bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tidal Instability and Superhump in Dwarf Novae Described by a Wave-Wave Resonant Process
Authors: Kato Shoji 
Published: March 2014

Abstract
On a disk deformed to a non-axisymmetric form, a set of oscillations can be excited by their resonant interaction through the disk deformation (Kato et al. 2011). This resonant instability process has been proposed to suggest a possible cause of the high-frequency quasi-periodic oscillations (HFQPOs) observed in black-hole low-mass X-ray binaries. In the present paper, we examine whether the above-mentioned wave-wave resonant process can describe the tidal instability and superhump in dwarf novae. The results show that the process seems to well describe the observations. If this process is really the cause of the tidal instability and superhump, a two-armed oscillation with high frequency roughly on the magnitude of three-times the orbital frequency is present on disks, although its expected amplitude may be small.
Multifrequency VLBI Observations of the Broad Absorption Line Quasar J1020 4320: Recently Restarted Jet Activity?
Authors: Doi Akihiro , Murata Yasuhiro , Mochizuki Nanako , Takeuchi Hiroshi , Asada Keiichi , Hayashi Takayuki J. , Nagai Hiroshi , Shibata Katsunori M. , Oyama Tomoaki , Jike Takaaki , Fujisawa Kenta , Sugiyama Koichiro , Ogawa Hideo , Kimura Kimihiro , Honma Mareki , Kobayashi Hideyuki , Koyama Shoka 
Published: March 2014

Abstract
This paper reports on very-long-baseline interferometry observations of the radio-loud broad absorption line (BAL) quasar J1020$ +$ 4320 at 1.7, 2.3, 6.7, and 8.4 GHz using the Japanese VLBI network (JVN) and European VLBI network (EVN). The radio morphology is compact with a size of $ \sim$ 10 pc. The convex radio spectrum has been stable over the last decade; an observed peak frequency of 3.2 GHz is equivalent to 9.5 GHz in the rest frame, suggesting an age on the order of $ \sim$ 100 years as a radio source, according to an observed correlation between the linear size and the peak frequency of compact steep spectrum (CSS) and giga-hertz peaked spectrum (GPS) radio sources. A low-frequency radio excess suggests a relic of past jet activity. J1020$ +$ 4320 may be one of the quasars with recurrent and short-lived jet activity during a BAL-outflowing phase.
Carbon Abundances of Metal-Poor Stars Determined from the C I 1.068–1.069 μm Lines
Authors: Takeda Yoichi , Takada-Hidai Masahide 
Published: March 2014

Abstract
A non-LTE analysis of C I lines at 1.068–1.069 $ \mu$ m was carried out for selected 46 halo/disk stars covering a wide metallicity range ($-$ 3.7 $ ≲$ [Fe$ /$ H] $ ≲$ $ +$ 0.3), based on spectral data collected with IRCS $ +$ AO188 of the Subaru Telescope. This was done in order to examine whether and how these strong neutral carbon lines of multiplet 1 can be exploited for establishing stellar carbon abundances, especially for very metal-poor stars where CH molecular lines have been commonly used. These C I lines were confirmed to be clearly visible for all stars down to [Fe$ /$ H] $ \sim$ $-$ 3.7, from which the C abundances could be successfully determined. The resulting [C$ /$ Fe] vs. [Fe$ /$ H] diagram revealed almost the same trend established from previous studies. When the results for individual stars are compared with published data collected from various literature, while a reasonable agreement is seen as a whole, a tendency is observed that our abundances are appreciably higher than those from CH lines, especially for very metal-poor giants of low gravity. Since the abundances of these C I lines are subject to rather large non-LTE corrections (typically by several tenths dex), whose importance progressively grows as the metallicity is lowered, attention should be paid to how the collisional rates (especially due to neutral hydrogen) are treated in non-LTE calculations.
Non-Thermal Radio and Gamma-Ray Emissions from a Supernova Remnant by Blast Wave Breaking Out of the Circumstellar Matter
Authors: Shimizu Takafumi , Masai Kuniaki , Koyama Katsuji 
Published: March 2014

Abstract
We calculated synchrotron radio emission and $ \gamma $-ray emission due to bremsstrahlung, inverse-Compton scattering, and $ \pi ^0$-decay from the remnant of supernova that exploded in the circumstellar matter (CSM) formed by the progenitor's stellar wind. This sort of situation is a possible origin of mixed-morphology supernova remnants (SNRs), like W 49B, which exhibit recombination-radiation spectra in X-ray emission. We assumed that the CSM of 1.5 $ M_{\odot}$ exists at 0.07–3 pc away from the supernova in the interstellar medium (ISM) of density 0.016 cm$ ^{-3}$ . When the blast wave breaks out of the CSM into the ISM, its velocity rapidly increases, and hence particle acceleration is enhanced. The maximum energy of protons reaches $ \sim$ 1300 TeV just after the break-out with $ \sim$ 0.5% of the explosion energy. We considered the non-thermal emission from the blast-shocked ISM shell after the break-out. Synchrotron radio flux at 1 GHz is tens of Jy, comparable to that observed from mixed-morphology SNRs. Because of low density, the $ \gamma $-ray luminosity is dominated by inverse-Compton scattering, which is higher than the $ \pi ^0$-decay luminosity by an order of magnitude. The total $ \gamma $-ray luminosity, including bremsstrahlung, is on the order of 10$ ^{33}$ erg s$ ^{-1}$ lower than the typical value of 10$ ^{35}$ –10$ ^{36}$ erg s$ ^{-1}$ observed from mixed-morphology SNRs. However, if, e.g., $ \sim$ 10% of accelerated protons interact with some matter of density of $ \sim$ 100 cm$ ^{-3}$ , the $ \pi ^0$-decay $ \gamma $-ray luminosity would be enhanced to be comparable with the observed value.
A 1.85-m mm-submm Telescope for Large-Scale Molecular Gas Surveys in 12CO, 13CO, and C18O (J = 2–1)
Authors: Onishi Toshikazu , Nishimura Atsushi , Ota Yuya , Hashizume Akio , Kojima Yoshiharu , Minami Akihito , Tokuda Kazuki , Touga Shiori , Abe Yasuhiro , Kaiden Masahiro , Kimura Kimihiro , Muraoka Kazuyuki , Maezawa Hiroyuki , Ogawa Hideo , Dobashi Kazuhito , Shimoikura Tomomi , Yonekura Yoshinori , Asayama Shin’ichiro , Handa Toshihiro , Nakajima Taku , Noguchi Takashi , Kuno Nario 
Published: March 2014

Abstract
We have developed a new mm-submm telescope with a diameter of 1.85-m installed at the Nobeyama Radio Observatory. The scientific goal is to precisely reveal the physical properties of molecular clouds in the Milky Way Galaxy by obtaining a large-scale distribution of molecular gas, which can also be compared with large-scale observations at various wavelengths. The target frequency is $\sim$230 GHz; simultaneous observations at the molecular rotational lines of $J =$2–1 of three carbon monoxide isotopes ($^{12}$CO, $^{13}$CO, C$^{18}$O) are achieved with a beam size (HPBW) of 2${.}{}^\prime$7. In order to accomplish the simultaneous observations, we have developed waveguide-type sideband-separating SIS mixers to obtain spectra separately in the upper and lower side bands. A Fourier digital spectrometer with a 1 GHz bandwidth having 16384 channels is installed, and the bandwidth of the spectrometer is divided into three parts, corresponding to each of the three spectra; the IF system has been designed so as to inject these three lines into the spectrometer. A flexible observation system was created mainly in Python on Linux PCs, enabling effective OTF (On-The-Fly) scans for large-area mapping. The telescope is enclosed in a radome with a membrane covered to prevent any harmful effects of sunlight, strong wind, and precipitation in order to minimize errors in the telescope pointing, and to stabilize the receiver and the IF devices. From 2011 November, we started science operation, resulting in a large-scale survey of the Orion A/B clouds, Cygnus OB7, Galactic Plane, Taurus, and so on. We also updated the receiver system for dual-polarization observations.
Precessing Warped Be Disk Triggering the Giant Outbursts in 2009 and 2011 in A 0535 + 262/V725 Tau
Authors: Moritani Yuki , Nogami Daisaku , Okazaki Atsuo T. , Imada Akira , Kambe Eiji , Honda Satoshi , Hashimoto Osamu , Mizoguchi Sahori , Kanda Yuichi , Sadakane Kozo , Ichikawa Kohei 
Published: March 2014

Abstract
We carried out optical high-dispersion spectroscopic monitoring of the Be disk in a Be/X-ray binary, A 0535$+$ 262/V725 Tau, from 2009 to 2012, covering two giant outbursts and several normal ones. This monitoring was performed in order to investigate any variabilities of the Be disk due to interactions with the neutron star in the recent X-ray active phase from 2008 to 2011. Such variabilities give a clue to any uncleared detailed mechanism for very bright X-ray outbursts, which are unique to some Be/X-ray binaries with a relatively wide and eccentric orbit. In a previous letter (Moritani et al. 2011, PASJ, 63, L25), a brief overview of the line-profile variabilities around the 2009 giant outburst was given, and the possibility of a warped Be disk was discussed. In this paper, a full analysis of the H$\alpha$ line profiles as well as other line profiles is carried out. A bright blue component, or blue “shoulder,” showing up after periastron indicates the presence of a dense gas stream toward the neutron star, which is associated with observed outbursts. We re-analyze the H$\alpha$ line profiles before 2009 (down to 2005) in order to investigate the variability of the disk structure in the innermost region, which seems to have detached from the Be star surface by 2008. A redshifted enhanced component is remarkable in all emission lines observed around the 2009 giant outburst, occasionally forming a triple peak. These features indicate that the Be disk was warped in the X-ray active phase. We estimated the position of the warped region from fitting the radial velocity of the redshifted enhanced component of H$\alpha$, and found that it was very close to the periastron when two giant outbursts in 2009 and 2011 and a bright normal outburst in 2010 March occurred. These facts strongly suggest that the precessing warped Be disk triggered these giant outbursts.
Direct Imaging Search for Extrasolar Planets in the Pleiades
Authors: Yamamoto Kodai , Matsuo Taro , Shibai Hiroshi , Itoh Yoichi , Konishi Mihoko , Sudo Jun , Tanii Ryoko , Fukagawa Misato , Sumi Takahiro , Kudo Tomoyuki , Hashimoto Jun , Kusakabe Nobuhiko , Abe Lyu , Brandner Wolfgang , Timothy D. Brandt , Carson Joseph , Currie Thayne , Sebastian E. Egner , Feldt Markus , Goto Miwa , Grady Carol , Guyon Olivier , Hayano Yutaka , Hayashi Masahiko , Hayashi Saeko , Henning Thomas , Hodapp Klaus , Ishii Miki , Iye Masanori , Janson Markus , Kandori Ryo , Gillian R. Knapp , Kuzuhara Masayuki , Kwon Jungmi , McElwain Mike , Miyama Shoken , Jun-Morino Ichi , Amaya Moro-Martin , Nishikawa June , Nishimura Tetsuo , Tae-Pyo Soo , Serabyn Eugene , Suto Hiroshi , Suzuki Ryuji , Takami Michihiro , Takato Naruhisa , Terada Hiroshi , Thalmann Christian , Tomono Daigo , Edwin L. Turner , Wisniewski John , Watanabe Makoto , Yamada Toru , Takami Hideki , Usuda Tomonori , Tamura Motohide 
Published: March 2014

Abstract
We carried out an imaging survey for extrasolar planets around stars in the Pleiades (125 Myr, 135 pc) in the $H$ and $K_{\rm S}$ bands using HiCIAO combined with adaptive optics, AO188, on the Subaru telescope. We found 13 companion candidates fainter than 14.5 mag in the $H$ band around 9 stars. Five of these 13 were confirmed to be background stars by measurement of their proper motion. One was not found in the second epoch observation, and thus was not a background or companion object. One had multi-epoch images, but the precision of its proper motion was not sufficient to conclude whether it was a background object. Four other candidates are waiting for second-epoch observations to determine their proper motion. Finally, the remaining two were confirmed to be 60 $M_{\rm {J}}$ brown dwarf companions orbiting around HD 23514 (G0) and HII 1348 (K5), respectively, as had been reported in previous studies. In our observations, the average detection limit for a point source was 20.3 mag in the $H$ band beyond 1$.{\prime\prime}$ 5 from the central star. On the basis of this detection limit, we calculated the detection efficiency to be 90% for a planet with 6 to 12 Jovian masses and a semi-major axis of 50–1000 AU. For this reason we extrapolated the distribution of the planet mass and the semi-major axis derived from radial velocity observations, and adopted the planet evolution model Baraffe et al. (2003, A&A, 402, 701). Since there was no detection of a planet, we estimated the frequency of such planets to be less than 17.9% (2 $\sigma$) around one star of the Pleiades cluster.
Erratum: Hard X-Ray Spectrum from the West Lobe of Radio Galaxy Fornax A Observed with Suzaku
Authors: Tashiro Makoto S. , Isobe Naoki , Seta Hiromi , Matsuta Keiko , Yaji Yuichi 
Published: March 2014

Abstract
In the paper [PASJ 61, S327–S335 (2009)], there were two kinds of typos in the units of flux density and the column density. The correct unit of flux density at 1 keV employed in this paper is $\mu$ Jy not nJy, which appears in line 9 of abstract, line 29 of subsection 3.3, and row (d) of table 2. The correct column density in table 2 row (a) is 2.06 $\times 10^{20}$ cm$^{-2}$ not 2.06 $\times 10^{22}$ cm$^{-2}$. Both the discussion and coclusions are based on the correct units and are not affected by these changes.
Recurrent Outbursts and Jet Ejections Expected in Swift J1644+57: Limit-Cycle Activities in a Supermassive Black Hole
Authors: Kawashima Tomohisa , Ohsuga Ken , Usui Ryuichi , kawai Nobuyuki , Negoro Hitoshi , Matsumoto Ryoji 
Published: March 2014

Abstract
A tidal disruption event by a supermassive black hole in Swift J1644$+$57 can trigger limit-cycle oscillations between a supercritically accreting X-ray bright state and a subcritically accreting X-ray dim state. The time evolution of debris gas around a black hole with mass $M = 10^{6} M_\odot$ is studied by performing axisymmetric, two-dimensional radiation hydrodynamic simulations. We assume the $\alpha$-prescription of viscosity, in which the viscous stress is proportional to the total pressure. The mass supply rate from the outer boundary was assumed to be ${\dot M}_{\rm supply} = 100 L_{\rm Edd}/c^2$, where $L_{\rm Edd}$ is the Eddington luminosity, and $c$ is the light speed. Since the mass accretion rate decreases inward by outflows driven by radiation pressure, the state transition from a supercritically accreting slim disk state to a subcritically accreting Shakura–Sunyaev disk starts from the inner disk, and propagates outward on a timescale of one day. The sudden drop of the X-ray flux observed in Swift J1644$+$57 in 2012 August can be explained by this transition. As long as ${\dot M}_{\rm supply}$ exceeds the threshold for the existence of a radiation pressure dominant disk, the accumulation of accreting gas in the subcritically accreting region triggers the transition from a gas pressure dominant Shakura–Sunyaev disk to a slim disk. This transition takes place at $t {\sim} 50 /$ (${\alpha}/$ 0.1) d after the X-ray darkening. We expect that if $\alpha \gt $ 0.01, X-ray emission with luminosity $\gtrsim 10^{44}$ erg s$^{-1}$ and jet ejection will revive in Swift J1644$+$57 in 2013–2014.
Effect of the Remnant Mass in Estimating the Stellar Mass of Galaxies
Authors: Shimizu Ikkoh , Inoue Akio K. 
Published: March 2014

Abstract
The definition of the galactic stellar mass estimated from the spectral energy distribution is ambiguous in the literature; whether the stellar mass includes the mass of the stellar remnants, i.e., white dwarfs, neutron stars, and black holes, is not well described. The remnant mass fraction in the total (living + remnant) stellar mass of a simple stellar population monotonically increases with the age of the population, and the initial mass function and metallicity affect the increasing rate. Since galaxies are composed of a number of stellar populations, the remnant mass fraction may depend on the total stellar mass of galaxies in a complex way. As a result, the shape of the stellar mass function of galaxies may change, depending on the definition of the stellar mass. In order to explore this issue, we ran a cosmological hydrodynamical simulation, and subsequently found that the remnant mass fraction indeed correlates with the total stellar mass of galaxies. However, this correlation is weak, and the remnant fraction can be regarded as a constant that depends only on the redshift. Therefore, the shape of the stellar mass function is almost unchanged, but it simply shifts horizontally if the remnant mass is included or not. The shift is larger at lower redshift, and it reaches 0.2-dex at z = 0 for a Chabrier IMF. Since this causes a systematic difference, we should take care of the definition of the ‘stellar’ mass, when comparing one's result with others.
Viscous Decretion Discs around Rapidly Rotating Stars
Authors: Lee Umin 
Published: March 2014

Abstract
We discuss steady viscous Keplerian decretion discs around rapidly rotating stars. We assume that low-frequency modes, which may be excited by the opacity bump mechanism, convective motion in the core, or tidal force if the star is in a binary system, can transport a sufficient amount of angular momentum to the region close to the stellar surface. Under this assumption, we construct a star-disc system, in which there forms a viscous decretion disc around a rapidly rotating star because of the angular-momentum supply. We find a series of solutions of steady viscous decretion discs around a rapidly rotating star that extend to $R_{\textrm{disc}} \gtrsim 10 R_{\ast}$, with $R_{\ast}$ being the equatorial radius of the star, depending on the amount of angular momentum supply.
Long-Term Oscillations of Sunspots from Simultaneous Observations with the Nobeyama Radioheliograph and Solar Dynamics Observatory
Authors: Abramov-Maximov Vladimir E. , Efremov Vyacheslav I. , Parfinenko Leonid D. , Solov'Ev Alexander A. , Shibasaki Kiyoto 
Published: March 2014

Abstract
We present an investigation of oscillatory processes with periods in the range of several tens of minutes for some single sunspots of a new solar cycle, observed in 2010-2011 at the same time intervals in the optical and radio ranges. We used magnetograms from SDO/HMI with a cadence of 45 s, and radio images at a frequency of 17 GHz obtained with the Nobeyama Radioheliograph (NoRH). Radio images in intensity (Stokes parameter I ) and circular polarization (Stokes parameter V ) were synthesized with a cadence of ten seconds and ten-second averaging. Time profiles obtained with NoRH and SDO/HMI show a correlation between the radio emission of sunspots and a magnetic field. Wavelet spectra and cross-wavelet transforms give similar oscillation periods: 30-40 min, 60-70 min, 100-110 min, and 150-200 min. The same periods found by fundamentally different methods from ground-based and space observations confirm the solar nature of these oscillations. One of the possible interpretations of our results is that detected oscillations reflect eigen oscillations of a sunspot as a whole predicted by the shallow sunspot model.
Clinical and Radiographic Outcomes From Repeat Whole-brain Radiation Therapy for Brain Metastases in the Age of Stereotactic Radiosurgery
Authors: Guo Susan , Balagamwala Ehsan H. , Reddy Chandana , Elson Paul , Suh John H. , Chao Samuel T. 
Published: March 2014

Objectives:
Repeating whole-brain radiation therapy (WBRT) in patients with progressive/recurrent brain metastases is controversial. We retrospectively reviewed our experience of repeat WBRT in an era where stereotactic radiosurgery was also available.

Methods:
In our IRB-approved database, 49 patients received repeat WBRT from 1996 to 2011. Median initial dose of WBRT was 30 Gy in 10 fractions (range, 27 to 37.5 Gy); median reirradiation dose was 20 Gy in 10 fractions (range, 14 to 30 Gy). Median Karnofsky performance status (KPS) at reirradiation was 70 (range, 40 to 90). Median number of discrete lesions at reirradiation was 6 (range, 1 to 30). Median interval between initial diagnosis of brain metastases and relapse requiring repeat WBRT was 11.5 months (range, 1.5 to 49.2 mo). Overall survival and relapse-free survival were summarized using the Kaplan-Meier method. The log-rank test was used to compare outcomes between groups.

Results:
Ninety percent of patients completed repeat WBRT. Median survival after repeat WBRT was 3 months (95% CI, 1.9-4.0). Thirteen patients had improved neurological symptoms (27%), 12 were stable (24%), and 14 had worsening symptoms (29%). On radiographic follow-up of 22 patients, 10 (46%) were improved, 4 (18%) were stable, and 8 (36%) progressed. Improved neurological symptoms after repeat WBRT and higher KPS at first follow-up were associated with improved survival (P=0.05 and 0.02).

Conclusions:
Repeat WBRT was well tolerated. Modest survival times are seen. Prognostic factors for survival include improved neurological symptoms after repeat WBRT and higher KPS at first follow-up. Repeat WBRT may be useful to improve neurological symptoms in patients with limited treatment options, especially those who are not appropriate stereotactic radiosurgery candidates.
Update to the Management of Pediatric Acute Pancreatitis
Authors: Abu‐El‐Haija Maisam , Lin Tom K. , Palermo Joseph 
Published: March 2014

ABSTRACTAcute pancreatitis is an emerging problem in pediatrics, with an incidence that is rising in the last 2 decades. Data regarding the optimal management and physician practice patterns are lacking. We present a literature review and updates on the management of pediatric pancreatitis. Prospective multicenter studies defining optimal management of pediatric pancreatitis are needed to guide care and improve outcomes for this patient population.