bluuebunny/crossref_metadata_2025_split huggingface dataset:
Superburst with Outburst from EXO 1745−248 in Terzan 5 with MAXI
Authors: Serino Motoko , Mihara Tatehiro , Matsuoka Masaru , Nakahira Satoshi , Sugizaki Mutsumi , Ueda Yoshihiro , Kawai Nobuyuki , Ueno Shiro 
Published: March 2014

Abstract
MAXI/GSC detected a superburst from EXO 1745$-$ 248 in the globular cluster Terzan 5 on 2011 October 24. The GSC light curve shows an exponential decay with an $ e$-folding time of 0.3 d. The spectra are consistent with the blackbody radiation, whose temperature is 2.2 keV and 1.2 keV at MJD 55858.56 and 55859.20, respectively. The fluence is 1.4 $ \times$ 10$ ^{42}$ erg in 2–20 keV, assuming an 8.7 kpc distance. The sphere radius of the blackbody and its luminosity are estimated to be 6.2 km and 1.1 $ \times$ 10$ ^{38}$ erg s$ ^{-1}$ , respectively, from a spectral fitting at the flux peak. Those $ e$-folding time, temperature, softening, fluence, and radius are typical of superbursts from low-mass X-ray binaries. The superburst was followed by an outburst 28 hours after the superburst onset. The outburst lasted for 5 d and the fluence was 4.3 $ \times$ 10$ ^{42}$ erg. The instability of the accretion disk caused by the superburst would be an explanation for the outburst, whereas the mass accretion of the matter evaporated from the surface of the companion star by the superburst would be another possibility.
Reconstruction of the Structure of Accretion Disks in Dwarf Novae from the Multi-Band Light Curves of Early Superhumps
Authors: Uemura Makoto , Kato Taichi , Ohshima Tomohito , Maehara Hiroyuki 
Published: March 2014

Abstract
We propose a new method to reconstruct the structure of accretion disks in dwarf novae using multi-band light curves of early superhumps. Our model assumes that early superhumps are caused by the rotation effect of non-axisymmetrically flaring disks. We have developed a Bayesian model for this reconstruction, in which a smoother disk-structure tends to have a higher prior probability. We analyzed simultaneous optical and near-infrared photometric data of early superhumps of the dwarf nova, V455 And using this technique. The reconstructed disk has two flaring parts in the outermost region of the disk. These parts are responsible for the primary and secondary maxima of the light curves. The height-to-radius ratio is $ h/r$$ =$ 0.20–0.25 in the outermost region. In addition to the outermost flaring structures, flaring arm-like patterns can be seen in an inner region of the reconstructed disk. The overall profile of the reconstructed disk is reminiscent of the disk structure that is deformed by the tidal effect. However, an inner arm-like pattern, which is responsible for the secondary minimum in the light curve, cannot be reproduced only by the tidal effect. It implies the presence of another mechanism that deforms the disk structure. Alternatively, the temperature distribution of the disk could be non-axisymmetric. We demonstrate that the disk structure with weaker arm-like patterns is optimal in the model including the irradiation effect. However, the strongly irradiated disk gives quite blue colors, which may conflict with the observation. Our results suggest that the amplitude of early superhumps depends mainly on the height of the outermost flaring regions of the disk. We predict that early superhumps can be detected with an amplitude of $ \gt$ 0.02 mag in about 90% of WZ Sge stars.
New Period Investigation of Near Contact Binary BF Virginis
Authors: Liying Zhu , Sheng-Bang Qian , Linjia Li 
Published: March 2014

Abstract
The near contact binary BF Virginis was monitored by us from 2007 to 2011 with the 60-cm telescope of Yunnan Observatory. Eight new observed times of light minimum were derived. All of the available eclipse times, spanning more than 100 yr, were analyzed. It is found that there exists a cyclic variation with a semi-amplitude of 0.034 d and a period of 63.3 yr, superposed by an upward parabolic variation. The upward parabolic change can be explained as a continuous period increase due to mass transfer from the secondary to the primary component of BF Vir, which supports the secondary filling near contact configuration. The period oscillation can be explained either by the light-time effect due to the presence of a third body or by magnetic activity. If it is caused by the light-time effect, the minimum mass and the corresponding orbital radius of the additional body should be $ m_{3}$$ =$ 0.93 $ M_{\odot}$ and $ a_{3}$$ =$ 19.4 AU, respectively. On the other hand, the period oscillation may be explained as a consequence of magnetic cycles in its secondary component. In this case, the required variation of the quadrupole moment is calculated to be $ \Delta{Q}$$ =$ 2.1 $ \times$ 10$ ^{50}$ g cm$ ^2$ .
Near-Infrared Survey of Bright Rimmed Clouds
Authors: Hayashi Miyuki , Itoh Yoichi , Oasa Yumiko 
Published: March 2014

Abstract
We conducted wide-field near-infrared imaging observations of 32 bright rimmed clouds (BRCs). Given a detection limit of 17.7 mag at the $ K$-band, we identified 2099 objects as young stellar object (YSO) candidates that displayed near-infrared excesses. Their masses, estimated from luminosities, range from 0.006 $ M_{\odot}$ to 2.7 $ M_{\odot}$ . The candidates are not uniformly distributed. For 21 BRCs, more than half of the associated YSO candidates are located inside the cloud. We found clear evidence of triggered star formation. The number of YSO candidates is not correlated with the core mass of the molecular clouds. Instead, the YSO number increases with increasing UV photon flux from the exciting star illuminating the cloud surface. UV radiation activates star formation in the BRCs.
HAT-P-38b: A Saturn-Mass Planet Transiting a Late G Star
Authors: Sato Bun'ei , Hartman Joel D. , Bakos Gáspár Á. , BÉKy Bence , Torres Guillermo , Latham David W. , KovÁcs Géza , Csubry Zoltán , Penev Kaloyan , Noyes Robert W. , Buchhave Lars A. , Quinn Samuel N. , Everett Mark , Esquerdo Gilbert A. , Fischer Debra A. , Howard Andrew W. , Johnson John A. , Marcy Geoff W. , Sasselov Dimitar D. , SzklenÁr Tamás , LÁzÁr József , Papp István , SÁri Pál 
Published: March 2014

Abstract
We report on the discovery of HAT-P-38b, a Saturn-mass exoplanet, transiting the $ V$$ =$ 12.56 dwarf star GSC 2314-00559 on a $ P$$ =$ 4.6404 d circular orbit. The host star is a 0.89 $ M_{\odot}$ late G dwarf, with solar metallicity and a radius of 0.92 $ R_{\odot}$ . The planetary companion has a mass of 0.27 $ M_{\rm J}$ and a radius of 0.82 $ R_{\rm J}$ . HAT-P-38b is one of the planets the mass and radius of which have ever been discovered to be the closest to those of Saturn.
Extremely Strong 13CO J = 3→2 Line in the ``Water Fountain'' IRAS 16342−3814: Evidence for the Hot-Bottom Burning
Authors: Imai Hiroshi , Chong Sze Ning , He Jin-Hua , Nakashima Jun-Ichi , Hsia Chih-Hao , Sakai Takeshi , Deguchi Shuji , Koning Nico 
Published: March 2014

Abstract
We observed four ``water fountain'' sources in the CO $ J$ $ =$ 3$ \rightarrow$ 2 line emission with the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope in 2010–2011. The water fountain sources are evolved stars that form high-velocity collimated jets traced by H$ _{2}$ O maser emission. The CO line was detected only from IRAS 16342$-$ 3814. The present work confirmed that the $ ^{12}$ CO to $ ^{13}$ CO line intensity ratio is $ \sim$ 1.5 at the systemic velocity. We discuss the origins of the very low $ ^{12}$ CO-to-$ ^{13}$ CO intensity ratio, as possible evidence for ``hot-bottom burning'' in an oxygen-rich star, and the CO intensity variation in IRAS 16342$-$ 3814.
Discovery of Superhumps during a Normal Outburst of SU Ursae Majoris
Authors: Imada Akira , Izumiura Hideyuki , Kuroda Daisuke , Yanagisawa Kenshi , Kawai Nobuyuki , Omodaka Toshihiro , Miyanoshita Ryo 
Published: March 2014

Abstract
We report on time-resolved photometry during a 2012 January normal outburst of SU UMa. The light curve shows hump-like modulations with a period of 0.07903(11) d, which coincides with the known superhump period of SU UMa during superoutbursts. We interpret this as a superhump, based on the observed periodicity, profiles of the averaged light curve, and the $g'$$-$$I_{\rm c}$ variation during the normal outburst. This is the first case that superhumps have been detected during an isolated normal outburst of SU UMa-type dwarf novae. The present result strongly suggests that the radius of the accretion disk already reaches the 3:1 resonance, even in the midst of the supercycle.
Search for Diffuse X-Rays from the Bow Shock Region of Runaway Star BD +43 3654 with Suzaku
Authors: Terada Yukikatsu , Tashiro Makoto S. , Bamba Aya , Yamazaki Ryo , Kouzu Tomomi , Koyama Shu , Seta Hiromi 
Published: March 2014

Abstract
The bow shocks of runaway stars with strong stellar winds of over 2000 km s$ ^{-1}$ can serve as particle acceleration sites. The conversion from stellar wind luminosity into particle acceleration power has an efficiency of the same order of magnitude as those in supernova remnants, based on the radio emission from the bow shock region of runaway star BD $ +$ 43 3654 (Benaglia et al. 2010, A&A, 517, L10). If this object exhibits typical characteristics, then runaway star systems can contribute a non-negligible fraction of Galactic cosmic-ray electrons. To constrain the maximum energy of accelerated particles from measurements of possible non-thermal emissions in the X-ray band, Suzaku observed BD $ +$ 43 3654 in 2011 April with an exposure of 99 ks. Because the onboard instruments have a stable and low background level, Suzaku detected a possible enhancement over the background of 7.6 $ \pm$ 3.4 counts arcmin$ ^{-2}$ at the bow shock region, where the error represents the 3 $ \sigma$ statistics only. However, the excess is not significant within the systematic errors of non-X-ray and cosmic-ray backgrounds of the X-ray Imaging Spectrometer, which are $ \pm$ 6.0 and $ \pm$ 34 counts arcmin$ ^{-2}$ , respectively, and the 3 $ \sigma$ upper limit in the X-ray luminosity from the shock region, which is 1.1 $ \times$ 10$ ^{32}$ erg s$ ^{-1}$ per 41.2 arcmin$ ^2$ in the 0.5 to 10 keV band. This result leads to three conclusions: (1) a shock-heating process is inefficient on this system; (2) the maximum energy of electrons does not exceed $ \sim$ 10 TeV, corresponding to a Lorentz factor of less than $ 10^7$ ; and (3) the magnetic field in the shock acceleration site might not be as turbulent as those in pulsar wind nebulae and supernova remnants.
Recombining Plasma and Hard X-Ray Filament in the Mixed-Morphology Supernova Remnant W 44
Authors: Uchida Hiroyuki , Katsuji Koyama , Yamaguchi Hiroya , Sawada Makoto , Ohnishi Takao , Tsuru Takeshi Go , Tanaka Takaaki , Yoshiike Satoshi , Fukui Yasuo 
Published: March 2014

Abstract
We report on new features of the typical mixed-morphology supernova remnant W 44. In X-ray spectra obtained with Suzaku, radiative recombination continua of highly ionized atoms were detected for the first time. The spectra are well reproduced by a thermal plasma in a recombining phase. The best-fit parameters suggest that the electron temperature of the shock-heated matter rapidly cooled down from $\sim$ 1 keV to $\sim$ 0.5 keV, possibly due to adiabatic expansion (rarefaction), occurred $\sim$ 20000 yr ago. We also discovered hard X-ray emission, which shows an arclike structure spatially correlating with a radio continuum filament. The surface-brightness distribution has a clear anticorrelation with $^{12}$ CO ($J$ $=$ 2–1) emission from a molecular cloud observed with NANTEN2. While the hard X-ray is most likely due to a synchrotron enhancement in the vicinity of the cloud, no current model can quantitatively predict the observed flux.
Phase Relationship between Polar Faculae and Sunspot Numbers Revisited: Wavelet Transform Analyses
Authors: Deng Linhua , Qu Zhongquan , Dun Guangtao , Xu Chenglin 
Published: March 2014

Abstract
Cross-correlation analysis and wavelet transform methods are proposed to investigate the phase relationship between the polar faculae (PF) and the sunspot numbers (SNs). It was found that: (1) the PF begin 52 months earlier than the SNs on the average of the considered time interval, which should lead to phase asynchrony between them; (2) the length of the Schwabe cycle for the PF obviously differs from that for the SNs at all time points, and the mean length of the Schwabe cycle of the PF (10.28 yr) is slightly smaller than that of the SNs (10.37 yr); (3) the phase relationship between the PF and the SNs is not only time-dependent but also frequency-dependent.
An X-Ray Detected Group of Quiescent Early-Type Galaxies at z = 1.6 in the Chandra Deep Field South
Authors: Tanaka Masayuki , Alexis Finoguenov , Mirkazemi Mohammad , Wilman David J. , Mulchaey John S. , Ueda Yoshihiro , Xue Yongquan , Brandt William N. , Cappelluti Nico 
Published: March 2014

Abstract
We report the discovery of an X-ray group of galaxies located at a high redshift of $ z$ $ =$ 1.61 in the Chandra Deep Field South. Based on 4 Ms Chandra data, the group is first identified as an extended X-ray source. We have used a wealth of deep multi-wavelength data to identify the optical counterpart—our red sequence finder detects a significant over-density of galaxies at $ z$ $ \sim$ 1.6. The brightest group galaxy is spectroscopically confirmed at $ z$ $ =$ 1.61, based on published spectroscopic redshifts. Using this as a central redshift of the group, we measure an X-ray luminosity of $ L_{0.1{\rm-}2.4\rm keV}$ $ =$ (1.8 $ \pm$ 0.6) $ \times$ 10$ ^{43}$ erg s$ ^{-1}$ , which then translates into a group mass of (3.2 $ \pm$ 0.8) $ \times$ 10$ ^{13}$ $ M_{\odot}$ . This is the lowest-mass group ever confirmed at $ z$ $ &gt;$ 1.5. Deep optical–nearIR images from CANDELS reveal that the group exhibits a surprisingly prominent red sequence, and most of the galaxies are consistent with a formation redshift of $ z_{\rm f}$ $ =$ 3. A detailed analysis of the spectral energy distributions of the group member candidates confirms that most of them are indeed passive galaxies. Furthermore, their structural parameters measured from near-IR CANDELS images show that they are morphologically early-type. The newly identified group at $ z$ $ =$ 1.61 is dominated by quiescent early-type galaxies, and the group appears to be similar to those in the local Universe. One possible difference is the high fraction of AGN—38$ ^{+23}_{\hskip.4mm-20}$ % of the bright group member candidates are AGN, which might indicate a role for AGN in the quenching of star formation. However, a statistical sample of high-$ z$ groups is needed to draw a general picture of groups at this redshift. Such a sample will hopefully be available in near-future surveys.
Moment Approach to Determining the Orbital Elements of an Astrometric Binary with a Low Signal-to-Noise Ratio
Authors: Iwama Hirofumi , Asada Hideki , Yamada Kei 
Published: March 2014

Abstract
A moment approach to the orbit determination of an astrometric binary with a low signal-to-noise ratio from astrometric observations alone is proposed, especially aiming at a close binary system with a short orbital period, such as Cyg X-1, and also at a star wobbled by planets. As an exact solution to the nonlinearly coupled equation, the orbital elements are written in terms of the second and third moments of projected positions that are measured by astrometry. This may hold the possibility of the true orbit estimate.
The GENJI Programme: Gamma-Ray Emitting Notable AGN Monitoring by Japanese VLBI
Authors: Nagai Hiroshi , Kino Motoki , Niinuma Kotaro , Akiyama Kazunori , Hada Kazuhiro , Koyama Shoko , Orienti Monica , Hiura Koichiro , Sawada-Satoh Satoko , Honma Mareki , Giovannini Gabriele , Giroletti Marcello , Shibata Katsunori , Sorai Kazuo 
Published: March 2014

Abstract
We introduce the gamma-ray emitting notable active galactic nucleus (AGN) monitoring by Japanese VLBI programme, which is the monitoring of gamma-ray bright AGNs with the VLBI Exploration of Radio Astrometry (VERA) array. This programme aims to conduct dense monitoring at 22 GHz toward the $ \gamma$-ray emitting AGNs to investigate the time variation of the radio core and possible ejection of a new radio component, the motion of jets, and their relations with the emission at other wavelengths, especially at $ \gamma$-rays. We are currently monitoring 8 notable $ \gamma$-ray-emitting AGNs (DA 55, 3C 84, M 87, PKS 1510$-$ 089, DA 406, NRAO 530, BL Lac, and 3C 454.3) about once every two weeks. This programme is promising for tracing the trend of radio time variation on shorter time scale than conventional VLBI monitoring programmes and is complementary to data of other programmes (e.g., MOJAVE; Boston University Blazar Project). In particular, we successfully carried out quick follow-up observations after the GeV $ \gamma$-ray flare in NRAO 530 and 3C 454.3 reported by the Fermi Gamma-ray Space Telescope. Here, we present the initial results of morphology and light curves for the first 7-month operation.
Density Profile of a Cool Core of Galaxy Clusters
Authors: Ota Naomi , Onzuka Kiyokazu , Masai Kuniaki 
Published: March 2014

Abstract
The density profile of a cool core of intracluster gas is investigated for a cluster of galaxies that is initially in the virial equilibrium state, and then undergoes radiative cooling. The initial gas profile is derived under the assumption that the gas is hydrostatic within the dark-matter potential presented by the “NFW” or King model, and has a polytropic profile. The contribution of masses of gas and galaxies to the potential in the calculation is ignored compared to the dark matter. The temperature and density profiles of gas in its quasi-hydrostatic cooling phase, which is expected to last for $ \sim$ Gyr, are then calculated for different initial gas profiles. It is found that in the quasi-hydrostatic cooling phase, while the temperature decreases to about one-third, the density increases by a factor of 4–6 at the cluster center in comparison with its initial polytropic value, though the profiles over the core depend on the dark-matter potential. Hence, the core radius in the quasi-hydrostatic cooling gas appears to be smaller than that in the initial polytropic gas. We compared the density profile of the cool core with observations to find that, while the initial density is around the upper bounds of large-core ($ &gt;$ 100 kpc) clusters, most likely relaxed, but the cooling is not yet significant, the central density under quasi-hydrostatic cooling falls between the mid- and high-values of small ($ &lt;$ 100 kpc)- or cool-core clusters. It is also found for the quasi-hydrostatic cooling gas that the entropy profile roughly agrees with the best-fit model to the ACCEPT cluster sample with a low central entropy; also, the pressure gradient in the core is close to that of the REXCESS sample. X-ray surface brightness calculated for the quasi-hydrostatic cooling gas is well represented by the conventional double $ \beta $-model, giving a physical basis for applying the double $ \beta $-model to cool-core clusters.
Detection of a 522 s Pulsation from the Transient X-Ray Source Suzaku J0102.8–7204 (SXP 523) in the Small Magellanic Cloud
Authors: Wada Qazuya , Tsujimoto Masahiro , Ebisawa Ken , Miller Eric D. 
Published: March 2014

Abstract
During a routine calibration observation of 1E 0102.2$-$ 7219 in the Small Magellanic Cloud (SMC), carried out in 2012 October for the Suzaku satellite, we detected a transient X-ray source at (RA, Dec) $ =$ (01$ ^{\rm h}$ 02$ ^{\rm m}$ 47$ ^{\rm s}$ , $-$ 72$ ^\circ$ 04$ ^{\rm m}$ 54$ ^{\rm s}$ ) in the equinox J2000.0 with a positional uncertainty of $ \sim$ 14. We conducted a temporal and spectral analysis of the source and found a coherent pulse signal with a period of 522.3 $ \pm$ 0.1 s. We also found a featureless spectrum described by a single power-law model with a photon index of 1.0$ ^{+0.1}_{-0.1}$ and a 0.5–10 keV luminosity of $ \sim$ 8.8 $ \times$ 10$ ^{35}$ erg s$ ^{-1}$ at an assumed distance of 60 kpc. The Suzaku source is likely to be the counterpart of 2XMM J010247.4$-$ 720449, which has been observed several times, including outburst detected by Swift. Based on the X-ray characteristics from our data, as well as the transient record and optical and near-infrared features described in the literature, we conclude that this source is a high-mass X-ray binary pulsar with a Be star companion in the SMC, which is known to harbor an exceptionally large ($ \sim$ 80) number of such sources compared to that in our Galaxy.
The Cause of the Superoutburst in SU UMa Stars is Finally Revealed by Kepler Light Curve of V1504 Cygni
Authors: Osaki Yoji , Kato Taichi 
Published: March 2014

Abstract
We have studied the short-cadence Kepler light curve of an SU UMa star, V1504 Cyg, which covers a period of $ \sim$ 630 d. All superoutbursts in V1504 Cyg have turned out to be of precursor-main types, and the superhump first appears near the maximum of the precursor. The superhumps grow smoothly from the precursor to the main superoutburst, showing that the superoutburst was initiated by a tidal instability (as evidenced by the growing superhump) as envisioned in the thermal-tidal instability (TTI) model proposed by Osaki (1989, PASJ, 41, 1005). We performed a power spectral analysis of the light curve of V1504 Cyg. One of the outstanding features is the appearance of a negative superhump extending over around 300 d, well over a supercycle. We found that the appearance of the negative superhump tends to decrease the frequency of occurrence of normal outbursts. Two types of supercycles are recognized in V1504 Cyg, which are similar to those of the Type L and Type S supercycles in the light curve of VW Hyi, a prototype SU UMa star, introduced by Smak (1985, Acta Astron., 35, 357). It is found that the Type L supercycle is the one accompanied by the negative superhump, and Type S is that without the negative superhump. If we adopt a tilted disk as an origin of the negative superhump, two types of the supercycles are understood to be due to a difference in the outburst interval, which is in turn caused by a difference in mass supply from the secondary to different parts of the disk. The frequency of the negative superhump varies systematically during a supercycle in V1504 Cyg. This variation can be used as an indicator of the disk-radius variation, and we have found that the observed disk-radius variation in V1504 Cyg fits very well with a prediction of the TTI model.