bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectral Evolution of the Unusual Slow Nova V5558 Sagittarii
Authors: Tanaka Jumpei , Nogami Daisaku , Fujii Mitsugu , Ayani Kazuya , Kato Taichi , Maehara Hiroyuki , Kiyota Seiichiro , Nakajima Kazuhiro 
Published: March 2014

Abstract
We report on the spectral evolution of the enigmatic, very slow nova V5558 Sgr, based on low-resolution spectra obtained at the Fujii-Bisei Observatory and the Bisei Astronomical Observatory, Japan during the period of 2007 April 6 to 2008 May 3. V5558 Sgr shows a pre-maximum halt, and then several flare-like rebrightenings, which is similar to another very slow nova, V723 Cas. In our observations, the spectral type of V5558 Sgr evolved from the He/N type toward the Fe II type during a pre-maximum halt, and then toward the He/N type again. This course of spectral transition was observed for the first time in the long history of nova research. In the rebrightening stage after the initial brightness maximum, we could identify many emission lines accompanied by a stronger absorption component of the P Cyg profile at the brightness maxima. We found that the velocity of the P Cyg absorption component, measured from the emission peak, decreased at the brightness maxima. Furthermore, we compared the spectra of V5558 Sgr with V723 Cas, and other novae that exhibited several rebrightenings during the early phase.
Skewed Distributions and Opposite Velocity Gradients of Submillimeter Molecular Lines in Low-Mass Protostellar Envelopes
Authors: Takakuwa Shigehisa , Kamazaki Takeshi 
Published: March 2014

Abstract
We have made mapping observations of L 1551 IRS 5, L 1551 NE, L 723, and L 43 and single-point observations of IRAS 16293$-$2422 in the submillimeter CS ($J$ $=$ 7–6) and HCN ($J$ $=$ 4–3) lines with Atacama Submillimeter Telescope Experiment (ASTE). Using the present data and our previous ASTE observations of L 483 and B 335 together, we found a definite correlation between source bolometric luminosities and total integrated intensities of the submillimeter lines ($I_{\rm CS}$ $\propto$ $L_{\rm bol}^{0.92}$). The combined ASTE $+$ Submillimeter Array CS (7–6) image of L 1551 IRS 5 exhibits an extended ($\sim$ 2000 AU) component tracing the associated reflection nebula at west and southwest, as well as a compact ($\lesssim$ 500 AU) component centered on the protostellar position. The peaks of the CS and HCN emissions in L 1551 NE are not located at the protostellar position but offset ($\sim$ 1400 AU) toward the associated reflection nebula at west. By statistical analyses, we confirmed the velocity gradients of the CS (7–6) emission that are opposite to those of the millimeter lines along the outflow direction, which we reported in our early paper. The magnitudes of the submillimeter velocity gradients are estimated to be (9.7$\ \pm\ $1.7) $\times$ 10$^{-3}\ $km s$^{-1}\ $arcsec$^{-1}\ $ in L 1551 IRS 5 and (7.6$\ \pm\ $2.4) $\times$ 10$^{-3}\ $km s$^{-1}\ $arcsec$^{-1}\ $ in L 483. We suggest that the “skewed” submillimeter molecular emissions toward the associated reflection nebulae at a few thousand AU scale trace the warm ($\gtrsim$ 40 K) walls of the envelope cavities, excavated by the associated outflows and directly irradiated by the central protostars. The opposite velocity gradients along the outflow direction likely reflect the dispersing gas motion at the wall of the cavity in envelopes perpendicular to the outflow.
Stellar Parameters and Chemical Abundances of G Giants
Authors: Wang Liang , Liu Yujuan , Zhao Gang , Sato Bun'ei 
Published: March 2014

Abstract
We present basic stellar parameters of 99 late-type G giants based on high-resolution spectra obtained by the High Dispersion Spectrograph attached to Subaru Telescope. These stars are targets of a Doppler survey program searching for extra-solar planets among evolved stars, with a metallicity of $-$0.8 $\lt$ [Fe$/$H] $\lt$ $+$0.2. We also derived their abundances of 15 chemical elements, including four $\alpha $-elements (Mg, Si, Ca, Ti), three odd-Z light elements (Al, K, Sc), four iron peak elements (V, Cr, Fe, Ni), and four neutron-capture elements (Y, Ba, La, Eu). Kinematic properties reveal that most of the program stars belong to the thin disk.
Oscillation Phenomena in the Disk around the Massive Black Hole Sagittarius A*
Authors: Miyoshi Makoto , Shen Zhi-Qiang , Oyama Tomoaki , Takahashi Rohta , Kato Yoshiaki 
Published: March 2014

We report the detection of radio QPOs with structure changes using the Very Long Baseline Array (VLBA) at 43 GHz. We found conspicuous patterned changes of the structure with $P$ $=$ 16.8$\ \pm\ $1.4, 22.2$\ \pm\ $1.4, 31.4$\ \pm\ $1.5, 56.4$\ \pm\ $6 min roughly in a 3:4:6:10 ratio. The first two periods show a rotating one-arm structure, while $P$ $=$ 31.4 min shows a rotating 3-arm structure, as if viewed edge-on. At the central 50$\ \mu$as the $P$ $=$ 56.4 min period shows a double-amplitude variation of those in its surroundings. The spatial distributions of the oscillation periods suggest that the disk of Sgr A$^{*}$ is roughly edge-on, rotating around an axis with $PA$ $=$ $-$10$^{\circ}$. Presumably, the observed VLBI images of Sgr A$^{*}$ at 43 GHz retain several features of the black hole accretion disk of Sgr A$^{*}$ in spite of being obscured and broadened by scattering of surrounding plasma.
Correlation between Interstellar Polarization and Dust Temperature: Is the Alignment of Grains by Radiative Torques Ubiquitous?
Authors: Matsumura Masafumi , Kameura Youko , Kawabata Koji S. , Akitaya Hiroshi , Isogai Mizuki , Seki Munezo 
Published: March 2014

We have investigated the efficiency of interstellar polarization, $p_\lambda/A_\lambda$, where $p_\lambda$ is the fractional linear polarization and $A_\lambda$ is the extinction, in 14 lines of sight as a function of the wavelength, $\lambda$. We used the data of lines of sight to the Pleiades cluster obtained with the low-dispersion spectropolarimeter HBS as well as those in literature. It has been found that the polarization efficiency, $p_\lambda/A_\lambda$, is proportional to exp ($-\beta/\lambda$) in wavelength, $\lambda$ $\approx$ 0.4–0.8$\ \mu$m, where $\beta$ is a parameter that varies from 0.5 to 1.2$\ \mu$m. We find that $\beta$ is negatively correlated with the dust temperature deduced from infrared data by Schlegel et al. (1998, ApJ, 500, 525), suggesting that the polarization efficiency is higher in short wavelengths for higher temperature. According to the alignment theory by radiative torques (RATs), if the radiation is stronger, RATs will make small grains align better, and the polarization efficiency will increase at short wavelengths. Our finding of the correlation between $\beta$ and the temperature is consistent with what is expected with the alignment mechanism by RATs.
AKARI/IRC Broadband Mid-Infrared Data as an Indicator of the Star-Formation Rate
Authors: Yuan Fang-Ting , Takeuchi Tsutomu T. , Buat Véronique , Heinis Sébastien , Giovannoli Elodie , Murata Katsuhiro L. , Iglesias-PÁRamo Jorge , Burgarella Denis 
Published: March 2014

Abstract
AKARI/Infrared Camera (IRC) Point Source Catalog provides a large amount of flux data at S9W (9$\ \mu$m) and L18W (18$\ \mu$m) bands. With the goal of constructing Star-Formation Rate (SFR) calculations using IRC data, we analyzed an IR selected GALEX-SDSS-2MASS-AKARI(IRC/Far-Infrared Surveyor) sample of 153 nearby galaxies. The far-infrared fluxes were obtained from AKARI diffuse maps to correct an underestimation for extended sources raised by the point-spread function photometry. SFRs of these galaxies were derived by the spectral energy distribution fitting program CIGALE. In spite of complicated features contained in these bands, both the S9W and L18W emission correlate with the SFR of galaxies. The SFR calibrations using S9W and L18W are presented for the first time. These calibrations agree well with previous works based on Spitzer data within the scatters, and should be applicable to dust-rich galaxies.
Rotating Black Holes as Central Engines of Long Gamma-Ray Bursts: Faster is Better
Authors: Nagataki Shigehiro 
Published: March 2014

Abstract
We performed simulations of collapsars with different Kerr parameters of $a$ $=$ 0, 0.5, 0.9, and 0.95. It was shown that a more rapidly rotating black hole is driving a more energetic jet. No jet is seen for the case of the Schwartzschild black-hole case, while the total energy of the jet is as large as 10$^{50}\ $erg for a rapidly rotating Kerr black-hole case ($a$ $=$ 0.95). In order to explain the high luminosity of a gamma-ray burst, it is concluded that a rapidly rotating black hole is favored ('faster is better'). We also find that in the case of $a$ $=$ 0.95, (i) a stagnation region is clearly found in the jet region, (ii) ordered poloidal field lines are seen in the jet, (iii) the jet region is surrounded by a 'wall-like' structure that has a higher pressure than the jet region, and contains strong vertical magnetic fields, and (iv) the jet is initiated by an outgoing Poynting flux from the outer horizon of the black hole (Blandford–Znajek effect). The bulk Lorentz factor of the jet is still on the order of unity. However, the energy density of electro-magnetic fields is dominated by the one of rest-mass in the jet. It can be expected that a relativistic jet will be seen if we perform a simulation for a longer time scale (of the order of 10–100 s).
Center-to-Limb Variation of Radio Emissions from Thermal-Rich and Thermal-Poor Solar Flares
Authors: Kawate Tomoko , Asai Ayumi , Ichimoto Kiyoshi 
Published: March 2014

Abstract
A statistical analysis of radio flare events was conducted by using the event list of Nobeyama Radioheliograph in the years 1996–2009. We examined center-to-limb variations of 17 GHz and 34 GHz fluxes by dividing the flare events into different groups according to the ``thermal plasma richness'' (ratio of the peak flux of soft X-ray to nonthermal radio emissions) and the duration of radio bursts. It was found that the peak flux at 17 and 34 GHz tended to be higher toward the limb for thermal-rich flares with short durations. We propose that the thermal-rich flares, which are supposed to be associated with an efficient precipitation of high-energy particles into the chromosphere, have a pitch-angle distribution of nonthermal electrons with a higher population along the flare loop.
Radio Imaging of the NGC 1333 IRAS 4A Region: Envelope, Disks, and Outflows of a Protostellar Binary System
Authors: Choi Minho , Kang Miju , Tatematsu Ken'ichi , Lee Jeong-Eun , Park Geumsook 
Published: March 2014

Abstract
The NGC 1333 IRAS 4A protobinary was observed in the 1.3 cm and 6.9 mm continuum and the ammonia and SiO lines, with an angular resolution of $\sim$ 0$''\!\!\!.$4. The continuum maps show the circumstellar structures of two protostars, A1 and A2. The A1 system is brighter and more massive than the A2 system. The ratio of mass, including dense gas and the protostar, is $\sim$ 6. The properties of the circumstellar disks and outflows suggest that A1 may be younger than A2. The deflected part of the northeastern jet of A2 is bright in the SiO line, and the distance between the brightest peak and the deflection point suggests that the enhancement of SiO takes $\sim$ 100 yr after a collision with a dense core. Ammonia maps show a small structure that seems to be a part of the obstructing core. The outflow properties were studied by comparing interferometric maps of the SiO, ammonia, formaldehyde, and HCN lines. Their overall structures agree well, suggesting that these species are excited by the same mechanism. However, the intensity distributions show that SiO is chemically unique. SiO may be directly linked to the primary jet, while the other species may be tracing the entrained ambient gas.
Fast Automatic Redshift Determination Using Absorption Lines Recognition
Authors: Han Jin-Shu , Luo A-Li , Zhao Yong-Heng 
Published: March 2014

Abstract
To precisely measure the redshifts of non-ELGs (ELGs: emission-line galaxies), weaker-ELGs and galaxies with only one emission line that is clearly visible in the optical band, a fast automatic redshift determination algorithm (FRA) is proposed, which is different from the widely used cross-correlation method. The algorithm has higher speed because it determines the redshift by extracting and recognizing two pairs of prominent absorption lines in the blue band of a spectrum, G-band $\lambda$4306 and H${\gamma}$$\lambda$4342 (vacuum wavelength), H${\beta}$$\lambda$4863 and Mg $\lambda$5177, rather than through matching an observational galaxy spectrum with the complete galaxy templates. Moreover, a wide range of redshift measurements from 0 to 0.65 and relatively high success rates can be reached by FRA. For spectra with a relatively wide wavelength range and with a resolution above $R$$=$ 1000, FRA is an efficient automatic algorithm that can be used in spectra redshift surveys with large amounts of data.
XO-2b: a Prograde Planet with Negligible Eccentricity and an Additional Radial Velocity Variation
Authors: Narita Norio , Hirano Teruyuki , Sato Bun'ei , Harakawa Hiroki , Fukui Akihiko , Aoki Wako , Tamura Motohide 
Published: March 2014

Abstract
We present precise radial velocities of XO-2 taken with the Subaru HDS, covering two transits of XO-2b with an interval of nearly two years. The data suggest that the orbital eccentricity of XO-2b is consistent with zero within 2$\ \sigma$ ($e$$=$ 0.045$\ \pm\ $0.024), and that the orbit of XO-2b is prograde (the sky-projected spin–orbit alignment angle $\lambda$$=$ 10$^{\circ}\ \pm\ $72$^{\circ}$). The poor constraint of $\lambda$ is due to a small impact parameter (the orbital inclination of XO-2b is almost 90$^{\circ}$). The data also provide an improved estimate of the mass of XO-2b as 0.62$\ \pm\ $0.02$\ M_{\rm Jup}$. Further, we find a long-term radial velocity variation in this system. Additional radial velocity measurements are necessary to specify the cause of this additional variation.
In-Orbit Performance of MAXI Gas Slit Camera (GSC) on ISS
Authors: Sugizaki Mutsumi , Mihara Tatehiro , Serino Motoko , Yamamoto Takayuki , Matsuoka Masaru , Kohama Mitsuhiro , Tomida Hiroshi , Ueno Shiro , Kawai Nobuyuki , Morii Mikio , Sugimori Kousuke , Nakahira Satoshi , Yamaoka Kazutaka , Yoshida Atsumasa , Nakajima Motoki , Negoro Hitoshi , Eguchi Satoshi , Isobe Naoki , Ueda Yoshihiro , Tsunemi Hiroshi 
Published: March 2014

Abstract
We report on the in-orbit performance of the Gas Slit Camera (GSC) on the MAXI (Monitor of All-sky X-ray Image) mission carried on the International Space Station (ISS). Its commissioning operation, which started on 2009 August 8, confirmed the basic performances of the effective area in the energy band of 2–30 keV, the spatial resolution of the slit-and-slat collimator and detector with 1 $^\circ\!\!\!.$ 5 FWHM, the source visibility of 40–150 seconds for each scan cycle, and the sky coverage of 85% per 92-minute orbital period and 95% per day. The gas gains and read-out amplifier gains have been stable within 1%. The background rate is consistent with the past X-ray experiments operated at a similar low-earth orbit if its relation with the geomagnetic cutoff rigidity is extrapolated to high latitude. We also present the status of the in-orbit operation and a calibration of the effective area and the energy response matrix using Crab-nebula data.
The First MAXI/GSC Catalog in the High Galactic-Latitude Sky
Authors: Hiroi Kazuo , Ueda Yoshihiro , Isobe Naoki , Hayashida Masaaki , Eguchi Satoshi , Sugizaki Mutsumi , Kawai Nobuyuki , Tsunemi Hiroshi , Matsuoka Masaru , Mihara Tatehiro , Yamaoka Kazutaka , Ishikawa Masaki , Kimura Masashi , Kitayama Hiroki , Kohama Mitsuhiro , Matsumura Takanori , Morii Mikio , Nakagawa Yujin E. , Nakahira Satoshi , Nakajima Motoki , Negoro Hitoshi , Serino Motoko , Shidatsu Megumi , Sootome Tetsuya , Sugimori Kousuke , Suwa Fumitoshi , Toizumi Takahiro , Tomida Hiroshi , Tsuboi Yohko , Ueno Shiro , Usui Ryuichi , Yamamoto Takayuki , Yamazaki Kyohei , Yoshida Atsumasa 
Published: March 2014

Abstract
We present the first unbiased source catalog of the Monitor of All-sky X-ray Image (MAXI) mission at high Galactic latitudes ( $\vert b\vert$$&gt;$ 10 $^{\circ}$ ), produced from the first 7-month data (2009 September 1 to 2010 March 31) of the Gas Slit Camera in the 4–10 keV band. We have developed an analysis procedure to detect faint sources from the MAXI data, utilizing a maximum likelihood image fitting method, where the image response, background, and detailed observational conditions are taken into account. The catalog consists of 143 X-ray sources above the 7 $\sigma$ significance level with a limiting sensitivity of $\sim\ $ 1.5 $\times$ 10 $^{-11}\ $ erg cm $^{-2}\ $ s $^{-1}$ (1.2 mCrab) in the 4–10 keV band. Among them, we have identified 38 Galactic/LMC/SMC objects, 48 galaxy clusters, 39 Seyfert galaxies, 12 blazars, and 1 galaxy. Four other sources are confused with multiple objects, and one remains unidentified. The log $\ N$ –log $\ S$ relation of extragalactic objects is in good agreement with the HEAO-1 A-2 result, although the list of the brightest AGNs in the entire sky has significantly changed since that produced 30 yr ago.
A Large X-Ray Flare from a Single Weak-Lined T Tauri Star TWA-7 Detected with MAXI GSC
Authors: Uzawa Akiko , Tsuboi Yohko , Morii Mikio , Yamazaki Kyohei , Kawai Nobuyuki , Matsuoka Masaru , Nakahira Satoshi , Serino Motoko , Matsumura Takanori , Mihara Tatehiro , Tomida Hiroshi , Ueda Yoshihiro , Sugizaki Mutsumi , Ueno Shiro , Daikyuji Arata , Ebisawa Ken , Eguchi Satoshi , Hiroi Kazuo , Ishikawa Masaki , Isobe Naoki , Kawasaki Kazuyoshi , Kimura Masashi , Kitayama Hiroki , Kohama Mitsuhiro , Kotani Taro , Nakagawa Yujin E. , Nakajima Motoki , Negoro Hitoshi , Ozawa Hiroshi , Shidatsu Megumi , Sootome Tetsuya , Sugimori Kousuke , Suwa Fumitoshi , Tsunemi Hiroshi , Usui Ryuichi , Yamamoto Takayuki , Yamaoka Kazutaka , Yoshida Atsumasa 
Published: March 2014

Abstract
We present a large X-ray flare from a nearby weak-lined T Tauri star TWA-7 detected with the Gas Slit Camera (GSC) on the Monitor of All-sky X-ray Image (MAXI). The GSC captured X-ray flaring from TWA-7 with a flux of 3 $\times$ 10 $^{-9}\ $ erg cm $^{-2}\ $ s $^{-1}$ in 2–20 keV band during the scan transit starting at 2010-09-07 18:24:30 (UT). The estimated X-ray luminosity at the scan in the energy band is 3 $\times$ 10 $^{32}\ $ erg s $^{-1}$ , indicating that the event is among the largest X-ray flares from T Tauri stars. Since MAXI GSC monitors a target only during a scan transit of about a minute per 92 min orbital cycle, the luminosity at the flare peak might have been higher than that detected. At the scan transit, we observed a high X-ray-to-bolometric luminosity ratio, log $\ L_{\rm X}/L_{\rm bol}$$=$$-$ 0.1 $^{+0.2}_{-0.3}$ ; i.e., the X-ray luminosity is comparable to the bolometric luminosity. Since TWA-7 has neither an accreting disk nor a binary companion, the observed event implies that none of those are essential to generate such big flares in T Tauri stars.
Suzaku Observation of the Intermediate Polar V1223 Sagittarii
Authors: Hayashi Takayuki , Ishida Manabu , Terada Yukikatsu , Bamba Aya , Shionome Takeshi 
Published: March 2014

Abstract
We report on the Suzaku observation of the intermediate polar V1223 Sagittarii. Using a multi-temperature plasma emission model with its reflection from a cold matter, we obtained the shock temperature to be 37.9 $^{+5.1}_{-4.6}\ $ keV. This constrains the mass and the radius of the white dwarf (WD) in the ranges 0.82 $^{+0.05}_{-0.06}\ M_\odot$ and (6.9 $\ \pm\ $ 0.4) $\times$ 10 $^{8}\ $ cm, respectively, with the aid of a WD mass–radius relation. The solid angle of the reflector viewed from the post-shock plasma was measured to be $\Omega/$ 2 $\pi$$=$ 0.91 $\ \pm\ $ 0.26. A fluorescent iron K $\alpha $ emission line was detected, whose central energy was discovered to be modulated with the WD rotation for the first time in magnetic-CVs. Detailed spectral analysis indicates that the line comprises a stable 6.4 keV component and a red-shifted component, the latter of which appears only around the rotational intensity-minimum phase. The equivalent width ( $EW$ ) of the former stable component, $\sim\ $ 80 eV, together with the measured $\Omega$ indicates that the major reflector is the WD surface, and the shock height is not more than 7% of the WD radius. Comparing this limitation to the height predicted by the Aizu model (Aizu, 1973, Prog. Theor. Phys., 50, 344), we estimated the fractional area onto which the accretion occurs to be $&lt;\ $ 7 $\times$ 10 $^{-3}$ of the WD radius, which is the most severe constraint in non-eclipsing IPs. The red-shifted iron line component, on the other hand, can be interpreted as emanating from the pre-shock accretion flow via fluorescence. Its $EW$ (28 $^{+44}_{-13}\ $ eV) and the central energy (6.30 $_{-0.05}^{+0.07}\ $ keV) at the intensity-minimum phase are consistent with this interpretation.
Near-Infrared and X-Ray Observations of XSS J12270−4859
Authors: Saitou Kei , Tsujimoto Masahiro , Ebisawa Ken , Ishida Manabu , Mukai Koji , Nagayama Takahiro , Nishiyama Shogo , Gandhi Poshak 
Published: March 2014

Abstract
XSS J12270 $-$ 4859 (J12270) is an enigmatic source of unknown nature. Previous studies revealed that the source has unusual X-ray temporal characteristics, including repetitive short-term flares, followed by spectral hardening, non-periodic dips, and dichotomy in activity; i.e., intervals filled with flares and those without. Together with a power-law X-ray spectrum, it is suggested to be a low-mass X-ray binary. In order to better understand the object, we present the results of our near-infrared (NIR) photometry and linear polarimetry observations as well as X-ray spectroscopy observations, which overlap with each other partially in time, taken respectively with the InfraRed Survey Facility (IRSF) and the Rossi X-ray Timing Explorer (RXTE). We detected several simultaneous NIR and X-ray flares for the first time. No significant NIR polarization was obtained. We assembled data taken with IRSF, RXTE, Suzaku, Swift, and other missions in the literature and compared the flare profile and the spectral energy distribution (SED) with some representative high-energy sources. Based on some similarities of the repetitive NIR and X-ray flaring characteristics and the broad SED, we argue that J12270 is reminiscent of microquasars with a synchrotron jet, which is at a very low-luminosity state of $\approx$ 10 $^{-4}$ Eddington luminosity for a stellar mass black hole or neutron star at a reference distance of 1 kpc.
Suzaku Discovery of Twin Thermal Plasma from the Tornado Nebula
Authors: Sawada Makoto , Go Tsuru Takeshi , Koyama Katsuji , Oka Tomoharu 
Published: March 2014

Abstract
The Tornado nebula (G357.7 $-$ 0.1) is a mysterious radio source with a bright “head” and faint “tail” located in the direction of the Galactic center (GC) region. We here report on the discovery of two diffuse X-ray sources at the head and tail of Tornado with the Suzaku satellite. We found emission lines from highly ionized atoms in the two sources. The spectra have been reproduced by an optically thin thermal plasma with a common temperature of 0.6–0.7 keV. The interstellar absorption ( $N_{\rm H}$ ) of these sources are the same, and are slightly larger than that of the GC distance. Since the estimated distance using the $N_{\rm H}$ value is consistent with radio observations of Tornado, these X-ray sources are likely to be associated with the Tornado nebula. The twin-plasma morphology at both ends of Tornado suggests that the system is a bipolar/outflow source.