bluuebunny/crossref_metadata_2025 huggingface dataset:
A Deep Optical Observation for an Enigmatic Unidentified Gamma-Ray Source 3EG J1835+5918
Authors: Totani Tomonori , Kawasaki Wataru , Kawai Nobuyuki
Published: March 2014

We report on a deep optical imaging observation using the Subaru Telescope for a very soft X-ray source, RX J1836.2$+$5925, which has been suspected to be an isolated neutron star associated with the brightest as-yet unidentified EGRET source outside the Galactic plane, 3EG J1835$+$5918. An extended source having a complex, bipolar shape is found at $B\sim 26$, which might be an extended pulsar nebular whose flux is about 5–6 orders of magnitude lower than gamma-ray flux, although finding a galaxy of this magnitude by chance in the error circle is of order unity. We have found two even fainter, possible point sources at $B \sim 28$, although their detections are not firm because of a low signal-to-noise ratio. If the extended object of $B\sim 26$ is a galaxy and not related to 3EG J1835$+$5918, a lower limit on the X-ray/optical flux ratio can be set as $f_\mathrm{X}/f_B \gtrsim 2700$, giving further strong support for the neutron-star identification of 3EG J1835$+$5918. Interestingly, if either of the two sources at $B \sim 28$ is the real counterpart of RX J1836.2$+$5925 and thermal emission from the surface of an isolated neutron star, the temperature and distance to the source become $\sim 4 \times 10^5 \,\mathrm{K}$ and $\sim 300 \,\mathrm{pc}$, respectively, showing a striking similarity of its spectral energy distribution to the proto-type radio-quiet gamma-ray pulsar Geminga. No detection of nonthermal hard X-ray emission is consistent with the ASCA upper limit, if the nonthermal flux of $\mbox{3EG J1835$+$5918} / \mbox{RX J1836.2$+$5925}$ 3EG J1835$+$5918$/$RX J1836.2$+$5925 is at a similar level to that of Geminga.
Discovery of Extremely Large-Amplitude Quasi-Periodic Photometric Variability in a WC9-Type Wolf–Rayet Binary, WR 104
Authors: Taichi KATO , Haseda Katsumi , Yamaoka Hitoshi , Takamizawa Kesao
Published: March 2014

We discovered that the Wolf–Rayet (WR)$+$OB star binary WR 104, renowned for its associated “dusty pinwheel nebula”, recently spatially resolved with infrared interferometry, exhibits strong quasi-periodic optical variations with a full amplitude of 2.7 mag. Such a large-amplitude, continuous variation has been unprecedented in a WR star. The optical quasi-period ($\sim 241 \,\mathrm{d}$) is in almost perfect agreement with the interferometric period ($243.5 \pm 3 \,\mathrm{d}$). The remarkable agreement of the dominant period in optical variability with the orbital period supports that the strongly varying dust obscuration is physically related to the binary motion, rather than sporadic dust-forming episodes. Considering the low orbital inclination ($11^{\circ} \pm 7^{\circ}$) and the nearly circular orbit inferred from the interferometric observations, the strongly variable line-of-sight extinction suggests that the highly structured extinction might be in the process of being formed via the ejection of dust in the direction of the binary rotation axis. Another viable explanation is that the three-dimensional structure of the shock front, itself, is the obscuring body. Depending on the geometry, the dusty shock front near the conjunction phase of the binary can completely obscure the inner WR-star wind and the OB star, which can explain the amplitude of the optical fading and the past observation of remarkable spectral variation.
Reliability of Merger Tree Realizations of Dark Halos in the Monte Carlo Modeling of Galaxy Formation
Authors: Shimizu Mamoru , Kitayama Tetsu , Sasaki Shin , Suto Yasushi
Published: March 2014

We examine the reliability of the merger trees generated for the Monte Carlo modeling of galaxy formation. In particular we focus on the cold gas fraction predicted from merger trees with different assumptions on the progenitor distribution function, the timestep, and the mass resolution. We show that the cold gas fraction is sensitive to the accuracy of the merger trees at small-mass scales of progenitors at high redshifts. One can reproduce the Press–Schechter prediction to a reasonable degree by adopting a fairly large number of redshift bins, $ N_\mathrm{step}\sim 1000$, in generating merger trees, which is a factor of ten larger than the canonical value used in previous literature.
Chandra Observations and Optical Identification of Hard X-Ray Sources Discovered with ASCA
Authors: Watanabe Shin , Akiyama Masayuki , Ueda Yoshihiro , Ohta Kouji , Mushotzky Richard , Takahashi Tadayuki , Yamada Toru
Published: March 2014

We present the first results of Chandra and optical follow-up observations of hard X-ray sources detected in the ASCA Medium Sensitivity Survey (AMSS). Optical identifications were made for five objects. Three of them show either weak or absent optical narrow emission lines, and are at low redshift $ \langle z \rangle \sim 0.06$. One of them is a broad line object at $ z = 0.910$ and one is a $ z = 0.460$ object with only narrow lines. All of the narrow-line objects show strong evidence of absorption in their X-ray spectra. Their line ratios are consistent with a Seyfert II/LINER identification, as are the line widths. The three low-redshift objects have the colors of normal galaxies, and apparently the light is dominated by stars. This could be due to extinction of the underlying nuclear continuum by the same matter that absorbs X-rays and/or due to dilution of the central source by starlight. These results suggest that X-ray sources that appear as “normal” galaxies in optical and near-IR bands significantly contribute to the hard X-ray background. This population of objects has a high space density, and probably dominates the entire population of active galaxies.
Flat Spectrum X-Ray Emission from the Direction of a Molecular Cloud Associated with SNR RX J1713.7–3946
Authors: Uchiyama Yasunobu , Takahashi Tadayuki , Aharonian Felix A.
Published: March 2014

We report on the discovery of a diffuse X-ray source with ASCA, presumably associated with a molecular cloud in the vicinity of the supernova remnant RX J1713.7$-$3946. The energy spectrum (1–10 keV) of the hard X-ray source shows a flat continuum, which is described by a power-law with a photon index of $ \Gamma = 1.0^{+0.4}_{-0.3}$. We argue that this unusually flat spectrum can be best interpreted in terms of characteristic bremsstrahlung emission from the loss-flattened distribution of either sub-relativistic protons or mildly relativistic electrons. The strong shock of RX J1713.7$-$3946, which is likely to interact with the molecular cloud, as evidenced by CO-line observations, seems to be a natural site of acceleration of such nonthermal particles. The observed luminosity of $ L_\mathrm{X} = 1.7 \times 10^{35} \,\mathrm{erg} \,\mathrm{s}^{-1}$ (for a distance of 6 kpc) seems to require a huge kinetic energy of about $ 10^{50} \,\mathrm{erg}$ in the form of nonthermal particles to illuminate the cloud. The shock-acceleration at RX J1713.7$-$3946 can barely satisfy this energetic requirement, unless (i) the source is located much closer than the preferred distance of 6 kpc and/or (ii) the mechanical energy of the supernova explosion essentially exceeds $ 10^{51} \,\mathrm{erg}$. Another possibility would be that an essential part of the lost energy due to the ionization and heating of gas, is somehow converted to plasma waves, which return this energy to nonthermal particles through their turbulent reacceleration on the plasma waves.
V463 Scuti (Nova Sct 2000): Rapidly Evolving Nova with a Prominent Premaximum Halt
Authors: Kato Taichi , Uemura Makoto , Haseda Katsumi , Yamaoka Hitoshi , Takamizawa Kesao , Fujii Mitsugu , Kiyota Seiichiro
Published: March 2014

We summarize photometric and spectroscopic observations of V463 Sct (Nova Sct 2000), which was originally thought to be a red variable. The spectrum taken on 2000 March 16.81 UT showed prominent emission lines with a FHWM of $990 \,\mathrm{km} \,\mathrm{s}^{-1}$ ($\mathrm{H}\alpha$). The light curve shows a conspicuous premaximum halt lasting for at least 24d, and a late-phase flare-like maximum. The nova then started rapidly fading at a rate corresponding to $t_2 = 15 \pm 3 \,\mathrm{d}$. Long premaximum halts have been considered as a unique character of the “slowest” novae. The present observation, however, suggests that the long premaximum halts are not a unique character of the slowest novae, but a more general phenomenon spreading over a wider range of nova speed classes than has been previously believed. A recent interpretation of premaximum halts requires that the conditions of thermonuclear runaway were only marginally satisfied. Since such conditions are more difficult to meet in rapidly evolving novae, V463 Sct would provide an unique opportunity for testing this interpretation. The early post-outburst spectrum showed a co-existence of Fe II lines and some forbidden lines, which suggests that a substantial amount of material may have been ejected before the observed optical maximum. The impact of the modern global network (VSNET) on confirmatory processes of transient objects is briefly discussed.
Outburst Photometry of the Eclipsing Dwarf Nova GY Cancri
Authors: Kato Taichi , Ishioka Ryoko , Uemura Makoto
Published: March 2014

We observed the ROSAT-selected eclipsing dwarf nova GY Cnc ($= \mathrm{RX}\,\mathrm{J}0909.8{+}1849$) during the 2001 November outburst. We refined the orbital period to be 0.17544251(5)d. The fading portion of the outburst was indistinguishable from those of typical dwarf novae with similar orbital periods. However, the signature of the orbital humps (or a hot spot) was far less prominently observed in the orbital light curves and eclipse profiles than in usual dwarf novae with similar orbital periods. The combination of a low frequency of outbursts and an apparent lack of slowly rising, long outbursts in GY Cnc is difficult to reconcile within the standard framework of dwarf novae. We suspect that GY Cnc may be the first above-the-gap counterpart of the unusual eclipsing dwarf novae HT Cas and IR Com.
Dramatic Changes in the Outburst Properties in V503 Cygni
Authors: Kato Taichi , Ishioka Ryoko , Uemura Makoto
Published: March 2014

We examined the VSNET light curve of the unusual SU UMa-type dwarf nova V503 Cyg, which is known to show a short (89 d) supercycle length and exceptionally small (a few) normal outbursts within a supercycle. In 1999–2000, V503 Cyg displayed frequent normal outbursts with typical recurrence times of 7–9 d. The behavior during this period is characteristic to an usual SU UMa-type dwarf nova with a short supercycle length. On the other hand, V503 Cyg showed very infrequent normal outbursts in 2001–2002. Some of the superoutbursts during this period were observed to be shorter than usual. The remarkable alternations of the outbursting states in V503 Cyg support the presence of mechanisms of suppressing normal outbursts and prematurely quenching superoutbursts, which have been proposed to explain some unusual SU UMa-type outbursts. The observed temporal variability of the suppressing/quenching mechanisms in the same object suggests that these mechanisms are not primarily governed by a fixed system parameter, but more reflect the state changes in the accretion disk.
Spectroscopic Determination of Stellar Atmospheric Parameters: Application to Mid-F through Early-K Dwarfs and Subgiants
Authors: Takeda Yoichi , Sato Bun’ei , Kambe Eiji , Sadakane Kozo , Ohkubo Michiko
Published: March 2014

Takeda et al.–s (2002, PASJ, 54, 451) method for the spectroscopic determination of stellar atmospheric parameters ($T_\mathrm{eff}, \log g, v_\mathrm{t}$, and $[\mathrm{Fe/H}]$) from the equivalent widths of Fe I and Fe II lines was applied to 32 dwarfs/subgiants of mid-F through early-K types based on high-quality echelle spectra obtained at Okayama Astrophysical Observatory, for the purpose of examining the numerical performance of this technique as well as the precision of the results. The solutions of the parameters were confirmed to successfully converge, except for a few cases (e.g., for lower temperature and lower metallicity stars) where the microturbulent velocity could not be well determined. A comparison of the present results with the literature values, especially those of Fuhrmann (1998, AAA070.155.024), revealed that the agreement is mostly satisfactory, though a systematic tendency appears to exist that our method yields slightly lower (i.e., by $\sim 100 \,\mathrm{K}$) $T_\mathrm{eff}$ values. The results are further discussed in relation to the stellar fundamental parameters (mass, luminosity, etc.), while referring to the Hipparcos parallaxes or theoretical stellar evolutionary tracks.
Roche Potential with Luminous Accretion Disks
Authors: Fukue Jun , Hanamoto Keishi
Published: March 2014

The radiative environments of an interacting binary, which contains a luminous accretion disk, are investigated. The disk radiation field has no effect in the direction of the orbital plane, while it significantly affects in the polar direction. As the disk luminosity increases, the Roche potential around the compact star becomes hollow in the polar direction. It further crashes toward the pole, and a cone of avoidance appears at the normalized luminosity $\Gamma_\mathrm{d} \equiv L_\mathrm{d}/L_\mathrm{E} =0.5$, where $L_\mathrm{d}$ is the disk luminosity and $L_\mathrm{E}$ the Eddington luminosity of the compact star. The disk corona, the wind-fed accretion flow, and the common envelope suffer a remarkable influence by the luminous disk in active binaries. Of these, the wind-fed accretion is briefly discussed.
Statistical Method for Deriving Spatial and Size Distributions of Sub-km Main-Belt Asteroids from Their Sky Motions
Authors: Nakamura Tsuko , Yoshida Fumi
Published: March 2014

The importance of sub-kilometer-sized objects among the main-belt asteroids (MBAs) has been progressively recognized in relation to the origin of near-Earth asteroids and the formation of rubble-pile asteroids. However, exact orbit determinations of those individual objects are practically impossible, because both their discovery and subsequent follow-up observations require 8–10 m class telescopes, in which observation-time competition is severe. Therefore, we examine here instead a statistical method to deduce the spatial and size distributions of sub-km MBAs from only their apparent motion vectors on the sky. Assuming their near-opposition and near-ecliptic observations, we made simulations to estimate the accuracy of the semi-major axis ($a$) and inclination ($I$) obtained from their sky-motion vectors. The mean errors of $a$ and $I$ for each asteroid were found to be about 0.15 AU and $1^\circ \hbox{--} 2^\circ$ (for the asteroids with $I<10^\circ$), respectively. Then, under a certain assumption, we calculated magnitudes and the size distribution of those computer-synthesized sub-km MBAs. Our statistical method could reproduce the slope of the cumulative size distribution for the original asteroid populations with errors of $\sim0.05 \hbox{--} 0.1$. These values are small enough for our survey purposes using the Subaru Telescope.
Decomposition of the Superwind in M 82
Authors: Ohyama Youichi , Taniguchi Yoshiaki , Iye Masanori , Yoshida Michitoshi , Sekiguchi Kazuhiro , Takata Tadafumi , Saito Yoshihiko , Kawabata Koji S. , Kashikawa Nobunari , Aoki Kentaro , Sasaki Toshiyuki , Kosugi George , Okita Kiichi , Shimizu Yasuhiro , Inata Motoko , Ebizuka Noboru , Ozawa Tomohiko , Yadoumaru Yasushi , Taguchi Hiroko , Asai Ryo
Published: March 2014

We present new optical images ($B, V$, and $\mathrm{H}\alpha$) of the archetypical starburst/superwind galaxy M 82 obtained with the 8.2 m Subaru Telescope to reveal new detailed structures of the superwind-driven nebula and the high-latitude dark lanes. The emission-line nebula is decomposed into (1) a ridge-dominated component comprising numerous filament/loop sub-structures whose overall morphology appears as a pair of narrow cylinders, and (2) a diffuse component extended over much wider opening angle from the nucleus. We suggest that these two components have different origins. The ridge-dominated component appears as a pair of cylinders rather than a pair of cones. Since this morphological property is similar to that of hot plasma probed by soft X-ray, this component seems to surround the hot plasma. On the other hand, the diffuse component may arise from dust grains which scatter stellar light from the galaxy. Since inner region of this component is seen over the prominent “X”-shaped dark lanes streaming out from the nuclear region and they can be reproduced as a conical distribution of dust grains, there seems to be a dusty cold outflow as well as the hot one probed by soft X-ray and shock-excited optical emission lines. If this is the case, the presence of such high-latitude dust grains implies that neutral gaseous matter is also blown out during the course of the superwind activity.
Na I D Lines in the SN 2002ap Spectrum
Authors: Takada-Hidai Masahide , Aoki Wako , Zhao Gang
Published: March 2014

High-dispersion, high-$\mathrm{S/N}$ spectroscopic observations of SN 2002ap in M74 were carried out in the wavelength range of 4120–6860$\,{Å}$ using the High Dispersion Spectrograph of the Subaru Telescope. Neither emission nor absorption features relating to SN 2002ap itself were identified in the high-dispersion echelle spectrum, but a pair of Na I D1 and D2 absorption lines were detected at a redshift corresponding to the disk of M74, and each was found to show three components. The column densities of these components are log $N(\mathrm{Na{I}}) = 11.47$, 10.47, and 10.72 for the first, second, and third components, respectively. The interstellar reddening in M74 was estimated from these components, and was combined with that in the Galaxy to yield a total value of $E(B-V) = 0.09 \pm 0.01$ along the line of sight to SN 2002ap.
Carbon Monoxide in the Type Ic Supernova 2000ew
Authors: Gerardy Christopher L. , Fesen Robert A. , Nomoto Ken’ichi , Maeda Keiichi , Höflich Peter , Wheeler J. Craig
Published: March 2014

We present $K$-band (1.9–2.5$\,{\mu \mathrm {m}}$) spectra of the Type Ic SN 2000ew observed with IRCS on the Subaru Telescope. These data show the first detection of carbon monoxide (CO) emission in a Type Ic supernova. The detection of CO in SN 2000ew provides further evidence that molecule formation may be a common occurrence in core-collapse supernova ejecta. The spectrum also contains narrow emission lines of [Fe II] and He I probably from dense clumps of hydrogen-poor circumstellar gas surrounding SN 2000ew. Our spectrum of SN 2000ew shows no trace of an unidentified feature seen near 2.26$\,{\mu \mathrm {m}}$, just blueward of the CO emission, in the spectrum of SN 1987 A; we discuss proposed detections of this feature in other Type II supernovae.
Abundance Analyses of 12 Parent Stars of Extrasolar Planets Observed with the SUBARU/HDS
Authors: Sadakane Kozo , Ohkubo Michiko , Takeda Yoichi , Sato Bun’ei , Kambe Eiji , Aoki Wako
Published: March 2014

High $\mathrm{S/N}$ ratio (350–600) and high resolution ($R \sim 90000$) spectral data covering the wavelength region between 4200–8800$\,{Å}$ were obtained for 12 planet-harboring stars with the SUBARU/HDS. Detailed abundance analyses were carried out for these stars using the solar spectrum as a reference. Atmospheric parameters ($T_\mathrm{eff}, \log g$, microturbulent velocity $\xi_\mathrm{t}$, and $[\mathrm{Fe/H}]$) were determined spectroscopically using selected Fe I and Fe II lines. The abundances of 25 other elements have been determined relative to the Sun in a strictly differential manner. Three out of 12 stars (HD 82943, HD 92788, and HD 134987) are definitely metal rich, and two stars (HD 114762 and HD 190228) are metal deficient. The abundances in the remaining seven stars (HD 106252, HD 130322, HD 141937, HD 168746, HD 187123, HD 192263, HD 209458) coincide with the Sun. We find that the abundances of both volatile and refractory elements behave similarly in these stars, and do not confirm any significant dependence on the condensation temperature, $T_\mathrm{c}$. Comparisons of the $[\mathrm{X/Fe}]$ vs $[\mathrm{Fe/H}]$ relations for 19 elements between planet-harboring stars and nearby field stars reveal no distinct anomaly, except for possible enhancements of V and Co in the former group. These results suggest that the observed over-abundances of metallic elements in planet-harboring stars relative to normal disk stars in the solar neighborhood are primordial, and can be interpreted as being a consequence of the galactic chemical evolution.
Subaru Near-IR Coronagraphic Image of LkHα 198
Authors: Fukagawa Misato , Tamura Motohide , Suto Hiroshi , Itoh Yoichi , Murakawa Koji , Oasa Yumiko , Hayashi Saeko S. , Naoi Takahiro , Kaifu Norio , Doi Yoshiyuki
Published: March 2014

High-resolution near-infrared imaging of a Herbig Ae/Be star $\mathrm{LkH}\alpha$ 198 has been carried out using the coronagraphic camera CIAO (Coronagraphic Imager with Adaptive Optics) on the Subaru 8.2 m Telescope. Obtained images resolve the infrared companion (IRC) and an associated reflection nebula. The IRC exhibits near-infrared colors suggestive of a class I-like source. Faint nebulae associated with outflow activity and a bright flattened envelope are also found around the primary. Our observations provide morphological evidence of the IRC being an outflow source as well as the primary star.
SDSSp J104433.04−012502.2 at z=5.74 is Gravitationally Magnified by an Intervening Galaxy
Authors: Shioya Yasuhiro , Taniguchi Yoshiaki , Murayama Takashi , Ajiki Masaru , Nagao Tohru , Fujita Shinobu S. , Kakazu Yuko , Komiyama Yutaka , Okamura Sadanori , Oyabu Shinki , Kawara Kimiaki , Ohyama Youichi , Kawabata Koji S. , Ando Hiroyasu , Nishimura Tetsuo , Hayashi Masahiko , Ogasawara Ryusuke , Ichikawa Shin-ichi
Published: March 2014

During the course of our optical deep survey program on $\mathrm{L}\alpha$ emitters at $z \approx 5.7$ in the sky area surrounding the quasar SDSSp J104433.04$-$012502.2 at $z=5.74$, we found that a faint galaxy with $m_{B}(\mathrm{AB}) \approx 25$ is located at ${1\rlap {.}{}^{\mathrm {\prime \prime }}9}$ southwest of the quasar. Its broad-band color properties from $B$ to $z^\prime$ suggest that the galaxy is located at a redshift of $z \sim 1.5 \hbox{--} 2.5$. This is consistent with no strong emission line in our optical spectroscopy. Since the counter-image of the quasar cannot be seen in our deep optical images, the magnification factor seems not to be very high. Our modest estimate is that this quasar is gravitationally magnified by a factor of 2.
On the Origin of the Dispersion in the 7Li/6Li Ratio in the ISM
Authors: Casuso Emilio , Beckman John E.
Published: March 2014

Measurements of the ${{7\atop} \mathrm{Li}}/{{6\atop} \mathrm{Li}}$ ratio in the local interstellar medium (ISM) towards o Per and $\zeta$ Per by Knauth et al. (2000, AAA 073.131.129) show clouds with a range from near 2 (a value which points to GCR production by spallation or $\mbox{alpha} {+} \mbox{alpha}$ alpha${+}$ alpha fusion) to near 11 (the solar system value). These values can be very well accounted for within our model of general chemical enrichment of the Galaxy in which a key role is played by the continuing infall of metal-poor extragalactic gas to the Galactic plane, in the form of high-velocity clouds. Within this model, light nuclides are produced in the ISM, but destroyed in dense hot interstellar regions around massive stars, the process of which yields a differential depletion of ${{6\atop} \mathrm{Li}}$ relative to ${{7\atop} \mathrm{Li}}$, which can vary on quite short-distance scales.
Close Correlation among Hα Surges, Magnetic Flux Cancellations, and UV Brightenings Found at the Edge of an Emerging Flux Region
Authors: Yoshimura Keiji , Kurokawa Hiroki , Shimojo Masumi , Shine Richard
Published: March 2014

Surge activities were observed at the edge of an emerging flux region. We studied the relations between the features around the surges in various data sets: magnetogram, $\mathrm{H}\alpha$, G-band, UV, EUV, and soft X-rays. We showed that the surge activities in $\mathrm{H}\alpha$ and the brightenings in TRACE 1600 Å images correlate well in both time and space with the cancellation of magnetic fluxes around an emerging flux region. In particular, at the onset of surge activity, a close correlation among them was clearly found. These facts are consistent with the magnetic reconnection model. The released energy through magnetic reconnection, which is estimated to be $10^{28} \,\mathrm{erg}$, is sufficiently large to produce surge activities. No prominent brightenings were observed in soft X-ray and EUV images during the surge activities. This may suggest that the energy releases occurred at a layer of high densities.
On the Association among Periodic Comet 96P/Machholz, Arietids, the Marsden Comet Group, and the Kracht Comet Group
Authors: Ohtsuka Katsuhito , Nakano Syuichi , Yoshikawa Makoto
Published: March 2014

The orbital energies ($a^{-1}$) of released meteoroids (or fragments) from the periodic Comet 96P/Machholz must be slightly different from that of 96P. This results in the differences in their evolutional rates; therefore, the time-lags of the orbital evolutions should apparently occur in the course of time, stably holding the same amplitude in their orbital variations. In the present study, integrating the motion of 96P, we found that the orbital elements of 96P at epoch 2319 correspond to those of both the Arietids and the Marsden comet group, currently observed, and those of 96P at epoch 2408 agree with those of the Kracht comet group, similarly observable now. We also estimated a difference of the perihelion times, $\Delta T$, as: $\sim 320 \,\mathrm{yr}$ for 96P$-$Marsden comet group; $\sim 360 \,\mathrm{yr}$ for 96P$-$Arietids; and $\sim 410 \,\mathrm{yr}$ for 96P$-$ Kracht comet group, respectively. These may indicate such time-lags of orbital evolutions between 96P and released meteoroids (or fragments) from 96P. As a consequence, we conclude that 96P, Arietids, the Marsden group, and the Kracht group are further possibly associated with each other now.
The Virgo High-Resolution CO Survey: III. NGC 4254
Authors: Sofue Yoshiaki , Koda Jin , Nakanishi Hiroyuki , Hidaka Makoto
Published: March 2014

We present high-angular-resolution (${1\rlap {.}{}^{\mathrm {\prime \prime }}5}$-${5{}^{\mathrm {\prime \prime }}}$) interferometer observations of the ${{12\atop} \mathrm{CO}}$ ($J=1 \hbox{--} 0$) line emission in the central region of the SA(s)c galaxy NGC 4254 (M 99). The observations were obtained using the Nobeyama Millimeter-wave Array (NMA) during the course of a long-term CO-line survey of Virgo spirals. We present the spectra, channel maps, integrated intensity distributions, velocity fields, position–velocity diagrams, and compare the data with various optical images. The rotation velocity is already finite at the nucleus, or at least it rises steeply to $80 \,\mathrm{km} \,\mathrm{s}^{-1}$ within the central $1^{\prime\prime}$, indicating the existence of a massive core of $10^8 \,{{{M}_{\odot}}}$ within $1^{\prime\prime}$ (80 pc) radius. The CO intensity maps show that the inner disk has well-developed multiple spiral arms, winding out from a bar-shaped elongated molecular complex. In addition to the bisymmetric spiral arms, an asymmetric tightly wound arm with high molecular gas density is found to wind out from the molecular bar. The molecular spiral arms, particularly the tightly wound arm, well traces optical dark lanes, and are associated with $\mathrm{H}\alpha$ arms having many H ii regions. The inner asymmetric spiral structures can be explained by ram-pressure distortion of inter-arm low density regions of the inner disk by the intra-cluster gas wind, and is indeed reproduced by a hydrodynamical simulation.
Enhanced HCN (1-0) Emission in the Type-1 Seyfert Galaxy NGC 1097
Authors: Kohno Kotaro , Ishizuki Sumio , Matsushita Satoki , Vila-Vilaró Baltasar , Kawabe Ryohei
Published: March 2014

The central kpc region of the low-luminosity type-1 Seyfert galaxy NGC 1097 has been observed in the CO (1–0) and HCN (1–0) lines with the Nobeyama Millimeter Array and the NRO 45 m telescope. We have found a striking enhancement of the HCN emission toward the active nucleus of NGC 1097; a large fraction of the CO emission comes from a circumnuclear starburst ring ($r \sim 10''$ or 700 pc at $D = 14.5 \,\mathrm{Mpc}$), whereas the HCN emission is dominated by a strong unresolved peak at the nucleus. The HCN-to-CO integrated intensity ratio on the brightness temperature scale, $R_\mathrm{HCN/CO}$, is about 0.11 in the aperture of the 45 m telescope beams (${15{}^{\mathrm {\prime \prime }}}$ for CO and ${19{}^{\mathrm {\prime \prime }}}$ for HCN), but reaches 0.34 in the smaller aperture (${10{}^{\mathrm {\prime \prime }}} \times {4\rlap {.}{}^{\mathrm {\prime \prime }}4}$). These CO and HCN properties in NGC 1097 are similar to those in the type-2 Seyfert galaxies NGC 1068 and NGC 5194 (M 51).
Wavy Stratus under Photon Surfing over Luminous Disks
Authors: Fukue Jun
Published: March 2014

In a geometrically thin cloud layer under photon surfing over an infinite disk with uniform brightness, a wavy fluctuation automatically amplifies itself. This is a new type of instability for an inhomogeneous stratus moving at a relativistic speed in intense radiation fields. Under radiative flux and drag forces, the equilibrium speed of a wave top can reach ultra-relativistic speed, although the equilibrium speed of a wave base remains in the mildly relativistic regime ($\sim 0.45 \,c$) due to radiation drag. That is, the equilibrium speed of the wavy stratus with wavelength $\lambda$ becomes $0.99 \,c$ (Lorentz factor $\gamma \sim 10$) at height $z \sim 10 \,\lambda$. As a result, the radiation-drag limit in the astrophysical jets can be broken. The terminal speed, which depends on the strength of radiation fields as well as the wavelength, is also obtained.
Non-Linear Resonance in Nearly Geodesic Motion in Low-Mass X-Ray Binaries
Authors: Abramowicz Marek A. , Karas Vladimir , Kluźniak Wodzimierz , Lee William H. , Rebusco Paola
Published: March 2014

We have explored the ideas that parametric resonance affects nearly geodesic motion around a black hole or a neutron star, and that it may be relevant to the high-frequency (twin) quasi-periodic oscillations that occur in some low-mass X-ray binaries. We have assumed the particles or fluid elements of an accretion disc to be subject to an isotropic perturbation having a hypothetical but rather general form. We find that the parametric resonance is indeed excited close to the radius where epicyclic frequencies of the radial and meridional oscillations are in a $2:3$ ratio. The location and frequencies of the highest amplitude excitation vary with the strength of the perturbation. These results agree with actual frequency ratios of twin kHz QPOs that have been reported in some black hole candidates, and they may be consistent also with correlation of the twin peaks in Sco X-1.
X-Ray and Gamma-Ray Emissions from the PSR 1259$-$63/Be Star System
Authors: Murata Kenji , Tamaki Hidenori , Maki Hideki , Shibazaki Noriaki
Published: March 2014

PSR1259$-$63 is a radio pulsar orbiting a Be star in a highly eccentric orbit. Soft and hard X-rays are observed from this binary system. We applied a shock-powered emission model to this system. The collision of the pulsar and Be star winds forms a shock, which accelerates electrons and positrons to relativistic energies. We derived the energy distribution of relativistic electrons and positrons as a function of the distance from the shock in the pulsar nebula. We calculated the X-rays and $\gamma$-rays emitted from the relativistic electrons and positrons in the nebula at various orbital phases, while fully taking into account the Klein–Nishina effect. The shock-powered emission model can explain the observed X-ray properties approximately. We obtained from comparisons with observations that a fraction of $\sim 0.1$ of the pulsar spin-down luminosity should be transformed into the relativistic electrons and positrons. We found that the magnetization parameter of the pulsar wind, the ratio of the Poynting flux to the kinetic energy flux, is $\sim 0.1$ immediately upstream of the termination shock of the pulsar wind, and may decrease with the distance from the pulsar. We predict a flux of 10 MeV–100 GeV $\gamma$–rays, which may be nearly equal to the detection threshold in the future projects.
The SU UMa Nature of the Dwarf Nova, DM Lyrae
Authors: Nogami Daisaku , Baba Hajime , Matsumoto Katsura , Kato Taichi
Published: March 2014

We carried out time-resolved $V$-band photometry of DM Lyr during long outbursts in 1996 July and in 1996 February–March at Ouda Station, Kyoto University, and at Osaka Kyoiku University. Since superhumps were clearly detected in the light curves, DM Lyr was first identified as being an SU UMa-type dwarf nova. The superhump period is 0.0673(2) d, and the superhump excess is 2.8(3)%. The duration of the superoutburst, the outburst amplitude, the decline rate in the plateau phase, and the superhump excess were typical values for a usual SU UMa star. According to visual and CCD observations reported to VSNET, this star has experienced a dramatic change of the outburst pattern from a superoutburst phase to a normal outburst phase. There may exist mechanisms to decrease the number of normal outbursts between two successive superoutbursts and to elongate the recurrence cycle of the superoutburst.
Grazing Eclipsing Dwarf Nova CW Monocerotis: Dwarf Nova-Type Outburst in a Possible Intermediate Polar?
Authors: Kato Taichi , Uemura Makoto , Kiyota Seiichiro , Tanabe Kenji , Koizumi Mitsuo , Kida Mayumi , Nishi Yuichi , Tanaka Sawa , Ueoka Rie , Yasui Hideki , Vanmunster Tonny , Nogami Daisaku , Yamaoka Hitoshi
Published: March 2014

We observed the 2002 October–November outburst of the dwarf nova CW Mon. The outburst showed a clear signature of a premaximum halt, and a more rapid decline after reaching the outburst maximum. On two separate occasions, during the premaximum stage and near the outburst maximum, shallow eclipses were recorded. This finding confirms the previously suggested possibility of the grazing eclipsing nature of this system. The separate occurrence of the eclipses and the premaximum halt can be understood as being the result of a combination of a two-step ignition of an outburst and the inside-out propagation of the heating wave. We detected a coherent short-period (0.02549 d) signal on two subsequent nights around the optical maximum. This signal was likely present during the maximum phase of the 2000 January outburst. We interpret this signal as being a signature of the intermediate polar (IP) type pulses. The rather strange outburst properties, strong and hard X-ray emission, and the low luminosity of the outburst maximum might be understood as a consequence of the supposed IP nature. The ratio between the suggested spin period and the orbital period, however, is rather unusual for a system having an orbital period of $\sim 0.176 \,\mathrm{d}$.
Fading of Sunlight Scattered by a Meteoric Cloud of the Leonid Parent Comet 55P/Tempel-Tuttle
Authors: Usui Fumihiko , Ishiguro Masateru
Published: March 2014

During the Leonid meteor shower in 1998, a faint glow in the direction of the dust trail of comet 55P/Tempel-Tuttle was discovered using photometric observations (Nakamura et al. 2000, ApJ, 540, 1172). It is considered that this glow was due to sunlight scattered by sub-millimeter-sized dust particles located along the orbit of 55P/Tempel-Tuttle. To examine the spatial distribution of the dust particles, we observed the sky in the direction of the dust trail on 2001 November 18, but the data taken at this epoch showed no significant evidence of scattered sunlight. Based on data obtained at both epochs of observation, 1998 and 2001, we discuss two possible scenarios for the fading of the meteoric cloud: sublimation of volatiles in the dust grains, and/or an expansion of the width of the trail. If the latter scenario is correct, the trail at the time of the 2001 observations would have been four-times wider than in 1998.
High-Precision Radiant Analysis of the 2001 Leonids Using Telescopic Optics
Authors: Yanagisawa Toshifumi , Ohnishi Kouji , Torii Ken’ichi , Kohama Mitsuhiro , Nakajima Atsushi , Asher David
Published: March 2014

We employed a new line-detection method and tried to separate two radiant points corresponding to the dust trails of Comet 55P/Tempel–Tuttle’s perihelion passages in 1699 and 1866. This method integrates the pixel values of a CCD image along a line direction, which enables us to detect 30-times fainter meteors than when using the usual detection methods. It can also precisely determine the angle of the line direction. Two telescopic optics equipped with cooled CCD cameras were pointed to regions that make a right angle with the radiant points in order to precisely determine their positions. Radiant points of the 2001 Leonids derived by this method were found to be consistent with those predicted by McNaught and Asher.
Wide-Field Video Observation and Statistical Analysis of the Leonid Meteor Storm in 2001
Authors: Shiki Shigetomo , Fujiwara Hideaki , Kitazume Jun , Miyamoto Daisuke , Takeuchi Tsutomu T. , Utsumi Yousuke
Published: March 2014

We show a detailed analysis of a wide-field video observation of the Leonid Meteor Storm from ${14{}^{\mathrm {h}}41{}^{\mathrm {m}}}$ through ${20{}^{\mathrm {h}}03{}^{\mathrm {m}}}$ (UT) on 2001 November 18. We detected 1573 meteors of Leonids and 64 meteors of others. The peak of the storm appeared at ${18{}^{\mathrm {h}}20{}^{\mathrm {m}}}$ and its duration was 1.9 hr (FWHM). Bright ($m\leq2.5$) and faint ($m \geq 2.5$) meteors showed significantly different behavior in their activity. Especially, after ${19{}^{\mathrm {h}}15{}^{\mathrm {m}}}$, bright objects dominated the meteor events. We found many local peaks in the count record, and most of local peaks consisted of faint meteors. The autocorrelation function and the interval distribution between the meteor arrivals suggest that the distribution of dust in the cometary trails has no significant spatial structures that give rise to a temporally coherent behavior with a time-scale of seconds to minutes.
Dispersion of the Break Energy in the GRB Internal Shock Model
Authors: Asano Katsuaki , Kobayashi Shiho
Published: March 2014

In order to investigate the dispersion of the spectral break energy in gamma-ray bursts, we simulate internal shocks, including effects of shell-splitting after shell collisions and the Thomson optical depth due to electron–positron pairs produced by synchrotron photons. We produce pseudo-observational data and estimate the break energy. If the distribution of initial Lorentz factors of shells has only one peak, many pulses with a break energy much lower than the typical observed value should be detected, while the effect of the Thomson optical depth reduces pulses with a break energy of $ \gt 1 \,\mathrm{MeV}$$ \gt 1 \,\mathrm{MeV}$. If the Lorentz factor distribution has multiple peaks, the distribution of the break energy can be consistent with observations.
Detection of Molecular Clouds in the Interarm of the Flocculent Galaxy NGC 5055
Authors: Tosaki Tomoka , Shioya Yasuhiro , Kuno Nario , Nakanishi Kouichiro , Hasegawa Takashi
Published: March 2014

We present high-resolution ($\sim {4{}^{\mathrm {\prime \prime }}}$)${{12\atop} \mathrm{CO}}$ ($J = 1 \hbox{--} 0$) mapping observations with high-velocity resolution (${\sim 2.6 \,\mathrm{km} \,\mathrm{s}^{-1}}$) toward the disk of flocculent galaxy NGC 5055, using the Nobeyama Millimeter Array in order to study the physical properties of the molecular clouds in the arm and the interarm. The map shows clumpy structures. Although these are mainly distributed along an arm seen in NIR, some are located in the interarm. These clouds in the arm and the interarm have a typical size and mass of a few 100 pc and a few $10^6 \,{{{M}_{\odot}}}$. These correspond to the largest Giant Molecular Cloud (GMC) in our Galaxy, and are slightly smaller than Giant Molecular Associations (GMAs) in the grand design spiral M 51. Their CO flux-based masses show good agreement with their virial masses. A size–velocity dispersion relation is plotted on an extension of the relation for the Galactic GMCs. It suggest that the properties of these clouds are similar to that of the Galactic GMCs. We found no clear systematic offset between the molecular gas and H ii regions unlike M 51. This and no existense of GMAs suggest that, in NGC 5055, cloud formation and star formation in the arm and the interarm are due to enhancement of gas by local fluctuation; while, in grand design spiral galaxies, such as M 51, GMA formations may occur only in the arm due to a strong density wave and enhanced star formation in GMA formation may occur. These may control the optical morphology of spiral arms in spiral galaxies.
An X-Ray Detection Possibility of Star-Formation-Bursting Proto-Elliptical Galaxies
Authors: Inoue Hajime , Yamasaki Noriko Y.
Published: March 2014

A possibility to detect X-rays from star-formation burst activities in proto-elliptical galaxies is considered. The X-ray flux of an emission due to inverse-Compton scattering of the cosmic microwave background (CMB) by high energy electrons accelerated in SNRs is shown to increase as $z$ increases far beyond unity, since the local CMB flux largely increases in association with a $z$-increase. The flux is estimated for the case of a very high rate of type II supernovae at an initial star formation burst of a proto-elliptical galaxy and is found to be detectable with a future large X-ray telescope such as intended in the XEUS mission.
Size and Spatial Distributions of Sub-km Main-Belt Asteroids
Authors: Yoshida Fumi , Nakamura Tsuko , Watanabe Jun-ichi , Kinoshita Daisuke , Yamamoto Naotaka , Fuse Tetsuharu
Published: March 2014

This paper presents the result of the first systematic investigation of very small Main-Belt Asteroids (sub-km MBAs) using the Subaru Prime-Focus Camera (Suprime-Cam) with an $8 \,\mathrm{K} \times 10 \,\mathrm{K}$ mosaic CCD array attached to the 8.2m Subaru Telescope atop Mauna Kea, Hawaii. We call this survey SMBAS (Sub-km Main-Belt Asteroid Survey). Observations were carried out on 2001 February 22 and 25 (HST) and a $\sim 3.0 \,\mathrm{deg}^{2}$ sky area near the opposition and near the ecliptic was searched. We detected 1111 moving objects down to $R \sim 26 \,\mathrm{mag}$ (including very slow Trans-Neptunian Objects). In this survey, we could not determine the exact orbits of the moving objects, because of their short observational arc of only 2 hours. Instead, we statistically estimated the semi-major axis ($a$) and inclination ($I$) of each moving object from its apparent sky-motion vector, and then obtained the size and spatial distributions of sub-km MBAs. The main results of SMBAS are: (1) The sky number density of MBAs is found to be $\sim 290 \,\mathrm{deg}^{-2}$ down to $R\sim 24.4 \,\mathrm{mag}$ (for MBAs) near the opposition and near the ecliptic. (2) The slope of the cumulative size distribution for sub-km MBAs ranging from 0.5 km to 1 km in diameter is fairly shallower ($\sim 1.2$) than that for large MBAs of more than $\sim 5 \,\mathrm{km}$ in diameter ($\sim 1.8$), which was obtained from past asteroid surveys. This means that the number of sub-km MBAs is much more depleted than a result extrapolated from the size distributions for large asteroids. (3) The depletion of sub-km MBAs is clearer in the outer main-belt than in the inner main-belt. (4) It seems that SMBAS asteroids distribute more widely in the $I$-direction in the outer zone ($a= 2.8 \hbox{--} 3.1 \,\mathrm{AU}$) of the main-belt than known large asteroids do. We also discuss the possible causes for the characteristics of the distributions of SMBAS-observed small asteroids.
Slow and Fast MHD Shocks Associated with a Giant Cusp-Shaped Arcade on 1992 January 24
Authors: Shiota Daikou , Yamamoto Tetsuya T. , Sakajiri Takuma , Isobe Hiroaki , Chen Peng-Fei , Shibata Kazunari
Published: March 2014

We performed magnetohydrodynamic (MHD) simulations of a giant arcade formation with a model of magnetic reconnection coupled with heat conduction, to investigate the dynamical structure of slow and fast MHD shocks associated with reconnection. Based on the numerical results, theoretical soft X-ray images were calculated and compared with the Yohkoh soft X-ray observations of a giant arcade on 1992 January 24. The Y-shaped structure observed in the event was identified to correspond to the slow and fast shocks associated with the magnetic reconnection.
Probing the Star-Formation Epoch with the Wilkinson Microwave Anisotropy Probe (WMAP) Data and High-Redshift QSOs
Authors: Yokoyama Jun’Ichi
Published: March 2014

Using the values of the cosmological parameters obtained from the Wilkinson Microwave Anisotropy Probe (WMAP) and the cosmological chemical clock observed from high-redshift quasars, it is shown that the formation epoch of precursors of type Ia supernovae should have started at a redshift of $z_{\mathrm{F}} \gt 9.5$$z_{\mathrm{F}} \gt 9.5$, and that $z_\mathrm{F}$ is sensitive only to $\Omega_{\mathrm{m0}} \, h^2$ in flat $\Lambda$CDM cosmology.
Dusty ERO Search behind Two Massive Clusters
Authors: Takata Tadafumi , Kashikawa Nobunari , Nakanishi Kouichiro , Aoki Kentaro , Asai Ryo , Ebizuka Noboru , Inata Motoko , Iye Masanori , Kawabata Koji S. , Kosugi George , Ohyama Youichi , Okita Kiichi , Sasaki Toshiyuki , Saito Yoshihiko , Sekiguchi Kazuhiro , Shimizu Yasuhiro , Taguchi Hiroko , Yoshida Michitoshi
Published: March 2014

We performed deep $K'$-band imaging observations of 2 massive clusters, MS 0451.6$-$0305 at $z = 0.55$ and MS 0440.5$+$0204 at $z = 0.19$, for searching counterparts of the faint sub-mm sources behind these clusters, which would provide one of the deepest extremely red object (ERO) samples. Comparing our near-infrared images with optical images taken by the Hubble Space Telescope and by the Subaru Telescope, we identified 13 EROs in these fields. The sky distributions of EROs are consistent with the previous results, that there is a sign of strong clustering among detected EROs. Also, the surface density with corrected lensing amplification factors in both clusters are in good agreement with that derived from previous surveys. We found 7 EROs and 3 additional very red objects in a small area ($\sim 0.6 \,\mathrm{arcmin}^{2}$) of the MS 0451.6$-$0305 field around an extended SCUBA source. Many of their optical and near-infrared colors are consistent with dusty star-forming galaxies at high redshifts ($z \sim 1.0 \hbox{--} 4.0$), and they may be constituting a cluster of dusty starburst galaxies and/or lensed star-forming galaxies at high redshift. Their red $J-K'$ colors and faint optical magnitudes suggest they are relatively old massive stellar systems with ages ($ \gt 300$ mega years) suffering from dust obscuration. We also found a surface-density enhancement of EROs around the SCUBA source in the MS 0440.5$+$0204 field.