bluuebunny/crossref_metadata_2025 huggingface dataset:
Suzaku Discovery of Iron Absorption Lines in Outburst Spectra of the X-Ray Transient 4U 1630—472
Authors: Kubota Aya , Dotani Tadayasu , Cottam Jean , Kotani Taro , Done Chris , Ueda Yoshihiro , Fabian Andrew C. , Yasuda Tomonori , Takahashi Hiromitsu , Fukazawa Yasushi , Yamaoka Kazutaka , Makishima Kazuo , Yamada Shinya , Kohmura Takayoshi , Angelini Lorella
Published: March 2014

We present the results of six Suzaku observations of the recurrent black hole transient 4U 1630$-$472 during its decline from outburst from February 8 to March 23 in 2006. All observations show the typical high/soft state spectral shape in the 2–50 keV band, roughly described by an optically thick-disk spectrum in the soft energy band plus a weak power-law tail that becomes dominant only above $\sim 20 \,\mathrm{keV}$. The disk temperature decreases from 1.4 keV to 1.2 keV as the flux decreases by a factor of 2, consistent with a constant radius, as expected for disk-dominated spectra. All of the observations reveal significant absorption lines from highly ionized (H-like and He-like) iron $\mathrm{K}\alpha$’s at 7.0 keV and 6.7 keV. The energies of these absorption lines suggest a blue shift with an outflow velocity of $\sim 1000 \,\mathrm{km} \,\mathrm{s}^{-1}$. The H-like iron $\mathrm{K}\alpha$ equivalent width remains approximately constant at $\sim 30 \,\mathrm{eV}$ over all of the observations, while that of the He-like $\mathrm{K}\alpha$ line increases from 7 eV to 20 eV. Thus, the ionization state of the material decreases, as expected from the decline in flux. By fitting the profile with Voigt functions (curve of growth) together with detailed photo-ionization calculations, the total absorbing column, and the ionization parameter were estimated to be $(1.0 \hbox{--} 0.7) \times 10^{23} \,\mathrm{cm}^{-2}$ and $(6 \hbox{--} 4) \times 10^4$, respectively, for a velocity dispersion of $500 \,\mathrm{km} \,\mathrm{s}^{-1}$. This in turn constrains the size of the plasma to be $\sim 10^{10} \,\mathrm{cm}$, assuming a source distance of 10 kpc.
X-Ray Imaging Spectrometer (XIS) on Board Suzaku
Authors: Koyama Katsuji , Tsunemi Hiroshi , Dotani Tadayasu , Bautz Mark W. , Hayashida Kiyoshi , Tsuru Takeshi Go , Matsumoto Hironori , Ogawara Yoshiaki , Ricker George R. , Doty John , Kissel Steven E. , Foster Rick , Nakajima Hiroshi , Yamaguchi Hiroya , Mori Hideyuki , Sakano Masaaki , Hamaguchi Kenji , Nishiuchi Mamiko , Miyata Emi , Torii Ken’ichi , Namiki Masaaki , Katsuda Satoru , Matsuura Daisuke , Miyauchi Tomofumi , Anabuki Naohisa , Tawa Noriaki , Ozaki Masanobu , Murakami Hiroshi , Maeda Yoshitomo , Ichikawa Yoshinori , Prigozhin Gregory Y. , Boughan Edward A. , LaMarr Beverly , Miller Eric D. , Burke Barry E. , Gregory James A. , Pillsbury Allen , Bamba Aya , Hiraga Junko S. , Senda Atsushi , Katayama Haruyoshi , Kitamoto Shunji , Tsujimoto Masahiro , Kohmura Takayoshi , Tsuboi Yohko , Awaki Hisamitsu
Published: March 2014

The XIS is an X-ray Imaging Spectrometer system, consisting of state-of-the-art charge-coupled devices (CCDs) optimized for X-ray detection, camera bodies, and control electronics. Four sets of XIS sensors are placed at the focal planes of the grazing-incidence, nested thin-foil mirrors (XRT: X-Ray Telescope) onboard the Suzaku satellite. Three of the XIS sensors have front-illuminated CCDs, while the other has a back-illuminated CCD. Coupled with the XRT, the energy range of 0.2–12 keV with energy resolution of 130 eV at 5.9 keV, and a field of view of $18^\prime \times 18^\prime$ are realized. Since the Suzaku launch on 2005 July 10, the XIS has been functioning well.
Iron and Nickel Line Diagnostics for the Galactic Center Diffuse Emission
Authors: Koyama Katsuji , Hyodo Yoshiaki , Inui Tatsuya , Nakajima Hiroshi , Matsumoto Hironori , Tsuru Takeshi Go , Takahashi Tadayuki , Maeda Yoshitomo , Yamazaki Noriko Y. , Murakami Hiroshi , Yamauchi Shigeo , Tsuboi Yohko , Senda Atsushi , Kataoka Jun , Takahashi Hiromitsu , Holt Stephen S. , Brown Gregory V.
Published: March 2014

We have observed the diffuse X-ray emission from the Galactic Center (GC) using the X-ray Imaging Spectrometer (XIS) on Suzaku. The high-energy resolution and the low-background orbit provided excellent spectra of the GC diffuse X-rays (GCDX). The XIS found many emission lines in the GCDX near the energy of K-shell transitions of iron and nickel. The most pronounced features are Fe I $\mathrm{K}\alpha$ at 6.4 keV and K-shell absorption edge at 7.1 keV, which are from neutral and/or low ionization states of iron, and the K-shell lines at 6.7 keV and 6.9 keV from He-like (Fe XXV $\mathrm{K}\alpha$) and hydrogenic (Fe XXVI Ly$\alpha$) ions of iron. In addition, $\mathrm{K}\alpha$ lines from neutral or low ionization nickel (Ni I $\mathrm{K}\alpha$) and He-like nickel (Ni XXVII $\mathrm{K}\alpha$), Fe I $\mathrm{K}\beta$, Fe XXV $\mathrm{K}\beta$, Fe XXVI $\mathrm{Ly}\beta$, Fe XXV $\mathrm{K}\gamma$, and Fe XXVI $\mathrm{Ly}\gamma$ were detected for the first time. The line center energies and widths of Fe XXV $\mathrm{K}\alpha$ and Fe XXVI $\mathrm{Ly}\alpha$ favor a collisional excitation plasma for the origin of the GCDX. The electron temperature determined from the line flux ratio of Fe XXV $\mathrm{K}\alpha$$/$ Fe XXV $\mathrm{K}\beta$ is similar to the ionization temperature determined from that of Fe XXV $\mathrm{K}\alpha$$/$ Fe XXVI $\mathrm{Ly}\alpha$. Thus it would appear that the GCDX plasma is close to ionization equilibrium. The 6.7 keV flux and temperature distribution to the galactic longitude is smooth and monotonic, in contrast to the integrated point source flux distribution. These facts support the hypothesis that the GCDX is truly diffuse emission rather than the integration of the outputs of a large number of unresolved point sources. In addition, our results demonstrate that the chemical composition of Fe in the interstellar gas near the GC is constrained to be about 3.5 times solar abundance.
Suzaku Observations of the Hard X-Ray Variability of MCG −6–30–15: the Effects of Strong Gravity around a Kerr Black Hole
Authors: Miniutti Giovanni , Fabian Andrew C. , Anabuki Naohisa , Crummy Jamie , Fukazawa Yasushi , Gallo Luigi , Haba Yoshito , Hayashida Kiyoshi , Holt Steve , Kunieda Hideyo , Larsson Josefin , Markowitz Alex , Matsumoto Chiho , Ohno Masanori , Reeves James N. , Takahashi Tadayuki , Tanaka Yasuo , Terashima Yuichi , Torii Ken’ichi , Ueda Yoshihiro , Ushio Masayoshi , Watanabe Shin , Yamauchi Makoto , Yaqoob Tahir
Published: March 2014

Suzaku has, for the first time, enabled the hard X-ray variability of the Seyfert 1 galaxy MCG $-$6–30–15 to be measured. The variability in the 14–45 keV band, which is dominated by a strong reflection hump, is quenched relative to that at a few keV. This directly demonstrates that the whole reflection spectrum is much less variable than the power-law continuum. The broadband spectral variability can be decomposed into two components—a highly variable power-law and constant reflection—as previously inferred from other observations in the 2–10 keV band. The strong reflection and high iron abundance give rise to a strong broad iron line, which requires the inner disc radius to be at about 2 gravitational radii. Our results are consistent with the predictions of the light bending model which invokes the very strong gravitational effects expected very close to a rapidly spinning black hole.
Search for Oxygen Emission from Warm-Hot Intergalactic Medium around A2218 with Suzaku
Authors: Takei Yoh , Ohashi Takaya , Henry J. Patrick , Mitsuda Kazuhisa , Fujimoto Ryuichi , Tamura Takayuki , Yamasaki Noriko Y. , Hayashida Kiyoshi , Tawa Noriaki , Matsushita Kyoko , Bautz Mark W. , Hughes John P. , Madejski Grzegorz M. , Kelley Richard L. , Arnaud Keith A.
Published: March 2014

We searched for redshifted O emission lines from a possible warm-hot intergalactic medium (WHIM) surrounding the cluster of galaxies A2218 at $z=0.1756$ using the X-ray Imaging Spectrometer (XIS) instrument on Suzaku. This cluster is thought to have an elongated structure along the line of sight based on previous studies. We studied systematic uncertainties in the spectrum of the Galactic emission and in the soft X-ray response of the detectors due to the contamination building up on the XIS filters. We detected no significant redshifted O lines, and set a tight constraint on the intensity with upper limits for the surface brightness of O VII and O VIII lines of $1.1 \times 10^{-7}$ and $3.0 \times 10^{-7} \;\mathrm{photons} \;\mathrm{cm}^{-2} \,\mathrm{s}^{-1} \,\mathrm{arcmin}^{-2}$, respectively. These upper limits are significantly lower than the previously reported fluxes from the WHIM around other clusters of galaxies. We also discuss the prospect for detecting the WHIM lines with the Suzaku XIS in the future.
Suzaku Observations of the Centaurus Cluster: Absence of Bulk Motions in the Intracluster Medium
Authors: Ota Naomi , Fukazawa Yasushi , Fabian Andrew C. , Kanemaru Takehiro , Kawaharada Madoka , Kawano Naomi , Kelley Richard L. , Kitaguchi Takao , Makishima Kazuo , Matsushita Kyoko , Murase Kouichi , Nakazawa Kazuhiro , Ohashi Takaya , Sanders Jeremy S. , Tamura Takayuki , Urata Yuji
Published: March 2014

The Centaurus cluster ($z=0.0104$) was observed with the X-ray Imaging Spectrometer (XIS) onboard the Suzaku X-ray satellite in three pointings, one centered on the cluster core and the other two offset by $\pm 8 {{}^{\prime }}$ in declination. To search for possible bulk motions of the intracluster medium, the central energy of a He-like Fe K line (at a rest-frame energy of 6.7 kev) was examined to look for a positional dependence. Over spatial scales of 50 kpc to 140 kpc around the cluster core, the central line energy was found to be constant within a calibration error of 15 eV. The 90% upper limit on the line-of-sight velocity difference is $\vert\Delta v\vert < 1400 \,\mathrm{km} \,\mathrm{s}^{-1}$, giving a tighter constraint than previous measurements. The significant velocity gradients inferred from a previous Chandra study were not detected between two pairs of rectangular regions near the cluster core. These results suggest that the bulk velocity does not largely exceed the thermal velocity of the gas in the central region of the Centaurus cluster. The mean redshift of the intracluster medium was determined to be 0.0097, in agreement with the optical redshift of the cluster within the calibration uncertainty. Implications of the present results for estimating the cluster mass are briefly discussed.
The Infrared Astronomical Mission AKARI
Authors: Murakami Hiroshi , Baba Hajime , Barthel Peter , Clements David L. , Cohen Martin , Doi Yasuo , Enya Keigo , Figueredo Elysandra , Fujishiro Naofumi , Fujiwara Hideaki , Fujiwara Mikio , Garcia-Lario Pedro , Goto Tomotsugu , Hasegawa Sunao , Hibi Yasunori , Hirao Takanori , Hiromoto Norihisa , Hong Seung Soo , Imai Koji , Ishigaki Miho , Ishiguro Masateru , Ishihara Daisuke , Ita Yoshifusa , Jeong Woong-Seob , Jeong Kyung Sook , Kaneda Hidehiro , Kataza Hirokazu , Kawada Mitsunobu , Kawai Toshihide , Kawamura Akiko , Kessler Martin F. , Kester Do , Kii Tsuneo , Kim Dong Chan , Kim Woojung , Kobayashi Hisato , Koo Bon Chul , Kwon Suk Minn , Lee Hyung Mok , Lorente Rosario , Makiuti Sin’itirou , Matsuhara Hideo , Matsumoto Toshio , Matsuo Hiroshi , Matsuura Shuji , MÜller Thomas G. , Murakami Noriko , Nagata Hirohisa , Nakagawa Takao , Naoi Takahiro , Narita Masanao , Noda Manabu , Oh Sang Hoon , Ohnishi Akira , Ohyama Youichi , Okada Yoko , Okuda Haruyuki , Oliver Sebastian , Onaka Takashi , Ootsubo Takafumi , Oyabu Shinki , Pak Soojong , Park Yong-Sun , Pearson Chris P. , Rowan-Robinson Michael , Saito Toshinobu , Sakon Itsuki , Salama Alberto , Sato Shinji , Savage Richard S. , Serjeant Stephen , Shibai Hiroshi , Shirahata Mai , Sohn Jungjoo , Suzuki Toyoaki , Takagi Toshinobu , Takahashi Hidenori , TanabÉ Toshihiko , Takeuchi Tsutomu T. , Takita Satoshi , Thomson Matthew , Uemizu Kazunori , Ueno Munetaka , Usui Fumihiko , Verdugo Eva , Wada Takehiko , Wang Lingyu , Watabe Toyoki , Watarai Hidenori , White Glenn J. , Yamamura Issei , Yamauchi Chisato , Yasuda Akiko
Published: March 2014

AKARI, the first Japanese satellite dedicated to infrared astronomy, was launched on 2006 February 21, and started observations in May of the same year. AKARI has a 68.5 cm cooled telescope, together with two focal-plane instruments, which survey the sky in six wavelength bands from mid–to far-infrared. The instruments also have a capability for imaging and spectroscopy in the wavelength range 2-180$\mu$m in the pointed observation mode, occasionally inserted into a continuous survey operation. The in-orbit cryogen lifetime is expected to be one and a half years. The All-Sky Survey will cover more than 90% of the whole sky with a higher spatial resolution and a wider wavelength coverage than that of the previous IRAS all-sky survey. Point-source catalogues of the All-Sky Survey will be released to the astronomical community. Pointed observations will be used for deep surveys of selected sky areas and systematic observations of important astronomical targets. These will become an additional future heritage of this mission.
The Far-Infrared Properties of Spatially Resolved AKARI Observations
Authors: Jeong Woong-Seob , Nakagawa Takao , Yamamura Issei , Pearson Chris P. , Savage Richard S. , Lee Hyung Mok , Shibai Hiroshi , Makiuti Sin’itirou , Baba Hajime , Barthel Peter , Clements Dave , Doi Yasuo , Figueredo Elysandra , Goto Tomotsugu , Hasegawa Sunao , Kaneda Hidehiro , Kawada Mitsunobu , Kawamura Akiko , Kester Do , Kwon Suk Minn , Matsuhara Hideo , Matsuura Shuji , Murakami Hiroshi , Oh Sang Hoon , Oliver Sebastian , Pak Soojong , Park Yong-Sun , Serjeant Stephen , Shirahata Mai , Sohn Jungjoo , Takagi Toshinobu , Wang Lingyu , White Glenn J. , Yamauchi Chisato
Published: March 2014

We present spatially resolved observations of IRAS sources from the Japanese infrared astronomy satellite AKARI All-Sky Survey during the performance verification phase of the mission. We extracted reliable point sources matched with the IRAS point source catalogue. By comparing IRAS and AKARI fluxes, we found that the flux measurements of some IRAS sources could have been over or underestimated, and affected by the local background, rather than the global background. We also found possible candidates for new AKARI sources and confirmed that AKARI observations resolved IRAS sources into multiple sources. All-Sky Survey observations are expected to verify the accuracies of IRAS flux measurements and to find new extragalactic point sources.
Nature of Infrared Sources in 11 $\mu $m Selected Sample from Early Data of the AKARI North Ecliptic Pole Deep Survey
Authors: Lee Hyung Mok , Im Myungshin , Wada Takehiko , Shim Hyunjin , Kim Seong Jin , Lee Myung Gyoon , Hwang Narae , Matsuhara Hideo , Nakagawa Takao , Oyabu Shinki , Pearson Chris P. , Takagi Toshinobu , Onaka Takashi , Fujishiro Naofumi , Hanami Hitoshi , Ishihara Daisuke , Ita Yoshifusa , Kataza Hirokazu , Kim Woojung , Matusmoto Toshio , Murakami Hiroshi , Ohyama Youichi , Sakon Itsuki , Tanabé Toshihiko , Uemizu Kazunori , Ueno Munetaka , Usui Fumihiko , Watarai Hidenori
Published: March 2014

We present the properties of 11 $\mu $m selected sources detected in the early data of the North Ecliptic Pole Deep (NEP-Deep) Survey of AKARI. The data set covers 6 wavelength bands from 2.5 to 11 $\mu $m, with exposure times of 10–20 minutes. This field lies within the CFHT survey with four filter bands ($g^\prime, r^\prime, i^\prime, z^\prime$), enabling us to establish nearly continuous spectral energy distributions (SEDs) for wavelengths ranging from 0.4 to 11 $\mu $m. The main sample studied here consists of 72 sources whose 11 $\mu $m AB magnitudes are equal to or brighter than 18.5 (144 $\mu $Jy), which is complete to more than 90%. The 11 $\mu $m band has an advantage of sampling star-forming galaxies with low-to-medium redshifts, since the prominent PAH feature shifts into this band. As expected, we find that the majority (71%) of 11 $\mu $m bright sources are star-forming galaxies at $0.2 \lesssim z \lesssim 0.7$ with $L_{\rm IR} \sim 10^{10}-10^{12}~L_{\odot}$ based on detailed modelling of the SEDs. We also find four AGNs lying at various redshifts in the main sample. In addition, we discuss a few sources that have non-typical SEDs of the main sample, including a brown-dwarf candidate, a steep power-law source, a flat-spectrum object, and an early-type galaxy at moderate redshift.
The Analysis of Penumbral Fine Structure Using an Advanced Inversion Technique
Authors: Jurčák Jan , Bellot Rubio Luis , Ichimoto Kiyoshi , Katsukawa Yukio , Lites Bruce , Nagata Shin’ichi , Shimizu Toshifumi , Suematsu Yoshinori , Tarbell Theodore D. , Title Alan M. , Tsuneta Saku
Published: March 2014

We present a method to study the penumbral fine structure using data obtained by the spectropolarimeter on board Hinode. For the first time, the penumbral filaments can be considered as being resolved in spectropolarimetric measurements. This enables us to use inversion codes with only one-component model atmospheres, and thus to assign the obtained stratifications of the plasma parameters directly to the penumbral fine structure. This approach was applied to the limb-side part of the penumbra in the active region NOAA10923. Preliminary results show a clear dependence of the plasma parameters on the continuum intensity in the inner penumbra, i.e., a weaker and horizontal magnetic field along with an increased line-of-sight velocity are found in the low layers of the bright filaments. The results in the mid penumbra are ambiguous, and future analyses are necessary to unveil the magnetic field structure and other plasma parameters there.
Can High Frequency Acoustic Waves Heat the Quiet Sun Chromosphere?
Authors: Carlsson Mats , Hansteen Viggo H. , De Pontieu Bart , McIntosh Scott , Tarbell Theodore D. , Shine Dick , Tsuneta Saku , Katsukawa Yukio , Ichimoto Kiyoshi , Suematsu Yoshinori , Shimizu Toshifumi , Nagata Shin’ichi
Published: March 2014

We use Hinode/SOT Ca II H-line and blue continuum broadband observations to study the presence and power of high frequency acoustic waves at high spatial resolution. We find that there is no dominant power at small spatial scales; the integrated power using the full resolution of Hinode ($0\rlap{.}^{\prime\prime}05$ pixels, $0\rlap{.}^{\prime\prime}16$ resolution) is larger than the power in the data degraded to $0\rlap{.}^{\prime\prime}5$ pixels (TRACE pixel size) by only a factor of 1.2. At 20 mHz the ratio is 1.6. Combining this result with the estimates of the acoustic flux based on TRACE data of Fossum and Carlsson (2006, ApJ, 646, 579), we conclude that the total energy flux in acoustic waves of frequency 5–40 mHz entering the internetwork chromosphere of the quiet Sun is less than 800 Wm$^{-2}$, inadequate to balance the radiative losses in a static chromosphere by a factor of five.
Hinode EUV Imaging Spectrometer Observations of Solar Active Region Dynamics
Authors: Mariska John T. , Warren Harry P. , Ugarte-Urra Ignacio , Brooks David H. , Williams David R. , Hara Hirohisa
Published: March 2014

The EUV Imaging Spectrometer (EIS) on the Hinode satellite is capable of measuring emission line center positions for Gaussian line profiles to a fraction of a spectral pixel, resulting in relative solar Doppler-shift measurements with an accuracy of a less than a km s$^{-1}$ for strong lines. We show an example of the application of that capability to an active region sit-and-stare observation in which the EIS slit is placed at one location on the Sun and many exposures are taken while the spacecraft tracking keeps the same solar location within the slit. For the active region examined (NOAA10930), we find that significant intensity and Doppler-shift fluctuations as a function of time are present at a number of locations. These fluctuations appear to be similar to those observed in high-temperature emission lines with other space-borne spectroscopic instruments. With its increased sensitivity over earlier spectrometers and its ability to image many emission lines simultaneously, EIS should provide significant new constraints on Doppler-shift oscillations in the corona.
The Structure and Dynamics of the Quiet Corona from Observations with the Extreme Ultraviolet Imaging Spectrometer on Hinode
Authors: Dere Kenneth P. , Doschek George A. , Mariska John T. , Hansteen Viggo H. , Harra Louise K. , Matsuzaki Keiichi , Thomas Roger J.
Published: March 2014

The goal of the Hinode mission is to provide an observational basis for understanding the heating and acceleration of coronal plasmas. On 2007 January 20, the Extreme ultraviolet Imaging Spectrometer performed a raster of a quiet region near Sun center. Maps of intensities, velocities, and electron densities derived from these observations are presented and discussed. Intensity maps in He II $\lambda$256, formed at 9$\times$10$^4$ K, show the chromospheric network. Line intensities of Fe X-XIV, formed at temperatures from 1–2$\times$10$^6$ K, show small-scale bright points and more extended structures. The intensity map of Fe VIII shows a transition between the two temperatures. The coronal lines reveal regions of high outflow velocities on the order of 100 km s$^{-1}$ in a compact region and 12 km s$^{-1}$ in an extended region. The presence of such high velocities in the quiet corona is an entirely new and unexpected result. Electron densities derived from density sensitive line ratios of Fe XII and X III are typically 3–20$\times$10$^8$cm$^{-3}$. The highest densities are found in bright, compact areas. For the first time, explosive events in the quiet sun have been observed in the extreme-ultraviolet in He II $\lambda$256 profiles.
Fine Structures of Solar X-Ray Jets Observed with the X-Ray Telescope aboard Hinode
Authors: Shimojo Masumi , Narukage Noriyuki , Kano Ryohei , Sakao Taro , Tsuneta Saku , Shibasaki Kiyoto , Cirtain Jonathan W. , Lundquist Loraine L. , Reeves Katherine K. , Savcheva Antonia
Published: March 2014

The X-Ray Telescope (XRT) aboard Hinode has revealed the fine structure of solar X-ray jets. One of the fine structures observed by XRT is an expanding loop. The loop appeared near the footpoint of the jet when footpoint brightening was observed. Additionally, we have found that the X-ray jets began just after the expanding loop “breaks”. Other fine structures discovered by XRT are thread-like features along the axis of the jets. XRT has shown that these thread structures compose the cross-section of jets. The fine structures and their motions strongly support an X-ray jet model based on magnetic reconnection, and also suggest that we must consider the three-dimensional configuration of the magnetic field to understand the jet phenomenon. We also investigated the reverse jet associated with the X-ray jet in the quiet Sun, and propose that the reverse jet is produced by heat conduction, or a MHD wave subsequent to the main jet.
Hinode EUV Study of Jets in the Sun’s South Polar Corona
Authors: Len Culhane , Harra Louise K. , Baker Deborah , van Driel-Gesztelyi Lidia , Sun Jian , Doschek George A. , Brooks David H. , Lundquist Loraine L. , Kamio Suguru , Young Peter R. , Hansteen Viggo H.
Published: March 2014

A number of coronal bright points and associated plasma jet features were seen in an observation of the South polar coronal hole during 2007 January. The 40$^{\prime\prime}$ wide slot was used at the focus of the Hinode EUV Imaging Spectrometer to provide spectral images for two of these events. Light curves are plotted for a number of emission lines that include He II 256 Å (0.079 MK) and cover the temperature interval from 0.4 MK to 5.0 MK. Jet speed measurements indicate values less than the escape velocity. The light curves show a post-jet enhancement in a number of the cooler coronal lines indicating that after a few minutes cooling, the plasma fell back to its original acceleration site. This behavior has not been previously observed by e.g., the Yohkoh Soft X-ray Telescope due to the comparatively high temperature cut-off in its response. The observations are consistent with the existing models that involve magnetic reconnection between emerging flux and the ambient open field lines in the polar coronal hole. However we do not have sufficient coverage of lines from lower temperature ion species to register the H$\alpha$-emitting surge material that is associated with some of these models.
Coronal Dimming Observed with Hinode: Outflows Related to a Coronal Mass Ejection
Authors: Harra Louise K. , Hara Hirohisa , Imada Shinsuke , Young Peter R. , Williams David R. , Sterling Alphonse C. , Korendyke Clarence , Attrill Gemma D. R.
Published: March 2014

Coronal dimming has been a signature used to determine the source of plasma that forms part of a coronal mass ejection (CME) for many years. Generally dimming is detected through imaging instruments such as SOHO EIT by taking difference images. Hinode tracked active region 10930 from which there were a series of flares. We combined dimming observations from EIT with Hinode data to show the impact of flares and coronal mass ejections on the region surrounding the flaring active region, and we discuss evidence that the eruption resulted in a prolonged steady outflow of material from the corona. The dimming region shows clear structure with extended loops whose footpoints are the source of the strongest outflow ($\approx$ 40 km s$^{-1}$). This confirms that the loops that are disrupted during the event do lose plasma and hence are likely to form part of the CME. This is the first time the velocity of the coronal plasma has been measured in an extended dimming region away from the flare core. In addition there was a weaker steady outflow from extended, faint loops outside the active region before the eruption, which is also long lasting. These were disturbed and the velocity increased following the flare. Such outflows could be the source of the slow solar wind.
Flare Ribbons Observed with G-band and Fe I 6302 Å Filters of the Solar Optical Telescope on Board Hinode
Authors: Isobe Hiroaki , Kubo Masahito , Minoshima Takashi , Ichimoto Kiyoshi , Katsukawa Yukio , Tarbell Theodore D. , Tsuneta Saku , Berger Thomas E. , Lites Bruce , Nagata Shin’ichi , Shimizu Toshifumi , Shine Richard A. , Suematsu Yoshinori , Title Alan M.
Published: March 2014

The Solar Optical Telescope (SOT) on board the Hinode satellite observed an X3.4 class flare on 2006 December 13. A typical two-ribbon structure was observed, not only in the chromospheric Ca II H line, but also in the G-band and Fe I 6302 Å line. The high-resolution, seeing-free images achieved by SOT revealed, for the first time, sub-arcsec fine structures of the “white light” flare. The G-band flare ribbons on sunspot umbrae showed a sharp leading edge, followed by a diffuse inside, as well as a previously known core–halo structure. The underlying structures, such as umbral dots, penumbral filaments, and granules, were visible in the flare ribbons. Assuming that the sharp leading edge was directly heated by a particle beam and the diffuse parts were heated by radiative back-warming, we estimated the depth of the diffuse flare emission using an intensity profile of the flare ribbon. We found that the depth of the diffuse emission was about 100 km or less from the height of the source of radiative back-warming. The flare ribbons were also visible in the Stokes-$V$ images of Fe I 6302 Å, as a transient polarity reversal. This is probably related to a “magnetic transient” reported in the literature. The intensity increase in Stokes-$I$ images indicates that the Fe I 6302 Å line was significantly deformed by the flare, which may cause such a magnetic transient.
Diagnostics of Radio Fine Structures around 3 GHz with Hinode Data in the Impulsive Phase of an X3.4/4B Flare Event on 2006 December 13
Authors: Yan Yihua , Huang Jing , Chen Bin , Sakurai Takashi
Published: March 2014

On 2006 December 13 during the solar minimum, the superactive region NOAA 10930 at the S05W33 disk location produced an X3.4/4B flare at 02:40UT. Fine structures were observed in the radio spectra, which included spikes, reverse slope-type III bursts, type-U burst, V-shaped burst, pulsations, zebra patterns, and firstly discovered sub-second spiky zebra-like structures, superimposed on the 2.6–3.8 GHz type IV bursts. The radio fine structures during the impulsive phase of the flare may be closely associated with coronal structures during the magnetic-reconnection process, as revealed by Hinode soft X-ray images. Thus, these microwave fine structure observations may provide very useful diagnostics at the primary energy release sites when they occur in the impulsive flare phase. For this flare event, the estimated coronal magnetic field is about 50–170G in the rising phase of the flare with a source density of about 1$\times$10$^{11}$cm$^{-3}$. The field strength and plasma density are about 90–200G and 1.27$\times$10$^{11}$cm$^{-3}$ around the flare maximum.
Hinode Observations of the Onset Stage of a Solar Filament Eruption
Authors: Sterling Alphonse C. , Moore Ronald L. , Berger Thomas E. , Bobra Monica , Davis John M. , Jibben Patricia , Kano Ryohei , Lundquist Loraine L. , Myers D. , Narukage Noriyuki , Sakao Taro , Shibasaki Kiyoto , Shine Richard A. , Tarbell Theodore D. , Weber Mark
Published: March 2014

We used Hinode X-Ray Telescope (XRT) and Solar Optical Telescope (SOT) filtergraph (FG) Stokes-V magnetogram observations, to study the early onset of a solar eruption that includes an erupting filament that we observe in TRACE EUV images. The filament undergoes a slow rise for at least 20 min prior to its fast eruption and strong soft X-ray (SXR) flaring; such slow rises have been previously reported, and the new Hinode data elucidate the physical processes occurring during this period. XRT images show that during the slow-rise phase, an SXR sigmoid forms from apparent reconnection low in the sheared core field traced by the filament, and there is a low-level intensity peak in both EUV and SXRs during the slow rise. MDI and SOT FG Stokes-V magnetograms show that the pre-eruption filament is along a neutral line between opposing-polarity enhanced network cells, and the SOT magnetograms show that these opposing fields are flowing together and canceling for at least six hours prior to eruption. From the MDI data we measured the canceling network fields to be $\sim$ 40G, and we estimated that $\sim$10$^{19}$Mx of flux canceled during the five hours prior to eruption; this is only $\sim$5% of the total flux spanned by the eruption and flare, but apparently its tether-cutting cancellation was enough to destabilize the sigmoid field holding the filament and resulted in that field’s eruption.
Strategy for the Inversion of Hinode Spectropolarimetric Measurements in the Quiet +n
Authors: SuÁrez Orozco David , Rubio Bellot Luis R. , Iniesta Toro Jose Carlos del , Tsuneta Saku , Lites Bruce , Ichimoto Kiyoshi , Katsukawa Yukio , Nagata Shin’ichi , Shimizu Toshifumi , Shine Richard A. , Suematsu Yoshinori , Tarbell Theodore D. , Title Alan M.
Published: March 2014

In this paper we propose an inversion strategy for the analysis of spectropolarimetric measurements taken by Hinode in the quiet Sun. The Spectro-Polarimeter of the Solar Optical Telescope aboard Hinode records the Stokes spectra of the Fe I line pair at 630.2 nm with unprecendented angular resolution, high spectral resolution, and high sensitivity. We discuss the need to consider a local stray-light contamination to account for the effects of telescope diffraction. The strategy is applied to observations of a wide quiet Sun area at disk center. Using these data we examine the influence of noise and initial guess models in the inversion results. Our analysis yields the distributions of magnetic field strengths and stray-light factors. They show that quiet Sun internetwork regions consist mainly of hG fields with stray-light contamination of about 0.8.
An On-Orbit Determination of the On-Axis Point Spread Function of the Hinode X-Ray Telescope
Authors: Weber Mark , DeLuca Edward E. , Golub Leon , Cirtain Jonathan , Kano Ryouhei , Sakao Taro , Shibasaki Kiyoto , Narukage Noriyuki
Published: March 2014

The Hinode X-ray Telescope provides unprecedented observations of the solar corona in X-rays, due in part to its fine resolution. The X-ray point spread function (PSF) was measured before launch at the NASA X-ray Calibration Facility to have a FWHM of $0\rlap{.}^{\prime\prime}8$. This paper describes the work to verify the PSF measurements using on-orbit observations of planetary transits and solar eclipses. Analysis of a Mercury transit gives a PSF FWHM $= 1\rlap{.}^{\prime\prime}0 \pm 0\rlap{.}^{\prime\prime}12$.
Gravitational Instability of Shocked Interstellar Gas Layers
Authors: Iwasaki Kazunari , Tsuribe Toru
Published: March 2014

In this paper we investigate gravitational instability of shocked gas layers using linear analysis. An unperturbed state is a self-gravitating isothermal layer which grows with time by the accretion of gas through shock fronts due to a cloud-cloud collision. Since the unperturbed state is not static, and cannot be described by a self-similar solution, we numerically solved the perturbation equations and directly integrated them over time. We took account of the distribution of physical quantities across the thickness. Linearized Rankine-Hugoniot relations were imposed at shock fronts as boundary conditions. The following results are found from our unsteady linear analysis: the perturbation initially evolves in oscillatory mode, and begins to grow at a certain epoch. The wavenumber of the fastest growing mode is given by $k=2\sqrt{2\pi G\rho_\mathrm{E} {\cal M\mit}}/c_\mathrm{s}$, where $\rho_\mathrm{E},\;c_\mathrm{s}$ and $\cal M\mit$ are the density of the parent clouds, the sound velocity and the Mach number of the collision velocity, respectively. For this mode, the transition epoch from oscillatory to growing mode is given by $t_g = 1.2/\sqrt{2\pi G\rho_\mathrm{E} {\cal M\mit}}$. The epoch at which the fastest growing mode becomes non-linear is given by $2.4\delta_0^{-0.1}/\sqrt{2\pi G \rho_\mathrm{E}{\cal M\mit}}$, where $\delta_0$ is the initial amplitude of the perturbation of the column density. As an application of our linear analysis, we investigated criteria for collision-induced fragmentation. Collision-induced fragmentation will occur only when parent clouds are cold, or $\alpha_0=$ 5$c_\mathrm{s}^2 R/2G M < 1$, where $R$ and $M$ are the radius and the mass of parent clouds, respectively.
Optical CCD Photometry of the Variability of the BLLacertae Object ON231 in a Low State
Authors: Zhang Xiong , Zheng Yong Gang , Zhang Li , Zhang Hao Jing , Hu Sao Ming , Liu Yun , Wen Yuan Bin , Wang Wei
Published: March 2014

We present optical photometry ($B, V, R$, and $I$) of the BL Lac object ON231 (1219$+$285, $z$$=$0.102), which was observed with the 1 m telescope at Yunnan Astronomical Observatory and the 1.56 m telescope at Shanghai Astronomical Observatory from 2003 May to 2006 May. Our results indicate that (i) there is a short time variability of ${\Delta} I =$ 1.04 mag during 25 minutes; (ii) there is a strong correlation between the $R-I$ color and the $R$ magnitude in 72.2 hours; and (iii) our optical variability is consistent with those of Tosti et al. (2002, A&A, 395, 11).
Implications for Galaxy Evolution from Cosmic Evolution of the Supernova Rate Density
Authors: Oda Takeshi , Totani Tomonori , Yasuda Naoki , Sumi Takahiro , Morokuma Tomoki , Doi Mamoru , Kosugi George
Published: March 2014

We report on a comprehensive statistical analysis of observational data of the cosmic evolution of the supernova (SN) rate density, to derive constraints on cosmic star-formation history and the nature of a type Ia supernova (SNIa) progenitor. We use all available information concerning the magnitude, SN type, and redshift information of both type Ia and core-collapse (CC) SNe in GOODS and SDF, as well as SNIa rate densities reported in the literature. We also add 157 SN candidates in the past Subaru/Suprime-Cam data that are newly reported here, to increase the statistics. We find that the current data set of the SN rate density evolution already gives a meaningful constraint on the evolution of the cosmic star formation rate (SFR) at $z \lesssim 1$, though strong constraints cannot be derived for the delay time distribution (DTD) of SNe Ia. We derive a constraint of $\alpha \sim $ 3–4 [the evolutionary index of SFR density $\propto (1+z)^\alpha$ at $z \lesssim 1$] with evidence for a significant evolution of the mean extinction of CC SNe [$E(B-V) \sim$0.5 at $z \sim$0.5 compared with $\sim 0.2$ at $z=0$], which does not change significantly within a reasonable range of various DTD models. This result is consistent with the systematic trend of $\alpha $ estimates based on galactic SFR indicators at different wavelengths (ultraviolet, H$\alpha $, and infrared), indicating that there is a strong evolution in the mean extinction of star-forming regions in galaxies at relatively low redshift range of $z \lesssim$0.5. These results are obtained by a method that is completely independent of galaxy surveys and, especially, there is no detection limit about the host galaxy luminosity in our analysis, giving a strong constraint on the star-formation activity in high-$z$ dwarf galaxies or intergalactic space.
Detection of Small-Amplitude Oscillations in the G-Giant HD76294 (ζ Hydrae)
Authors: Ando Hiroyasu , Tan Kefeng , Kambe Eiji , Sato Bun’ei , Zhao Gang
Published: March 2014

We made a precise radial-velocity measurement of the G-giant $ \zeta$ Hya with an iodine cell technique, and found small-amplitude oscillations. The time scale of the oscillations was 6–10 hours, in which a wavy motion was clearly seen. Their power spectrum shows a maximum peak frequency of 38.3 $\mu$Hz. A further period analysis with a pre-whitening procedure reveals that the four peaks, including 38.3 $\mu$Hz, are significant. The peak frequency of the power envelope of the oscillations is about 35 $\mu$Hz, which is quite low compared with a value (about 60$\mu$Hz) predicted by the scaling law. We also point out that the power excess is confined to a very narrow bandwidth (40$\mu$Hz) compared with previously observed G giants, $\xi$ Hya and $\epsilon$ Oph.
Discovery of a WZ Sge-Type Dwarf Nova, SDSS J102146.44+234926.3: Unprecedented Infrared Activity during a Rebrightening Phase
Authors: Uemura Makoto , Arai Akira , Krajci Tom , Pavlenko Elena , Shugarov Sergei Yu. , Katysheva Nataly A. , Goranskij Vitalij P. , Maehara Hiroyuki , Imada Akira , Kato Taichi , Nogami Daisaku , Nakajima Kazuhiro , Ohsugi Takashi , Yamashita Takuya , Kawabata Koji S. , Nagae Osamu , Chiyonobu Shingo , Fukazawa Yasushi , Mizuno Tsunefumi , Katagiri Hideaki , Takahashi Hiromitsu , Ueda Atsushi , Hayashi Takehiro , Okita Kiichi , Yoshida Michitoshi , Yanagisawa Kenshi , Sato Shuji , Kino Masaru , Sadakane Kozo
Published: March 2014

Several SU UMa-type dwarf novae and WZ Sge-type stars tend to exhibit rebrightenings after superoutbursts. The rebrightening phenomenon is problematic for the disk instability theory of dwarf novae, since it requires a large amount of remnant matter in the disk, even after superoutbursts. Here, we report on our optical and infrared observations during the first-ever outburst of a new dwarf nova, SDSS J102146.44+234926.3. During the outburst, we detected superhumps with a period of 0.056281$\pm$0.000015 d, which is typical for superhump periods in WZ Sge stars. In conjunction with the appearance of a long-lived rebrightening, we concluded that the object is a new member of WZ Sge stars. Our observations, furthermore, revealed infrared behaviors for the first time in the rebrightening phase of WZ Sge stars. We discovered prominent infrared superhumps. We calculated the color temperature of the infrared superhump source to be 4600–6400 K. These temperatures are too low to be explained by a fully ionized disk appearing during dwarf-nova outbursts. We also found a $K_{s}$-band excess over the hot disk component. These unprecedented infrared activities provide evidence for the presence of mass reservoir at the outermost part of the accretion disk. We propose that a moderately high mass-accretion rate at this infrared active region leads to the long-lived rebrightening observed in SDSS J102146.44+234926.3.
Suzaku Observation of the Anomalous X-Ray Pulsar CXOU J164710.2—455216
Authors: Naik Sachindra , Dotani Tadayasu , Kawai Nobuyuki , Kokubun Motohide , Anada Takayasu , Morii Mikio , Mihara Tatehiro , Enoto Teruaki , Kawaharada Madoka , Murakami Toshio , Nakagawa Yujin E. , Takahashi Hiromitsu , Terada Yukikatsu , Yoshida Atsumasa
Published: March 2014

A Suzaku TOO observation of CXOU J164710.2$-$455216 was performed on 2006 September 23–24 for a net exposure of 38.8 ks. Pulsations were clearly detected in the XIS light curves with a pulse period of 10.61063(2) s. The XIS pulse profile is found to be highly non-sinusoidal. It shows 3 peaks of different amplitudes with an RMS fractional amplitude of $\sim$11% in the 0.2–6.0 keV energy band. The 1–10 keV XIS spectra were well fitted by two different models consisting of a power-law and a blackbody component and two blackbody components, respectively. Although both the models are statistically acceptable, a difference in the pulse profiles at soft (0.2–6.0 keV) and hard (6–12 keV) X-rays favors the model consisting of two blackbody components. The temperatures of two blackbody components are found to be 0.61$\pm$0.01 keV and 1.22$\pm$0.06 keV, and the value of the absorption column density is 1.73$\pm$0.03 $\times$ 10$^{22}$atoms cm$^{-2}$. Pulse phase resolved spectroscopy shows that the flux of the soft blackbody component consists of three narrow peaks, whereas the flux of the other component shows a single peak over the pulse period of the AXP. The blackbody radii change between 2.2–2.7 km and 0.28–0.38 km (assuming the source distance to be 5 kpc) over the pulse phases for the soft and hard components, respectively. The details of the results obtained from the timing and spectral analyses are presented.
Novel Spectral Imaging Method for Fizeau Interferometers
Authors: Matsuo Taro , Shibai Hiroshi , Kawada Mitsunobu , Hattori Makoto , Ohta Izumi S. , Matsuo Hiroshi
Published: March 2014

We propose a new spectral imaging method for Fizeau interferometers, based on double Fourier interferometry. It is possible to acquire two-dimensional spatial and one-dimensional spectral information of the sky by applying Fourier-transform spectrometer algorithm and the Van Cittert–Zernike theorem. This imaging scheme is referred to as double Fourier interferometry. We noticed that a delay axis in Michelson interferometers is equal to the axis of a fringe pattern on an image plane in Fizeau interferometers. Therefore, this new approach can acquire three-dimensional information of the sky using a linear array detector placed on the image plane. We formulated the new method and validated it by performing laboratory experiments. We performed image reconstruction based on the new method, and derived the spatial and spectral distributions of the source. Thus, the method was experimentally verified. Using the new method, it is possible to perform image reconstruction in principle, with brief observations for each baseline, and a delay-line system is not required as in a conventional interferometer. In addition, because the field of view is limited by the telescope’s optical system, it can be easily widened. Therefore, this new method of spectral imaging will be used for future astronomical observations with Fizeau interferometers.
Spherical Relativistic Radiation Flows with Variable Eddington Factor
Authors: Akizuki Chizuru , Fukue Jun
Published: March 2014

We solve spherically symmetric radiation flows under full special relativity with the help of a variable Eddington factor, $f(\tau, \beta)$, where $\tau$ is the optical depth and $\beta$ is the flow velocity normalized by the speed of light. Relativistic radiation hydrodynamics under the moment formalism has several complex problems, such as a closure relation. Conventional moment equations closed with the traditional Eddington approximation in the comoving frame have singularity, beyond which the flow cannot be accelerated. In order to avoid such a pathological behavior inherent in the relativistic moment formalism, we propose a variable Eddington factor, which depends on the flow velocity as well as the optical depth, for the case of sperically symmetric one-dimensional flow. We then calculate the relativistic spherical flow with such variable Eddington factors to investigate the case that gas is accelerated by radiative force. As a result, it is shown that the gas speed reaches around the speed of light by radiation pressure.
Suzaku Discovery of Hard X-Ray Pulsations from a Rotating Magnetized White Dwarf, AEAquarii
Authors: Terada Yukikatsu , Hayashi Takayuki , Ishida Manabu , Mukai Koji , Dotani Tadayasu , Okada Shunsaku , Nakamura Ryoko , Naik Sachindra , Bamba Aya , Makishima Kazuo
Published: March 2014

A fast rotating magnetized white dwarf, AEAquarii, was observed with Suzaku, in 2005 October–November and 2006 October with exposures of 53.1 and 42.4 ks, respectively. In addition to clear spin modulation in the 0.5–10 keV band of the XIS data at the barycentric period of 33.0769$\pm$0.0001 s, the 10–30 keV HXD data in the second half of the 2005 observation also showed statistically significant periodic signals at a consistent period. On that occasion, the spin-folded HXD light curve exhibited two sharp spikes separated by $\sim$0.2 cycles in phase, in contrast to approximately sinusoidal profiles observed at energies below $\sim$4 keV. The folded 4–10 keV XIS light curves are understood to be a superposition of those two types of pulse profiles. The phase-averaged 1.5–10 keV spectra can be reproduced by two thermal components with temperatures of $2.90_{-0.16}^{+0.20}$keV and 0.53${\;}_{-0.13}^{+0.14}$keV, but the 12–25 keV HXD data show a significant excess above the extrapolated model. This excess can be explained by either a power-law model with a photon index of $1.12_{-0.62}^{+0.63}$ or a third thermal component with a temperature of 54${\;}_{-47}^{+26}$keV. At a distance of 102 pc, the 4–30 keV luminosities of the thermal and the additional components become $1.7_{-0.6}^{+1.3}$ and 5.3${\;}_{-0.3}^{+15.3}$$\times10^{29}$ergs$^{-1}$, respectively. The latter corresponds to 0.09% of the spin-down energy of the object. Possible emission mechanisms of the hard pulsations are discussed, including non-thermal ones, in particular.
A Possible Spin-Orbit Misalignment in the Transiting Eccentric Planet HD 17156b
Authors: Narita Norio , Sato Bun’ei , Ohshima Osamu , Winn Joshua N.
Published: March 2014

We present simultaneous photometric and spectroscopic observations of HD17156b spanning a transit on 2007 November 12 (UT). This system is of special interest because of its 21 d period (unusually long for a transiting planet) and its high orbital eccentricity of 0.67. By modeling the Rossiter–McLaughlin effect, we find the angle between the sky projections of the orbital axis and the stellar rotation axis to be $62^{\circ} \pm 25^{\circ}$. Such a large spin-orbit misalignment, as well as the high eccentricity, could be explained as a relic of a previous gravitational interaction with other planets.