bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interpretation of the Expansion Law of Planetary Nebulae
Authors: Matsumoto Hiroko , Fukue Tsubasa , Kamaya Hideyuki 
Published: March 2014

Abstract
We reproduce the expansion velocity-radius ($V_{\mathrm{exp}} \hbox{--} R_{\mathrm{n}}$) relation in planetary nebulae by considering a simple dynamical model, in order to investigate the dynamical evolution and formation of planetary nebulae. In our model, a planetary nebula is formed and evolves by the interaction of a fast wind from the central star with a slow wind from its progenitor, an AGB star. In particular, taking account of the mass-loss history of the AGB star makes us succeed in reproducing the observed $V_{\mathrm{exp}} \hbox{--} R_{\mathrm{n}}$ sequence. As a result, by examining an ensemble of the observational and theoretical evolution models of PNe, we find that if the AGB star pulsates and its mass-loss rate changes with time (from $\sim 10^{-6.4} \,{{{M}_{\odot}}} \,\mathrm{yr}^{-1}$ to $\sim 10^{-5} \,{{{M}_{\odot}}} \,\mathrm{yr}^{-1}$), the model agrees with the observations. In terms of observation, we suggest that there are few planetary nebulae with a larger expansion velocity and a smaller radius because the evolutionary time-scale of such nebulae is so short, and the size of nebulae is so compact that it is difficult for us to observe them.
Phase-Reference VLBI Observations of the Compact Steep-Spectrum Source 3C 138
Authors: Shen Zhi-Qiang , Shang Lin-Lin , Jiang Dong-Rong , Cai Hong-Bing , Chen Xi 
Published: March 2014

Abstract
We describe a phase-reference VLBI observation that was conducted at 15.4 GHz by fast-switching VLBA antennas between the compact steep-spectrum radio source 3C 138 and the quasar PKS 0528$+$134, which are about $4^\circ$ away on the sky. By comparing the phase-reference mapping with the conventional hybrid mapping, we demonstrate the feasibility of high-precision astrometric measurements for sources separated by $4^\circ$. VLBI phase-reference mapping preserves the relative phase information, and thus provides an accurate relative position between 3C 138 and PKS 0528$+$134 of $\Delta\alpha =- {9{}^{\mathrm {m}}46\rlap {.}{}^{\mathrm {s}}531000} \pm {0\rlap {.}{}^{\mathrm {s}}000003}$ and $\Delta\delta = {3{}^{\mathrm {\circ }}6{}^{\mathrm {\prime }}26\rlap {.}{}^{mathrm {\prime }}90311} \pm {0\rlap {.}{}^{\mathrm {\prime\prime}}00007}$ (J2000.0) in right ascension and declination, respectively. This gives an improved position of the nucleus (component A) of 3C 138 in J2000.0 to be $\mathrm{RA} = {05{}^{\mathrm {h}}21{}^{\mathrm {m}}09\rlap {.}{}^{\mathrm {s}}885748}$ and $\mathrm{Dec} = {16{}^{\mathrm {\circ }}38{}^{\mathrm {\prime }}22\rlap {.}{}^{\mathrm {\prime \prime }}05261}$ under the assumption that the position of calibrator PKS 0528$+$134 is correct. We further made a hybrid map by performing several iterations of CLEAN and self-calibration on the phase-referenced data with the phase-reference map as an input model for the first phase self-calibration. Compared with the hybrid map from the limited visibility data directly obtained from fringe fitting 3C 138 data, this map has a similar dynamic range, but a higher angular resolution. Therefore, the phase-reference technique is not only a means of phase connection, but also a means of increasing the phase coherence time, and thus allowing the self-calibration technique to be applied to much weaker sources.
Detailed Spectral Study of an Ultra-Luminous Compact X-Ray Source, M81 X-9, in the Disk-Dominated State
Authors: Tsunoda Naoko , Kubota Aya , Namiki Masaaki , Sugiho Masahiko , Kawabata Kiyoshi , Makishima Kazuo 
Published: March 2014

Abstract
We report on the results of detailed spectral studies of an ultra-luminous X-ray source (ULX), M81 X-9 (Holmberg IX X-1), conducted with XMM-Newton on 2001 April 22 and with ASCA on 1999 April 6. On both occasions, the source showed an unabsorbed 0.5–10 keV luminosity of $\sim 2 \times 10^{40} \,\mathrm{erg} \,\mathrm{s}^{-1}$ (assuming a distance of 3.4 Mpc) and a soft spectrum, apparently represented by a multi-color disk model with an innermost disk temperature of 1.3–1.5 keV. Adding a power-law model further improved the fit. However, as previously reported, the high luminosity cannot be reconciled with the high disk temperature within the framework of the standard accretion disk radiating at a sub-Eddington luminosity. Therefore, we modified the multi-color disk model, and allowed the local disk temperature to scale as $\propto r^{-p}$ on the distance $r$ from the black hole, with $p$ being a free parameter. We then found that the XMM-Newton and the ASCA spectra can be both successfully reproduced with $p \sim 0.6$ and the innermost disk temperature of 1.4–1.8 keV. These flatter temperature profiles suggest a deviation from the standard Shakura-Sunyaev disk, and are consistent with predictions of a slim-disk model.
Color Variation of a Very Young Asteroid, Karin
Authors: Ito Takashi , Yoshida Fumi 
Published: March 2014

Abstract
We present current results of our long-term campaign to make photometric observations of the new-born Karin family asteroids, especially those of (832) Karin. Karin, an S-type main-belt asteroid, is the largest member of the Karin family. This asteroid is likely a large fragment of a disruption event in the main asteroid belt that occurred about 5.8 million years ago. We obtained multi-color photometric observations of this asteroid in 2003 and 2004. We have reported a potential surface color variation of this asteroid, which indicates the existence of both mature and fresh surfaces on it. However, as of 2004 September, this asteroid apparently does not show a strong surface color difference, which might give us some insight into its spin axis orientation and shape. This is quite an interesting result, but it has to be confirmed by future observations.
The Differences of Star Formation History between Merging Galaxies and Field Galaxies in the Early Data Release of the SDSS
Authors: Luo Zhi-Jian , Shu Cheng-Gang , Jia-Sheng Huang 
Published: March 2014

Abstract
Based on the catalog of merging galaxies in the Early Data Release of the Sloan Digital Sky Survey, the differences of star-formation history between merging galaxies and field galaxies were studied statistically by means of three spectroscopic indicators: the 4000-Å break strength, the Balmer absorption-line index, and the specific star formation rate. It is found that for early-type merging galaxies the interactions will not induce any significant enhancement of the star-formation activity because of its stability and lack of cool gas. On the other hand, late-type merging galaxies always in general display more active star formation than field galaxies on different timescales within about 1 Gyr. We also conclude that the mean stellar ages of late-type merging galaxies are younger than those of late-type field galaxies.
The Structure of Accretion Disks Formed by Merging of White Dwarfs
Authors: Shioya Toshinao , Sano Takayoshi , Takabe Hideaki , Tsuribe Toru 
Published: March 2014

Abstract
The coalescence of two white dwarfs in a close binary system was investigated using hydrodynamical simulations. The Godunov Smoothed Particle Hydrodynamics method was adopted for the calculations. We performed various models of binary systems with different masses and mass ratios of the white dwarfs. As a result of coalescence, an accretion disk is formed around the primary star. The characteristic quantities of the disks, such as the temperature and rotation profile, were found to be independent of the initial binary parameters. We also discuss the subsequent evolution of the accretion disk and the possibility of a Type Ia supernova explosion from the merging of two white dwarfs.
Magnetorotational Collapse of Population III Stars
Authors: Suwa Yudai , Takiwaki Tomoya , Kotake Kei , Sato Katsuhiko 
Published: March 2014

Abstract
We performed a series of two-dimensional magnetorotational core-collapse simulations of Population III stars. Changing the initial distributions of the rotation and magnetic fields prior to collapse in a parametric manner, we computed 19 models. By so doing, we systematically investigated how rotation and magnetic fields affect the collapse dynamics, and explored how the properties of black-hole formations and neutrino emissions could be affected. As for microphysics, we employed a realistic equation of state, and approximated neutrino transfer by a multiflavour leakage scheme. With these computations, we found that jet-like explosions are obtained by magneto-driven shock waves if the initial magnetic field is as large as $10^{12}$G. We point out that although the black-hole masses at formation decrease with the initial field strength, they increase with the initial rotation rates. As for the neutrino properties, we point out that the degree of differential rotation plays an important role in determining which species of the neutrino luminosity is more dominant than the others. Furthermore, we find that stronger magnetic fields make the peak neutrino luminosities smaller, because the magnetic pressure acts to halt collapse in the central regions, leading to a suppression of the releasable gravitational binding energies.
Origin of the 2006 Orionid Outburst
Authors: Sato Mikiya , Watanabe Jun-ichi 
Published: March 2014

Abstract
The Orionid outburst observed in 2006 resulted in strong activity, continuing for about four days. We have found that this activity was caused by the dust trails formed by meteoroids ejected from 1P/Halley in $-$1265, $-$1197, and $-$910. These meteoroids had six times the Jovian orbital period, and their orbit was able to intersect the Earth’s orbit at the present day because of this mean motion resonance with Jupiter.
A New 60-cm Radio Survey Telescope with the Sideband-Separating SIS Receiver for the 200 GHz Band
Authors: Nakajima Taku , Kaiden Masahiro , Korogi Jun , Kimura Kimihiro , Yonekura Yoshinori , Ogawa Hideo , Nishiura Shingo , Dobashi Kazuhito , Handa Toshihiro , Kohno Kotaro , Morino Jun-Ichi , Asayama Shin’ichiro , Noguchi Takashi 
Published: March 2014

Abstract
We have upgraded the 60-cm radio survey telescope located in Nobeyama, Japan. We developed a new waveguide-type sideband-separating SIS mixer for the telescope, which enables the simultaneous detection of distinct molecular emission lines in both the upper and lower sidebands. Over the RF frequency range of 205–240 GHz, the single-sideband receiver noise temperatures of the new mixer are 40–100 K for the 4.0–8.0 GHz IF frequency band. The image rejection ratios are greater than 10 dB over the same range. For dual IF signals obtained by the receiver, we have developed two sets of acousto-optical spectrometers and a telescope control system. Using the new telescope system, we successfully detected the $^{12}$CO ($J =$ 2$-$1) and $^{13}$CO ($J =$ 2$-$1) emission lines simultaneously toward Orion KL in 2005 March. Using the waveguide-type sideband-separating SIS mixer for the 200 GHz band, we initiated the first simultaneous $^{12}$CO ($J =$ 2$-$1) and $^{13}$CO ($J =$ 2$-$1) survey of the galactic plane as well as large-scale mapping observations of nearby molecular clouds.
Near-Infrared Spectroscopic Monitoring Observations of Three Yellow Hypergiants and Time Variation of 2.3 $\mu$m CO Features of $\rho $ Cassiopeia
Authors: Yamamuro Tomoyasu , Nishimaki Yuichirou , Motohara Kentaro , Miyata Takashi , Tanaka Masuo 
Published: March 2014

Abstract
We made spectroscopic monitoring observations of the three yellow hypergiants ($\rho $ Cassiopeia, HR8752, and IRC$+$10420) in the 0.9–2.4 $\mu$m wavelength range with a resolution of $\sim$ 2600 over a fifteen month period. The spectra of HR8752 and IRC$+$10420 showed no time variations. On the other hand, those of $\rho $ Cas showed just a series of time variation in 2.3 $\mu$m CO features from nondetection to absorption through emission during 2002–2004. We interpret this variation as being a result of an expanding gas shell whose excitation temperature was being cooled down to $\sim$ 800 K. The CO column densities were estimated from the CO absorption depths. Moreover, assuming spherical symmetry of the expanding shell with a constant expansion velocity of 35 km s$^{-1}$, a stellar effective temperature of 7000 K, a stellar radius of 400 $R_{\odot}$, solar abundance, and all carbon atoms forming CO molecules, we estimated the mass of the shell to be $\sim 2 \times 10^{-3} M_{\odot}$ for a model with a single shell expanding from the photosphere, or $\sim 5 \times 10^{-4} M_{\odot}$ for another model with an expanding shell and a static envelope. These estimates of the released mass strongly depend on assumptions of the expansion velocity, the abundance, and the dissociation of the CO molecules.
Astrometry of H$_2$O Masers in Nearby Star-Forming Regions with VERA I. IRAS 16293$-$2422 in $\rho$ Oph East
Authors: Imai Hiroshi , Nakashima Kohichiro , Bushimata Takeshi , Choi Yoon Kyung , Hirota Tomoya , Honma Mareki , Horiai Koji , Inomata Noritomo , Iwadate Kenzaburo , Jike Takaaki , Kameya Osamu , Kamohara Ryuichi , Kan-ya Yukitoshi , Kawaguchi Noriyuki , Kijima Masachika , Kobayashi Hideyuki , Kuji Seisuke , Kurayama Tomoharu , Manabe Seiji , Miyaji Takeshi , Nagayama Takumi , Nakagawa Akiharu , Oh Chung Sik , Omodaka Toshihiro , Oyama Tomoaki , Sakai Satoshi , Sakakibara Seiichiro , Sato Katsuhisa , Sasao Tetsuo , Shibata Katsunori M. , Shimizu Rie , Shintani Motonobu , Sofue Yoshiaki , Sora Kasumi , Suda Hiroshi , Tamura Yoshiaki , Tsushima Miyuki , Ueno Yuji , Yamashita Kazuyoshi 
Published: March 2014

Abstract
We report on results of multi-epoch VLBI observations of H$_2$O masers associated with a low-mass young stellar object, IRAS 16293$-$2422 in $\rho$ Oph East, and a fringe-phase and position reference source, ICRF J162546.8$-$252738, using the VLBI Exploration of Radio Astrometry (VERA) for high-precision astrometry. We obtained an annual parallax of a maser feature to be $\pi=$ 5.6$^{+1.5}_{-0.5}$ mas, corresponding to a distance of $D=178^{+18}_{-37}$ pc. We also found 10 relative proper motions of maser features with respect to the maser feature mentioned above. The motion of the accompanying young stellar object (YSO) has already been found in thermal continuum emission previously observed with the Very Large Array. The intrinsic motions of masers have been estimated from the relative proper motions after the YSO’s motion is subtracted from, and a systemic secular motion of the position reference feature is added to the proper motions originally measured. The intrinsic maser kinematical structure may trace a bipolar outflow.
Detection of Highly-Ionized Carbon and Nitrogen Emission Lines from the Cygnus Loop Supernova Remnant with the Suzaku Observatory
Authors: Miyata Emi , Katsuda Satoru , Tsunemi Hiroshi , Hughes John P. , Kokubun Motohide , Porter F. Scott 
Published: March 2014

Abstract
We present the results of a Suzaku observation at the northeastern limb of the Cygnus Loop supernova remnant. The high detection efficiency together with the high spectral resolution of the Suzaku X-ray CCD cameras enables us to detect highly-ionized C and N emission lines from the Cygnus Loop for the first time. We performed an annular spectral analysis to our data set and investigated the plasma structure along the radial direction. Our data are well characterized by a two-component non-equilibrium ionization model with different values of electron temperature. Abundances of C to Fe are all depleted to typically 0.1 solar, even for Ne. Relative abundances to O are roughly consistent with solar values.
The Infrared Camera (IRC) for AKARI–Design and Imaging Performance
Authors: Onaka Takashi , Matsuhara Hideo , Wada Takehiko , Fujishiro Naofumi , Fujiwara Hideaki , Ishigaki Miho , Ishihara Daisuke , Ita Yoshifusa , Kataza Hirokazu , Kim Woojung , Matsumoto Toshio , Murakami Hiroshi , Ohyama Youichi , Oyabu Shinki , Sakon Itsuki , TanabÉ Toshihiko , Takagi Toshinobu , Uemizu Kazunori , Ueno Munetaka , Usui Fumio , Watarai Hidenori , Cohen Martin , Enya Keigo , Ootsubo Takafumi , Pearson Chris P. , Takeyama Norihide , Yamamuro Tomoyasu , Ikeda Yuji 
Published: March 2014

Abstract
The Infrared Camera (IRC) is one of two focal-plane instruments on the AKARI satellite. It is designed for wide-field deep imaging and low-resolution spectroscopy in the near–to mid-infrared (1.8–26.5$\mu$m) in the pointed observation mode of AKARI. The IRC is also operated in the survey mode to make an All-Sky Survey at 9 and 18$\mu$m. It comprises three channels. The NIR channel (1.8–5.5$\mu$m) employs a 512 $\times$ 412 InSb array, whereas both the MIR-S (4.6–13.4$\mu$m) and MIR-L (12.6–26.5$\mu$m) channels use 256 $\times$ 256 Si:As impurity band conduction arrays. Each of the three channels has a field-of-view of about $10^\prime \times 10^\prime$, and they are operated simultaneously. The NIR and MIR-S share the same field-of-view by virtue of a beam splitter. The MIR-L observes the sky about 25$^\prime$ away from the NIR/MIR-S field-of-view. The IRC gives us deep insights into the formation and evolution of galaxies, the evolution of planetary disks, the process of star-formation, the properties of interstellar matter under various physical conditions, and the nature and evolution of solar system objects. The in-flight performance of the IRC has been confirmed to be in agreement with the pre-flight expectation. This paper summarizes the design and the in-flight operation and imaging performance of the IRC.
AKARI Detection of the Infrared-Bright Supernova Remnant B0104$-$72.3 in the Small Magellanic Cloud
Authors: Koo Bon-Chul , Lee Ho-Gyu , Moon Dae-Sik , Lee Jae-Joon , Seok Ji Yeon , Lee Hyung Mok , Hong Seung Soo , Lee Myung Gyoon , Kaneda Hidehiro , Ita Yoshifusa , Jeong Woong-Seob , Onaka Takashi , Sakon Itsuki , Nakagawa Takao , Murakami Hiroshi 
Published: March 2014

Abstract
We present a serendipitous detection of the infrared-bright supernova remnant (SNR) B0104$-$72.3 in the Small Magellanic Cloud by the Infrared Camera (IRC) onboard AKARI. An elongated, partially complete shell has been detected in all four observed IRC bands, covering 2.6–15 $\mu$m. The infrared shell surrounds radio, optical, and X-ray emission associated with the SNR, and is probably a radiative SNR shell. This is the first detection of an SNR shell in this near/mid-infrared waveband in the Small Magellanic Cloud. The IRC color indicates that the infrared emission might be from shocked H$_2$ molecules with some possible contributions from ionic lines. We conclude that B0104$-$72.3 is a middle-aged SNR interacting with molecular clouds, similar to the Galactic SNR IC 443. Our results highlight the potential of AKARI IRC observations in studying SNRs, especially for diagnosing SNR shocks.
Far-Infrared Distributions in Nearby Spiral Galaxies NGC 2841 and NGC 2976 Observed with AKARI/Far-Infrared Surveyor (FIS)
Authors: Kaneda Hidehiro , Suzuki Toyoaki , Onaka Takashi , Doi Yasuo , Kawada Mitsunobu , Koo Bon-Chul , Makiuti Sin’itirou , Nakagawa Takao , Okada Yoko , Serjeant Stephen , Shibai Hiroshi , Shirahata Mai 
Published: March 2014

Abstract
Far-infrared (IR) images of the nearby Sb galaxy NGC 2841 and the Sc galaxy NGC 2976 at wavelengths of 65, 90, 140, and 160 $\mu$m have been obtained with the Far-Infrared Surveyor (FIS) onboard AKARI. Both galaxies reveal similar morphologies of dust rings. They are, however, significantly different in the dust temperature: a cold ($\sim$ 21 K) ring for NGC 2841 and a warm ($\sim$ 30 K) ring for NGC 2976, which presumably reflects the difference in the origin of the ring structure for the different Hubble types of the galaxy. In addition to the dust-ring structure, a warm dust component was detected from the central region of NGC 2841, which may be attributed to heating by its Low-Ionization Nuclear Emission-line Region nucleus. As for NGC 2976, an extended dust component was observed along the minor axis, which shows a distribution somewhat asymmetrical to the galactic disk; this might be associated with the H I bridge in the M 81/M 82 group that NGC 2976 belongs to. By taking advantage of a wealth of the far-IR bands of the FIS, it has been demonstrated that the spectral energy distribution of NGC 2841 is spatially more variable than that of NGC 2976.
AKARI Far-Infrared Source Counts in the Lockman Hole
Authors: Matsuura Shuji , Shirahata Mai , Kawada Mitsunobu , Doi Yasuo , Nakagawa Takao , Shibai Hiroshi , Pearson Chris P. , Takagi Toshinobu , Jeong Woong-Seob , Oyabu Shinki , Matsuhara Hideo 
Published: March 2014

Abstract
We report initial results of far-infrared observations of the Lockman Hole with Far-Infrared Surveyor onboard the AKARI infrared satellite. On the basis of slow-scan observations of a $0\rlap{.}^{\circ}6 \times 1\rlap{.}^{\circ}2$ contiguous area, we obtained source number counts at 65, 90, and 140 $\mu $m down to 77, 26, and 194 mJy (3$\sigma$), respectively. The counts at 65 and 140 $\mu $m show good agreement with the Spitzer results. However, our 90 $\mu $m counts are clearly lower than the predicted counts by recent evolutionary models that fit the Spitzer counts in all the MIPS bands. Our 90 $\mu $m counts above 26 mJy account for about 7% of the cosmic background. These results provide strong constraints on the evolutionary scenario, and suggest that the current models may require modifications.
Hot and Cool Loops Composing the Corona of the Quiet Sun
Authors: Matsuzaki Keiichi , Hara Hirohisa , Watanabe Tetsuya , Dere Kenneth P. , Brown Charles M. , Culhane Len 
Published: March 2014

Abstract
We performed a raster scan observation of the quiet Sun with the EUV Imaging Spectrometer (EIS) aboard Hinode and simultaneously analyzed observed emission lines of Fe VIII to XV. From a combined analysis, radiance maps from the observed emission lines were deconvolved into plasma components at five representative temperatures between 0.40 MK and 2.63 MK. While the lowest temperature component shows network structures on spatial scales of between 10${}^{\prime\prime}$ and 20${}^{\prime\prime}$, the higher temperature components show thread-like patterns on larger scales. A comparison of emission measures at the different temperatures suggests that the lowest temperature component is mainly composed of bodies of small loops, rather than a collection of foot points of the higher temperature loops. The difference in morphologies is interpreted as being due to different magnetic field configurations, loops within super-granule cells and fields extending beyond the boundaries of super-granule cells, with distinct peak temperatures following a loop scaling law.
Two-Step Reconnections in a C3.3 Flare and Its Preflare Activity Observed by Hinode XRT
Authors: Kim Sujin , Moon Young-Jae , Kim Khan-Hyuk , Kim Yeon-Han , Sakurai Takashi , Chae Jongchul , Kim Kap-Sung , Choe Gwangson 
Published: March 2014

Abstract
We investigated the evolution of a C3.3 impulsive flare and its preflare activity, which occurred in NOAA Active Region 10923 on 2006 November 12, using Hinode X-Ray Telescope (XRT) data. For an extensive investigation, we also used GOES X-ray flux, TRACE 171 Å, and SOHO MDI data. Examining the time-series of the XRT and TRACE images, we can identify the following evolutionary sequences: (1) There were three bundles of loops along the sheared polarity inversion line forming a sigmoidal structure during the preflare phase. (2) Preflare brightening occurred between two upper-loop bundles, and they consequently formed one larger bundle. (3) The main flare occurred near the location where this new loop bundle and the third bundle met together. (4) As a result, a single stacked loop structure was formed. This morphological evolution of the X-ray loops is quite consistent with a tether-cutting model involving a single-bipole explosion. Our result shows that the preflare and the main flare in this event are a two-step reconnection process, which strongly suggests that the preflare activity plays an important role in triggering the main flare.