J. Sylwester - Academia.edu (original) (raw)
Solar Physicist, Spectroscopist
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Saint-Petersburg Stieglitz State Academy of Art and Design
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Papers by J. Sylwester
Monthly Notices of the Royal Astronomical Society, 1995
19th Polish-Slovak-Czech Optical Conference on Wave and Quantum Aspects of Contemporary Optics, 2014
We present an innovative soft X-ray polarimeter and spectrometer SOLPEX, the instrument to be mou... more We present an innovative soft X-ray polarimeter and spectrometer SOLPEX, the instrument to be mounted aboard the International Space Station (ISS) in 2015/2016. The SOLPEX will be composed of three individual measuring units: the soft X-ray polarimeter with 1-2% linear polarization detection limit, a fast-rotating drum X-ray spectrometer with very high time resolution (0.1s) and a simple pin-hole soft X-ray imager-spectrometer with moderate spatial (~20arcsec), spectral (0.5 keV) and high time resolution (0.1s). This set of instruments will provide unique opportunity to complement the efforts to reliably measure the X-ray polarization and contribute towards understanding the physics of solar flares. The standard flare model states that electrons are being accelerated in specific regions of the corona at or near magnetic reconnection site and then propagate along reconnected magnetic field lines toward the atmospheric denser layers. There, they are decelerated and lose their energy mainly through the bremsstrahlung process. Deposited energy is readily converted to directed evaporation of the plasma to be detected through the Doppler-shifted emission lines in extreme ultraviolet and soft X-ray spectral ranges Due to highly anisotropic character of impulsive phase electron beams, resulting emission is expected to be polarized. Both these processes: bremsstrahlung emission of supposedly polarized X-ray flux and accompanying plasma evaporation velocities are to be simultaneously observed by the proposed SOLPEX instruments.
Astrophysics and Space Science Library, 1993
It is known that X-ray observations of the solar corona contain information on the flare energy r... more It is known that X-ray observations of the solar corona contain information on the flare energy release. In this paper we shall describe the use of density-temperature and emission measure-temperature diagrams for the analysis of the flare heating function. Simple considerations of flare behaviour in the diagrams are supported by results of calculations of hydrodynamic flare models. The model calculations have been performed using the PALERMO-HARVARD 1D code. We start our considerations from a description of the so called quasi-steady-state type of changes in a coronal solar loop. Next we discuss the flare decay phase and the dependence of the pattern of evolution in the diagrams on the time variations of flare heating rates. Finally we discuss a simplified energetics model for the flare rise phase and the dependence of the form of global flare thermal energy rise on the equivalent geometrical flare characteristics, i.e. loop semilength, L, and cross-sectional area, A. We illustrate our considerations by examples of flares observed in soft X-rays by the Solar Maximum Mission Bent Crystal Spectrometer (BCS).
The Astrophysical Journal, 2010
SphinX (Solar PHotometer IN X-rays), a full-disk-integrated spectrometer, observed 137 flare-like... more SphinX (Solar PHotometer IN X-rays), a full-disk-integrated spectrometer, observed 137 flare-like/transient events with active region (AR) 11024 being the only AR on disk. The Hinode X-Ray Telescope (XRT) and Solar Optical Telescope observe 67 of these events and identified their location from 12:00 UT on July 3 through 24:00 UT 2009 July 7. We find that the predominant mechanisms for flares observed by XRT are (1) flux cancellation and (2) the shearing of underlying magnetic elements. Point-and cusp-like flare morphologies seen by XRT all occur in a magnetic environment where one polarity is impeded by the opposite polarity and vice versa, forcing the flux cancellation process. The shearing is either caused by flux emergence at the center of the AR and separation of polarities along a neutral line or by individual magnetic elements having a rotational motion. Both mechanisms are observed to contribute to single-and multiple-loop flares. We observe that most loop flares occur along a large portion of a polarity inversion line. Point-and cusp-like flares become more infrequent as the AR becomes organized with separation of the positive and negative polarities. SphinX, which allows us to identify when these flares occur, provides us with a statistically significant temperature and emission scaling law for A and B class flares: EM = 6.1 × 10 33 T 1.9±0.1 .
Solar Physics, 1981
ABSTRACT
Solar Physics, 1983
In part III of the paper containing the analysis of the INTERCOSMOS 16 ADP spectra, it is shown t... more In part III of the paper containing the analysis of the INTERCOSMOS 16 ADP spectra, it is shown that by assuming the existence of a small admixture (1 To) of non-thermal electrons in the active-region plasma it is possible to improve the agreement between measured and calculated fluxes for some spectra. The analysis follows the suggestion contained in the paper by Karev et al. (1980).
The Solar photometer in X-rays (SphinX) experiment is scheduled for launch late summer 2008 on-bo... more The Solar photometer in X-rays (SphinX) experiment is scheduled for launch late summer 2008 on-board the Russian CORONAS-Photon satellite. SphinX will use three silicon PIN diode detectors with selected effective areas in order to record solar spectra in the X-ray energy range 0.3-15 keV with unprecedented temporal and medium energy resolution. High sensitivity and large dynamic range of the SphinX instrument will give for the first time possibility of observing solar soft X-ray variability from the weakest levels, ten times below present thresholds, to the largest X20+ flares. We present the results of the ground X-ray calibrations of the SphinX instrument performed at the X-ray Astronomy Calibration and Testing (XACT) facility of INAF-OAPA. The calibrations were essential for determination of SphinX detector energy resolution and efficiency. We describe the ground tests instrumental set-up, adopted measurement techniques and present results of the calibration data analysis.
Monthly Notices of the Royal Astronomical Society, 1995
19th Polish-Slovak-Czech Optical Conference on Wave and Quantum Aspects of Contemporary Optics, 2014
We present an innovative soft X-ray polarimeter and spectrometer SOLPEX, the instrument to be mou... more We present an innovative soft X-ray polarimeter and spectrometer SOLPEX, the instrument to be mounted aboard the International Space Station (ISS) in 2015/2016. The SOLPEX will be composed of three individual measuring units: the soft X-ray polarimeter with 1-2% linear polarization detection limit, a fast-rotating drum X-ray spectrometer with very high time resolution (0.1s) and a simple pin-hole soft X-ray imager-spectrometer with moderate spatial (~20arcsec), spectral (0.5 keV) and high time resolution (0.1s). This set of instruments will provide unique opportunity to complement the efforts to reliably measure the X-ray polarization and contribute towards understanding the physics of solar flares. The standard flare model states that electrons are being accelerated in specific regions of the corona at or near magnetic reconnection site and then propagate along reconnected magnetic field lines toward the atmospheric denser layers. There, they are decelerated and lose their energy mainly through the bremsstrahlung process. Deposited energy is readily converted to directed evaporation of the plasma to be detected through the Doppler-shifted emission lines in extreme ultraviolet and soft X-ray spectral ranges Due to highly anisotropic character of impulsive phase electron beams, resulting emission is expected to be polarized. Both these processes: bremsstrahlung emission of supposedly polarized X-ray flux and accompanying plasma evaporation velocities are to be simultaneously observed by the proposed SOLPEX instruments.
Astrophysics and Space Science Library, 1993
It is known that X-ray observations of the solar corona contain information on the flare energy r... more It is known that X-ray observations of the solar corona contain information on the flare energy release. In this paper we shall describe the use of density-temperature and emission measure-temperature diagrams for the analysis of the flare heating function. Simple considerations of flare behaviour in the diagrams are supported by results of calculations of hydrodynamic flare models. The model calculations have been performed using the PALERMO-HARVARD 1D code. We start our considerations from a description of the so called quasi-steady-state type of changes in a coronal solar loop. Next we discuss the flare decay phase and the dependence of the pattern of evolution in the diagrams on the time variations of flare heating rates. Finally we discuss a simplified energetics model for the flare rise phase and the dependence of the form of global flare thermal energy rise on the equivalent geometrical flare characteristics, i.e. loop semilength, L, and cross-sectional area, A. We illustrate our considerations by examples of flares observed in soft X-rays by the Solar Maximum Mission Bent Crystal Spectrometer (BCS).
The Astrophysical Journal, 2010
SphinX (Solar PHotometer IN X-rays), a full-disk-integrated spectrometer, observed 137 flare-like... more SphinX (Solar PHotometer IN X-rays), a full-disk-integrated spectrometer, observed 137 flare-like/transient events with active region (AR) 11024 being the only AR on disk. The Hinode X-Ray Telescope (XRT) and Solar Optical Telescope observe 67 of these events and identified their location from 12:00 UT on July 3 through 24:00 UT 2009 July 7. We find that the predominant mechanisms for flares observed by XRT are (1) flux cancellation and (2) the shearing of underlying magnetic elements. Point-and cusp-like flare morphologies seen by XRT all occur in a magnetic environment where one polarity is impeded by the opposite polarity and vice versa, forcing the flux cancellation process. The shearing is either caused by flux emergence at the center of the AR and separation of polarities along a neutral line or by individual magnetic elements having a rotational motion. Both mechanisms are observed to contribute to single-and multiple-loop flares. We observe that most loop flares occur along a large portion of a polarity inversion line. Point-and cusp-like flares become more infrequent as the AR becomes organized with separation of the positive and negative polarities. SphinX, which allows us to identify when these flares occur, provides us with a statistically significant temperature and emission scaling law for A and B class flares: EM = 6.1 × 10 33 T 1.9±0.1 .
Solar Physics, 1981
ABSTRACT
Solar Physics, 1983
In part III of the paper containing the analysis of the INTERCOSMOS 16 ADP spectra, it is shown t... more In part III of the paper containing the analysis of the INTERCOSMOS 16 ADP spectra, it is shown that by assuming the existence of a small admixture (1 To) of non-thermal electrons in the active-region plasma it is possible to improve the agreement between measured and calculated fluxes for some spectra. The analysis follows the suggestion contained in the paper by Karev et al. (1980).
The Solar photometer in X-rays (SphinX) experiment is scheduled for launch late summer 2008 on-bo... more The Solar photometer in X-rays (SphinX) experiment is scheduled for launch late summer 2008 on-board the Russian CORONAS-Photon satellite. SphinX will use three silicon PIN diode detectors with selected effective areas in order to record solar spectra in the X-ray energy range 0.3-15 keV with unprecedented temporal and medium energy resolution. High sensitivity and large dynamic range of the SphinX instrument will give for the first time possibility of observing solar soft X-ray variability from the weakest levels, ten times below present thresholds, to the largest X20+ flares. We present the results of the ground X-ray calibrations of the SphinX instrument performed at the X-ray Astronomy Calibration and Testing (XACT) facility of INAF-OAPA. The calibrations were essential for determination of SphinX detector energy resolution and efficiency. We describe the ground tests instrumental set-up, adopted measurement techniques and present results of the calibration data analysis.