共查询到20条相似文献,搜索用时 46 毫秒
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We describe solar observations carried out for the first time jointly with Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) and Aalto University Metshovi Radio Observatory (MRO). KAIRA is new radio antenna array observing the decimeter and meter wavelength range. It is located near Kilpisjärvi, Finland, and operated by the SodankyläGeophysical Observatory, University of Oulu. We investigate the feasibility of KAIRA for solar observations, and the additional benefits of carrying out multi‐instrument solar observations with KAIRA and the MRO facilities, which are already used for regular solar observations. The data measured with three instruments at MRO, and with KAIRA during time period 2014 April–October were analyzed. One solar radio event, measured on 2014 April 18, was studied in detail. Seven solar flares were recorded with at least two of the three instruments at MRO, and with KAIRA during the chosen time period. KAIRA is a great versatile asset as a new Finnish instrument that can also be used for solar observations. Collaboration observations with MRO instruments and KAIRA enable detailed multi‐frequency solar flare analysis. Flare pulsations, flare statistics and radio spectra of single flares can be investigated due to the broad frequency range observations. The Northern locations of both MRO and KAIRA make as long as 15‐hour unique solar observations possible during summer time. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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The day/night cycle at a single observatory prevents definitive observations of many aspects of solar activity, convection, and oscillations with timescales near 1 day. Solutions to this problem include multi-site networks, spacecraft observatories, and observations from high-latitude sites during their summer season. We report here on our experience in using Alaska as a high-latitude site for observations of solar oscillations. 相似文献
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S. Rifai Habbal H. Morgan M. Druckmüller A. Ding J. F. Cooper A. Daw E. C. Sittler Jr. 《Solar physics》2013,285(1-2):9-24
Imaging and spectroscopy of the solar corona, coupled with polarimetry, are the only tools available at present to capture signatures of physical processes responsible for coronal heating and solar wind acceleration within the first few solar radii above the solar limb. With the recent advent of improved detector technology and image processing techniques, broad-band white light and narrow-band multi-wavelength observations of coronal forbidden lines, made during total solar eclipses, have started to yield new views about the thermodynamic and magnetic properties of coronal structures. This paper outlines these unique capabilities, which until present, have been feasible primarily with observations during natural total solar eclipses. This work also draws attention to the exciting possibility of greatly increasing the frequency and duration of solar eclipse observations with Moon orbiting observatories utilizing lunar limb occultation of the solar disk for coronal measurements. 相似文献
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日冕物质抛射与共生射电爆发的地面和空间联测研究 总被引:1,自引:0,他引:1
引述了近年来太阳和空间物理的一大研究成果;产生日地空间射电爆发和地球物理响应的主因不是太阳耀斑,而是日冕物质抛射(CME),论述了射电爆发在研究CME中的作用;分析了1991-06-15CME事件中射电爆发和质子事件产生的物理过程;介绍了地面/空间对CME和共生射电爆发联测研究的新进展;提出了我国今后开展地面/空间联测研究的设想和建议。 相似文献
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Recent observational studies on solar flares made by solar radio groups in Japan during the period around the maximum of Cycle 21 are briefly reviewed. Much attention is paid especially to comparison studies of microwave observations with hard X-ray and γ-ray observations.
相似文献9.
Magnetic flux ropes are created in the ionosphere of Venus and Mars during the interaction of the solar wind with their ionospheres and also at Titan during the interaction of the Saturnian magnetospheric plasma flow with Titan’s ionosphere. The flux ropes at Venus and Mars were extensively studied from Pioneer Venus Orbiter and Mars Global Surveyor observations respectively during solar maximum. Based on the statistical properties of the observed flux ropes at Venus and Mars, the formation of a flux rope in the ionosphere is thought first to arise near the boundary between the magnetic barrier and the ionosphere and later to sink into the lower ionosphere. Venus flux ropes are also observed during solar minimum by Venus Express and the observations of developing and mature flux ropes are consistent with the proposed mechanism. With the knowledge of flux rope structure in the Venus ionosphere, the twisted fields in the lower ionosphere of Titan from Cassini observations are studied and are found to resemble the Venus flux ropes. 相似文献
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Density cavity observed over a strong lunar crustal magnetic anomaly in the solar wind: A mini-magnetosphere? 总被引:1,自引:0,他引:1
J.S. Halekas G.T. Delory D.A. Brain R.P. Lin D.L. Mitchell 《Planetary and Space Science》2008,56(7):941-946
We present observations of what may be the inner region of a lunar mini-magnetosphere. If so, these likely represent the first such observations. Previous studies of solar wind interaction with lunar crustal magnetic fields found increased particle fluxes associated with magnetic amplifications, suggesting a shock/sheath region. The central density cavity expected in the inner mini-magnetosphere (if analogous to other planetary magnetospheres) has proven elusive. We now present Lunar Prospector fly-throughs of a density cavity near a strong crustal magnetic source in the solar wind, and compare these unique observations with typical orbits in the solar wind and wake. We observed the density cavity on two consecutive orbits on July 14, 1999 with optimal viewing geometry, downstream from one of the strongest lunar crustal sources (an anomaly centered at 235E, 20S), during very unusual solar wind conditions. We found no other similar features in the solar wind in 7 months of low-altitude orbits, suggesting that fully formed lunar mini-magnetospheres are rare and/or difficult to observe from orbit. 相似文献
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The reconstruction of solar activity during the late 18th century is a puzzle for researchers due to the scarcity of sunspot
observations in that epoch. In this work, we analyse some details of the solar activity during the years 1781–1788, inferred
from geomagnetic measurements and visual observations of aurorae performed by the Portuguese scientist Bento Sanches Dorta
from Rio de Janeiro. We describe in greater detail four large solar storms that induced large changes in daily values of geomagnetic
declination and, simultaneously, correspond to visual observations of aurorae described by Sanches Dorta. 相似文献
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Knowledge of solar spectral irradiance (SSI) is important in determining the impact of solar variability on climate. Observations of UV SSI have been made by the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) on the Upper Atmosphere Research Satellite (UARS), the Solar-Stellar Irradiance Comparison Experiment (SOLSTICE), and the Solar Irradiance Monitor (SIM), both on the Solar Radiation and Climate Experiment (SORCE) satellite. Measurements by SUSIM and SORCE overlapped from 2003 to 2005. SUSIM and SORCE observations represent ~?20 years of absolute UV SSI. Unfortunately, significant differences exist between these two data sets. In particular, changes in SORCE UV SSI measurements, gathered at moderate and minimum solar activity, are a factor of two greater than the changes in SUSIM observations over the entire solar cycle. In addition, SORCE UV SSI have a substantially different relationship with the Mg ii index than did earlier UV SSI observations. Acceptance of these new SORCE results impose significant changes on our understanding of UV SSI variation. Alternatively, these differences in UV SSI observations indicate that some or all of these instruments have changes in instrument responsivity that are not fully accounted for by the current calibration. In this study, we compare UV SSI changes from SUSIM with those from SIM and SOLSTICE. The primary results are that (1) long-term observations by SUSIM and SORCE generally do not agree during the overlap period (2003?–?2005), (2) SUSIM observations during this overlap period are consistent with an SSI model based on Mg ii and early SUSIM SSI, and (3) when comparing the spectral irradiance for times of similar solar activity on either side of solar minimum, SUSIM observations show slight differences while the SORCE observations show variations that increase with time between spectra. Based on this work, we conclude that the instrument responsivity for SOLSTICE and SIM need to be reevaluated before these results can be used for climate-modeling studies. 相似文献
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Konrad Dennerl 《Planetary and Space Science》2008,56(10):1414-1423
X-ray observations of Venus are so challenging that the first detection of Venusian X-rays succeeded only in January 2001, with the Chandra satellite. The X-rays from Venus were found to result from fluorescent scattering of solar X-rays in the Venusian thermosphere. An additional component, caused by charge exchange of highly charged heavy ions in the solar wind with atoms in the Venusian exosphere, was suspected, but could not be unambiguously detected. This was hampered by the fact that the observation occurred during solar maximum, when the solar X-ray flux is highest. In order to investigate the presence of an additional charge exchange component, Venus was observed again in March 2006 and October 2007 with Chandra, taking advantage of the fact that the solar X-ray flux had decreased considerably on its way to solar minimum. In fact, these subsequent observations were able to show that also the Venusian exosphere is emitting X-rays, due to its interaction with the solar wind. Here an overview of all the existing X-ray observations of Venus is presented, including first results from the most recent one, which took place after the arrival of Venus Express, providing the first ever opportunity to combine a remote X-ray observation of a planetary exosphere with simultaneous in situ measurements of the solar wind. 相似文献
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S. Ananthakrishnan 《Journal of Astrophysics and Astronomy》2000,21(3-4):439-444
The ground-based radio astronomy method of interplanetary scintillations (IPS) and spacecraft observations have shown, in
the past 25 years, that while coronal holes give rise to stable, reclining high speed solar wind streams during the minimum
of the solar activity cycle, the slow speed wind seen more during the solar maximum activity is better associated with the
closed field regions, which also give rise to solar flares and coronal mass ejections (CME’s). The latter events
increase significantly, as the cycle maximum takes place. We have recently shown that in the case of energetic flares one
may be able to track the associated disturbances almost on a one to one basis from a distance of 0.2 to 1 AU using IPS methods.
Time dependent 3D MHD models which are constrained by IPS observations are being developed. These models are able to simulate
general features of the solar-generated disturbances. Advances in this direction may lead to prediction of heliospheric propagation
of these disturbances throughout the solar system. 相似文献
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简要介绍了在1988-1995年期间冕洞观测研究的主要进展。文中共分五个方面:1.冕洞磁场观测研究的新进展;2.冕洞在太阳活动周不同位相时的规律性;3.冕洞区高速太阳风观测的新结果;4.冕洞加热问题;5.存在问题。 相似文献
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M. Shimojo T. S. Bastian A. S. Hales S. M. White K. Iwai R. E. Hills A. Hirota N. M. Phillips T. Sawada P. Yagoubov G. Siringo S. Asayama M. Sugimoto R. Brajša I. Skokić M. Bárta S. Kim I. de Gregorio-Monsalvo S. A. Corder H. S. Hudson S. Wedemeyer D. E. Gary B. De Pontieu M. Loukitcheva G. D. Fleishman B. Chen A. Kobelski Y. Yan 《Solar physics》2017,292(7):87
Observations of the Sun at millimeter and submillimeter wavelengths offer a unique probe into the structure, dynamics, and heating of the chromosphere; the structure of sunspots; the formation and eruption of prominences and filaments; and energetic phenomena such as jets and flares. High-resolution observations of the Sun at millimeter and submillimeter wavelengths are challenging due to the intense, extended, low-contrast, and dynamic nature of emission from the quiet Sun, and the extremely intense and variable nature of emissions associated with energetic phenomena. The Atacama Large Millimeter/submillimeter Array (ALMA) was designed with solar observations in mind. The requirements for solar observations are significantly different from observations of sidereal sources and special measures are necessary to successfully carry out this type of observations. We describe the commissioning efforts that enable the use of two frequency bands, the 3-mm band (Band 3) and the 1.25-mm band (Band 6), for continuum interferometric-imaging observations of the Sun with ALMA. Examples of high-resolution synthesized images obtained using the newly commissioned modes during the solar-commissioning campaign held in December 2015 are presented. Although only 30 of the eventual 66 ALMA antennas were used for the campaign, the solar images synthesized from the ALMA commissioning data reveal new features of the solar atmosphere that demonstrate the potential power of ALMA solar observations. The ongoing expansion of ALMA and solar-commissioning efforts will continue to enable new and unique solar observing capabilities. 相似文献
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Recent observational studies on solar flares made by solar radio groups in Japan during the period around the maximum of Cycle 21 are briefly reviewed. Much attention is paid especially to comparison studies of microwave observations with hard X-ray and -ray observations. 相似文献
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In this work the galactic cosmic ray modulation in relation to solar activity indices and heliospheric parameters during the years 1996??C?2010 covering solar cycle 23 and the solar minimum between cycles 23 and 24 is studied. A new perspective of this contribution is that cosmic ray data with a rigidity of 10 GV at the top of the atmosphere obtained from many ground-based neutron monitors were used. The proposed empirical relation gave much better results than those in previous works concerning the hysteresis effect. The proposed models obtained from a combination of solar activity indices and heliospheric parameters give a standard deviation <?10?% for all the cases. The correlation coefficient between the cosmic ray variations of 10?GV and the sunspot number reached a value of r=?0.89 with a time lag of 13.6±0.4 months. The best reproduction of the cosmic ray intensity is obtained by taking into account solar and interplanetary indices such as sunspot number, interplanetary magnetic field, CME index, and heliospheric current sheet tilt. The standard deviation between the observed and calculated values is about 7.15?% for all of solar cycle 23; it also works very well during the different phases of the cycle. Moreover, the use of the cosmic ray intensity of 10?GV during the long minimum period between cycles 23 and 24 is of special interest and is discussed in terms of cosmic ray intensity modulation. 相似文献
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The brightness temperature distributions of the solar atmosphere in the polar region at the distances from one to two solar radii during the solar activity minimum are reported. Observations of the maximum phase of the solar eclipse of March 29, 2006 were carried out simultaneously on two sectors of the RATAN-600 radio telescope over a wide range of centimeter waves, 1–31 cm. This study is based on a comparison of models and observations carried out on the northeastern sector of the RATAN-600. 相似文献
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