bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of Three-Dimensional Kinematics of the Narrow-Line Region of the Seyfert Galaxy NGC 4151 Based on Integral Field Spectroscopy
Authors: Shimono Atsushi , Sugai Hajime , Kawai Atsushi , Matsubayashi Kazuya , Ohtani Hiroshi , Ozaki Shinobu , Hattori Takashi , Kosugi George
Published: March 2014

By using the Integral Field Spectroscopy mode of the Kyoto Tri-dimensional Spectrograph II we have mapped the two-dimensional distribution of kinematics in a wide variety of emission lines in the narrow-line region of NGC 4151. We decomposed the emission lines and defined two components: a narrow component and a broad component. The narrow component has smaller FWHM values, and is spatially more extended than the broad component. We applied a simple model to each component, a rotation in the galactic plane for the narrow component and a biconical outflow model for the broad one. The two-dimensional velocity distributions of the narrow component was well-fitted to a normal rotation in the galactic plane, with the best-fit parameters being similar among the emission lines. We found that the residual maps show similar large positive values at a knot around 6$^{\prime\prime}$ southwest form the nucleus. For the central region, excluding the knot, the velocity field was fitted better, and the residual was small as the relative wavelength-calibration accuracy of the instrument among lenslets. We modeled the broad component with a simple biconical outflow axisymmetrical with respect to its axis by assuming a constant outflowing velocity, a constant FWHM value, and the emission line strength declining according to a power law with the distance from the nucleus. The best-fit model suggests that PA for the axis of the biconical outflow is close to the direction of the [O III] line emission elongation. Our line of sight was included within the outflowing bicone, which had filled cones.
Probing the Peculiar Behavior of GRS 1915$+$105 at Near-Eddington Luminosity
Authors: Vierdayanti Kiki , Mineshige Shin , Ueda Yoshihiro
Published: March 2014

To understand the nature of supercritical accretion, we systematically analyzed the RXTE/PCA data of GRS 1915$+$105 in its quasi-steady states, by choosing data with small variability during 1999–2000. We applied a multicolor disk plus a thermal Comptonization model, and took into consideration accurate interstellar absorption, a reflection component (with an iron-K emission line), and absorption features from the disk wind self-consistently. The total luminosity ranges from $\sim $0.2$L_{\rm E}$ to slightly above $L_{\rm E}$. There is a strong correlation between the inner disk temperature and the fraction of the disk component. Most of the Comptonization-dominated ($\gt$50% total flux) spectra show $T_{\rm in} \sim $ 1 keV with a high electron temperature of $\gt$10 keV, which may correspond to the very high state in canonical black hole X-ray binaries (BHBs). In contrast, the disk-dominated spectra have $T_{\rm in} \sim $ 2 keV with a low temperature ($<$10 keV) and optically thick Comptonization, and show two separate branches in the luminosity vs. innermost temperature ($L$–$T_{\rm in}$) diagram. The lower branch clearly follows the $L \propto T_{\rm in}^4$-track. Furthermore, by applying the extended disk blackbody (or $p$-free disk) model, we found that 9 out of 12 datasets with disk luminosity above 0.3$L_{\rm E}$ prefer a flatter temperature gradient than that in the standard disk ($p <$ 0.7). We interpret that, in the lower branch, the disk extends down to the innermost stable circular orbit, and the source is most probably in the slim-disk state. A rapidly spinning black hole can explain both the lack of the $L \propto T_{\rm in}^2$-track and a high value of the spectral hardening factor ($\sim $4) that would be required for a non-rotating black hole. The spectra in the upper branch are consistent with the picture of a truncated disk with low-temperature Comptonization. This state was uniquely observed from GRS 1915$+$105 among BHBs, which may be present at near-Eddington luminosity.
X-Ray Temperature and Mass Measurements to the Virial Radius of Abell 1413 with Suzaku
Authors: Hoshino Akio , Henry J. Patrick , Sato Kosuke , Akamatsu Hiroki , Yokota Wataru , Sasaki Shin , Ishisaki Yoshitaka , Ohashi Takaya , Bautz Marshall , Fukazawa Yasushi , Kawano Naomi , Furuzawa Akihiro , Hayashida Kiyoshi , Tawa Noriaki , Hughes John P. , Kokubun Motohide , Tamura Takayuki
Published: March 2014

We present X-ray observations of the northern outskirts of the relaxed galaxy cluster A 1413 with Suzaku, whose XIS instrument has the low intrinsic background needed to make measurements of these low surface brightness regions. We excised 15 point sources superimposed on the image above a flux of 1 $\times$ 10$^{-14}$erg cm$^{-2} $s$^{-1}$ (2–10 keV) using XMM-Newton and Suzaku images of the cluster. We quantified all known systematic errors as part of our analysis, and showed that our statistical errors encompass them for the most part. Our results extend previous measurements with Chandra and XMM-Newton, and show a significant temperature drop to about 3 keV at the virial radius, $r_{200}$. Our entropy profile in the outer region ($> $0.5$r_{200}$) joins smoothly onto that of XMM-Newton, and shows a flatter slope compared with simple models, similar to a few other clusters observed at the virial radius. The integrated mass of the cluster at the virial radius is approximately 7.5 $\times$ 10$^{14} M_{\odot}$, and varies by about 30%, depending on the particular method used to measure it.
Dense and Warm Molecular Gas and Warm Dust in Nearby Galaxies
Authors: Matsushita Satoki , Kawabe Ryohei , Kohno Kotaro , Tosaki Tomoka , Vila-Vilaró Baltasar
Published: March 2014

We performed $^{12}$CO (1–0), $^{13}$CO (1–0), and HCN (1–0) single-dish observations (beam size $\sim $14–18) toward nearby starburst and non-starburst galaxies using the Nobeyama 45-m telescope. The $^{13}$CO (1–0) and HCN (1–0) emissions were detected from all seven starburst galaxies, with the intensities of both lines being similar (i.e., the ratios are around unity). On the other hand, for the case of non-starburst galaxies, $^{13}$CO (1–0) emission was detected from all three galaxies, while HCN (1–0) emission was weak, or not detected in past observations. This result indicates that the HCN$/{}^{13}$CO intensity ratios are significantly larger ($\sim $1.15$ \pm $0.32) in the starburst galaxy samples than the non-starburst galaxy samples ($\lt$ 0.31$ \pm $0.14). The large-velocity-gradient model suggests that the molecular gas in the starburst galaxies has warmer and denser conditions than that in the non-starburst galaxies, and the photon-dominated-region model suggests that denser molecular gas is irradiated by a stronger interstellar radiation field in starburst galaxies than that in non-starburst galaxies. In addition, HCN$/{}^{13}$CO ratios in our sample galaxies exhibit strong correlations with the IRAS 25$ \mu$m flux ratios. It is a well-established fact that there exists a strong correlation between dense molecular gas and star-formation activities, but our results suggest that the molecular gas temperature is also an important parameter.
Discovery of K-Shell Emission Lines of Neutral Atoms in the Galactic Center Region
Authors: Nobukawa Masayoshi , Koyama Katsuji , Tsuru Takeshi Go , Ryu Syukyo G. , Tatischeff Vincent
Published: March 2014

The K-shell emission line of neutral iron from the Galactic center (GC) region is one of the keys concerning the structure and activity of the GC. The origin is still an open question, but possibly due either to X-ray radiation or to electron bombarding to neutral atoms. To address this issue, we analyzed the Suzaku X-ray spectrum from the GC region of intense neutral iron line emission, and report on the discovery of K$\alpha$ lines of neutral argon, calcium, chrome, and manganese atoms. The equivalent widths of these K$\alpha$ lines indicate that the metal abundances in the GC region should be $\sim $1.6 and $\sim $4 of the solar value, depending on the X-ray and electron origins, respectively. On the other hand, the metal abundances in the hot plasma in the GC region are found to be $\sim $1–2 solar. These results favor that the origin of the neutral K$\alpha$ lines is due to X-ray irradiation.
Evidence of Early Enrichment of the Galactic Disk by Large-Scale Winds
Authors: Tsujimoto Takuji , Bland-Hawthorn Joss , Freeman Kenneth C.
Published: March 2014

Large-scale homogeneous surveys of Galactic stars may indicate that the elemental abundance gradient evolves with cosmic time, which is a phenomenon that was not foreseen in existing models of Galactic chemical evolution (GCE). If this phenomenon is confirmed in future studies, we can show that this effect, at least in part, is due to large-scale winds that once enriched the disk. These set up a steep abundance gradient in the inner disk ($R_{\rm GC} \lesssim$ 14 kpc). At the close of the wind phase, chemical enrichment through accretion of metal-poor material from the halo to the disk gradually reduced the metallicity of the inner region, whereas a slight increase in the metallicity proceeded beyond the solar circle. Our “wind$+$infall” model accounts for a flattening of the abundance gradient in the inner disk, in agreement with observations. Accordingly, we propose that enrichment by large-scale winds is a crucial factor in chemical evolution in the disk. We anticipate that rapid flattening of the abundance gradient is the hallmark of disk galaxies with significant central bulges.
Time-Resolved Spectral Variability of the Prompt Emission from GRB 070125 Observed with Suzaku/WAM
Authors: Onda Kaori , Tashiro Makoto S. , Nakagawa Yujin E. , Yamaoka Kazutaka , Terada Yukikatsu , Ohno Masanori , Sugita Satoshi , Sakamoto Takanori , Toma Kenji , Gandhi Poshak , Kodaka Natsuki , Iwakiri Wataru , Urata Yuji , Yamauchi Makoto , Fukazawa Yasushi
Published: March 2014

Time-resolved spectral analyses of GRB 070125 with significant photon detections over the MeV regime using Suzaku/WAM data are reported. The prompt emission interval was divided into 10 time regions, and their spectra were reproduced by a Band function or a cutoff power-law model. The spectra show a complex evolution; a soft-hard-soft trend is seen, rather than a typical hard-to-soft monotonic variation. In addition, a flat spectral slope in the low-energy band exceeding the slope expected from a simple synchrotron emission model is suggested in one of the time regions. These results imply that the internal shocks in the relativistic jet of GRB 070125 have different physical conditions. There is a possible excess at $\sim $ 2.2 MeV in the spectrum of 33 seconds after the trigger at a significant level of $\approx $98.5%, where the continuum spectrum is not reproduced by the Band function. These properties are only shown during the short prompt time interval of the prompt emission, and emphasize the utility of the Suzaku/WAM for the study of gamma-ray bursts.
Trapped, Two-Armed, Nearly Vertical Oscillations in Polytropic Disks
Authors: Kato Shoji
Published: March 2014

We have examined the trapping of two-armed nearly vertical oscillations in polytropic disks. Two-armed nearly vertical oscillations are interesting in the sense that they are trapped in an inner region of disks with proper frequencies, if the inner edge of disks is a boundary that reflects oscillations. The frequencies of the trapped oscillations cover the frequency range of kHz quasi-periodic oscillations (QPOs) to low-frequency QPOs in low-mass X-ray binaries (LMXBs), depending on the modes of oscillations. Low-frequency trapped oscillations are particularly interesting since their trapped region is wide. These low-frequency oscillations are, however, present only when $\mathit{\Gamma}$($\equiv $1 $+$ 1$/N$) is close to, but smaller than, 4$/$3 (when spin parameter $a_*$ is zero), where $N$ is the polytropic index. The above critical value, 4$/$3, slightly increases as $a_*$ increases.
Multiband Photopolarimetric Monitoring of an Outburst of the Blazar 3C 454.3 in 2007
Authors: Sasada Mahito , Uemura Makoto , Arai Akira , Fukazawa Yasushi , Kawabata Koji S. , Ohsugi Takashi , Yamashita Takuya , Isogai Mizuki , Nagae Osamu , Uehara Takeshi , Mizuno Tsunefumi , Katagiri Hideaki , Takahashi Hiromitsu , Sato Shuji , Kino Masaru
Published: March 2014

We report on optical—near-infrared photopolarimetric observations of a blazar 3C 454.3 over 200 d. The object experienced an optical outburst in 2007 July. This outburst was followed by a short state fainter than $V =$ 15.2 mag, lasting $\sim $25 d. The object then entered an active state during which we observed short flares having a timescale of 3–10 d. The object showed two types of features in the color–magnitude relationship. One was a “bluer-when-brighter” trend in the outburst state, and the other was a “redder-when-brighter” trend in the faint state. These two types of features suggest a contribution of thermal emission to the observed flux, as suspected in previous studies. Our polarimetric observation detected two episodes of rotation of the polarization vector. The first one was a counterclockwise rotation in the $QU$ plane during the outburst state. After this rotation event of the polarization vector, the object entered a rapidly fading stage. The second one was seen in a series of flares during the active state. Each flare had a specific position angle of polarization, which apparently rotated clockwise from the first to the last flares. Thus, the object exhibited rotations of the polarization vector in opposite directions. We estimated a decay timescale of the short flares during the active state, and then calculated an upper limit of the strength of the magnetic field, $B =$ 0.2 G, assuming a typical beaming factor of blazars, $\delta =$ 20. This upper limit of $B$ is smaller than those previously estimated from spectral analysis.
The Spectral Features of Disk and Corona with Mass Evaporation in the Low/Hard State
Authors: Qiao Erlin , Liu Bi Fang
Published: March 2014

We investigate the spectral features of accretion flows composed of an outer cool, optically thick disk and inner hot, optically thin, advection dominated accretion flows (ADAF) within the framework of disk and corona with mass evaporation (Liu et al. 2002a, ApJ, 575, 117). In this work, both the magnetic field and Compton scattering of soft photons from the disk by electrons in the corona are included to calculate the evaporation rates at different distances. The disk is truncated at the distance where the evaporation rate equals to the accretion rate [$\dot m_{\rm evap}$($r_{\rm tr}$) $= \dot m$]. For a series of accretion rates, the corresponding truncation radii are calculated out, with which we are able to calculate the emergent spectra from the inner ADAF $+$ outer disk $+$ corona. At very low accretion rates, the spectra are similar to that of a pure ADAF because the disk is truncated at large distances. The disk component becomes important at high accretion rates since the truncation occurs at small distances. An anti-correlation between the Eddington ratio, $\xi \equiv L_{0.5-25 \ {\rm keV}}/L_{\rm Edd}$, and the hard X-ray photon index, $\Gamma_{3-25 \ {\rm keV}}$, in low/hard states is predicted by the model. Comparing the theoretical results with observations, we find that our model can reproduce the anti-correlation between the Eddington ratio, $\xi$, and the hard X-ray photon index observed for the X-ray binary XTE J1118$+$480.
Orbital Period Change of the Eclipsing Binary System SZ Piscium
Authors: Wang Xiao-Liang , Xiang Fu-Yuan , Tian Yong-Po , Shi Xiao-Min
Published: March 2014

We collected and tabulated all available times of the light minimum of the eclipsing RS CVn-type binary system SZ Psc that we could find in the literature. The $O-C$ curve was constructed by means of a weighted least-squares method. It was found that a sinusoidal variation, with a period of 55.5 yr and an amplitude of 0.$^{\rm d}$2667, is superimposed on a long-term period decrease at a rate of $dP/dt = -$(2.7$\pm $0.2) $\times$ 10$^{-8} $days$/$day. Since one component of SZ Psc is a late-type star, which shows strong Ca II H & K emission lines, the orbital period variation may be caused by the magnetic activity of the system.
X-Ray Spectroscopy of Galactic Hot Gas along the PKS 2155$-$304 Sight Line
Authors: Hagihara Toshishige , Yao Yangsen , Yamasaki Noriko Y. , Mitsuda Kazuhisa , Wang Q. Daniel , Takei Yoh , Yoshino Tomotaka , McCammon Dan
Published: March 2014

We present a detailed spectroscopic study of the hot gas in the Galactic halo toward the direction of a blazer PKS 2155$-$304 ($z =$ 0.117). The O VII and O VIII absorption lines were measured with the Low and High Energy Transmission Grating Spectrographs aboard Chandra, and the O VII, O VIII, and Ne IX emission lines produced in an adjacent field of the PKS 2155$-$304 direction were observed with the X-ray Imaging Spectrometer aboard Suzaku. Assuming vertically exponential distributions of the gas temperature and the density, we performed a combined analysis of the absorption and emission data. The gas temperature and the density at the galactic plane were determined to be (2.5$^{+0.6}_{-0.3}$) $\times$ 10$^{6} $K and ($1.4^{+0.5}_{-0.4}$) $\times$ 10$^{-3} $cm$^{-3} $, and the scale heights of the gas temperature and density were 5.6$^{+7.4}_{-4.2}$ kpc and 2.3$^{+0.9}_{-0.8}$ kpc, respectively. These values are consistent with those obtained in the LMC X-3 direction.
Prospects for a Very High-Energy Blazar Survey by the Next-Generation Cherenkov Telescopes
Authors: Inoue Yoshiyuki , Totani Tomonori , Mori Masaki
Published: March 2014

The prospects for future blazar surveys by next-generation very high-energy (VHE) gamma-ray telescopes, such as Advanced Gamma-ray Imaging System (AGIS) and Cherenkov Telescope Array (CTA), are investigated using the latest model of blazar luminosity function and its evolution, which is in good agreement with the flux and redshift distribution of observed blazars as well as the extragalactic gamma-ray background. We extend and improve the template of spectral energy distributions (SEDs) based on the blazar SED sequence paradigm, to make it reliable also in the VHE bands (above 100 GeV) by comparing with the existing VHE blazar data. Assuming the planned CTA sensitivities, a blind survey using a total survey time of $\sim\ $100 hr could detect $\sim\ $3 VHE blazars, with larger expected numbers for wider/shallower surveys. We also discuss a following-up of Fermi blazars. The detectability of VHE blazars in the plane of the Fermi flux and redshift is presented, which would be useful for future survey planning. Prospects and strategies are discussed to constrain the extragalactic background light (EBL) by using the absorption feature of brightest blazar spectra, as well as cut-offs in the redshift distribution. We will be able to get useful constraints on EBL by VHE blazars at different redshifts ranging 0.3–1 TeV corresponding to $z =$ 0.10–0.36.
The Mass Distribution of SDSS J1004$+$4112 Revisited
Authors: Oguri Masamune
Published: March 2014

We present a strong lens analysis of SDSS J1004$+$4112, a unique quasar lens produced by a massive cluster of galaxies at $z =$ 0.68, using newly developed software for gravitational lensing. We find that our parametric mass model well reproduces all observations, including the positions of quasar images as well as those of multiply imaged galaxies with measured spectroscopic redshifts, time delays between quasar images, and the positions of faint central images. The predicted large total magnification of $\mu \sim$ 70 suggests that the lens system is indeed a useful site for studying the fine structure of a distant quasar and its host galaxy. The dark halo component is found to be unimodal, centered on the brightest cluster galaxy and the Chandra X-ray surface brightness profile. In addition, the orientation of the halo component is quite consistent with those of the brightest cluster galaxy and member galaxy distribution, implying that the lensing cluster is a relaxed system. The radial profile of the best-fit mass model is in good agreement with a mass profile inferred from the X-ray observation. While the inner radial slope of the dark halo component is consistent with being $-$1, a clear dependence of the predicted A–D time delay on the slope indicates that an additional time-delay measurement will improve constraints on the mass model.
Substellar Companions to Evolved Intermediate-Mass Stars: HD 145457 and HD 180314
Authors: Sato Bun’ei , Omiya Masashi , Liu Yujuan , Harakawa Hiroki , Izumiura Hideyuki , Kambe Eiji , Toyota Eri , Murata Daisuke , Lee Byeong-Cheol , Masuda Seiji , Takeda Yoichi , Yoshida Michitoshi , Itoh Yoichi , Ando Hiroyasu , Kokubo Eiichiro , Ida Shigeru , Zhao Gang , Han Inwoo
Published: March 2014

We report on the detection of two substellar companions orbiting around evolved intermediate-mass stars by precise Doppler measurements at Subaru Telescope and Okayama Astrophysical Observatory. HD 145457 is a K0 giant with a mass of 1.9$\ M_{\odot}$, and has a planet of minimum mass, $m_2$ sin $i =$ 2.9$\ M_{\rm J}$, orbiting with a period of $P=176$ d and eccentricity of $e=0.11$. HD 180314 is also a K0 giant with 2.6$\ M_{\odot}$, and hosts a substellar companion of $m_2$ sin $i =$ 22$\ M_{\rm J}$, which falls in the brown-dwarf mass regime, in an orbit with $P =$ 396 d and $e =$ 0.26. HD 145457 b is one of the innermost planets and HD 180314 b is the seventh candidate of a brown-dwarf-mass companion found around evolved intermediate-mass stars.
Oscillations in G-Type Giants
Authors: Ando Hiroyasu , Tsuboi Yusuke , Kambe Eiji , Sato Bun’ei
Published: March 2014

Precise radial-velocity measurements of 4 G-type giants, 11 Com, $\zeta$ Hya, $\epsilon$ Tau, and $\eta$ Her, were carried out. Short-term variations with amplitudes of 1–7 m s$^{-1}$ and periods of 3–10 hr were detected. A period analysis shows that the individual power distribution has a Gaussian shape, and that their peak frequencies ($\nu_{\rm max}$) are in a good agreement with a prediction by the scaling law. With using a pre-whitening procedure, significant frequency peaks of more than 3$\ \sigma$ were extracted for these giants. From these peaks, we determined the large frequency separation by constructing the highest peak distribution of the collapsed power spectrum, which is also in good agreement with what the scaling law for the large separation predicts. Echelle diagrams of the oscillation frequency were created based on the extracted large separations, which is very useful to clarify the properties of the oscillation modes. In these echelle diagrams, odd-even mode sequences are clearly seen. Therefore, it is certain that in these G-type giants, non-radial modes are detected in addition to the radial mode. As a consequence, these properties of oscillation modes are shown to follow what Dziembowski et al. (2001, MNRAS, 328, 601) and Dupret et al. (2009, A&A, 506, 57) theoretically predicted. The damping times for these giants were estimated with the same method as that developed by Stello et al. (2004, Sol. Phys., 220, 207). The relation of the $Q$-value (ratio of damping time to period) to the period was discussed by adding data of other stars, ranging from dwarfs to giants.
Spicule Dynamics over a Plage Region
Authors: Anan Tetsu , Kitai Reizaburo , Kawate Tomoko , Matsumoto Takuma , Ichimoto Kiyoshi , Shibata Kazunari , Hillier Andrew , Otsuji Kenichi , Watanabe Hiroko , UeNo Satoru , Nagata Shin’ichi , Ishii Takako T. , Komori Hiroyuki , Nishida Keisuke , Nakamura Tahei , Isobe Hiroaki , Hagino Masaoki
Published: March 2014

We studied spicular jets over a plage area and derived their dynamic characteristics using Hinode Solar Optical Telescope (SOT) high-resolution images. A target plage region was near to the west limb of the solar disk. This location permitted us to study the dynamics of spicular jets without any overlapping effect of spicular structures along the line of sight. In this work, to increase the ease with which we could identify spicules on the disk, we applied the image processing method ‘MadMax’ developed by Koutchmy et al. (1989). It enhances fine, slender structures (like jets), over a diffuse background. We identified 169 spicules over the target plage. This sample permited us to derive statistically reliable results regarding spicular dynamics. The properties of plage spicules can be summarized as follows: (1) In a plage area, we clearly identified spicular jet features. (2) They were shorter in length than the quiet region limb spicules, and followed a ballistic motion under constant deceleration. (3) The majority (80%) of the plage spicules showed a cycle of rise and retreat, while 10% of them faded out without a complete retreat phase. (4) The deceleration of the spicule was proportional to the velocity of ejection (i.e., the initial velocity).
Ca II K Spectral Study of an Emerging Flux Region using the Domeless Solar Telescope in Hida Observatory
Authors: Otsuji Kenichi , Kitai Reizaburo , Matsumoto Takuma , Ichimoto Kiyoshi , UeNo Satoru , Nagata Shin’ichi , Isobe Hiroaki , Shibata Kazunari
Published: March 2014

A cooperative observation with Hida Observatory and the Hinode satellite was performed on an emerging flux region. Successive Ca II K spectro-heliograms of the emerging flux region were taken by the Domeless Solar Telescope of Hida Observatory. Hinode observed the emerging flux region with Ca II H and FeI Stokes IQUV filtergrams. In this study, detailed dynamics and the temporal evolution of the magnetic flux emergence was studied observationally. The event was first detected in the photospheric magnetic field signals; 3 minutes later, a horizontal expansion of the dark area was detected. Then, 7 minutes later than the horizontal expansion, the emerging loops were detected with a maximal rise speed of 2.1 km s$^{-1}$ at chromospheric heights. The observed dynamics of the emerging magnetic flux from the photosphere to the upper chromosphere was very consistent with the results of previous simulation studies. A gradual rising phase of flux tubes with a weak magnetic strength was confirmed by our observation.
Observations of Chromospheric Anemone Jets with Hinode Ca II Broadband Filtergraph and Hida Ca II Spectroheliograph
Authors: Morita Satoshi , Shibata Kazunari , UeNo Satoru , Ichimoto Kiyoshi , Kitai Reizaburo , Otsuji Ken-ichi
Published: March 2014

We report on the first simultaneous observations of chromospheric “anemone” jets in solar active regions with the Hinode Solar Optical Telescope (SOT) Ca II H broadband filtergraph and the Ca II K spetroheliograph on the Domeless Solar Telescope (DST) at Hida Observatory. During the period of coordinated observations, nine chromospheric anemone jets were simultaneously observed with the two instruments. These observations revealed three important features: (1) the jets are generated in the lower chromosphere; i.e., these cannot be seen in Ca II K$_{3}$; (2) the length and lifetime of the jets are 0.4–5 Mm and 40–320 s, respectively; (3) the apparent velocity of the jets observed with the SOT is 3–24 km s$^{-1}$, while the Ca II K$_{3}$ component at the jets shows a blueshift (in 5 events) in the range of 2–6 km s$^{-1}$. The chromospheric anemone jets are associated with mixed polarity regions, which are either small emerging flux regions or moving magnetic features. It is found that the Ca II K line often shows red or blue asymmetry in the K$_{2}$/K$_{1}$ component; the footpoint of the jets associated with emerging flux regions often shows a redshift (2–16 km s$^{-1}$), while the one with moving magnetic features shows a blueshift ($\sim\ $5 km s$^{-1}$). A detailed analysis of the magnetic evolution of the jet-forming regions revealed that the reconnection rate (or canceling rate) of the total magnetic flux at the footpoint of the jets is on the order of 10$^{16}\ $Mx s$^{-1}$, and the resulting magnetic energy release rate is (1.1–10) $\times$ 10$^{24}\ $erg s$^{-1}$, with a total energy release of (1–13) $\times$ 10$^{26}\ $erg for the duration of the magnetic cancellation, $\sim\ $130 s. These are comparable to the estimated total energy, $\sim\ $10$^{26}\ $erg, in a single chromospheric anemone jet. In addition to the DST Ca II K spectroheliogram and the SOT Ca II H broadband filtergram, we also used for analysis an SOT magnetogram as well as a Hida H$\alpha $ filtergram. We present a physical model of the jet based on the observation, and discuss the relation between chromospheric anemone jets and Ellerman bombs.
Modeling the Gamma-Ray Emission Produced by Runaway Cosmic Rays in the Environment of RX J1713.7$-$3946
Authors: Casanova Sabrina , Jones David I. , Aharonian Felix A. , Fukui Yasuo , Gabici Stefano , Kawamura Akiko , Onishi Toshikazu , Rowell Gavin , Sano Hidetoshi , Torii Kazufumi , Yamamoto Hiroaki
Published: March 2014

Diffusive shock acceleration in supernova remnants is the most widely invoked paradigm to explain the Galactic cosmic ray spectrum. Cosmic rays escaping from supernova remnants diffuse into the interstellar medium and collide with the ambient atomic and molecular gas. From such collisions gamma-rays are created, which can possibly provide the first evidence of a parent population of runaway cosmic rays. We present model predictions for the GeV to TeV gamma-ray emission produced by the collisions of runaway cosmic rays with the gas in the surroundings of the shell-type supernova remnant RX J1713.7$-$3946. The spectral and spatial distributions of the emission, which depend upon the source age, the source injection history, the diffusion regime, and the distribution of the ambient gas, as mapped by the LAB and NANTEN surveys, are studied in detail. For the surrounding region of RX J1713$-$3946 in particular, we find out that it depends on the energy band one is observing whether one may observe startlingly different spectra or may not detect any enhanced emission with respect to the diffuse emission contributed by background cosmic rays. This result has important implications for current and future gamma-ray experiments.
The Primordial Origin Model of Magnetic Fields in Spiral Galaxies
Authors: Sofue Yoshiaki , Machida Mami , Kudoh Takahiro
Published: March 2014

We propose a primordial-origin model for composite configurations of global magnetic fields in spiral galaxies. We show that a uniform tilted magnetic field wound up into a rotating disk galaxy can evolve into composite magnetic configurations comprising bisymmetric spiral (S $=$ BSS), axisymmetric spiral (A $=$ ASS), plane-reversed spiral (PR), and/or ring (R) fields in the disk, and vertical (V) fields in the center. By MHD simulations we show that these composite galactic fields are indeed created from a weak primordial uniform field, and that different configurations can co-exist in the same galaxy. We show that spiral fields trigger the growth of two-armed gaseous arms. The centrally accumulated vertical fields are twisted and produce a jet toward the halo. We found that the more vertical was the initial uniform field, the stronger was the formed magnetic field in the galactic disk.
Evolution of the Kippenhahn–Schlüter Prominence Model Magnetic Field under Cowling Resistivity
Authors: Hillier Andrew , Shibata Kazunari , Isobe Hiroaki
Published: March 2014

We present the results from 1.5D diffusion simulations of the Kippenhahn–Schlüter prominence model magnetic field evolution under the influence of the ambipolar terms of Cowling resistivity. We show that initially the evolution is determined by the ratio of the horizontal and vertical magnetic fields, which gives current sheet thinning (thickening) when this ratio is small (large) and a marginal case where a new characteristic current sheet length scale is formed. After a timespan greater than the Cowling resistivity time, the current sheet thickens as a power law of $t$ independent of the ratio of the field strengths. These results imply that when Cowling resistivity is included in the model, the tearing instability time scale is reduced by more than one order of magnitude when the ratio of the horizontal field to the vertical field is 20% or less. These results imply that, over the course of its lifetime, the structure of the prominence can be significantly altered by Cowling resistivity, and in some cases will allow the tearing instability to occur.
Absolute Dimensions and Apsidal Motion of the Young Detached System LT Canis Majoris
Authors: Bakiş Volkan , Bulut İbrahim , Bilir Selçuk , Bakiş Hicran , Demircan Osman , Hensberge Herman
Published: March 2014

New high-resolution spectra of the short-period ($P \sim$ 1.76 days) young detached binary LT CMa are reported for the first time. By combining the results from an analysis of new radial-velocity curves and published light curves, we determine values for the masses, radii, and temperatures as follows: $M_{\rm 1} =$ 5.59 (0.20)$\ M_{\odot}, R_{\rm 1} =$ 3.56 (0.07)$\ R_{\odot}$, and $T_{\rm eff1} =$ 17000 (500) K for the primary and $M_{\rm 2} =$ 3.36 (0.14)$\ M_{\odot}, R_{\rm 2} =$ 2.04 (0.05)$\ R_{\odot}$, and $T_{\rm eff2} =$ 13140 (800) K for the secondary. Static absorbtion features apart from those coming from the close binary components were detected in the several spectral regions. If these absorbtion features are from a third star, as the light-curve solutions support, its radial velocity is measured to be $RV_{\rm 3} =$ 70 (8) km s$^{-1}$. The orbit of the binary system has been proved to be eccentric ($e =$ 0.059) and thus apsidal motion exists. The estimated linear advance in longitude of periastron corresponds to an apsidal motion of $U =$ 69$\ \pm\ $5 yr for the system. The average internal structure constant, log $k_{\rm 2,obs} = -$2.53 of LT CMa, is found to be smaller than its theoretical value of log $k_{\rm 2,theo} = -$2.22, suggesting that the stars would have a more central concentration in mass. The photometric distance of LT CMa ($d =$ 535$\ \pm\ $45 pc) is found to be much smaller than the distance of the CMa OB1 association (1150 pc), which rules out membership. A comparison with current stellar evolution models for solar metallicity indicates that LT CMa (35 Myr) is much older than the CMa OB1 association (3 Myr), confirming that LT CMa is not a member of CMa OB1. Kinematical and dynamical analyses indicate that LT CMa is orbiting the Galaxy in a circular orbit, and belongs to the young thin-disk population.
Suzaku Observations of the Supernova Remnant N23 in the Large Magellanic Cloud
Authors: Someya Kentaro , Bamba Aya , Ishida Manabu
Published: March 2014

X-ray emission from the supernova remnant N23 in the Large Magellanic Cloud (LMC) has been studied using the X-ray Imaging Spectrometer (XIS) onboard Suzaku. Thanks to a superior energy resolution of the XIS in the soft X-ray band, we resolved H-like and He-like Oxygen K$\alpha$ emission lines from N23 with unprecedentedly high quality, and as a result, identified a new optically thin thermal emission component with a temperature of $\sim\ $0.2 keV, as well as that with a temperature of $\sim\ $0.5–0.7 keV, previously known. This alters the estimate of the ionization timescale, $n_{\rm e}t$, from $\sim\ $10$^{10-11}\ $cm$^{-3}\ $s to $\gtrsim\ $10$^{12}\ $cm$^{-3}\ $s. Under the assumption that N23 is still in the Sedov phase, its age, evaluated from the newly discovered low-temperature component, is $\sim\ $8000 yr, although it is possible that N23 has already moved into the radiative phase. The abundances of the heavy elements are found to be roughly consistent with those of the LMC average, which indicates that the origin of the X-ray emission of N23 is swept-up ambient material, as expected from its ionization timescale.
A New System Noise Measuring Method Using a 2-Bit Analog-to-Digital Converter
Authors: Nakatake Aki , Kameno Seiji , Takeda Koji
Published: March 2014

We propose a new measuring method for the system noise temperature, $T_{\rm sys}$, using a 2-bit analog-to-digital converter (ADC). Statistics of the digitized signal in a four-level quantization gives us information about the bias voltage and the variance, which reflects the power of the input signal. A comparison of the variances in hot and sky circumstances yields $T_{\rm sys}$ without a power meter. We performed experimental tests using the Kagoshima 6 m radio telescope and a 2-bit ADC. The linearity in the power–variance relation was better than 99% within the dynamic range of 10 dB. Digitally measured $T_{\rm sys}$ was in agreement with that of a conventional measurement with a power meter, although the temperatures differed by 1.8%, or less, for elevations of 10$^{\circ}$–88$^{\circ}$. No significant impact was found by the bias voltages within a range of $-$3.7% to $+$12.8% with respect to the threshold voltage. The proposed method is available for existing interferometers that have a multilevel ADC, and release us from troubles caused by power meters.
Astrometry of H$_{2}$ O Masers in Nearby Star-Forming Regions with VERA. IV. L 1448 C
Authors: Hirota Tomoya , Honma Mareki , Imai Hiroshi , Sunada Kazuyoshi , Ueno Yuji , Kobayashi Hideyuki , Kawaguchi Noriyuki
Published: March 2014

We have carried out multi-epoch VLBI observations with VERA (VLBI Exploration of Radio Astrometry) of 22 GHz H$_{2}$ O masers associated with a Class 0 protostar, L 1448 C, in the Perseus molecular cloud. The maser features trace the base of a collimated bipolar jet driven by one of the infrared counter parts of L 1448 C, named as L 1448 C(N) or L 1448-mm A. We detected possible evidence for apparent acceleration and precession of the jet according to the three-dimensional velocity structure. Based on phase-referencing VLBI astrometry, we successfully detected an annual parallax of the H$_{2}$ O maser in L 1448 C to be 4.31$\ \pm\ $ 0.33 milliarcseconds (mas), which corresponds to a distance of 232$\ \pm\ $ 18 pc from the Sun. The present result is in good agreement with that of another H$_{2}$ O maser source, NGC 1333 SVS 13, in the Perseus molecular cloud, 235 pc. It is also consistent with the photometric distance, 220 pc. Thus, the distance to the western part of the Perseus molecular cloud complex would be constrained to be about 235 pc, rather than a larger value, 300 pc, previously reported.
Measurements of Transit Timing Variations for WASP-5b
Authors: Fukui Akihiko , Narita Norio , Tristram Paul J. , Sumi Takahiro , Abe Fumio , Itow Yoshitaka , Sullivan Denis J. , Bond Ian A. , Hirano Teruyuki , Tamura Motohide , Bennett David P. , Furusawa Kei , Hayashi Fumiya , Hearnshaw John B. , Hosaka Shun , Kamiya Koki , Kobara Shuhei , Korpela Aarno , Kilmartin Pam M. , Lin Wei , Ling Cho Hong , Makita Shota , Masuda Kimiaki , Matsubara Yutaka , Miyake Noriyuki , Muraki Yasushi , Nagaya Maiko , Nishimoto Kenta , Ohnishi Kouji , Omori Kengo , Perrott Yvette , Rattenbury Nicholas , Saito Toshiharu , Skuljan Ljiljana , Suzuki Daisuke , Sweatman Winston L. , Wada Kohei
Published: March 2014

We observed 7 new transits of the “hot Jupiter” WASP-5b using a 61 cm telescope located in New Zealand, in order to search for transit timing variations (TTVs), which can be induced by additional bodies existing in the system. Combining them with other available photometric and radial velocity (RV) data, we find that its transit timings do not match a linear ephemeris; the best-fit $\chi^2$ value is 32.2 with 9 degrees of freedom, which corresponds to a confidence level of 99.982% or 3.7 $\sigma$. This result indicates that excess variations of transit timings have been observed, either due to unknown systematic effects, or possibly due to real TTVs. The TTV amplitude is as large as 50 s, and if this is real it cannot be explained by some effect other than an additional body, or bodies. From RV data, we put an upper limit on the RV amplitude caused by a possible secondary body (planet) as 21 m s$^{-1}$, which corresponds to its mass of 22–70$\ M_{\oplus}$ over the orbital period ratio of the two planets from 0.2 to 5.0. From the TTV data, using numerical simulations, we narrowed the limits down to 2$\ M_{\oplus}$ near 1:2 and 2:1 mean-motion resonances (MMRs) with WASP-5b at the 3$\sigma$ level, assuming that the two planets are co-planer. We also put an upper limit of 43$\ M_{\oplus}$ (3$\sigma$) on excess of Trojan mass using both RV and photometric data. We also find that if the orbit of the possible secondary planet is a circle or an ellipse of small eccentricity, it would be likely an orbit near that of low-order MMRs.
Physical Properties of the Transiting Planetary System TrES-3
Authors: Lee Jae Woo , Youn Jae-Hyuck , Kim Seung-Lee , Lee Chung-Uk , Koo Jae-Rim
Published: March 2014

We present four new transits of the planetary system TrES-3 observed between 2009 May and 2010 June. Among these, the third transit by itself indicates possible evidence for brightness disturbance, which might be a result of the planet blocking a cool starspot on the stellar surface. A total of 109 transit times, including our measurements, were used to determine the improved ephemeris with a transit epoch of 2454185.910944$\ \pm\ $0.000072 HJED and an orbital period of 1.30618700$\ \pm\ $0.00000015 d. We analyzed the transit light curves using the JKTEBOP code and adopting the quadratic limb-darkening law. In order to derive the physical properties of the TrES-3 system, the transit parameters were combined with the empirical relations from eclipsing binary stars and stellar evolutionary models. The stellar mass and radius obtained from a calibration using $T_{\rm A}$, log$\ \rho_{\rm A}$, and [Fe$/$H] are consistent with those from an isochrone analysis. We found that the exoplanet TrES-3b has a mass of 1.93$\ \pm\ $0.07$\ M_{\rm Jup}$, a radius of 1.30$\ \pm\ $0.04$\ R_{\rm Jup}$, a surface gravity of log$\ g_{\rm b}$$=$ 3.45$\ \pm\ $0.02, a density of 0.82$\ \pm\ $0.06 $\rho_{\rm Jup}$, and an equilibrium temperature of 1641$\ \pm\ $23 K. The results are in good agreement with theoretical models for gas giant planets.
Astrometry of AGB Variables with VERA: Annual Parallax and the Orbit of SY Sculptoris in the Galaxy
Authors: Nyu Daisuke , Nakagawa Akiharu , Matsui Makoto , Imai Hiroshi , Sofue Yoshiaki , Omodaka Toshihiro , Kurayama Tomoharu , Kamohara Ryuichi , Hirota Tomoya , Honma Mareki , Shibata Katsunori M. , Kobayashi Hideyuki , Iwadate Kenzaburo , Miyaji Takeshi
Published: March 2014

We report on the results of astrometric observations of H$_{2}$O masers toward a Mira variable, SY Sculptoris (SY Scl), with the VLBI Exploration of Radio Astrometry (VERA) from 2006 October to 2008 October. We determined that SY Scl's annual parallax is 0.75$\ \pm\ $0.03 mas, corresponding to a distance of 1.33$\ \pm\ $0.05 kpc. SY Scl is 1.3 kpc south of the Galactic plane and moves approximately south from the plane with a velocity of 63$\ \pm\ $2 km s$^{-1}$ with respect to the LSR. From the present position and motion, we calculated SY Scl's orbit for the last 1 Gyr based on a parametrized model of the Galactic gravitational potential. SY Scl has an orbit as a member of the Galactic thick disk stars. Subtracting the averaged absolute proper motions of masers, we derived an internal motion of H$_2$O masers in SY Scl. The kinematics of the masers is consistent with motion in a single plane. The masers around SY Scl were found to be distributed in an area of 70 AU $\times$ 80 AU, corresponding to 15 times as large as the stellar photosphere diameter of 5 AU. Based on the measured distance and apparent magnitude of SY Scl, we find the absolute magnitude of SY Scl to be $M_K$$=$$-$8.07$\ \pm\ $0.08 mag. This is approximately consistent with the value of $-$8.09$\ \pm\ $0.07 mag, which was derived from the Galactic Mira period–luminosity relation (2008, MNRAS, 386, 313).
Astrometry of H2O Masers in the Massive Star-Forming Region IRAS 06061+2151 with VERA
Authors: Niinuma Kotaro , Nagayama Takumi , Hirota Tomoya , Honma Mareki , Motogi Kazuhito , Nakagawa Akiharu , Kurayama Tomoharu , Kan-Ya Yukitoshi , Kawaguchi Noriyuki , Kobayashi Hideyuki , Ueno Yuji
Published: March 2014

We measured the trigonometric annual parallax of an H$_2$O maser source associated with the massive star-forming region IRAS 06061$+$2151 with VERA. The annual parallax of 0.496$\ \pm\ $0.031 mas, corresponding to a distance of 2.02$^{+0.13}_{\-0.12}\ $kpc, was obtained by 10 epochs of observations during the period from 2007 October to 2009 September. This distance was obtained more accurately than the photometric one previously measured, and places IRAS 06061$+$2151 in the Perseus spiral arm. We found that IRAS 06061$+$2151 also has a peculiar motion of larger than 15 km s$^{-1}$ which is counter to the Galactic rotation. This is similar to the motions of five sources in the Perseus spiral arm, whose parallaxes and proper motions have already been measured with satisfactory accuracy. Moreover, these sources move with an average of 27 km s$^{-1}$ toward the Galactic center and counter to the Galactic rotation.
An Implicit Scheme for Ohmic Dissipation with Adaptive Mesh Refinement
Authors: Matsumoto Tomoaki
Published: March 2014

An implicit method for the ohmic dissipation is proposed. The proposed method is based on the Crank–Nicolson method and exhibits second-order accuracy in time and space. The proposed method has been implemented in the SFUMATO adaptive mesh refinement (AMR) code. The multigrid method on the grids of the AMR hierarchy converges the solution. The convergence is fast but depends on the time step, resolution, and resistivity. Test problems demonstrated that decent solutions are obtained even at the interface between fine and coarse grids. Moreover, the solution obtained by the proposed method shows good agreement with that obtained by the explicit method, which required many time steps. The present method reduces the number of time steps, and hence the computational costs, as compared with the explicit method.
Effect of Irradiation on the Disk of the Epsilon Aurigae System
Authors: Takeuti Mine
Published: March 2014

The epsilon Aurigae system consists of a luminous F star and a dusty disk surrounding an unseen object. The obscuring body for the eclipse, which occurs every 27 years, is the dusty disk. Light-variation and spectroscopic features are affected by the physical properties of the disk. To study the properties of the disk, a simplified model including the irradiation of the F star and the rotation of the disk is presented. The maximum temperature depends on the transmissivity of the edge toward the F star, and the heat capacity of irradiated portion determines the temperature of the dark side of disk. The large heat capacity of the edge produces remarkable asymmetry on the temperature of the edge, and also on the thickness of the irradiated edge. The observed asymmetry of the light curve and the absorption lines is comparable to the properties of the rotating-disk model.
The Millimeter Sky Transparency Imager (MiSTI)
Authors: Tamura Yoichi , Kawabe Ryohei , Kohno Kotaro , Fukuhara Masayuki , Momose Munetake , Ezawa Hajime , Kuboi Akihito , Sekiguchi Tomohiko , Kamazaki Takeshi , Vila-VilarÓ Baltasar , Nakagawa Yuki , Okada Norio
Published: March 2014

The Millimeter Sky Transparency Imager (MiSTI) is a small millimeter-wave scanning telescope with a 25-cm diameter dish operating at 183 GHz. MiSTI is installed at Atacama, Chile, and it measures emission from atmospheric water vapor and its fluctuations to estimate atmospheric absorption in the millimeter to submillimeter range. MiSTI observes the water vapor distribution at a spatial resolution of 0$^\circ\!\!\!.$5, and it is sensitive enough to detect an excess path length of $\lesssim\ $0.05 mm for an integration time of 1 s. By comparing the MiSTI measurements with those by a 220 GHz tipper, we validated that the 183 GHz measurements of MiSTI are correct, down to the level of any residual systematic errors in the 220 GHz measurements. Since 2008, MiSTI has provided real-time (every 1 hr) monitoring of the all-sky opacity distribution and atmospheric transmission curves in the (sub)millimeter through the internet, allowing us to know the (sub)millimeter sky conditions at Atacama.