bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial Distribution of the Galactic Center Diffuse X-Rays and the Spectra of the Brightest 6.4 keV Clumps
Authors: Koyama Katsuji , Takikawa Yojiro , Hyodo Yoshiaki , Inui Tatsuya , Nobukawa Masayoshi , Matsumoto Hironori , Tsuru Takeshi Go
Published: March 2014

The high energy resolution and low background, particularly in the hard X-ray band, of the X-ray Imaging Spectrometer onboard Suzaku provide excellent spectra of the Galactic center diffuse X-rays (GCDX). This paper reports on the results of spatially resolved spectroscopy of the GCDX. The most pronounced features of the GCDX are the K-shell transition lines from neutral (Fe i) and He-like (Fe xxv) irons at energies of 6.4 keV and 6.7 keV, respectively. The fluxes of these lines are non-uniformly and asymmetrically distributed with respect to Sgr A$^\ast$. The 6.4 keV lines are particularly bright on the positive side of the Galactic longitude (east-side) with clumpy structures. A bright clump near the GC exhibits a time variability over a timescale of a few years. Neither the 6.4 keV nor 6.7 keV line flux shows close proportionality to the continuum flux (5–10 keV band); the 6.4 keV line shows excess on the high flux side, and vice versa for the 6.7 keV line. On the other hand, the sum of the 6.4 keV plus 6.7 keV line fluxes with a ratio of 1:2 shows good proportionality to the continuum flux, and hence we phenomenologically decomposed the continuum flux of the GCDX into the 6.4 keV- and 6.7 keV-associated continuums with a flux ratio of 1:2. Based on these facts, we have tried to estimate the contribution of diffuse and integrated flux of point sources to the GCDX.
Constraint of Non-Thermal X-Ray Emission from the On-Going Merger Cluster Abell 3376 with Suzaku
Authors: Kawano Naomi , Fukazawa Yasushi , Nishino Sho , Nakazawa Kazuhiro , Kitaguchi Takao , Makishima Kazuo , Takahashi Tadayuki , Kokubun Motohide , Ota Naomi , Ohashi Takaya , Isobe Naoki , Henry J.Patrick , Hornschemeier Ann
Published: March 2014

Clusters of galaxies are among the best candidates for particle acceleration sources in the universe, a signature of which is non-thermal hard X-ray emission from the accelerated relativistic particles. We present early results on Suzaku observations of non-thermal emission from Abell 3376, which is a nearby on-going merger cluster. Suzaku observed the cluster twice, while focusing on the cluster center containing the diffuse radio emission to the east, and a cluster peripheral region to the west. For both observations, we detected no excess hard X-ray emission above the thermal cluster emission. An upper limit on the non-thermal X-ray flux of 2.1 $\times$ 10$^{-11}$ erg cm$^{-2}$s$^{-1}$ (15–50 keV) at the 3$\sigma$ level from a 34$^\prime$$\times$ 34$^\prime$ region, derived with the Hard X-ray Detector (HXD), is similar to that obtained with the BeppoSAX/PDS. Using the X-ray Imaging Spectrometer (XIS) data, the upper limit on the non-thermal emission from the West Relic is independently constrained to be $<$1.1 $\times$ 10$^{-12}$ erg s$^{-1}$ cm$^{-2}$ (4–8 keV) at the 3$\sigma$ level from a 122 arcmin$^2$ region. Assuming Compton scattering between relativistic particles and the cosmic microwave background photons, the intracluster magnetic field $B$ is limited to be $>$0.03$\mu$G (HXD) and $>$0.10$\mu$G (XIS).
X-Ray Spectroscopy of the Classical Nova V458 Vulpeculae with Suzaku
Authors: Tsujimoto Masahiro , Takei Dai , Drake Jeremy J. , Ness Jan-Uwe , Kitamoto Shunji
Published: March 2014

We conducted a target of opportunity X-ray observation of the classical nova V458 Vulpeculae 88 d after the explosion using the Suzaku satellite. With a $\sim$20 ks exposure, the X-ray Imaging Spectrometer detected X-ray emission significantly harder than typical super-soft source emission. The X-ray spectrum shows K$\alpha$ lines from N, Ne, Mg, Si, and S, and L-series emission from Fe in highly ionized states. The spectrum can be described by a single-temperature ($\sim$0.64 keV) thin thermal plasma model in collisional equilibrium with a hydrogen-equivalent extinction column density of $\sim$3 $\times$ 10$^{21}$cm$^{-2}$, a flux of $\sim$10$^{-12}$ergs$^{-1}$cm$^{-2}$, and a luminosity of $\sim$6 $\times$ 10$^{34}$ergs$^{-1}$ in the 0.3–3.0 keV band at an assumed distance of 13 kpc. We found a hint of an enhancement of N and deficiencies of O and Fe relative to other metals. The observed X-ray properties can be interpreted as the emission arising from shocks of ejecta from an ONe-type nova.
Chemical Abundances of Outer Halo Stars in the Milky Way
Authors: Ishigaki Miho , Chiba Masashi , Aoki Wako
Published: March 2014

We present the chemical abundances of 57 metal-poor ([Fe$/$H] $< -$1) stars that are likely constituents of the outer stellar halo in the Milky Way. Almost all of the sample stars have an orbit reaching a maximum vertical distance ($Z_{\rm max}$) of $>$ 5 kpc above and below the Galactic plane. High-resolution ($R \sim$ 50000$-$55000), high signal-to-noise (S$/$N $>$ 100) spectra for the sample stars obtained with Subaru/HDS were used to derive the chemical abundances of Na, Mg, Ca, Ti, Cr, Mn, Fe, Ni, Zn, Y, and Ba with an LTE abundance analysis code. The resulting abundance data were combined with those presented in the literature that mostly targeted at smaller $Z_{\rm max}$ stars, and both data were used to investigate any systematic trends in detailed abundance patterns depending on their kinematics. It was shown that, in the metallicity range of $-$2 $<$ [Fe$/$H] $< -$1, the [Mg$/$Fe] ratios for stars with $Z_{\rm max} >$ 5 kpc are systematically lower ($\sim$ 0.1 dex) than those with a smaller $Z_{\rm max}$. For this metallicity range, a modest degree of depression in the [Si$/$Fe] and the [Ca$/$Fe] ratios was also observed. This result of lower [$\alpha/$Fe] for the assumed outer halo stars is consistent with previous studies that found a signature of lower [$\alpha/$Fe] ratios for stars with extreme kinematics. The distribution of the [Mg$/$Fe] ratios for the outer halo stars partly overlaps with that for stars belonging to the Milky Way dwarf satellites in the metallicity interval of $-$2 $<$ [Fe$/$H] $< -$1 and spans a range intermediate between the distributions for the inner halo stars and the stars belonging to the satellites. Our results confirm the inhomogeneous nature of the chemical abundances within the Milky Way stellar halo, depending on the kinematic properties of the constituent stars, as suggested by earlier studies. Possible implications for the formation of the Milky Way halo and its relevance to the suggested dual nature of the halo are discussed.
Dwarf Novae in the Shortest Orbital Period Regime. I A New Short Superhump Period Dwarf Nova, OT J055717+683226
Authors: Uemura Makoto , Arai Akira , Kato Taichi , Maehara Hiroyuki , Nogami Daisaku , Kubota Kaori , Moritani Yuuki , Imada Akira , Omodaka Toshihiro , Oizumi Shota , Ohsugi Takashi , Yamashita Takuya , Kawabata Koji S. , Isogai Mizuki , Nagae Osamu , Sasada Mahito , Miyamoto Hisashi , Uehara Takeshi , Tanaka Hiroyuki , Matsui Risako , Fukazawa Yasushi , Sato Shuji , Kino Masaru
Published: March 2014

We report on the observation of a new dwarf nova (DN), OT J055717$+$683226 (OT: optical transient), during the period of its first-recorded superoutburst in 2006 December. Our observation shows that this object is an SU UMa-type dwarf nova having a very short superhump period of 76.67$\pm$0.03 min (0.05324$\pm$0.00002 d). The next superoutburst was observed in 2008 March. The recurrence time of superoutbursts (supercycle) is, hence, estimated to be $\sim$480 d. The supercycle ($\sim$ 480 d) is much shorter than those ($>rsim$10 yr) of WZ Sge-type dwarf novae which are in the major of dwarf novae in the shortest orbital period regime ($\lesssim$85 min). Using a hierarchical cluster analysis, we divided the dwarf nova in the shortest orbital period regime in seven groups. We found that objects, which have short supercycles, small outburst amplitudes, and large superhump period excesses compared with those of WZ Sge stars, form a small group. OT J055717$+$683226 probably belongs to this group.
Bayesian Approach to Find a Long-Term Trend in Erratic Polarization Variations Observed in Blazars
Authors: Uemura Makoto , Kawabata Koji S. , Sasada Mahito , Ikejiri Yuki , Sakimoto Kiyoshi , Itoh Ryosuke , Yamanaka Masayuki , Ohsugi Takashi , Sato Shuji , Kino Masaru
Published: March 2014

We developed a method of separating a long-term trend from observed temporal variations of polarization in blazars using a Bayesian approach. The temporal variation of the polarization vector is apparently erratic in most blazars, while several objects have occasionally exhibited systematic variations, for example an increase of the polarization degree associated with a flare of the total flux. We assume that the observed polarization vector is a superposition of two distinct components: a long-term trend and a short-term variation component responsible for short flares. Our Bayesian model estimates a long-term trend that satisfies the condition that the total flux correlates with the polarized flux of the short-term component. We demonstrate that assumed long-term polarization components are successfully separated by the Bayesian model for artificial data. We applied this method to the three photopolarimetric data of OJ 287, S5 0716$+$714, and S2 0109$+$224. Simple and systematic long-term trends were obtained in OJ 287 and S2 0109$+$224, while no such trend was confirmed in S5 0716$+$714. We propose that the apparently erratic variations of polarization in OJ 287 and S2 0109$+$224 are due to the presence of the long-term polarization component. The behavior of polarization in S5 0716$+$714 during the period of observation implies the presence of a number of polarization components showing variations on a quite short time-scale.
Photometric Investigation and Possible Light-Time Effect in the Orbital Period of a Marginal Contact System, CW Cassiopeiae
Authors: Jiang Tian-Yu , Li Li-Fang , Han Zhan-Wen , Jiang Deng-Kai
Published: March 2014

The first complete charge-coupled device (CCD) light curves in $B$ and $V$ passbands of a neglected contact binary system, CW Cassiopeiae (CW Cas), are presented. They were analyzed simultaneously by using the Wilson and Devinney (WD) code (1971, ApJ, 166, 605). The photometric solution indicates that CW Cas is a W-type W UMa system with a mass ratio of $m_{2}/m_{1} =$ 2.234, and that it is in a marginal contact state with a contact degree of $\sim$ 6.5% and a relatively large temperature difference of $\sim$ 327 K between its two components. Based on the minimum times collected from the literature, together with the new ones obtained in this study, the orbital period changes of CW Cas were investigated in detail. It was found that a periodical variation overlaps with a secular period decrease in its orbital period. The long-term period decrease with a rate of $dP/dt = -$3.44 $\times$ 10$^{-8} $d yr$^{-1}$ can be interpreted either by mass transfer from the more-massive component to the less-massive with a rate of ${d}m_{2}/dt = -$3.6 $\times$ 10$^{-8} M_{\odot} $yr$^{-1}$, or by mass and angular-momentum losses through magnetic braking due to a magnetic stellar wind. A low-amplitude cyclic variation with a period of $T =$ 63.7 yr might be caused by the light-time effect due to the presence of a third body.
Optical Light Curves of Luminous Eclipsing Black Hole X-Ray Binaries
Authors: Watarai Ken-ya , Fukue Jun
Published: March 2014

We examined optical $V$-band light curves in luminous eclipsing black hole X-ray binaries, using a supercritical accretion/outflow model that is more realistic than the formerly used ones. In order to compute the theoretical light curve in the binary system, we did not only apply the global analytic solution of the disk, but also included the effect of optically thick outflow. We found that the depth of eclipse of the companion star by the disk changed dramatically when including the effect of the outflow. Due to the effect of outflow, we could reproduce the optical light curve for typical binary parameters in SS 433. Our model with an outflow velocity of $v \sim$ 3000 km s$^{-1}$ could fit the whole shape of the averaged $V$-band light curve in SS 433, but we found a possible parameter range consistent with observations, such as $\dot{M} \sim$ 5000–10000$ L_{\rm E}/c^2$ (with $L_{\rm E}$ being the Eddington luminosity and $c$ being the speed of light) and $T_{\rm C} =$ 10000$ \gt $K–14000 K for the accretion rate and donor star temperature, respectively. Furthermore, we briefly discuss observational implications for ultraluminous X-ray sources.
Detection of a Cyclic Period Change in the W UMa-Type System HT Virginis
Authors: Liao Wen-Ping , Qian Sheng-Bang
Published: March 2014

HT Vir is a well-known quadruple system with three components visible in the spectra. However, the cyclic variation of the $O - C$ diagram has not been presented until now. To search for a variation in the $O - C$ diagram of HT Vir, we monitored it from 2007 March to 2009 February, and as a result, 7 times of light minimum were obtained. Also, 3 times of light minimum were determined by us with photoelectric data obtained at Mt. Suhora observatory by using three channel photometers attached on the 60-cm Cassegrain telescope (Zola et al. 2005). Based on 56 times of light minimum, we report the discovery of a cyclic variation in the orbital period of HT Vir. It was found that the orbital period of the binary shows a 30.5 yr cyclic change with a semiamplitude of 0.0066 d. The period variation may be caused by a disturbance of component A to the contact system orbit. More times of light minimum with high precision are needed to check the nature of the $O - C$ plot in the future.
NANTEN Survey of Molecular Clouds toward the Galactic Center; Association of Compact Astronomical Objects
Authors: Takeuchi Tomotake , Yamamoto Hiroaki , Torii Kazufumi , Kudo Natsuko , Hayakawa Takahiro , Kawamura Akiko , Mizuno Norikazu , Onishi Toshikazu , Mizuno Akira , Ogawa Hideo , Fukui Yasuo
Published: March 2014

In order to better understand molecular clouds and their properties toward the Galactic center region, we have analyzed the NANTEN database of $^{12}$CO ($J =$ 1–0) and $^{13}$CO ($J =$ 1–0) to search for associations with candidates for young high-mass star-forming regions, such as IRAS point sources, radio continuum sources, recombination line sources, maser line sources, and other molecular line sources. We have also compared the data with TeV $\gamma$-ray sources. The analyzed region covers $-$12$^{\circ} \leq l \leq$ 12$^{\circ}$ and $-$1${\rlap{\hskip.75pt{^\circ}}\hskip.75pt.\hskip1pt}$5 $\leq b \leq$ 1${\rlap{\hskip.75pt{^\circ}}\hskip.75pt.\hskip1pt}$5 for $^{12}$CO, and $-$6$^{\circ} \leq l \leq$ 8$^{\circ}$ and $-$1$^{\circ} \leq b \leq$ 1$^{\circ}$ for $^{13}$CO. As a result, we identified 167 IRAS point sources, 73 recombination line sources, 58 maser sources, 107 radio continuum sources, and 77 molecular line sources associated with 169 positions with the CO emission. The associations among the objects with known velocity are fairly certain (68%), while those with only positional coincidence are less reliable (32%). We present a catalog of these CO clouds in a form useful for future follow-up studies. As specific examples of usage of the catalog, we highlight three outstanding regions of active star formation: W 28, W 30, and W 31. In particular, we have discovered that the W 30 region shows a striking correlation between the extended TeV $\gamma$-ray source and the molecular gas. This is a second case of such a good correlation identified from the NANTEN dataset subsequent to W 28 (Aharonian et al. 2008, A&A, 481, 401). We suggest that the pulsar PSR J1803$-$2137 near the molecular features may play a role in $\gamma$-ray production. The W 31 region exhibits another active star formation, while no $\gamma$-ray source is yet known.
Dwarf Novae in the Shortest Orbital Period Regime: II. WZ Sge Stars as the Missing Population near the Period Minimum
Authors: Uemura Makoto , Kato Taichi , Nogami Daisaku , Ohsugi Takashi
Published: March 2014

WZ Sge-type dwarf novae are characterized by long recurrence times of outbursts ($\sim$ 10 yr) and short orbital periods ($\lesssim$ 85 min). A significant part of WZ Sge stars may remain undiscovered because of low outburst activity. Recently, the observed orbital period distribution of cataclysmic variables (CVs) has changed partly because outbursts of new WZ Sge stars have been discovered routinely. Hence, estimations of the intrinsic population of WZ Sge stars are important to study the population and the evolution of CVs. In this paper, we present a Bayesian approach to estimate the intrinsic period distribution of dwarf novae from observed samples. In this Bayesian model, we assumed a simple relationship between the recurrence time and the orbital period, which is consistent with observations of WZ Sge stars and other dwarf novae. As a result, the minimum orbital period was estimated to be $\sim $ 70 min. The population of WZ Sge stars exhibited a spike-like feature at the shortest period regime in the orbital period distribution. These features are consistent with the orbital period distribution previously predicted by population synthesis studies. We propose that WZ Sge stars and CVs with a low mass-transfer rate are excellent candidates for the missing population predicted by the evolution theory of CVs.
Temperature and Density in the Foot Points of the Molecular Loops in the Galactic Center; Analysis of Multi-J Transitions of 12CO (J = 1–0, 3–2, 4–3, 7–6), 13CO (J = 1–0), and C18O (J = 1–0)
Authors: Torii Kazufumi , Kudo Natsuko , Fujishita Motosuji , Kawase Tokuichi , Okuda Takeshi , Yamamoto Hiroaki , Kawamura Akiko , Mizuno Norikazu , Onishi Toshikazu , Machida Mami , Takahashi Kunio , Nozawa Satoshi , Matsumoto Ryoji , Ott Jürgen , Tanaka Kunihiko , Yamaguchi Nobuyuki , Ezawa Hajime , Stutzki Jürgen , Bertoldi Frank , Koo Bon-Chul , Bronfman Leonardo , Burton Michael , Benz Arnold O. , Ogawa Hideo , Fukui Yasuo
Published: March 2014

Fukui et al. (2006, Science, 314, 106) discovered two molecular loops in the Galactic center, and argued that the foot points of the molecular loops, two bright spots at both loop ends, represent gas accumulated by the falling motion along the loops, subsequent to magnetic flotation by the Parker instability. We have carried out sensitive CO observations of the foot points toward $l =$ 356$^\circ$ at a few pc resolution in the six rotational transitions of CO: $^{12}$CO ($J =$ 1–0, 3–2, 4–3, 7–6), $^{13}$CO ($J =$ 1–0), and C$^{18}$O ($J =$ 1–0). A high-resolution image of $^{12}$CO ($J =$ 3–2) has revealed the detailed distribution of the high-excitation gas, including U shapes, the outer boundary of which shows sharp intensity jumps accompanying strong velocity gradients. An analysis of the multi-$J$ CO transitions shows that the temperature is in the range from 30 to 100 K and the density is around 10$^{3}$–10$^{4} $cm$^{-3}$, confirming that the foot points have high temperature and density, although there is no prominent radiative heating source, such as high-mass stars in or around the loops. We argue that the high temperature is likely due to shock heating under the C-shock condition caused by magnetic flotation. We made a comparison of the gas distribution with theoretical numerical simulations, and note that the U shape is consistent with numerical simulations. We also find that the region of highest temperature of $\sim $100 K or higher inside the U shape corresponds to the spur having an upward flow, additionally heated up either by magnetic reconnection or bouncing in the interaction with the narrow neck at the bottom of the U shape. We note that these new findings further reinforce the magnetic floatation interpretation.
Suzaku Observations of the Merging Cluster Abell 85: Temperature Map and Impact Direction
Authors: Tanaka Nobuhiro , Furuzawa Akihiro , Miyoshi Shigeru J. , Tamura Takayuki , Takata Tadafumi
Published: March 2014

To investigate the present situation of the merging in the southern outer region of Abell 85, we carried out long-time ($\sim$ 100 ks) observations with Suzaku, and produced an X-ray hardness ratio map. We found a high hardness ratio peak on the east side of a subcluster located south of the cluster; an X-ray spectrum of the region including this peak indicates a high temperature of $\sim$ 8.5 keV. This hot spot has not been reported so far. We consider that this hot spot is a postshock region produced by the infall of the subcluster from the southwest. By using the Rankine–Hugoniot jump conditions for shocks, the Mach number and the infall velocity of the subcluster were obtained as 1.5$\ \pm\ $0.2 and 1950$^{+290}_{-280}\ $km s$^{-1}$, respectively, in the case of merging with the subcluster from the southwest direction. By using the difference in redshift between A 85 and the subcluster obtained from optical observations, the angle between the line of sight and the direction of the motion of the subcluster is estimated to be 75$^{\circ}$$^{+7^{\circ}}_{-8^\circ}$. We estimate the kinetic energy of the subcluster and the energy used for the intracluster medium (ICM) heating to be $\sim$ 10$^{63}$ and $\lesssim\ $8 $\times$ 10$^{60}\ $erg, respectively. This shows that the deceleration of the subcluster by the ICM heating has been negligibly small.
Search for Outer Massive Bodies around Transiting Planetary Systems: Candidates of Faint Stellar Companions around HAT-P-7
Authors: Narita Norio , Kudo Tomoyuki , Bergfors Carolina , Nagasawa Makiko , Thalmann Christian , Sato Bun’ei , Suzuki Ryuji , Kandori Ryo , Janson Markus , Goto Miwa , Brandner Wolfgang , Ida Shigeru , Abe Lyu , Carson Joseph , Egner Sebastian E. , Feldt Markus , Golota Taras , Guyon Olivier , Hashimoto Jun , Hayano Yutaka , Hayashi Masahiko , Hayashi Saeko S. , Henning Thomas , Hodapp Klaus W. , Ishii Miki , Knapp Gillian R. , Kusakabe Nobuhiko , Kuzuhara Masayuki , Matsuo Taro , McElwain Michael W. , Miyama Shoken M. , Morino Jun-Ichi , Moro-Martin Amaya , Nishimura Tetsuo , Pyo Tae-Soo , Serabyn Eugene , Suenaga Takuya , Suto Hiroshi , Takahashi Yasuhiro Haruhi , Takami Michihiro , Takato Naruhisa , Terada Hiroshi , Tomono Daigo , Turner Edwin L. , Watanabe Makoto , Yamada Toru , Takami Hideki , Usuda Tomonori , Tamura Motohide
Published: March 2014

We present results of direct imaging observations for HAT-P-7 taken with the Subaru HiCIAO and the Calar Alto AstraLux. Since the close-in transiting planet HAT-P-7b was reported to have a highly tilted orbit, massive bodies such as giant planets, brown dwarfs, and a binary star are expected to exist in the outer region of this system. We show that there are indeed two candidates for distant faint stellar companions around HAT-P-7. We discuss how such companions can play a role on the orbital evolution of HAT-P-7b. We conclude that since there is a third body in the system, as reported by Winn et al. (2009, ApJ, 763, L99), Kozai migration is less likely, while planet–planet scattering is possible.
Solar Eclipses in the First Half of the Chunqiu Period
Authors: Tanikawa Kiyotaka , Yamamoto Tadato , SÔma Mitsuru
Published: March 2014

In the Chinese chronicle Chunqiu, which describes a partial (722 BC–481 BC) history of the Chunqiu Period (770 BC–403 BC), there are recorded 37 solar eclipse observations, starting in 720 BC and ending in 481 BC. Among these, there are 10 eclipse records that lack either the cyclic day number or a statement of ‘the new moon’, or both. Three explanatory books Zuoshi-Zhuan, Guliang-Zhuan, and Gongyang-Zhuan written in the Zhanguo Period (403 BC–221 BC) have different interpretations concerning these records. Zuoshi-Zhuan simply says that royal astronomers forgot to record these data. On the other hand, Guliang-Zhuan says that these eclipses were observed on the last day of the month or during the night. Gongyang-Zhuan says that these were mainly observed on the second day of the month. A famous astronomer, Liuxin in the Han Dynasty, argued close to the idea of Gongyang-Zhuan. These discussions are related to the problem of establishing a precise calendar system in the Chunqiu Period. Controversial arguments continue until today. A Japanese astronomer, Toshio Watanabe (1958), conjectured that these eclipses may have been observed at sunrise or sunset. In the present report, we intend to confirm Watanabe’s conjecture, and after confirming this we use this property to accurately determine the range of $\Delta T$ (see section 1 for definition) in this period. We have obtained new $\Delta T$ ranges in seconds from five eclipses which accompanied deep contemporaneous solar eclipses: 20153 $\leq \Delta T \leq$ 21094 at around 720 BC February 22,18526 $\leq \Delta T \leq$ 20686 at around 676 BC April 15,19409 $\leq \Delta T \leq$ 20402 at around 648 BC April 6if the site is Paros,or18353 $\leq \Delta T \leq$ 19235 at around 648 BC April 6if the site is Thasos,19172 $\leq \Delta T \leq$ 20910 at around 599 BC March 6,16134 $\leq \Delta T \leq$ 19101 at around 558 BC May 31.
AKARI Infrared Observations of the Edge-On Spiral Galaxy NGC 3079
Authors: Yamagishi Mitsuyoshi , Kaneda Hidehiro , Ishihara Daisuke , Komugi Shinya , Suzuki Toyoaki , Onaka Takashi
Published: March 2014

We present AKARI near- to far-infrared images of the nearby edge-on spiral galaxy NGC 3079 in 10 photometric bands. The spectral energy distribution consists of continuum emission from dust with a single temperature of 28–33 K together with strong mid-infrared emission features from polycyclic aromatic hydrocarbons (PAHs). We derived dust masses of 5.6 $\times$ 10$^{6}\ M$$_{\odot}$ and 1.4 $\times$ 10$^7\ M$$_{\odot}$ for the central 4 kpc region and the whole galaxy, respectively, and found that the gas-to-dust mass ratio is unusually high in the central region ($\sim\ $1100), and even for the whole galaxy ($\sim\ $860). The ratio of the surface brightness distribution at a wavelength of 7$\ \mu$m to that at 11$\ \mu$m suggests that the properties of PAHs have spatial variations. The emission from ionized and neutral PAHs is relatively strong in the center and the disk regions, respectively, suggesting a stronger radiation field, and thus relatively active star formation in the center. Yet, the total infrared luminosities of the galaxy indicate rather low star formation rates. These results suggest that NGC 3079 is in an early-phase starburst stage.
On the Relation between Surge Activities and a Photospheric Horizontal Velocity Field
Authors: Kitai Reizaburo
Published: March 2014

A photospheric horizontal velocity field was observed in an active region, NOAA 8375, which showed high H$\alpha $ surge activities on 1998 November 6. From analyses of H$\alpha $ images, the photospheric horizontal velocity field, and the magnetic field in and around the active region, we found the following: (1) Meso-granular or supergranular photospheric horizontal motions were found to be suppressed in the active region where the magnetic filed strength was high. No systematic large-scale flows were found carrying the moving satellite spots with them. (2) Roots of H$\alpha $ surges were situated near a magnetic neutral line, where photospheric horizontal flow converged. Anti-polar magnetic fields on both sides of the neutral line were pushed together by the photospheric horizontal velocity field of meso-granular scales. Magnetic cancellation or magnetic reconnection in the chromospheric and/or photospheric layers at a magnetic neutral line accelerated by photospheric horizontal flows may be the origin of the observed H$\alpha $ surge activities.
Spectroscopic Studies of Limb Spicules. I Radial and Turbulent Velocities
Authors: Shoji Makiko , Nishikawa Takara , Kitai Reizaburo , UeNo Satoru
Published: March 2014

We made high-resolution spectroscopic observations of limb spicules in H$\alpha$ using the Vertical Spectrograph of Domeless Solar Telescope at Hida Observatory. While more than half of the observed spicules have Gaussian line-profiles, some spicules have distinctly asymmetric profiles, which can be fitted to two Gaussian components. The faster component has radial velocities of 10–40 km s$^{-1}$ and Doppler widths of $\sim\ $0.4 $Å$, which suggest that it is from a single spicule oriented nearly along the line-of-sight. Profiles of the slower components and the single-Gaussian type show very similar characteristics. Their radial velocities are less than 10 km s$^{-1}$, and the Doppler widths are 0.6–0.9 $Å$. Nonthermal “macroturbulent” velocities on the order of 30 km s$^{-1}$ are required so as to explain these width values.
Suzaku Observations of the Great Annihilator and the Surrounding Diffuse Emissions
Authors: Nakashima Shinya , Nobukawa Masayoshi , Tsuru Takeshi Go , Koyama Katsuji , Uchiyama Hideki
Published: March 2014

We report the Suzaku observations of 1E 1740.7$-$2942, a black hole candidate called the “Great Annihilator” (GA). The high-quality spectrum of Suzaku provides the severest constraints on the parameters of the GA. Two clumpy structures are found around the GA in the line images of FeI K$\alpha$ at 6.4 keV and SXV K$\alpha$ at 2.45 keV. One clump, named M 359.23$-$0.04, exhibits the 6.4-keV line with an equivalent width of $\sim\ $1.2 keV, and is associated with a molecular cloud in the radio CS ($J =$ 1–0) map. Thus, the 6.4-keV line from M 359.23$-$0.04 is likely due to X-ray fluorescence irradiated by an external X-ray source. The irradiating X-rays would be either a past flare of Sagittarius A$^\ast$ or a bright nearby source, the GA. The other clump, named G 359.12$-$0.05, is associated with the radio supernova remnant candidate G 359.07$-$0.02. We therefore propose that G 359.12$-$0.05 is an X-ray counterpart of G 359.07$-$0.02. G 359.12$-$0.05 has a thin thermal plasma spectrum with a temperature of kT$\sim\ $ 0.9 keV. The plasma parameters of G 359.12$-$0.05 are consistent with those of a single supernova remnant in the Galactic center region.
Calibration of the AKARI Far-Infrared Imaging Fourier-Transform Spectrometer
Authors: Murakami Noriko , Kawada Mitsunobu , Takahashi Hidenori , Okada Yoko , Yasuda Akiko , Ootsubo Takafumi , Kaneda Hidenori , Matsuo Hiroshi , Baluteau Jean-Paul , Davis-Imhof Peter , Gom Brad G. , Naylor David A. , Zavagno Annie , Yamamura Issei , Matsuura Shuji , Shirahata Mai , Doi Yauso , Nakagawa Takao , Shibai Hiroshi
Published: March 2014

The Far-Infrared Surveyor (FIS) onboard the AKARI satellite has a spectroscopic capability provided by a Fourier transform spectrometer (FIS–FTS). FIS–FTS is the first space-borne imaging FTS dedicated to far-infrared astronomical observations. We describe the calibration process of the FIS–FTS, and discuss its accuracy and reliability. The calibration is based on observational data of bright astronomical sources as well as two instrumental sources. We have compared the FIS–FTS spectra with the spectra obtained from the Long Wavelength Spectrometer (LWS) of the Infrared Space Observatory (ISO), having a similar spectral coverage. The present calibration method accurately reproduces the spectra of several solar system objects having a reliable spectral model. Under this condition the relative uncertainty of the calibration of the continuum is estimated to be $\pm$ 15% for SW, $\pm$ 10% for 70–85 cm$^{-1}$ of LW, and $\pm$ 20% for 60–70 cm$^{-1}$ of LW; and the absolute uncertainty is estimated to be $+$35%/$-$55% for SW, $+$35%/$-$55% for 70–85 cm$^{-1}$ of LW, and $+$40%/$-$60% for 60–70 cm$^{-1}$ of LW. These values have been confirmed by comparisons with theoretical models and previous observations by the ISO / LWS.
Spitzer Space Telescope Constraint on the Stellar Mass of a z = 6.96 Lyα Emitter
Authors: Ota Kazuaki , Ly Chun , Malkan Matthew A. , Motohara Kentaro , Hayashi Masao , Shimasaku Kazuhiro , Morokuma Tomoki , Iye Masanori , Kashikawa Nobunari , Hattori Takashi
Published: March 2014

We obtained mid-infrared 3.6 and 4.5$\ \mu$m imaging of a $z =$ 6.96 Ly$\alpha $ emitter (LAE), IOK-1, discovered in the Subaru Deep Field, using Spitzer Space Telescope Infrared Array Camera observations. After removal of a nearby bright source, we found that IOK-1 is not significantly detected in any of these infrared bands to $m_{3.6\mu{\rm m}} \sim$ 24.00 and $m_{4.5\mu{\rm m}} \sim$ 23.54 at 3$\ \sigma$. Fitting population synthesis models to the spectral energy distribution consisting of the upper limit fluxes of the optical-to-infrared non-detection images and fluxes in detection images, we constrained the stellar mass, $M_\ast$, of IOK-1. This LAE could have either a mass as low as $M_\ast \lesssim$ 2–9 $\times$ 10$^{8}\ M_{\odot}$ for young age ($\lesssim$10 Myr) and low dust reddening ($A_V \sim$ 0) or a mass as large as $M_\ast \lesssim$ 1–4 $\times$ 10$^{10}\ M_{\odot}$ for either old age ($ \gt \ $100 Myr) or high dust reddening ($A_V \sim$ 1.5). This would be within the range of masses of $z \sim$ 3–6.6 LAEs studied to date, $\sim$10$^6$–10$^{10}\ M_{\odot}$. Hence, IOK-1 is not a particularly unique galaxy with extremely high mass or low mass, but is similar to one of the LAEs seen at later epochs.
Transiting Extrasolar Planet with a Companion: Effects of Orbital Eccentricity and Inclination
Authors: Sato Masanao , Asada Hideki
Published: March 2014

Continuing work initiated in an earlier publication (Sato & Asada, 2009, PASJ, 61, L29), we consider light curves influenced by the orbital inclination and eccentricity of a companion in orbit around a transiting extrasolar planet (in a planet–satellite system or a hypothetical true binary). We show that the semimajor axis, eccentricity and inclination angle of a ‘moon’ orbit around the host planet can be determined by the transit method alone. For this purpose, we present a formulation for the parameter determinations in a small-eccentricity approximation as well as in the exact form. As a result, the semimajor axis is expressed in terms of observables, such as brightness changes, transit durations and intervals in light curves. We also discuss a narrow region of parameters that produce a mutual transit by an extrasolar satellite.
Mass-Loss Timescale of Star Clusters in an External Tidal Field. II. Effect of Mass Profile of Parent Galaxy
Authors: Tanikawa Ataru , Fukushige Toshiyuki
Published: March 2014

We investigate the long-term dynamical evolution of star clusters in a steady tidal field produced by its parent galaxy. In this paper, we focus on the influence of the mass profile of the parent galaxy. Previous studies were done with simplification, where the parent galaxy was expressed by the point mass. We express different mass profiles of the parent galaxy by the tidal fields in which the ratios of the epicyclic frequency, $\kappa$, to the angular velocity, $\omega$, are different. We compare the mass-loss timescale of star clusters whose tidal radii are identical, but in parent galaxies with different mass profiles, by means of orbits calculations in fixed cluster potential and $N$-body simulations. In this situation, a cluster rotates around the parent galaxy more rapidly, since the parent galaxy has a shallower mass profile. We found that the mass-loss timescale increase by 20% and 50% for the cases that the mass-density profiles of the parent galaxies are proportional to $R^{-2}$ and $R^{-1.5}$, where $R$ is the distance from the galaxy center, compared to the point-mass case, in a moderately strong tidal field. Counterintuitively, a cluster that rotates around the parent galaxy more rapidly has a longer lifetime. The increase of the lifetime is due to the fact that the fraction occupied by a regular-like orbit increases in a shallower profile. Finally, we derive an evaluation formula for the mass-loss timescale of clusters. Our formula can explain a property of the population of the observed galactic globular clusters, that their half-mass radii become smaller as their distances from the galactic center become smaller.
Oxygen and Neon Abundances of B-Type Stars in Comparison with the Sun
Authors: Takeda Yoichi , Kambe Eiji , Sadakane Kozo , Masuda Seiji
Published: March 2014

To revisit the long-standing problem of a possible inconsistency concerning the oxygen composition in the current Galactic gas and in the solar atmosphere (i.e., the former being appreciably lower by $\sim\ $0.3 dex), apparently contradicting the Galactic chemical evolution, we carried out oxygen abundance determinations for 64 mid- through late-B stars by using the O I 6156–8 lines while taking into account the non-LTE effect, and compared them with the solar O abundance established in the same manner. The resulting mean oxygen abundance was $\langle A^{\rm O} \rangle =$ 8.71 ($\pm$ 0.06), which means that [O$/$H] (star $-$ Sun differential abundance) is $\sim-$0.1, the difference being less significant than previously thought. Moreover, since the 3D correction may further reduce the reference solar oxygen abundance (8.81) by $\sim\ $0.1 dex, we conclude that the photospheric O abundances of these B stars are almost the same as that of the Sun. We also determined the non-LTE abundances of neon for sample B stars from Ne I 6143/6163 lines to be $\langle A^{\rm Ne} \rangle =$ 8.02 ($\pm$ 0.09), leading to an Ne-to-O ratio of $\sim\ $0.2, consistent with recent studies. This excludes the possibility of a considerably high Ne$/$O ratio once proposed as a solution to the confronted solar model problem.
The AMANOGAWA-2SB Galactic Plane Survey I. Data on the Galactic Equator
Authors: Yoda Takahiro , Handa Toshihiro , Kohno Kotaro , Nakajima Taku , Kaiden Masahiro , Yonekura Yoshinori , Ogawa Hideo , Morino Jun-ichi , Dobashi Kazuhito
Published: March 2014

Using a waveguide-type sideband-separating receiver (2SB receiver) on the Tokyo-NRO 60-cm telescope (renamed the AMANOGAWA telescope), we carried out simultaneous observations in the $^{12}$CO ($J =$ 2–1) and $^{13}$CO ($J =$ 2–1) lines over the galactic plane $l =$ 10$^\circ$–245$^\circ$ along $b =$ 0$^\circ$ with a 3$'\!\!.$75 grid. Using the $^{12}$CO ($J =$ 1–0) data of Dame et al. (2001, ApJ, 547, 792), who used a beam size almost the same as ours, we show $^{12}$CO ($J =$ 2–1)$/^{12}$CO ($J =$ 1–0) and $^{13}$CO ($J =$ 2–1)$/^{12}$CO ($J =$ 2–1) intensity ratios on the $l$–$v$ map and the intensity correlations among the $^{12}$CO ($J =$ 2–1), $^{13}$CO ($J =$ 2–1), and $^{12}$CO ($J =$ 1–0) lines. As a result, a linear correlation between $^{12}$CO ($J =$ 2–1) and $^{12}$CO ($J =$ 1–0) and a curved correlation between $^{12}$CO ($J =$ 2–1) and $^{13}$CO ($J =$ 2–1), as produced by most of the data, have been found. We investigated these correlations with simple radiative transfer equations to ascertain a number of restrictions on the physical quantities of molecular gas on a galactic scale.
Identification of CXOU J171405.7−381031 as a New Magnetar with XMM-Newton
Authors: Sato Takuro , Bamba Aya , Nakamura Ryoko , Ishida Manabu
Published: March 2014

We observed the 3.8 s pulsar CXOU J171405.7$-$381031 with XMM-Newton, and discovered a significant $\dot P$ of 6.40$\ \pm\ $0.05 $\times$ 10$^{-11}\ $s s$^{-1}$ from this source for the first time, with the aid of archival Chandra data. The characteristic age (950 yr), the magnetic field strength (5 $\times$ 10$^{14}\ $G), and the spin-down luminosity (4.5 $\times$ 10$^{34}\ $erg s$^{-1}$) derived from $P$ and $\dot P$ lead us to conclude that CXOU J171405.7$-$381031 should be identified as a new magnetar. The obtained characteristic age indicates that CXOU J171405.7$-$381031 is the youngest among all known anomalous X-ray pulsars, and is consistent with the age estimated from the thermal X-rays of the associated supernova remnant. The ratio between the 2–10 keV luminosity and the spin-down luminosity is almost unity, which implies that CXOU J171405.7$-$381031 is the key source to connect magnetars with traditional radio pulsars.
New Panoramic View of 12CO and 1.1 mm Continuum Emission in the Orion A Giant Molecular Cloud. I. Survey Overview and Possible External Triggers of Star Formation
Authors: Shimajiri Yoshito , Kawabe Ryohei , Takakuwa Shigehisa , Saito Masao , Tsukagoshi Takashi , Momose Munetake , Ikeda Norio , Akiyama Eiji , Austermann Jason E. , Ezawa Hajime , Fukue Kei , Hiramatsu Masaaki , Hughes David , Kitamura Yoshimi , Kohno Kohtaro , Kurono Yasutaka , Scott Kimberly S. , Wilson Grant W. , Yoshida Atsumasa , Yun Min S.
Published: March 2014

We present new, wide, and deep images in the 1.1 mm continuum and the $^{12}$CO ($J$$=$ 1–0) emission toward the northern part of the Orion A Giant Molecular Cloud (Orion-A GMC). The 1.1 mm data were taken with the AzTEC camera mounted on the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope in Chile, and the $^{12}$CO ($J$$=$ 1–0) data were with the 25 beam receiver (BEARS) on the Nobeyama Radio Observatory (NRO) 45 m telescope in the On-The-Fly (OTF) mode. The present AzTEC observations are the widest (1$^\circ\!\!\!.$7 $\times$ 2$^\circ\!\!\!.$3, corresponding to 12 pc $\times$ 17 pc) and the highest-sensitivity ($\sim\ $9 mJy beam$^{-1}$) 1.1 mm dust-continuum imaging of the Orion-A GMC with an effective spatial resolution of $\sim\ $40$”$. The $^{12}$CO ($J$$=$ 1–0) image was taken over the northern 1$^\circ\!\!\!.$2 $\times$ 1$^\circ\!\!\!.$2 (corresponding 9 pc $\times$ 9 pc) area with a sensitivity of 0.93 K in $T_{\rm MB}$, a velocity resolution of 1.0 km s$^{-1}$, and an effective spatial resolution of 21$”$. With these data, together with the MSX 8$\ \mu$m, Spitzer 24$\ \mu$m, and the 2MASS data, we have investigated the detailed structure and kinematics of molecular gas associated with the Orion-A GMC, and have found evidence for interactions between molecular clouds and the external forces that may trigger star formation. Two types of possible triggers were revealed: (1) Collisions of the diffuse gas on the cloud surface, particularly at the eastern side of the OMC-2/3 region, and (2) Irradiation of UV on the pre-existing filaments and dense molecular cloud cores. Our wide-field and high-sensitivity imaging has provided the first comprehensive view of the potential sites of triggered star formation in the Orion-A GMC.
High Excitation Molecular Gas in the Galactic Center Loops; 12CO (J = 2–1 and J = 3–2) Observations
Authors: Kudo Natsuko , Torii Kazufumi , Machida Mami , Davis Timothy A. , Tsutsumi Kazuki , Fujishita Motusuji , Moribe Nayuta , Yamamoto Hiroaki , Okuda Takeshi , Kawamura Akiko , Mizuno Norikazu , Onishi Toshikazu , Maezawa Hiroyuki , Mizuno Akira , Tanaka Kunihiko , Yamaguchi Nobuyuki , Ezawa Hajime , Takahashi Kunio , Nozawa Satoshi , Matsumoto Ryoji , Fukui Yasuo
Published: March 2014

We have carried out $^{12}$CO ($J$  $=$ 2–1) and $^{12}$CO ($J$  $=$ 3–2) observations at spatial resolutions of 1.0–3.8 pc toward the entirety of loops 1 and 2 and part of loop 3 in the Galactic center with NANTEN2 and ASTE. These new results have revealed detailed distributions of the molecular gas and the line intensity ratio of the two transitions, $R_{3-2/2-1}$. In the three loops, $R_{3-2/2-1}$ is in a range from 0.1 to 2.5 with a peak at $\sim\ $0.7, while that in the disk molecular gas is in a range from 0.1 to 1.2 with a peak at 0.4. This supports that the loops are more highly excited than the disk molecular gas. An LVG analysis of three transitions, $^{12}$CO $J$  $=$ 3–2 and 2–1 and $^{13}$CO $J$  $=$ 2–1, toward six positions in loops 1 and 2 shows that the density and temperature are in the range 10$^{2.2}$–10$^{4.7}\ $cm$^{-3}$ and 15–100 K or higher, respectively. Three regions, extended by 50–100 pc in the loops, tend to have higher excitation conditions, as characterized by $R_{3-2/2-1}$ greater than 1.2. The highest ratio of 2.5 is found in the most developed foot points between loops 1 and 2. This is interpreted that the foot points indicate strongly shocked conditions, as inferred from their large linewidths of 50–100 km s$^{-1}$, confirming a suggestion by Torii et al. (2010, PASJ, 62, 675). The other two regions outside the foot points suggest that the molecular gas is heated up by some additional heating mechanisms, possibly including magnetic reconnection. A detailed analysis of four foot points has shown a U shape, an L shape or a mirrored-L shape in the $b$–$v$ distribution. It is shown that a simple kinematical model that incorporates global rotation and expansion of the loops is able to explain these characteristic shapes.
New Distance and Revised Natures of High-Mass Star Formation in G5.89–0.39
Authors: Motogi Kazuhito , Sorai Kazuo , Habe Asao , Honma Mareki , Kobayashi Hideyuki , Sato Katsuhisa
Published: March 2014

We report on astrometric observations of the 22 GHz H$_{2}$O masers in the high-mass star-forming region G5.89$-$0.39 with VERA (VLBI Exploration of Radio Astrometry). A newly derived distance of 1.28$^{+0.09}_{\-0.08}$ kpc is the most precise, and is significantly nearer than the previous values. We revised the physical parameters and reconsidered the nature of G5.89$-$0.39 based on the new distance as follows: (1) The ionizing star of the ultra compact (UC) H II region is a late O-type (O8–O8.5) zero age main sequence (ZAMS) star, consistent with previously established limits based on its infrared spectral line emission. (2) Crescent-like maser alignment at the position of the O-type ZAMS star may trace an accretion disk (or its remnant), which suggests that the star is still young, and before complete evaporation of circumstellar materials. (3) Although the revised mass for the east-west outflow has been reduced, it is still quite large (100 $M_\odot$), which indicates that a significant fraction of the mass is entrained material, and that the dynamical age significantly underestimates the actual outflow age. Our newly-derived distance emphasizes that G5.89$-$0.39 is one of the nearest targets to investigate ongoing high-mass star formation and evolution in a compact cluster containing a young O-type star.
Spatially Extended [P II] 1.188 μm and [Fe II] 1.257 μm Emission Lines in a Nearby Seyfert Galaxy NGC1068 Observed with OAO/ISLE
Authors: Hashimoto Tetsuya , Nagao Tohru , Yanagisawa Kenshi , Matsuoka Kenta , Araki Nobuo
Published: March 2014

We present $J$-band long-slit spectroscopic observation of NGC 1068 classified as a Seyfert 2 galaxy. $J$-band observations with OAO/ISLE provide clear detection of spatially extended [Fe II] 1.257 $\mu$m and [P II] 1.188 $\mu$m lines. We found that [Fe II] 1.257 $\mu$m$/$[P II] 1.188 $\mu$m increases with distance from a central continuum peak. Observed line ratios around the nucleus (continuum peak) are consistent with a typical value expected from photoionization models, while the ratios at 3$”$–4$”$ (210–280 pc) east and west of the nucleus are slightly higher than this. In the off nucleus region of NGC 1068 we also found a possible association between [Fe II] 1.257 $\mu$m$/$[P II] 1.188 $\mu$m and the radio continuum. This suggests a mild contribution of shock ionization induced by a radio jet outside nucleus while photoionization by the central energy source is dominant near the nucleus.