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Philip R Goode - One of the best experts on this subject based on the ideXlab platform.
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earth s albedo variations 1998 2014 as measured from ground based earthshine observations
Geophysical Research Letters, 2016Co-Authors: Philip R Goode, E Palle, Pilar Montanesrodriguez, A Shumko, B Gonzalezmerino, Martinez C LombillaAbstract:The Earth's albedo is a fundamental climate parameter for understanding the radiation budget of the atmosphere. It has been traditionally measured not only from space platforms but also from the ground for 16 years from Big Bear Solar Observatory by observing the Moon. The photometric ratio of the dark (earthshine) to the bright (moonshine) sides of the Moon is used to determine nightly anomalies in the terrestrial albedo, with the aim of quantifying sustained monthly, annual, and/or decadal changes. We find two modest decadal scale cycles in the albedo, but with no significant net change over the 16 years of accumulated data. Within the evolution of the two cycles, we find periods of sustained annual increases, followed by comparable sustained decreases in albedo. The evolution of the earthshine albedo is in remarkable agreement with that from the Clouds and the Earth's Radiant Energy System instruments, although each method measures different slices of the Earth's Bond albedo.
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earth s albedo variations 1998 2014 as measured from ground based earthshine observations
arXiv: Earth and Planetary Astrophysics, 2016Co-Authors: Philip R Goode, E Palle, Pilar Montanesrodriguez, A Shumko, B Gonzalezmerino, Martinez C LombillaAbstract:The Earth's albedo is a fundamental climate parameter for understanding the radiation budget of the atmosphere. It has been traditionally measured from space platforms, but also from the ground for sixteen years from Big Bear Solar Observatory by observing the Moon. The photometric ratio of the dark (earthshine) to the bright (moonshine) sides of the Moon is used to determine nightly anomalies in the terrestrial albedo, with the aim is of quantifying sustained monthly, annual and/or decadal changes. We find two modest decadal scale cycles in the albedo, but with no significant net change over the sixteen years of accumulated data. Within the evolution of the two cycles, we find periods of sustained annual increases, followed by comparable sustained decreases in albedo. The evolution of the earthshine albedo is in remarkable agreement with that from the CERES instruments, although each method measures different slices of the Earth's Bond albedo.
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fast imaging Solar spectrograph of the 1 6 meter new Solar telescope at big bear Solar Observatory
Solar Physics, 2013Co-Authors: Jongchul Chae, Wenda Cao, Kwangsu Ahn, Hyungmin Park, Heesu Yang, Youngdeuk Park, Jakyoung Nah, Bi Ho Jang, K Cho, Philip R GoodeAbstract:For high resolution spectral observations of the Sun – particularly its chromosphere, we have developed a dual-band echelle spectrograph named Fast Imaging Solar Spectrograph (FISS), and installed it in a vertical optical table in the Coude Lab of the 1.6 meter New Solar Telescope at Big Bear Solar Observatory. This instrument can cover any part of the visible and near-infrared spectrum, but it usually records the Hα band and the Ca ii 8542 A band simultaneously using two CCD cameras, producing data well suited for the study of the structure and dynamics of the chromosphere and filaments/prominences. The instrument does imaging of high quality using a fast scan of the slit across the field of view with the aid of adaptive optics. We describe its design, specifics, and performance as well as data processing
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profiles of the daytime atmospheric turbulence above big bear Solar Observatory
Astronomy and Astrophysics, 2012Co-Authors: Aglae Kellerer, Wenda Cao, Nicolas Gorceix, Jose Marino, Philip R GoodeAbstract:Context. Space weather has become acutely critical for today’s global communication networks. To understand its driving forces we need to observe the Sun with high angular-resolution, and within large fields-of-view, i.e. with multi-conjugate adaptive optics correction.Aims. The design of a multi-conjugate adaptive optical system requires the knowledge of the altitude distribution of atmospheric turbulence. We have therefore measured daytime turbulence profiles above the New Solar Telescope (NST), on Big Bear Lake.Methods. To this purpose, a wide-field wavefront sensor was installed behind the NST. The variation of the wavefront distortions with angular direction allows the reconstruction of the distribution of turbulence.Results. The turbulence is found to have three origins: 1. a ground layer ( A multi-conjugate adaptive optical system should thus aim at correcting the ground turbulence, the center of the boundary layer at roughly 3 km altitude and, eventually, the upper boundary layer around 6 km altitude.
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statistical distribution of size and lifetime of bright points observed with the new Solar telescope
The Astrophysical Journal, 2010Co-Authors: V I Abramenko, Vasyl Yurchyshyn, Philip R Goode, A KilcikAbstract:We present results of 2 hr non-interrupted observations of Solar granulation obtained under excellent seeing conditions with the largest aperture ground-based Solar telescope?the New Solar Telescope (NST)?of Big Bear Solar Observatory. Observations were performed with adaptive optics correction using a broadband TiO filter in the 705.7?nm spectral line with a time cadence of 10 s and a pixel size of 00375. Photospheric bright points (BPs) were detected and tracked. We find that the BPs detected in NST images are cospatial with those visible in Hinode/SOT G-band images. In cases where Hinode/SOT detects one large BP, NST detects several separated BPs. Extended filigree features are clearly fragmented into separate BPs in NST images. The distribution function of BP sizes extends to the diffraction limit of NST (77?km) without saturation and corresponds to a log-normal distribution. The lifetime distribution function follows a log-normal approximation for all BPs with lifetime exceeding 100 s. A majority of BPs are transient events reflecting the strong dynamics of the quiet Sun: 98.6% of BPs live less than 120 s. The longest registered lifetime was 44 minutes. The size and maximum intensity of BPs were found to be proportional to their lifetimes.
Haimin Wang - One of the best experts on this subject based on the ideXlab platform.
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intelligent recognition of time stamp characters in Solar scanned images from film
arXiv: Solar and Stellar Astrophysics, 2019Co-Authors: Jiafeng Zhang, Guangzhong Lin, Shuguang Zeng, Sheng Zheng, Xiao Yang, Ganghua Lin, Xiangyun Zeng, Haimin WangAbstract:Prior to the availability of digital cameras, the Solar observational images are typically recorded on films, and the information such as date and time were stamped in the same frames on film. It is significant to extract the time stamp information on the film so that the researchers can efficiently use the image data. This paper introduces an intelligent method for extracting time stamp information, namely, the Convolutional Neural Network (CNN), which is an algorithm in deep learning of multilayer neural network structures and can identify time stamp character in the scanned Solar images. We carry out the time stamp decoding for the digitized data from the National Solar Observatory from 1963 to 2003. The experimental results show that the method is accurate and quick for this application. We finish the time stamp information extraction for more than 7 million images with the accuracy of 98\%.
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strong transverse photosphere magnetic fields and twist in light bridge dividing delta sunspot of active region 12673
Research Notes of the American Astronomical Society, 2018Co-Authors: Haimin Wang, Vasyl Yurchyshyn, Kwangsu Ahn, Chang Liu, Shin Toriumi, Wenda CaoAbstract:Solar Active Region (AR) 12673 is the most flare productive AR in the Solar cycle 24. It produced four X-class flares including the X9.3 flare on 06 September 2017 and the X8.2 limb event on 10 September. Sun and Norton (2017) reported that this region had an unusual high rate of flux emergence, while Huang et al. (2018) reported that the X9.3 flare had extremely strong white-light flare emissions. Yang at al. (2017) described the detailed morphological evolution of this AR. In this report, we focus on usual behaviors of the light bridge (LB) dividing the delta configuration of this AR, namely the strong magnetic fields (above 5500 G) in the LB and apparent photospheric twist as shown in observations with a 0.1 arcsec spatial resolution obtained by the 1.6m telescope at Big Bear Solar Observatory.
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unprecedented fine structure of a Solar flare revealed by the 1 6 m new Solar telescope
Scientific Reports, 2016Co-Authors: Ju Jing, Dale E. Gary, Wenda Cao, Chang Liu, Haimin WangAbstract:Solar flares signify the sudden release of magnetic energy and are sources of so called space weather. The fine structures (below 500 km) of flares are rarely observed and are accessible to only a few instruments world-wide. Here we present observation of a Solar flare using exceptionally high resolution images from the 1.6 m New Solar Telescope (NST) equipped with high order adaptive optics at Big Bear Solar Observatory (BBSO). The observation reveals the process of the flare in unprecedented detail, including the flare ribbon propagating across the sunspots, coronal rain (made of condensing plasma) streaming down along the post-flare loops, and the chromosphere's response to the impact of coronal rain, showing fine-scale brightenings at the footpoints of the falling plasma. Taking advantage of the resolving power of the NST, we measure the cross-sectional widths of flare ribbons, post-flare loops and footpoint brighenings, which generally lie in the range of 80-200 km, well below the resolution of most current instruments used for flare studies. Confining the scale of such fine structure provides an essential piece of information in modeling the energy transport mechanism of flares, which is an important issue in Solar and plasma physics.
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temporal evolution of free magnetic energy associated with four x class flares
The Astrophysical Journal, 2009Co-Authors: Ju Jing, P F Chen, T Wiegelmann, Sunghong Park, Haimin WangAbstract:We study the temporal variation of free magnetic energy E free around the time of four X-class flares. The high-cadence photospheric vector magnetograms obtained by the digital vector magnegograph system at the Big Bear Solar Observatory are used as the boundary conditions to reconstruct the three-dimensional nonlinear force-free (NLFF) coronal field. In order to remove the effect of the net Lorentz force and torque acting in the photosphere, the vector magnetograms are preprocessed using the method devised by Wiegelmann et al.. Then a well-tested multigrid-like optimization code by Wiegelmann is applied to the preprocessed boundary data to extrapolate the NLFF coronal field with which we are able to estimate the free energy E free. In all the four events, we find a significant drop of E free starting ~15 minutes before the peak time of the associated nonthermal flare emission, although long-term trend varies from event to event. We discuss the physical implication of the result, i.e., the magnetic relaxation is already going on in the corona well before the flare reconnection.
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diffraction limited polarimetry from the infrared imaging magnetograph at big bear Solar Observatory
Publications of the Astronomical Society of the Pacific, 2006Co-Authors: Wenda Cao, Haimin Wang, Ju Jing, Philip R GoodeAbstract:ABSTRACT The Infrared Imaging Magnetograph (IRIM) system developed by Big Bear Solar Observatory (BBSO) has been put into preliminary operation. It is one of the first imaging spectropolarimeters working at 1565 nm and is used for the observations of the Sun at its opacity minimum, exposing the deepest photospheric layers. The tandem system, which includes a 4.2 nm interference filter, a unique 0.25 nm birefringent Lyot filter, and a Fabry‐Perot etalon, is capable of providing a bandpass as low as 0.01 nm in a telecentric configuration. A fixed quarter‐wave plate and a nematic liquid crystal variable retarder are employed for analyzing the circular polarization of the Zeeman components. The longitudinal magnetic field is measured for the highly Zeeman‐sensitive Fe i line at 1564.85 nm (Lande factor \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,x...
Wenda Cao - One of the best experts on this subject based on the ideXlab platform.
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strong transverse photosphere magnetic fields and twist in light bridge dividing delta sunspot of active region 12673
Research Notes of the American Astronomical Society, 2018Co-Authors: Haimin Wang, Vasyl Yurchyshyn, Kwangsu Ahn, Chang Liu, Shin Toriumi, Wenda CaoAbstract:Solar Active Region (AR) 12673 is the most flare productive AR in the Solar cycle 24. It produced four X-class flares including the X9.3 flare on 06 September 2017 and the X8.2 limb event on 10 September. Sun and Norton (2017) reported that this region had an unusual high rate of flux emergence, while Huang et al. (2018) reported that the X9.3 flare had extremely strong white-light flare emissions. Yang at al. (2017) described the detailed morphological evolution of this AR. In this report, we focus on usual behaviors of the light bridge (LB) dividing the delta configuration of this AR, namely the strong magnetic fields (above 5500 G) in the LB and apparent photospheric twist as shown in observations with a 0.1 arcsec spatial resolution obtained by the 1.6m telescope at Big Bear Solar Observatory.
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magnetic separatrix as the source region of the plasma supply for an active region filament
The Astrophysical Journal, 2017Co-Authors: P Zou, P F Chen, C Fang, Kai Yang, Wenda CaoAbstract:Solar filaments can be formed via chromospheric evaporation followed by condensation in the corona or by the direct injection of cool plasma from the chromosphere to the corona. In this paper, with high-resolution H$\alpha$ data observed by the 1.6 m New Solar Telescope of the Big Bear Solar Observatory on 2015 August 21, we confirmed that an active-region filament is maintained by the continuous injection of cold chromospheric plasma. We find that the filament is rooted along a bright ridge in H$\alpha$, which corresponds to the intersection of a magnetic quasi-separatrix layer with the Solar surface. This bright ridge consists of many small patches and the sizes of these patches are comparable to the width of the filament threads. It is found that upflows originate from the brighter patches of the ridge, whereas the downflows move toward the weaker patches of the ridge. The whole filament is composed of two opposite directional streams, implying that longitudinal oscillations are not the only cause of the counterstreamings, and unidirectional siphon flows with alternative directions are another possibility.
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objective image quality assessment for high resolution photospheric images by median filter gradient similarity
arXiv: Instrumentation and Methods for Astrophysics, 2017Co-Authors: Hui Deng, Dandan Zhang, Tianyu Wang, Feng Wang, Zhong Liu, Yongyuan Xiang, Zhenyu Jin, Wenda CaoAbstract:All next generation ground-based and space-based Solar telescopes require a good quality assessment metric in order to evaluate their imaging performance. In this paper, a new image quality metric, the median filter gradient similarity (MFGS) is proposed for photospheric images. MFGS is a no-reference/blind objective image quality metric (IQM) by a measurement result between 0 and 1 and has been performed on short-exposure photospheric images captured by the New Vacuum Solar Telescope (NVST) of the Fuxian Solar Observatory and by the Solar Optical Telescope (SOT) onboard the Hinode satellite, respectively. The results show that: (1)the measured value of MFGS changes monotonically from 1 to 0 with degradation of image quality; (2)there exists a linear correlation between the measured values of MFGS and root-mean-square-contrast (RMS-contrast) of granulation; (3)MFGS is less affected by the image contents than the granular RMS-contrast. Overall, MFGS is a good alternative for the quality assessment of photospheric images.
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unprecedented fine structure of a Solar flare revealed by the 1 6 m new Solar telescope
Scientific Reports, 2016Co-Authors: Ju Jing, Dale E. Gary, Wenda Cao, Chang Liu, Haimin WangAbstract:Solar flares signify the sudden release of magnetic energy and are sources of so called space weather. The fine structures (below 500 km) of flares are rarely observed and are accessible to only a few instruments world-wide. Here we present observation of a Solar flare using exceptionally high resolution images from the 1.6 m New Solar Telescope (NST) equipped with high order adaptive optics at Big Bear Solar Observatory (BBSO). The observation reveals the process of the flare in unprecedented detail, including the flare ribbon propagating across the sunspots, coronal rain (made of condensing plasma) streaming down along the post-flare loops, and the chromosphere's response to the impact of coronal rain, showing fine-scale brightenings at the footpoints of the falling plasma. Taking advantage of the resolving power of the NST, we measure the cross-sectional widths of flare ribbons, post-flare loops and footpoint brighenings, which generally lie in the range of 80-200 km, well below the resolution of most current instruments used for flare studies. Confining the scale of such fine structure provides an essential piece of information in modeling the energy transport mechanism of flares, which is an important issue in Solar and plasma physics.
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objective image quality assessment for high resolution photospheric images by median filter gradient similarity
Solar Physics, 2015Co-Authors: Hui Deng, Dandan Zhang, Tianyu Wang, Feng Wang, Zhong Liu, Yongyuan Xiang, Zhenyu Jin, Wenda CaoAbstract:All next-generation ground-based and space-based Solar telescopes require a good quality-assessment metric to evaluate their imaging performance. In this paper, a new image quality metric, the median filter-gradient similarity (MFGS) is proposed for photospheric images. MFGS is a no-reference/blind objective image-quality metric (IQM) by a measurement result between 0 and 1 and has been performed on short-exposure photospheric images captured by the New Vacuum Solar Telescope (NVST) of the Fuxian Solar Observatory and by the Solar Optical Telescope (SOT) onboard the Hinode satellite, respectively. The results show that (1) the measured value of the MFGS changes monotonically from 1 to 0 with degradation of image quality; (2) there exists a linear correlation between the measured values of the MFGS and the root-mean-square contrast (RMS-contrast) of the granulation; (3) the MFGS is less affected by the image contents than the granular RMS-contrast. Overall, the MFGS is a good alternative for the quality assessment of photospheric images.
S K Solanki - One of the best experts on this subject based on the ideXlab platform.
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the second flight of the sunrise balloon borne Solar Observatory overview of instrument updates the flight the data and first results
Astrophysical Journal Supplement Series, 2017Co-Authors: Peter Barthol, T L Riethmuller, S K Solanki, W Deutsch, A Feller, S Danilovic, H P Doerr, Achim GandorferAbstract:The SUNRISE balloon-borne Solar Observatory, consisting of a 1~m aperture telescope that provided a stabilized image to a UV filter imager and an imaging vector polarimeter, carried out its second science flight in June 2013. It provided observations of parts of active regions at high spatial resolution, including the first high-resolution images in the Mg~{\sc ii}~k line. The obtained data are of very high quality, with the best UV images reaching the diffraction limit of the telescope at 3000~\AA\ after Multi-Frame Blind Deconvolution reconstruction accounting for phase-diversity information. Here a brief update is given of the instruments and the data reduction techniques, which includes an inversion of the polarimetric data. Mainly those aspects that evolved compared with the first flight are described. A tabular overview of the observations is given. In addition, an example time series of a part of the emerging active region NOAA AR~11768 observed relatively close to disk centre is described and discussed in some detail. The observations cover the pores in the trailing polarity of the active region, as well as the polarity inversion line where flux emergence was ongoing and a small flare-like brightening occurred in the course of the time series. The pores are found to contain magnetic field strengths ranging up to 2500~G and, while large pores are clearly darker and cooler than the quiet Sun in all layers of the photosphere, the temperature and brightness of small pores approach or even exceed those of the quiet Sun in the upper photosphere.
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spectropolarimetric evidence for a siphon flow along an emerging magnetic flux tube
Astrophysical Journal Supplement Series, 2017Co-Authors: Iker S Requerey, S K Solanki, J C Del Toro Iniesta, Blanco J Rodriguez, Orozco D Suarez, Ruiz B Cobo, Peter BartholAbstract:This work has been partially funded by the Spanish Ministerio de Economia y Competitividad, through Projects No. ESP2013-47349-C6 and ESP2014-56169-C6, including a percentage from European FEDER funds. The German contribution to sunrise and its reflight was funded by the Max Planck Foundation, the Strategic Innovations Fund of the President of the Max Planck Society (MPG), DLR, and private donations by supporting members of the Max Planck Society, which is gratefully acknowledged. The National Solar Observatory (NSO) is operated by the Association of Universities for Research in Astronomy (AURA) Inc. under a cooperative agreement with the National Science Foundation. The HAO contribution was partly funded through NASA grant number NNX13AE95G. This work was partly supported by the BK21 plus program through the National Research Foundation (NRF) funded by the Ministry of Education of Korea.
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the filter imager sufi and the image stabilization and light distribution system islid of the sunrise balloon borne Observatory instrument description
Solar Physics, 2011Co-Authors: Achim Gandorfer, Peter Barthol, B Grauf, T L Riethmuller, S K Solanki, B Chares, W Deutsch, S Ebert, A Feller, D GermerottAbstract:We describe the design of the Sunrise Filter Imager (SuFI) and the Image Stabilization and Light Distribution (ISLiD) unit onboard the Sunrise balloon borne Solar Observatory. This contribution provides the necessary information which is relevant to understand the instruments’ working principles, the relevant technical data, and the necessary information about calibration issues directly related to the science data.
Peter Barthol - One of the best experts on this subject based on the ideXlab platform.
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the second flight of the sunrise balloon borne Solar Observatory overview of instrument updates the flight the data and first results
Astrophysical Journal Supplement Series, 2017Co-Authors: Peter Barthol, T L Riethmuller, S K Solanki, W Deutsch, A Feller, S Danilovic, H P Doerr, Achim GandorferAbstract:The SUNRISE balloon-borne Solar Observatory, consisting of a 1~m aperture telescope that provided a stabilized image to a UV filter imager and an imaging vector polarimeter, carried out its second science flight in June 2013. It provided observations of parts of active regions at high spatial resolution, including the first high-resolution images in the Mg~{\sc ii}~k line. The obtained data are of very high quality, with the best UV images reaching the diffraction limit of the telescope at 3000~\AA\ after Multi-Frame Blind Deconvolution reconstruction accounting for phase-diversity information. Here a brief update is given of the instruments and the data reduction techniques, which includes an inversion of the polarimetric data. Mainly those aspects that evolved compared with the first flight are described. A tabular overview of the observations is given. In addition, an example time series of a part of the emerging active region NOAA AR~11768 observed relatively close to disk centre is described and discussed in some detail. The observations cover the pores in the trailing polarity of the active region, as well as the polarity inversion line where flux emergence was ongoing and a small flare-like brightening occurred in the course of the time series. The pores are found to contain magnetic field strengths ranging up to 2500~G and, while large pores are clearly darker and cooler than the quiet Sun in all layers of the photosphere, the temperature and brightness of small pores approach or even exceed those of the quiet Sun in the upper photosphere.
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spectropolarimetric evidence for a siphon flow along an emerging magnetic flux tube
Astrophysical Journal Supplement Series, 2017Co-Authors: Iker S Requerey, S K Solanki, J C Del Toro Iniesta, Blanco J Rodriguez, Orozco D Suarez, Ruiz B Cobo, Peter BartholAbstract:This work has been partially funded by the Spanish Ministerio de Economia y Competitividad, through Projects No. ESP2013-47349-C6 and ESP2014-56169-C6, including a percentage from European FEDER funds. The German contribution to sunrise and its reflight was funded by the Max Planck Foundation, the Strategic Innovations Fund of the President of the Max Planck Society (MPG), DLR, and private donations by supporting members of the Max Planck Society, which is gratefully acknowledged. The National Solar Observatory (NSO) is operated by the Association of Universities for Research in Astronomy (AURA) Inc. under a cooperative agreement with the National Science Foundation. The HAO contribution was partly funded through NASA grant number NNX13AE95G. This work was partly supported by the BK21 plus program through the National Research Foundation (NRF) funded by the Ministry of Education of Korea.
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Spectropolarimetric evidence for a siphon flow along an emerging magnetic flux tube
The Astrophysical Journal Supplement Series, 2017Co-Authors: Iker S Requerey, B Ruiz Cobo, Jose Carlos Del Toro Iniesta, Josefa Blanco-rodríguez, Sanket K Solanki, David Orozco Suárez, Laurent Gizon, Achim Gandorfer, Peter Barthol, Johann HirzbergerAbstract:We study the dynamics and topology of an emerging magnetic flux concentration using high spatial resolution spectropolarimetric data acquired with the Imaging Magnetograph eXperiment on board the Sunrise balloon-borne Solar Observatory. We obtain the full vector magnetic field and the line-of-sight (LOS) velocity through inversions of the Fe I line at 525.02 nm with the SPINOR code. The derived vector magnetic field is used to trace magnetic field lines. Two magnetic flux concentrations with different polarity and LOS velocities are found to be connected by a group of arch-shaped magnetic field lines. The positive polarity footpoint is weaker (1100 G) and displays an upflow, while the negative polarity footpoint is stronger (2200 G) and shows a downflow. This configuration is naturally interpreted as a siphon flow along an arched magnetic flux tube.
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the filter imager sufi and the image stabilization and light distribution system islid of the sunrise balloon borne Observatory instrument description
Solar Physics, 2011Co-Authors: Achim Gandorfer, Peter Barthol, B Grauf, T L Riethmuller, S K Solanki, B Chares, W Deutsch, S Ebert, A Feller, D GermerottAbstract:We describe the design of the Sunrise Filter Imager (SuFI) and the Image Stabilization and Light Distribution (ISLiD) unit onboard the Sunrise balloon borne Solar Observatory. This contribution provides the necessary information which is relevant to understand the instruments’ working principles, the relevant technical data, and the necessary information about calibration issues directly related to the science data.
