Shin , Yamaguchi Hiroya 
Published: March 2014

Abstract
We report on the wide-band spectra of SN1006, as observed by Suzaku. Thermal and nonthermal emissions were successfully resolved thanks to the excellent spectral response of Suzaku's X-ray CCD XIS. The nonthermal emission could not be reproduced by a simple power-law model, but needed a roll-off at 5.7$\times$10$^{16}$Hz $=$ 0.23keV. The roll-off frequency is significantly higher in the northeastern rim than in the southwestern rim. We also placed the most stringent upper limit of the flux above 10keV using the Hard X-ray Detector.
Suzaku Spectroscopy of an X-Ray Reflection Nebula and a New Supernova Remnant Candidate in the SgrB1 Region
Authors: Nobukawa Masayoshi , Tsuru Takeshi Go , Takikawa Yojiro , Hyodo Yoshiaki , Inui Tatsuya , Nakajima Hiroshi , Matsumoto Hironori , Koyama Katsuji , Murakami Hiroshi , Yamauchi Shigeo 
Published: March 2014

Abstract
We made a 100 ks observation of the Sagittarius (Sgr) B1 region at $(l,\ b)=$ (0D.5, $-$0D.1) near to the Galactic center (GC) with the Suzaku/XIS. Emission lines of SXV, FeI, FeXXV, and FeXXVI were clearly detected in the spectrum. We found that the FeXXV and FeXXVI line emissions smoothly distribute over the SgrB1 and B2 regions connecting from the GC. This result suggests that the GC hot plasma extends at least up to the SgrB region with constant temperature. There are two diffuse X-ray sources in the observed region. One of the two (G0.42$-$0.04) is newly discovered, and exhibits a strong SXV K$\alpha $ emission line, suggesting a candidate for a supernova remnant located in the GC region. The other one (M0.51$-$0.10), having a prominent FeI K$\alpha $ emission line and a strongly absorbed continuum, is likely to be an X-ray reflection nebula. There is no near source bright enough to irradiate M0.51$-$0.10. However, the FeI K$\alpha $ emission can be explained if SgrA* was $\sim10^6$ times brighter 300years ago, the light travel time for 100 pc to M0.51$-$0.10, than it is at present.