bluuebunny/crossref_metadata_2025 huggingface dataset:
Discovery of a Promising Candidate of WZ Sge-Type Dwarf Novae, ASAS 160048−4846.2: Evidence for Double-Peaked Humps
Authors: Imada Akira , Monard L. A. G. Berto
Published: March 2014

We report on time-resolved CCD photometry during the 2005 June outburst of a dwarf nova, ASAS 160048$-$4846.2. The observed light curves unambiguously showed embryonic humps with a period of 0.063381(41) days, after which genuine superhumps emerged with a period of 0.064927(3) days. Based on evidence for double-peaked humps in the earlier stage of the outburst, this object might be qualified as the seventh member of WZ Sge-type dwarf novae after Var Her 04. If the former period is the same as, or very close to the orbital period of the system, as in other WZ Sge systems, the fractional superhump excess is about 2.4%. This value is unexpectedly larger than that of other WZ Sge-type dwarf novae. The early phase of our observing run provided evidence for the transition from chaotic humps to genuine superhumps, together with increasing the amplitude.
Possible Global Magneto-Fluid Structure of the Stellar Convection Zone
Authors: Itoh Sanae I. , Itoh Kimitaka , Diamond Patrick H. , Yoshizawa Akira
Published: March 2014

Structures of the magnetic field and velocity in stars are discussed based on the mean field MHD equations. A special case is presented, where the solution is constructed by the Beltrami solution in the stellar convection zone with the symmetry in the azimuthal direction. Magnetic field lines form concentric toroidal magnetic surfaces. The cross-helicity dynamo mechanism induces a mean flow of plasmas. The structure of this driven flow is also shown to constitute toroidal surfaces. Considering the symmetry and the relation of this toroidal magnetic structure with the polarity, it is shown that the latitudinal component of this flow is pole-ward in the northern as well as southern hemispheres. This gives an insight into the role of the magnetic field for the meridional flow.
Soft X-Ray Transmission Spectroscopy of a Warm/Hot Intergalactic Medium with XEUS
Authors: Kawahara Hajime , Yoshikawa Kohji , Sasaki Shin , Suto Yasushi , Kawai Nobuyuki , Mitsuda Kazuhisa , Ohashi Takaya , Yamasaki Noriko Y.
Published: March 2014

We discuss the detectability of a Warm/Hot Intergalactic Medium (WHIM) via absorption lines toward bright point sources with a future X-ray satellite mission, XEUS. While we consider bright QSOs as specific examples, the methodology can be applied to bright gamma-ray burst afterglows. We created mock absorption spectra for bright QSOs (more than 20 QSOs over all sky) using the light-cone output of a cosmological hydrodynamic simulation. We assumed that the WHIM is under collisional and photo-ionization equilibrium. If WHIM has a constant metallicity of $Z = 0.1 \,Z_{ {\odot }}$, approximately 2 O VII absorption line systems with $ \gt 3 \,\sigma \gt 3 \,\sigma$ will be detected on average along a random line-of-sight toward bright QSOs up to $z=0.3$ for a 30 ks exposure.
Interpretation of the Expansion Law of Planetary Nebulae
Authors: Matsumoto Hiroko , Fukue Tsubasa , Kamaya Hideyuki
Published: March 2014

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.
A Collimated Jet and an Infalling-Rotating Disk in G192.16−3.84 Traced by H2O Maser Emission
Authors: Imai Hiroshi , Omodaka Toshihiro , Hirota Tomoya , Umemoto Tomofumi , Sorai Kazuo , Kondo Tetsuro
Published: March 2014

We report on $\mathrm{H}_2 \mathrm{O}$ masers associated with the massive-star forming region G192.16$-$3.84 observed with the new Japanese VLBI network at three epochs spanned for two months, which have revealed the three-dimensional kinematical structure of the whole $\mathrm{H}_2 \mathrm{O}$ maser region in G192.16$-$3.84, containing two young stellar objects separated by ${\sim 1200 \,\mathrm{AU}}$. The maser spatio-kinematical structure has well persisted since previous observations, in which the masers are expected to be associated with a highly collimated bipolar jet and an infalling-rotating disk in the northern and southern clusters of $\mathrm{H}_2 \mathrm{O}$ maser features, respectively. We estimated a jet expansion speed of ${\sim 100 \,\mathrm{km} \,\mathrm{s}^{-1}}$ and re-estimated the dynamical age of the whole jet to be $5.6 \times 10^{4} \,\mathrm{yr}$. We investigated the spatial distribution of the Doppler velocities during the previous and present observations and the relative proper motions of $\mathrm{H}_2 \mathrm{O}$ maser features in the southern cluster, as well as the relative bulk motion between the two maser clusters. They are well explained by a model of an infalling-rotating disk with a radius of $\sim 1000 \,\mathrm{AU}$ and a central stellar mass of 5–10${M}_{\odot}$, rather than by a model of a bipolar jet perpendicular to the observed CO outflow. Based on the derived $\mathrm{H}_2 \mathrm{O}$ maser spatio-kinematical parameters, we discuss the formation mechanism of the massive young stellar objects and the outflow development in G192.16$-$3.84.
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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Detection of an H$\alpha$ Emission Line on a Quasar, RX J1759.4$+$6638, at Z = 4.3 with AKARI
Authors: Oyabu Shinki , Wada Takehiko , Ohyama Youichi , Matsuhara Hideo , Takagi Toshinobu , Nakagawa Takao , Onaka Takashi , Fujishiro Naofumi , Ishihara Daisuke , Ita Yoshifusa , Kataza Hirokazu , Kim Woojung , Matsumoto Toshio , Murakami Hiroshi , Sakon Itsuki , TanabÉ Toshihiko , Uemizu Kazunori , Ueno Munetaka , Usui Fumihiko , Watarai Hidenori , Haze Kanae
Published: March 2014

We report on the detection of an H$\alpha$ emission line in the low-resolution spectrum of a quasar, RX J1759.4$+$6638, at a redshift of 4.3 with the Infrared Camera (IRC) onboard AKARI. This is the first spectroscopic detection of an H$\alpha$ emission line in a quasar beyond $z =$ 4. The overall spectral energy distribution (SED) of RX J1759.4$+$6638 in the near- and mid-infrared wavelengths agrees with a median SED of the nearby quasars; also, the flux ratio of $F$(Ly$\alpha$)$/$$F$(H$\alpha$) is consistent with those of previous reports for lower-redshift quasars.
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

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.
Center-to-Limb Variation of Stokes $V$ Asymmetries in Solar Pores Observed with the Hinode Spectro-Polarimeter
Authors: Morinaga Shuji , Nagata Shin’ichi , Ichimoto Kiyoshi , Suematsu Yoshinori , Tsuneta Saku , Katsukawa Yukio , Shimizu Toshifumi , Shine Richard A. , Tarbell Theodore D. , Title Alan M. , Lites Bruce , Kubo Masahito , Sakurai Takashi
Published: March 2014

Here we present spectro-polarimetric measurements of several pores and the surrounding regions taken with the Solar Optical Telescope aboard Hinode at various viewing angles. We analyzed the Stokes $V$ area asymmetry, and confirmed that it is depressed at the center of the pores, while it shows large positive values (a blue lobe larger than a red lobe) in the surrounding area; this is consistent with a previous report. In addition to this ring of positive asymmetry, we found regions of alternating positive and negative area asymmetries when weak $V$ regions were observed near the solar limb. The positive asymmetry occurs on the disk-center side and the negative asymmetry on the limb side of the magnetic concentrations. These center-to-limb variations of the Stokes $V$ area asymmetry can be interpreted as being a systematic inflow of plasma into the magnetic concentrations from their surroundings.
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

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

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.
Simulation of the EUV Spectrum of Ca XVI
Authors: Liang Ya Qiong , Liu Hong , Zhong Jia Yong
Published: March 2014

The extreme ultraviolet (EUV) spectrum of a Boron-like Ca ion was simulated by using a relativistic multi-configuration atomic package. As compared to previous work [Keenan et al.(1998)], the present study involved indirect processes, such as collision ionization, radiative recombination, dielectronic recombination, and resonance excitation from or to Beryllium-like and Carbon-like Ca ions. The effects of these processes were using three models, named one-, two-, and three-ion. We have found that these indirect processes are important to simulate the EUV spectrum of the Boron-like Ca ion, which will affect the diagnostics of astronomical and laboratory plasmas.
Astrometry of H2O Masers in Nearby Star-Forming Regions with VERA II SVS 13 in NGC 1333
Authors: Hirota Tomoya , Bushimata Takeshi , Choi Yoon Kyung , Honma Mareki , Imai Hiroshi , 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 , Sasao Tetsuo , Sato Katsuhisa , Shibata Katsunori M. , Tamura Yoshiaki , Yamashita Kazuyoshi
Published: March 2014

We report on the results of multiepoch very long baseline interferometry (VLBI) observations with VERA (VLBI Exploration of Radio Astrometry) of the 22 GHz H$_{2}$O masers associated with the young stellar object SVS 13 in the NGC 1333 region. We carried out phase-referencing VLBI astrometry, and measured the annual parallax of the maser features in SVS 13 of 4.25$\pm$0.32mas, corresponding to a distance of 235$\pm$18pc from the Sun. Our result is consistent with a photometric distance of 220 pc, previously reported. Even though the maser features were detectable only for 6 months, the present result provides the distance to NGC 1333 with much higher accuracy than photometric methods. The absolute positions and proper motions have been derived, revealing that the H$_{2}$O masers with LSR (local standard of rest) velocities of 7–8kms$^{-1}$ are most likely associated with VLA4A, which is a radio counterpart of SVS 13. It is currently difficult to attribute the observed proper motions of the maser features to either the jet or the rotating circumstellar disk associated with VLA4A, which should be investigated through future high-resolution astrometric observations of VLA4A and other radio sources in NGC 1333.
Shock Waves and Line-Profile Variation in roAp Stars
Authors: Shibahashi Hiromoto , Gough Douglas , Kurtz Donald W. , Kambe Eiji
Published: March 2014

Line-profile variation of NdIII and PrIII spectrum lines of roAp stars obtained with high spectral resolution and high time resolution seem to be similar to those seen in rapidly rotating B-type line-profile variables: features in the lines appear to move smoothly from blue to red, but return to the blue discontinuously. It has been argued in the past that such behaviour is in disagreement with the oblique-pulsator interpretion of the photometric observations. We point out why that argument is invalid. We propose that the properties of the observed line-profile variation can in principle be explained as a manifestation of a shocked wave train propagating upwards through an acoustically thick layer high in the atmosphere, and demonstrate that it is consistent with the underlying pulsation being an axisymmetric low-degree, probably dipole oscillation more-or-less aligned with the magnetic axis, in accord with the oblique-pulsator model.
Hot and Cool Plasmoid Ejections Associated with a Solar Flare
Authors: Ohyama Masamitsu , Shibata Kazunari
Published: March 2014

A 1993 May 14 flare was associated with both X-ray plasma ejection as hot plasmoid ejection and H$\alpha$ filament eruption as cool plasma ejection. The flare proceeded through two stages according to a GOES soft X-ray observation. In the first stage, an X-ray plasma ejection, an H$\alpha$ filament eruption, and a chain of pointlike H$\alpha$ brightenings occurred. In the second stage, an H$\alpha$ two-ribbon flare and an X-ray arcade structure were seen in H$\alpha$ and soft X-ray images, respectively. The X-ray plasmoid and the eruptive H$\alpha$ filament were in the same current sheet. The X-ray plasmoid started to rise with a speed of $\sim$270kms$^{-1}$ temporally after the H$\alpha$ filament eruption. The top part of the X-ray plasmoid moved together with the eruptive filament. They were then decelerated before the main peak of the hard X-ray emission. The X-ray plasmoid was not a bloblike feature, as the eruptive H$\alpha$ filament, but a loop structure. Our results indicate that the X-ray plasmoid was not the heated part of the H$\alpha$ filament.
Central Spiral Structure of Molecular Gas in Maffei 2
Authors: Kuno Nario , Nakanishi Kouichiro , Sorai Kazuo , Shibatsuka Toshihito
Published: March 2014

The distribution and kinematics of molecular gas in the central region of the barred spiral galaxy Maffei 2 were investigated using a data set of $^{12}$ CO(1-0), $^{12}$ CO(2–1), CS(2–1) lines, and 103 GHz continuum. We found that the offset ridges along the kpc-scale bar continue to the central spiral structure embedded in a weak oval structure, which is regarded as an $x$ 2 orbit in the bar potential. The spiral structure continues toward the center, diverging from the oval structure. The size of these structures is less than $R$$\sim$ 100 pc. The mass concentration within $R =$ 35 pc is estimated to be $2 \times 10^{8} M_{\odot}$ . The high mass concentration is consistent with theoretical predictions concerning the creation of such a nuclear spiral structure. A comparison with tracers of dense gas and star-forming region suggests that the dense molecular gas traced by the CS(2–1) line is formed at the crossing points of the $x$ 1 and $x$ 2 orbits and the star-forming region appears after $2 \times 10^{5}$ yr, which is comparable to the free-fall time of dense gas traced by the CS line ( $\sim$$10^{5}$ cm $^{-3}$ ).
Heavy Element Analysis of X-Ray Faint Elliptical Galaxies
Authors: Tozuka Miyako , Fukazawa Yasushi
Published: March 2014

Past ASCA and ROSAT observations could not support the general view that elliptical galaxies are sources of metals in the intracluster medium, since observational results have shown that X-ray faint elliptical galaxies exhibit too low metal abundances of hot interstellar medium (ISM). We investigated the radial profiles of the temperature and abundance of 9 X-ray faint elliptical galaxies using the Chandra data. It is found that the heavy element abundance is as high as $\sim$0.7 solar at the central region. Moreover, toward the periphery of galaxies, the metallicity sharply declines. Therefore, the existence of low-metallicity intergalactic gas around X-ray faint elliptical galaxies is indicated. We also investigated the abundance ratios among several elements of 5 X-ray faint elliptical galaxies using the XMM-Newton data, and obtained a hint that the O$/$Fe ratio of X-ray faint elliptical galaxies is smaller than that of X-ray bright elliptical galaxies. This result perhaps indicates that, in X-ray faint elliptical galaxies, the contribution of SNeIa is smaller than that in X-ray bright ones, and it is speculated that many of the metals in ISM of X-ray faint elliptical galaxies have escaped into the surrounding space.
Milne–Eddington Solutions for Relativistic Plane-Parallel
Flows
Authors: Fukue Jun
Published: March 2014

Radiative transfer in a relativistic plane-parallel flow, e.g., an accretion-disk wind, has been examined using a fully special-relativistic treatment. Under the assumption of a constant flow speed, for a relativistically moving atmosphere, we analytically obtained generalized Milne–Eddington solutions of radiative moment equations: the radiation energy density, the radiative flux, and the radiation pressure. In the static limit these solutions reduce to the traditional Milne–Eddington ones for a plane-parallel static atmosphere, whereas the source function nearly becomes constant as the flow speed increases. Using the analytical solutions, we analytically integrated the relativistic transfer equation to obtain the specific intensity. This specific intensity also reduces to the Milne–Eddington case in the static limit, while the emergent intensity is strongly enhanced toward the flow direction due to Doppler and aberration effects as the flow speed increases (relativistic peaking).
Aligned Molecular Clouds towards SS 433 and L = 348${\rlap{\hskip.75pt{^\circ}}\hskip.75pt.\hskip1pt}$5: Possible Evidence for a Galactic “Vapor Trail” Created by a Relativistic Jet
Authors: Yamamoto Hiroaki , Ito Shingo , Ishigami Shinji , Fujishita Motosuji , Kawase Tokuichi , Kawamura Akiko , Mizuno Norikazu , Onishi Toshikazu , Mizuno Akira , Clure-Griffiths McNaomi M. , Fukui Yasuo
Published: March 2014

We carried out a detailed analysis of the NANTEN $^{12}$CO ($J=$ 1–0) dataset in two large areas towards SS 433 ($l \sim$ 40$^\circ$) and $l \sim$ 348${\rlap{\hskip.75pt{^\circ}}\hskip.75pt.\hskip1pt}$5. In SS 433, we detected ten clouds, which are well aligned nearly along the axis of an X-ray jet emanating from SS 433 at $V_{\rm LSR}$ = 42–56 km s$^{-1}$. The total length of the feature is $\sim\;$300 pc, three-times longer than that of the X-ray jet, at 3 kpc. Towards $l \sim$348${\rlap{\hskip.75pt{^\circ}}\hskip.75pt.\hskip1pt}$5, we detected four aligned clouds at $V_{\rm LSR}$ = $-$80–$-$100 km s$^{-1}$, nearly perpendicular to the Galactic plane. The total length of the feature is $\sim\;$400 pc at 6 kpc. In both cases, the CO clouds are distributed at $\mid{b}\mid\;\sim$ 1${}^\circ$–5${}^\circ$ and their alignments and coincidence in velocity should be rare, suggesting that they are physically associated. We present a scenario to explain these aligned clouds in which the interaction between a relativistic jet and the interstellar medium induced molecular cloud formation over the last $\sim\;$10$^{5\hbox{--}6}$yr. It is suggested that the timescale of the relativistic jet may be considerably larger, on the order of 10$^{5\hbox{--}6}$yr, than previously thought in SS 433. The driving engine of the jet is obviously SS 433, itself, in SS 433, although the engine is not yet identified in $l \sim$348${\rlap{\hskip.75pt{^\circ}}\hskip.75pt.\hskip1pt}$5 among possible several candidates detected in X-rays and TeV gamma rays.
Vertical Temperature Structures of the Solar Corona Derived with the Hinode X-Ray Telescope
Authors: Kano Ryouhei , Sakao Taro , Narukage Noriyuki , Tsuneta Saku , Kotoku Jun’ichi , Bando Takamasa , Edward DeLuca , Lundquist Loraine , Golub Leon , Hara Hirohisa , Matsuzaki Keiichi , Shimojo Masumi , Shibasaki Kiyoto , Shimizu Toshifumi , Nakatani Ichiro
Published: March 2014

We obtained temperature structures in faint coronal features above and near the solar limb with the X-Ray Telescope aboard the Hinode satellite by accurately correcting the scattered X-rays from surrounding bright regions with occulted images during the solar eclipses. Our analysis yields a polar coronal hole temperature of about 1.0 MK and an emission measure in the range of 10$^{25.5}$–10$^{26.0}$cm$^{-5}$. In addition, our methods allow us to measure the temperature and emission measure of two distinct quiet-Sun structures: radial (plume-like) structures near the boundary of the coronal-hole and diffuse quiet Sun regions at mid-latitudes. The radial structures appear to have increasing temperature with height during the first 100 Mm, and constant temperatures above 100 Mm. For the diffuse quiet-Sun region the temperatures are the highest just above the limb, and appear to decrease with height. These differences may be due to different magnetic configurations.
VERA Observations of SiO Masers in the Symbiotic Star R Aquarii
Authors: Kamohara Ryuichi , Bujarrabal Valentin , Bushimata Takeshi , Choi Yoon Kyung , Hirota Tomoya , Honma Mareki , Imai Hiroshi , Iwadate Kenzaburo , Jike Takaaki , Kameya Osamu , Kan-Ya Yukitoshi , Kawaguchi Noriyuki , Kim Mi Kyoung , 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 , Sasao Tetsuo , Sato Katsuhisa , Sato Mayumi , Shibata Katsunori M. , Tamura Yoshiaki , Yamashita Kazuyoshi
Published: March 2014

We present phase-referenced maps of the SiO maser transitions $v =$ 1 $J =$ 1-0 and $v =$ 2 $J =$ 1-0 from the symbiotic stellar system R Aquarii, which hosts an evolved AGB star plus a hot companion. Observations were performed at two epochs: 2004.98 and 2005.98. Accurate absolute coordinates and proper motions of the emission centroid were obtained; the errors expected for these parameters are also given. We compare the VERA data with the previous astrometry by Hipparcos. This represents a possibility to improve the orbital parameters of the system in a different way than that done before. Thanks to our accurate astrometry, we have also estimated the percentage of spot coincidences between both maser transitions, a parameter that has been proposed to be relevant to discriminate between different maser pumping schemes. Although the overall distributions of both lines are always similar, the spots are rarely coincident, in a percentage ranging between 3% and 20% of the cases. The lack of systematic coincidence favors, in principle, radiative pumping. However, we argue that no firm conclusion can be reached due to a lack of models that include an overlap of rovibrational lines, and that accurately address the coincidence of very intense spots of different maser transitions.
Relative Astrometry of the J = 1→0, v = 1 and v = 2 SiO Masers toward R Leonis Minoris Using VERA
Authors: Rioja María J. , Dodson Richard , Kamohara Ryuichi , Colomer Francisco , Bujarrabal Valentín , Kobayashi Hideyuki
Published: March 2014

Oxygen-rich Asymptotic Giant Branch (AGB) stars are intense emitters of SiO and H$_2$O maser lines at 43 ($J =$ 1$\rightarrow$0, $v =$ 1 and 2) and 22GHz, respectively. VLBI observations of the maser emission provide a unique tool to sample the innermost layers of the circumstellar envelopes in AGB stars. Nevertheless, the difficulties in achieving astrometrically aligned $v =$ 1 and $v =$ 2 SiO maser maps have traditionally prevented a unique interpretation of the observations in terms of the physical underlying conditions, which depend on the nature of the SiO pumping mechanism. We have carried out observations of the SiO and H$_2$O maser emission towards RLMi, using the astrometric capabilities of VERA. Due to the too weak emission of the reference calibrator, we had to develop a special method to accurately relate the coordinates for both transitions. We present relative astrometrically aligned $v =$ 1 and $v =$ 2 $J =$ 1$\rightarrow$0 SiO maser maps, at multiple epochs, and discuss the astrophysical results. The incorporation of astrometric information into the maps of SiO masers challenges the weak points in the current theoretical models, which will need further refinements to address the observation results.
A Bipolar Outflow of the M-Type Giant IRC −10414 Traced by HO Maser Emission
Authors: Maeda Toshihisa , Imai Hiroshi , Omodaka Toshihiro , Kobayashi Hideyuki , Shibata Katsunori M. , Bushimata Takeshi , Choi Yoon Kyung , Hirota Tomoya , Honma Mareki , Horiai Koji , Inomata Noritomo , Iwadate Kenzaburo , Jike Takaaki , Kameno Seiji , Kameya Osamu , Kamohara Ryuichi , Kan-ya Yukitoshi , Kawaguchi Noriyuki , Kuji Seisuke , Kurayama Tomoharu , Manabe Seiji , Miyaji Takeshi , Nagayama Takumi , Nakagawa Akiharu , Nakashima Kouichiro , Oh Chung Sik , Oyama Tomoaki , Sakai Satoshi , Sakakibara Seiichiro , Sato Katsuhisa , Shimizu Rie , Shintani Motonobu , Sora Kasumi , Suda Hiroshi , Tamura Yoshiaki , Yamashita Kazuyoshi
Published: March 2014

We report on results of five-epoch VLBI observations of H$_{2}$O maser emission in the M-type star IRC $-$10414, carried out with the VLBI Exploration of Radio Astrometry (VERA). The maser distribution extends over an area of 70mas$\times$260mas and exhibits a bipolar structure. The relative proper motions of 17 maser features were measured during the monitoring observations spanning nine months. The distance to IRC $-$10414 was re-estimated on the basis of the statistical treatment of parallax and the model-fitting method, yielding $D=$ 3.1$\pm$0.4kpc and $D=$ 2.0$\pm$0.2kpc, respectively. The estimated distance, $D=$ 2-3kpc, is much larger than that previously adopted. The stellar luminosity of IRC $-$10414 is also re-estimated to be $L_{\ast}\sim 9\times10^{4}$($D/$2kpc)$^{2} L_{\odot}$, much brighter by a factor of 10-20 than previously adopted ($L_{\ast} \sim 10000L_{\odot}$). The maser motions exhibit not only a spherically expanding flow with a velocity of $\sim$ 10($D/$2kpc)kms$^{-1}$, but also a faster bipolar outflow with a major axis in the north-south direction and at a small inclination angle with respect to the celestial sphere. These characteristics of the star and the circumstellar envelope seen in IRC $-$10414 are very similar to those in some supergiants exhibiting bipolar stellar mass loss.