bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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$c_\mathrm{s}^2 R/2G M &lt; 1$, 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

Abstract
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

Abstract
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.
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

Abstract
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

Abstract
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

Abstract
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.