bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiwavelength Study of the NGC 281 Region
Authors: Sharma Saurabh , Pandey Anil K. , Pandey Jeewan C. , Chauhan Neelam , Ogura Katsuo , Ojha Devandra K. , Borrissova Jura , Mito Hiroyuki , Verdugo Thomas , Bhatt Bhuwan C. 
Published: March 2014

Abstract
We present a multiwavelength study of the NGC 281 complex, which contains the young cluster IC 1590 at the center, using deep wide-field optical $ UBVI_{\rm c}$ photometry, slitless spectroscopy along with archival data sets in the near-infrared (NIR) and X-ray regions. The extent of IC 1590 is estimated to be $ \sim$ 6.5 pc. The cluster region shows a relatively small amount of differential reddening. The majority of the identified young stellar objects (YSOs) are low-mass PMS stars having age $ \lt$ 1–2 Myr and mass 0.5–3.5 $ M_{\odot}$ . The slope ($ \Gamma$ ) of the mass function for IC 1590, in the mass range 2 $ \lt$$ M/M_\odot$$ \le$ 54, is found to be $-$ 1.11 $ \pm$ 0.15. The slope of the $ K$-band luminosity function (0.37 $ \pm$ 0.07) is similar to the average value ($ \sim$ 0.4) reported for young clusters. The distribution of gas and dust obtained from the IRAS, CO, and radio maps indicates clumpy structures around the central cluster. The radial distribution of the young stellar objects, their ages, $ \Delta$ ($ H$$-$$ K$ ) NIR-excess, and the fraction of classical T Tauri stars suggest triggered star formation at the periphery of the cluster region. However, deeper optical, NIR, and MIR observations are needed to have a conclusive view of the star-formation scenario in the region. The properties of the Class 0/I and Class II sources detected by using the Spitzer mid-infrared observations indicate that a majority of the Class II sources are X-ray emitting stars, whereas X-ray emission is absent from the Class 0/I sources. The spatial distribution of Class 0/I and Class II sources reveals the presence of three sub-clusters in the NGC 281 West region.
Do Environmental Conditions Affect the Dust-Induced Fragmentation in Low-Metallicity Clouds? Effect of Pre-Ionization and Far-Ultraviolet/Cosmic-Ray Fields
Authors: Omukai Kazuyuki 
Published: March 2014

Abstract
We study the effects of the fully ionized initial state, or pre-ionization, on the subsequent thermal evolution of low-metallicity clouds under various intensities of external far-ultraviolet (FUV) and cosmic-ray (CR) fields. Pre-ionization significantly affects the thermal and dynamical evolution of metal-free clouds without FUV/CRs by way of efficient HD formation. On the other hand, the pre-ionization effect on thermal evolution is limited in the very low-density regime for more metal-enriched clouds ([Z$ /$ H] $ \gtrsim$$-$ 4), or those under a modest FUV ($ \gtrsim$ 10$ ^{-3}$ ) field or CR field ($ \gtrsim$ 0.1) of the present-day galactic disk levels. In any case, for $ \gtrsim$ 10$ ^{8}$ cm$ ^{-3}$ , neither the initial ionization state nor the irradiating FUV strength affect the thermal evolution. The dust cooling is an important mechanism for making sub-solar mass fragments in low-metallicity gas. Since this fragmentation occurs at the temperature minimum by dust cooling at $ \gtrsim$ 10$ ^{10}$ cm$ ^{-3}$ , this process is not vulnerable either to the initial ionization state or external radiation.
Spatial Distribution of Abundance Patterns in the Starburst Galaxy NGC 3079 Revealed with Chandra and Suzaku
Authors: Konami Saori , Matsushita Kyoko , Gandhi Poshak , Tamagawa Toru 
Published: March 2014

Abstract
We performed simultaneous spectral analyses of Chandra (26.6 ks) and Suzaku (102.3 ks) X-ray data of the starburst galaxy NGC 3079. The spectra were extracted from four regions: 0$ .\!\!'$ 5 (2.25 kpc) circle, an inner 0$ .\!\!'$ 5–1$ '$ (2.25–4.5 kpc) ring, and an outer 1$ '$ –2$ '$ (4.5–9 kpc) ring from Chandra, and 4$ '$ (18 kpc) circle from Suzaku, all centered on the nucleus. Fittings of thermal plasma models yield interstellar medium (ISM) temperatures of 0.65$ ^{+0.05}_{-0.04}$ (0$ .\!\!'$ 5 circle), 0.45$ ^{+0.07}_{-0.06}$ (0$ .\!\!'$ 5–1$ '$ ring), and 0.24$ ^{+0.03}_{-0.02}$ (1$ '$ –2$ '$ ring) keV in the three regions. The combination of Chandra's high angular resolution and Suzaku's high spectral sensitivity enabled us to spatially resolve and measure the abundances of the metals O, Ne, Mg, Si, and Fe within the hot ISM. In particular, the abundance patterns of O$ /$ Fe, Ne$ /$ Fe, Mg$ /$ Fe, and Si$ /$ Fe in the central region ($ \lt$ 4.5 kpc) are consistent with those expected from a supernova (SN) II synthesis. On the other hand, the pattern in the region beyond 4.5 kpc is closer to solar. The central region is also where copious polycyclic aromatic hydrocarbon infrared emission related to the recent starburst activity is known to occur. This suggests that we are seeing starburst-related SN II metal enrichment in the hot X-ray-emitting nuclear ISM. The spatial extent of SN II-like abundance patterns is consistent with that of NGC 3079 being in a relatively-early phase of starburst activity.
Comparative Study of Manufacturing Techniques for Coronagraphic Binary Pupil Masks: Masks on Substrates and Free-Standing Masks
Authors: Enya Keigo , Haze Kanae , Kotani Takayuki , Abe Lyu 
Published: March 2014

Abstract
We present a comparative study of the manufacture of binary pupil masks for coronagraphic observations of exoplanets. A checkerboard mask design, a type of binary pupil mask design, was adopted, and identical patterns of the same size were used for all masks in order that we could compare the differences resulting from the different manufacturing methods. The masks on substrates had aluminum checkerboard patterns with thicknesses of 0.1/0.2/0.4/0.8/1.6 $ \mu$ m, constructed on substrates of BK7 glass, silicon, and germanium using photolithography and chemical processes. Free-standing masks made of copper and nickel with thicknesses of 2/5/10/20 $ \mu$ m were also realized using photolithography and chemical processes, which included careful release from the substrate used as an intermediate step in the manufacture. Coronagraphic experiments using a visible laser were carried out for all masks on BK7 glass substrate and the free-standing masks. The average contrasts were 8.4 $ \times$ 10$ ^{-8}$ , 1.2 $ \times$ 10$ ^{-7}$ , and 1.2 $ \times$ 10$ ^{-7}$ for the masks on BK7 substrates, the free-standing copper masks, and the free-standing nickel masks, respectively. No significant correlation was concluded between the contrast and the mask properties. The high-contrast masks have the potential to cover the needs of coronagraphs for both ground-based and space-borne telescopes over a wide wavelength range. Especially, their application to the infrared space telescope, SPICA, is appropriate.
Electron Impact Excitation of N-like Ca XIV
Authors: Dong Futong , Wang Feilu , Zhong Jiayong , Liang Guiyun , Zhao Gang 
Published: March 2014

Abstract
We present a close-coupling R-matrix calculation of the electron impact excitation of N-like Ca XIV. GRASP (general-purpose relativistic atomic structure package) was used to obtain the target states. Level energies are reported for the 272 levels of the target ion. The oscillator strengths and radiative rates were calculated for E1, E2, M1, and M2 transitions among these levels. In order to determine the collision strength, the lowest 84 levels were used as the target model, together with 40 partial waves included in the R-matrix calculation. The effective collision strengths were obtained by integrating the collision strengths over a Maxwellian electron energies distribution. Comparisons were made with our FAC and the LB results by Landi and Bhatia (2005, At. Data Nucl. Data Tables, 90, 177). Good agreements are shown for level energies, oscillator strengths and radiative rates, respectively. As to the collision strength, a mass of resonances appears in the R-matrix results, which are important in the determination of effective collision strengths. The discrepancies of the effective collision strengths between results from the R-matrix and from FAC are discussed. Finally, the effective collision strengths for transitions among the first 84 levels are reported. To test our results, we also compared the predicted line ratio with the observed values.
Radiative Transfer in Anisotropic Scattering Media
Authors: Fukue Jun 
Published: March 2014

Abstract
Transfer and moment equations in anisotropic scattering media are formulated under a simple linear model using the Eddington approximation. In the transfer equation, a term including the radiative flux appears, and the first moment equation is also modified, while the zeroth moment equation does not change, since the scattering processes exchange momentum, but not energy. Moment equations and transfer equation are solved for several simple cases to clarify the qualitative properties of radiative transfer in anisotropic scattering media. When forward scattering dominates, the radiative intensity is enhanced in some cases, while the gradient of the mean intensity decreases in other cases, depending on the boundary conditions for the problem. These analytic expressions are helpful in studying and understanding the radiative properties of stars with dusty envelopes, interstellar matter, protoplanetary disks and star forming regions, and the dusty universe.
Annual Parallax of the K-Type Star System IRAS 22480+6002 Measured with VERA
Authors: Imai Hiroshi , Sakai Nobuyuki , Nakanishi Hiroyuki , Sakanoue Hirofumi , Honma Mareki , Miyaji Takeshi 
Published: March 2014

Abstract
We present astrometric VLBI observations of H$_2$ O masers associated with IRAS 22480$+$ 6002 ($=$ IRC$+$ 60370, hereafter I22480) with the VLBI Exploration of Radio Astrometry (VERA). The stellar type of I22480 looks unusual in stellar maser sources, and has been debated since the 1970's. We successfully determined that an annual parallax of a group of H$_2$ O maser spots is $\pi$ $=$ 0.400 $\pm$ 0.025 mas, corresponding to a distance to I22480 of $D$ $=$ 2.50$^{+0.17}_{-0.15}$ kpc. This suggests that an estimated bolometric luminosity of I22480 should be revised to 35000 $L_{\odot}$ , preferring a K-type supergiant to an RV Tau-type variable star, previously suggested. Although its spectral type is unusual in stellar maser sources, internal motions of H$_2$ O maser features suggest that the H$_2$ O masers are associated with the circumstellar envelope of this star. We derived a secular proper motion of I22480, ($\mu_{\alpha}$ , $\mu_{\delta}$ ) $=$ ($-$ 2.58 $\pm$ 0.33, $-$ 1.91 $\pm$ 0.17) [mas yr$^{-1}$ ], from a possible stellar motion relative to the maser feature motion. The derived motion of I22480 in the Milky Way has a deviation of $\sim-$ 30 km s$^{-1}$ in the Galactic azimuthal direction from the circular motion, estimated from a galactocentric distance to I22480 and an assumption of a flat Galactic rotation curve. This peculiar motion is still comparable to those typically seen in H$_2$ O maser sources located in the Perseus Arm. Taking into account its peculiar motion and proximity to the Galactic midplane (z $\simeq$ 60 pc), I22480 may be a member of the Galactic thin disk.
Infrared Spectroscopy of CO Ro-Vibrational Absorption Lines toward the Obscured AGN IRAS 08572+3915
Authors: Shirahata Mai , Nakagawa Takao , Usuda Tomonori , Goto Miwa , Suto Hiroshi , Geballe Thomas R. 
Published: March 2014

Abstract
We present high-resolution spectroscopy of gaseous CO absorption in the fundamental ro-vibrational band toward the heavily obscured active galactic nucleus (AGN) IRAS 08572$ +$ 3915. We have detected absorption lines up to highly excited rotational levels ($ J$$ \leqq$ 17). The velocity profiles reveal three distinct components, the strongest and broadest ($ \Delta v$$ &gt;$ 200 km s$ ^{-1}$ ) of which is due to blueshifted ($-$ 160 km s$ ^{-1}$ ) gas at a temperature of $ \sim$ 270 K absorbing at velocities as high as $-$ 400 km s$ ^{-1}$ . A much weaker but even warmer ($ \sim$ 700 K) component, which is highly redshifted ($ +$ 100 km s$ ^{-1}$ ), is also detected, in addition to a cold ($ \sim$ 20 K) component centered at the systemic velocity of the galaxy. On the assumption of local thermodynamic equilibrium, the column density of CO in the 270 K component is $ N_{\rm {CO}}$$ \sim$ 4.5 $ \times$ 10$ ^{18}$ cm$ ^{-2}$ , which in fully molecular gas corresponds to an H$ _2$ column density of $ N_{\rm {H_2}}$$ \sim$ 2.5 $ \times$ 10$ ^{22}$ cm$ ^{-2}$ . The thermal excitation of CO up to the observed high rotational levels requires a density greater than $ n_{\rm c}$ (H$ _2$ ) $ &gt;$ 2 $ \times$ 10$ ^{7}$ cm$ ^{-3}$ , implying that the thickness of the warm absorbing layer is extremely small ($ \Delta d$$ &lt;$ 4 $ \times$ 10$ ^{-2}$ pc), even if it is highly clumped. The large column densities and high radial velocities associated with these warm components, as well as their temperatures, indicate that they originate in molecular clouds near the central engine of the AGN.
Catalog of SDSS Quasar Absorption Redshifts Measured from Mg II Absorption Lines. I. For Sources with z
em ≤ 0.8
Authors: Qin Yi-Ping , Chen Zhi-Fu , LÜ Lian-Zhong , Huang Wei-Rong , Li Mu-Sheng , Li Guo-Qiang , Wang Mei-Ping , Zhong Yu-Qing , Wen Sai-Qin , Liao Rong-Hua , Ye Feng 
Published: March 2014

Abstract
We are going to analyze the whole Sloan Digital Sky Survey (SDSS) quasar spectra by visually identifying Mg II absorption line systems one by one. In this paper, we limit our analysis to quasars with $ z_{\rm em}$$ \leq$ 0.8, which leaves 8006 quasars in total. Based on this, we are able to present the first catalog of these redshifts (in the interval of 0.36 $ &lt;$$ z_{\rm abs}$$ &lt;$ 0.81) in our series work (an analysis of higher redshift quasars will be performed later). Our work is based on spectral data previously analyzed by Quider et al. (2011, AJ, 141, 137). These authors identified Mg II absorption-line systems mainly based on search by machine; they found only 394 Mg II absorption lines from these 8006 quasars. However, for the same sample, we identified 4158 Mg II quasar absorption line systems. In our catalog, about 81% (3353/4158) of the absorbers have $ W_{\rm r}\lambda$ 2796 $ \ge$ 0.3 Å, and about 71% (2957/4158) of the absorbers have $ W_{\rm r}\lambda$ 2803 $ \ge$ 0.3 Å, showing that the main portion of our catalog is likely to be occupied by strong absorbers.
VLBI Imagings of a Kilo-Parsec Knot in 3C 380
Authors: Koyama Shoko , Kino Motoki , Nagai Hiroshi , Hada Kazuhiro , Kameno Seiji , Kobayashi Hideyuki 
Published: March 2014

Abstract
We investigated observational properties of a kilo-parsec scale knot in the radio-loud quasar 3C 380 by using two epoch archival data obtained by Very Long Baseline Interferometry (VLBI) at 5 GHz on 1998 July and 2001 April. We succeed to obtain the highest spatial resolution image of the bright knot K1 located at 732 mas, or $ \geqq$ 20 kpc de-projected, downstream from the nucleus three-times better than the previously obtained highest-resolution image by Papageorgiou et al. (2006, MNRAS, 373, 449). Our images reveal, with new clarity, an ``inverted bow-shock'' structure in K1 facing the nucleus; its morphology resembles a conical shock wave. By comparing the two epoch images directly, we explored the kinematics of K1, and obtained the upper limit of the apparent velocity, 0.25 mas yr$ ^{-1}$ or 9.8$ c$ of K1 for the first time. The upper limit of the apparent velocity is marginally smaller than superluminal motions seen in the core region. Further new epoch VLBI observations are necessary to measure the proper motion at K1.
Photosphere and Spectrum of Black-Hole Accretion Flow Near to the Eddington Rate
Authors: Kobayashi Hiroshi , Fukue Jun 
Published: March 2014

Abstract
We examine the observational appearance of optically thick, spherically symmetric accretion onto a black hole at around the critical accretion rate. We find that the apparent photosphere deviates markedly from a sphere, but becomes a parabolic-like shape. In addition, the observed temperature over the apparent photosphere is not uniform, but varies significantly from the center to the limb, which shows a strong limb-darkening effect. As a result, the expected spectrum is not a simple blackbody, but becomes a multi-color-type blackbody.
Phase Variation of Earthshine Polarization Spectra
Authors: Takahashi Jun , Itoh Yoichi , Akitaya Hiroshi , Okazaki Akira , Kawabata Koji , Oasa Yumiko , Isogai Mizuki 
Published: March 2014

Abstract
We present the results of the optical spectropolarimetry of Earthshine on the Moon for Earth phase angles ranging from 49$ ^{\circ}$ to 96$ ^{\circ}$ . The observations were conducted on 2011 March 9–13 (UT) using the spectropolarimeter HBS installed on the 1.88 m telescope at Okayama Astrophysical Observatory. The wavelength coverage was 450–850 nm with a resolution of 6 nm. The observed Earthshine polarization degree spectra exhibit decreasing polarization degree with increasing wavelength at any phase. The overall degree of polarization increases as the Earth approaches a quadrature phase. The phase dependence differs with the wavelengths; the maximum polarization for the $ V$ band occurs at a phase angle of $ \sim $ 90$ ^\circ$ , whereas that for longer wavelengths is reached at larger phase angles. This is interpreted as indicating that Earthshine polarization at shorter wavelengths is dominated by atmospheric Rayleigh scattering, whereas that at longer wavelengths has an increasingly effective contribution from the Earth surface reflection. The wavelength dependence of the phase angle of the maximum polarization appears to be unique among the terrestrial planetary bodies in the Solar System. Therefore, this might constitute important evidence pointing toward a distinctive characteristic of Earth: the planet has a scattering but transparent atmosphere above its surface.
High-Speed Imaging System for Solar-Flare Research at Hida Observatory
Authors: Ishii Takako T. , Kawate Tomoko , Nakatani Yoshikazu , Morita Satoshi , Ichimoto Kiyoshi , Masuda Satoshi 
Published: March 2014

Abstract
A high-speed imaging system for observing solar flares in the continuum and H$ \alpha$ wavelengths was installed on a $ \phi$ 25 cm telescope of the Solar Magnetic Activity Research Telescope (SMART) at Hida observatory of Kyoto University. The aim of this system is to diagnose the spatio-temporal evolution of high-energy particles in solar flares by capturing the explosive evolution of chromospheric and photospheric flare kernels. The system acquires flare images covering a field of view of 344$ ''$$ \times$ 258$ ''$ with a spatial sampling of 0$ \hskip1pt''\!\!\!.\hskip1pt$ 215 pixel$ ^{-1}$ and a frame rate of 25 frames s$ ^{-1}$ . Initial data, including two white-light flares, demonstrate the diffraction-limited performance of the system. Observations have been in regular operation since 2011 November. The system is expected to provide a data set that is highly complementary with Hinode/SOT, SDO/AIA, and other ground-based instruments for upcoming solar-flare research.
X-Ray Observations of the W 51 Complex with Suzaku
Authors: Hanabata Yoshitaka , Sawada Makoto , Katagiri Hideaki , Bamba Aya , Fukazawa Yasushi 
Published: March 2014

Abstract
We present a detailed analysis of X-ray emission from the middle-aged supernova remnant W 51 C and star-forming region W 51 B with Suzaku. The soft X-ray emission from W 51 C is well-represented by an optically thin thermal plasma in a non-equilibrium ionization state with a temperature of $ \sim$ 0.7 keV. The elemental abundance of Mg is significantly higher than the solar value. We find no significant feature of an over-ionized plasma in W 51 C. The hard X-ray emission is spatially coincident with the molecular clouds associated with W 51 B, overlapping with W 51 C. The spectrum is represented by an optically thin thermal plasma with a temperature of $ \sim$ 5 keV, or a powerlaw model with a photon index of $ \sim$ 2.2. The emission probably has a diffuse nature, since its luminosity of 1 $ \times$ 10$ ^{34}$ erg s$ ^{-1}$ in the 0.5–10 keV band cannot be explained by any emission from point sources in this region. We discuss the possibility that the hard X-ray emission comes from stellar winds of OB stars in W 51 B, or accelerated particles in W 51 C.
New Photometric Models of Four Near-Contact Binaries: EP Cassiopeiae, AK Canis Minoris, FG Geminorum, and DF Puppis
Authors: yang Yuan-Gui , dai Hai-Feng , He Jia-Jia , Zhang Jia , Ding Wei 
Published: March 2014

Abstract
We present new photometric observations of EP Cas, AK CMi, and FG Gem, which were obtained during the period from 2008 October to 2011 March using the 60 cm telescope at the Xinglong station. Several light-minimum times were determined, and orbital periods were revised. By using the 2003-version Wilson–Devinney code, photometric solutions of EP Cas, AK CMi, FG Gem, and DF Pup were deduced from multicolor light curves. The results imply that the four systems are Algol-type near-contact binaries (NCBs), whose less-massive components are filling their Roche lobes. With mass and angular-momentum loss, the separation between both components will decrease, and the primary will finally fill its Roche lobe. Algol-type NCBs of this kind, such as EP Cas, AK CMi, FG Gem, and DF Pup, may evolve into the contact configuration as a progenitor of a W UMa-type binary.
The Possibility of the Kelvin–Helmholtz Instability during Sedimentation of Dust Grains in the Protoplanetary Disk
Authors: Hasegawa Yukihiko , Tsuribe Toru 
Published: March 2014

Abstract
We reexamine the possibility of shear-driven turbulence during the sedimentation of dust grains in the protoplanetary disk. Shear-driven turbulence is expected to occur before the onset of a gravitational instability for the MMSN model. However, according to previous studies that did not account of the growth of dust grains, with a larger abundance of dust grains, the gravitational instability is indicated to occur before shear-driven turbulence. In this paper, the case including dust growth is considered, and it is found that a Kelvin–Helmholtz instability tends to occur before the gravitational instability, even in the case with a large abundance of dust grains. This is different from previous results without the dust growth.
Discovery of Diffuse Hard X-Ray Emission from the Vicinity of PSR J1648−4611 with Suzaku
Authors: Sakai Michito , Matsumoto Hironori , Haba Yoshito , Kanou Yasufumi , Miyamoto Youhei 
Published: March 2014

Abstract
We observed the pulsar PSR J1648$-$ 4611 with Suzaku. Two X-ray sources, Suzaku J1648$-$ 4610 (Src A) and Suzaku J1648$-$ 4615 (Src B), were found in the field of view. Src A is coincident with the pulsar PSR J1648$-$ 4611, which was also detected by the Fermi Gamma-ray Space Telescope. A hard-band image indicates that Src A is spatially extended. We found point sources in the vicinity of Src A by using a Chandra image of the same region, but the point sources have soft X-ray emission, and cannot explain the hard X-ray emission of Src A. The hard-band spectrum of Src A can be reproduced by a power-law model with a photon index of 2.0$ ^{+0.9}_{-0.7}$ . The X-ray flux in the 2–10 keV band is 1.4 $ \times$ 10$ ^{-13}$ erg cm$ ^{-2}$ s$ ^{-1}$ . The diffuse emission suggests a pulsar wind nebula around PSR J1648$-$ 4611, but the luminosity of Src A is much larger than that expected from the spin-down luminosity of the pulsar. Parts of the very-high-energy $ \gamma$-ray emission of HESS J1646$-$ 458 may be powered by this pulsar wind nebula driven by PSR J1648$-$ 4611. Src B has soft emission, and its X-ray spectrum can be described by a power-law model with a photon index of 3.0$ ^{+1.4}_{-0.8}$ . The X-ray flux in the 0.4–10 keV band is 6.4 $ \times$ 10$ ^{-14}$ erg s$ ^{-1}$ cm$ ^{-2}$ . No counterpart for Src B has been found in the literature.