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1.
Hector Socas-Navarro David Elmore Anna Pietarila Anthony Darnell Bruce W. Lites Steven Tomczyk Steven Hegwer 《Solar physics》2006,235(1-2):55-73
The Spectro-Polarimeter for Infrared and Optical Regions (SPINOR) is a new spectro-polarimeter that will serve as a facility
instrument for the Dunn Solar Telescope at the National Solar Observatory. This instrument is capable of achromatic polarimetry
over a very broad range of wavelengths, from 430 to 1600 nm, allowing for the simultaneous observation of several visible
and infrared spectral regions with full Stokes polarimetry. Another key feature of the design is its flexibility to observe
virtually any combination of spectral lines, limited only by practical considerations (e.g., the number of detectors available, space on the optical bench, etc.).
Visiting Astronomers, National Solar Observatory, operated by the Association of Universities for Research in Astronomy, Inc.
(AURA), under cooperative agreement with the National Science Foundation. 相似文献
2.
J. M. Borrero S. Tomczyk M. Kubo H. Socas-Navarro J. Schou S. Couvidat R. Bogart 《Solar physics》2011,273(1):267-293
In this paper we describe in detail the implementation and main properties of a new inversion code for the polarized radiative
transfer equation (VFISV: Very Fast Inversion of the Stokes Vector). VFISV will routinely analyze pipeline data from the Helioseismic
and Magnetic Imager (HMI) on-board of the Solar Dynamics Observatory (SDO). It will provide full-disk maps (4096×4096 pixels)
of the magnetic field vector on the Solar Photosphere every ten minutes. For this reason VFISV is optimized to achieve an
inversion speed that will allow it to invert sixteen million pixels every ten minutes with a modest number (approx. 50) of
CPUs. Here we focus on describing a number of important details, simplifications and tweaks that have allowed us to significantly
speed up the inversion process. We also give details on tests performed with data from the spectropolarimeter on-board of
the Hinode spacecraft. 相似文献
3.
Graham Jonathan D. López Ariste Arturo Socas-Navarro Hector Tomczyk Steven 《Solar physics》2002,208(2):211-232
We investigate the diagnostic potential of polarimetric measurements with filtergraph instruments. Numerical simulations are used to explore the possibility of inferring the magnetic field vector, its filling factor, and the thermodynamics of model atmospheres when only a few wavelength measurements are available. These simulations assume the magnetic Sun to be represented by Milne–Eddington atmospheres. The results indicate that two wavelength measurements are insufficient to reliably determine the magnetic parameters, regardless of whether magnetograph techniques or least-squares fitting inversions are used. However, as few as four measurements analyzed with the inversion technique provide enough information to retrieve the intrinsic magnetic field with an accuracy better than 10% in most cases. 相似文献
4.
J. Schou P. H. Scherrer R. I. Bush R. Wachter S. Couvidat M. C. Rabello-Soares R. S. Bogart J. T. Hoeksema Y. Liu T. L. Duvall Jr. D. J. Akin B. A. Allard J. W. Miles R. Rairden R. A. Shine T. D. Tarbell A. M. Title C. J. Wolfson D. F. Elmore A. A. Norton S. Tomczyk 《Solar physics》2012,275(1-2):229-259
5.
Lites B.W. Card G. Elmore D.F. Holzer T. Lecinski A. Streander K.V. Tomczyk S. Gurman J.B. 《Solar physics》1999,190(1-2):185-206
Solar Physics - This paper presents first observations of dynamics of the white-light solar corona detected during the few minutes of totality of a solar eclipse. Perturbations of a polar plume... 相似文献
6.
The Coronal Multichannel Polarimeter (CoMP) measures not only the polarization of coronal emission, but also the full radiance profiles of coronal emission lines. For the first time, CoMP observations provide high-cadence image sequences of the coronal line intensity, Doppler shift, and line width simultaneously over a large field of view. By studying the Doppler shift and line width we may explore more of the physical processes of the initiation and propagation of coronal mass ejections (CMEs). Here we identify a list of CMEs observed by CoMP and present the first results of these observations. Our preliminary analysis shows that CMEs are usually associated with greatly increased Doppler shift and enhanced line width. These new observations provide not only valuable information to constrain CME models and probe various processes during the initial propagation of CMEs in the low corona, but also offer a possible cost-effective and low-risk means of space-weather monitoring. 相似文献
7.
An instrument to observe low-degree solar oscillations 总被引：1，自引：0，他引：1
We have constructed an instrument optimized to observe solar oscillations of low degree. The primary goal of this instrument, which we call LOWL, is to measure the frequency splitting of the low-degree modes in order to determine the rotation rate of the solar core. The LOWL is a Doppler imager based on a magneto-optical filter. It employs a two-beam technique to simultaneously observe solar images in opposite wings of the absorption line of potassium at 769.9 nm. This instrument is very stable against drifts in the wavelength zero-point, is insensitive to noise sources due to intensity fluctuations and image motion, and has a Doppler analyzer with no moving parts. The LOWL has been deployed at HAO's observing station on Mauna Loa, Hawaii and will operate for a period of at least two years.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
8.
J. M. Borrero S. Tomczyk A. Norton T. Darnell J. Schou P. Scherrer R. Bush Y. Liu 《Solar physics》2007,240(1):177-196
We investigate the accuracy to which we can retrieve the solar photospheric magnetic field vector using the Helioseismic and
Magnetic Imager (HMI) that will fly onboard of the Solar Dynamics Observatory by inverting simulated HMI profiles. The simulated
profiles realistically take into account the effects of the photon noise, limited spectral resolution, instrumental polarization
modulation, solar p modes, and temporal averaging. The accuracy of the determination of the magnetic field vector is studied by considering the
different operational modes of the instrument. 相似文献
9.
J. Schou J. M. Borrero A. A. Norton S. Tomczyk D. Elmore G. L. Card 《Solar physics》2012,275(1-2):327-355
As part of the overall ground-based calibration of the Helioseismic and Magnetic Imager (HMI) instrument an extensive set of polarimetric calibrations were performed. This paper describes the polarimetric design of the instrument, the test setup, the polarimetric model, the tests performed, and some results. It is demonstrated that HMI achieves an accuracy of 1% or better on the crosstalks between Q, U, and V and that our model can reproduce the intensities in our calibration sequences to about 0.4%. The amount of depolarization is negligible when the instrument is operated as intended which, combined with the flexibility of the polarimeter design, means that the polarimetric efficiency is excellent. 相似文献
10.
Siteng Fan Jiansen He Limei Yan Steven Tomczyk Hui Tian Hongqiang Song Linghua Wang Lei Zhang 《Solar physics》2018,293(1):6
As a coronal mass ejection (CME) passes, the flank and wake regions are typically strongly disturbed. Various instruments, including the Large Angle and Spectroscopic Coronagraph (LASCO), the Atmospheric Imaging Assembly (AIA), and the Coronal Multi-channel Polarimeter (CoMP), observed a CME close to the east limb on 26 October 2013. A hot (\({\approx}\,10~\mbox{MK}\)) rising blob was detected on the east limb, with an initial ejection flow speed of \({\approx}\, 330~\mbox{km}\,\mbox{s}^{-1}\). The magnetic structures on both sides and in the wake of the CME were strongly distorted, showing initiation of turbulent motions with Doppler-shift oscillations enhanced from \({\approx}\, \pm 3~\mbox{km}\,\mbox{s}^{-1}\) to \({\approx}\, \pm 15~\mbox{km}\,\mbox{s}^{-1}\) and effective thermal velocities from \({\approx}\,30~\mbox{km}\,\mbox{s}^{-1}\) to \({\approx}\,60~\mbox{km}\,\mbox{s}^{-1}\), according to the CoMP observations at the Fe?xiii line. The CoMP Doppler-shift maps suggest that the turbulence behaved differently at various heights; it showed clear wave-like torsional oscillations at lower altitudes, which are interpreted as the antiphase oscillation of an alternating red/blue Doppler shift across the strands at the flank. The turbulence seems to appear differently in the channels of different temperatures. Its turnover time was \({\approx}\,1000\) seconds for the Fe 171 Å channel, while it was \({\approx}\,500\) seconds for the Fe 193 Å channel. Mainly horizontal swaying rotations were observed in the Fe 171 Å channel, while more vertical vortices were seen in the Fe 193 Å channel. The differential-emission-measure profiles in the flank and wake regions have two components that evolve differently: the cool component decreased over time, evidently indicating a drop-out of cool materials due to ejection, while the hot component increased dramatically, probably because of the heating process, which is suspected to be a result of magnetic reconnection and turbulence dissipation. These results suggest a new turbulence-heating scenario of the solar corona and solar wind. 相似文献