Cooperation with the SCOSTEP Project: Study of Travelling Interplanetary Phenomena (STIP)     

M. Dryer  M. A. Shea 《Solar physics》1976,47(1):413-429

The Flare Build-up Study (FBS) is primarily devoted to the study of various physical processes on the Sun prior to the occurrence of a solar flare. The relationship of these processes to the flare itself is then to be compared to similar, albeit smaller, processes in the magnetosopheric tail sometimes called the auroral flare. The Study of Travelling Interplanetary Phenomena (STIP) is devoted to specific studies of various phenomena from their inception on the Sun to their passage through the interplanetary medium. Some of these studies will be prior to and during both solar flare and magnetospheric substorm phenomena. Various scientific areas where the work of FBS and STIP would be mutually beneficial are discussed.  相似文献   

Interplanetary shock collisions: Forward with reverse shocks     

Smith  Z. K.  Dryer  M.  Han  S. M. 《Astrophysics and Space Science》1986,119(2):337-344

When one interplanetary shock overtakes another, the structure that results depends upon the nature of the interacting shocks. We examine, numerically, the results of collisions of forward with reverse shocks, in two dimensions, and show that the results depend primarily upon shock strength. We also note that such interactions could explain why many energy outbursts on the Sun that would be expected to cause geomagnetic effects at Earth, do not.  相似文献   

Initial Results of the Ichon Solar Radio Spectrograph     

Cho  K.-S.  Kim  K.-S.  Moon  Y.-J.  Dryer  M. 《Solar physics》2003,212(1):151-163

A new solar radio spectrograph to observe solar radio bursts has been installed at the Ichon branch of the Radio Research Laboratory, Ministry of Information and Communication, Korea. The spectrograph consists of three different antennas to sweep a wide band of frequencies in the range of 30 MHz ∼ 2500 MHz. Its daily operation is fully automated and typical examples of solar radio bursts have been successfully observed. In this paper we describe briefly its hardware and data processing methods. Then we present coronal shock speeds estimated for 34 type II bursts from May 1998 to November 2000 and compare them with those from other observatories. We also present the close relationship between onset time of type II bursts and X-ray flares as well as their associations with coronal mass ejections.  相似文献   

An Investigation of Solar Maximum Metric Type ii Radio Bursts: do two Kinds of Coronal Shock Sources Exist?     

A. Shanmugaraju  Y.-J. Moon  M. Dryer  S. Umapathy 《Solar physics》2003,215(1):161-184

A detailed statistical investigation of solar Type II radio bursts during the last solar maximum period 1999–2001 has been made to address the question if there exist two kinds of coronal shock sources. For this, the Type II bursts were classified into two classes: (i) those associated with flares only (Class I); and (ii) those associated with flares and CMEs (Class II) according to their temporal association. While the properties of all the type IIs agree in general with the common range of values, the properties of the shocks of the two classes differ slightly. For example, while the duration and shock speed for Class II are higher than those of Class I, the ending frequency for Class II is significantly lower. We have also examined in detail the physical association with other solar and interplanetary activities (Type IV bursts, Long Duration Events, Wind/WAVES deca-hectometric Type IIs, and interplanetary shocks) using the data in 2000. As a result, we have found noticeable differences between these two classes in terms of the following physical characteristics: First, the associations of these activities for Class II are much higher than those of Class I. Second, the correlation values between the flare parameters and the Type II properties for Class II are significantly smaller. Third, observed double Type IIs exist in only Class II events. The above results suggest that there are two kinds of coronal shocks or, rather, two general classes of coronal shock sources.  相似文献   

An acceleration mechanism for loop transients in the outer corona     

Tyan Yeh  Murray Dryer 《Solar physics》1981,71(1):141-149

The heliocentrifugal motion of coronal loop transients is likely driven largely by the buoyant force exerted by the ambient medium. In the outer corona where the solar wind is well formed, the buoyant force results mainly from the rapid outward decrease in the ambient pressure of the solar wind. The contribution from magnetic buoyancy is not so significant as in the vicinity of the solar surface. Therefore, the pertinent features of the loop transients in the outer corona are basically gasdynamical. As a conspicuous part of coronal expansion, the motion of the compressible masses in the transient loops is largely controlled by thermal forces. The translational motion of heliocentrifugal expansion is driven by the hydrodynamic buoyant force, and the lateral motion of peripheral expansion is driven by the pressure difference between the dense plasma of the ejecta and the tenuous plasma of the ambient medium.  相似文献   

Interaction of the solar wind with the outer planets     

Murray Dryer  Arthur W. Rizzi  Wen-Wu Shen 《Astrophysics and Space Science》1973,22(2):329-351

The hypersonic analog for the interaction of the solar wind with Jupiter, Saturn, Uranus, Neptune and Pluto is used to provide estimates of shock shapes and locations as well as average magnetosheath and/or ionosheath properties for these planets. Several representative spacecraft flyby trajectories (designed for outer-planet Grand Tour simulations) are superimposed upon a series of figures in order to provide estimates of potential plasma and field parameters which may be encountered. Consideration is given first to the possibility that several of these planets have intrinsic magnetic fields and, secondly, to the interaction of the solar wind directly on the ionosphere should there actually be no intrinsic field. Saturn and Pluto are chosen as examples of this latter case.  相似文献   

Application of the hypersonic analog to the standing shock of Mars     

Murray Dryer  Gary R. Heckman 《Solar physics》1967,2(1):112-124

A magnetospheric boundary and its associated standing-shock wave for the earth are scaled down in size to apply to Mars. A suggestion by the Mariner-IV experimenters that their magnetometer may have detected a Martian shock at 0123 UT (earth) on July 15, 1965, is accepted. The scaling procedure used previously in the case of the Mariner-II flyby of Venus on December 14, 1962, as well as in the present case of Mars is repeated but with a different model. We propose a magnetospheric boundary for the earth, which is based on a maximum radius of 22 R _E suggested by Imp-1 magnetometer data. We further suggest a low value (1.2) of the adiabatic exponent, . In addition we propose the use of the interplanetary magnetoacoustic Mach number, M_*, which is a combination of both Alfvén and ordinary gasdynamic Mach numbers. Our choice of values for these parameters is not unique since many such combinations exist which will show good agreement with observation. For example, the ratio of the Martian dipole moment to that for the earth is found to be 2.1 × 10^–4 by our application of the hypersonic analog. This value compares very closely with 3 × 10^–4 deduced as an upper bound by the Mariner-IV investigators. The present synthesis is presented as an independent calculation based on the above theoretical considerations, together with the experimenters' probable observation of a Martian shock wave.Since this paper was submitted for publication, theoretical calculations of the steady-state average magnetic induction in the transition region for an interplanetary field oriented at several angles to the velocity vector have been published by A. Y. Alksne, Planetary Space Science 15 (1967), 239–245. As anticipated in the text above, the magnitudes are slightly changed, but the polarities are significantly different.Formerly the Central Radio Propagation Laboratory of the National Bureau of Standards.  相似文献   

Re-Evaluation of the Flare–Type II–CME Association     

A.?ShanmugarajuEmail author  Y.-J.?Moon  Y.-H.?Kim  M.?Dryer  S.?Umapathy 《Solar physics》2004,225(1):141-155

We have re-evaluated the association of type II solar radio bursts with flares and/or coronal mass ejections (CMEs) using the year 2000 solar maximum data. For this, we consider 52 type II events whose associations with flares or CMEs were absent or not clearly identified and reported. These events are classified as follows; group I: 11 type IIs for which there are no reports of GOES X-ray flares and CMEs; group II: 12 type IIs for which there are no reports of GOES X-ray flares; and group III: 29 type IIs for which the flare locations are not reported. By carefully re-examining their association from GOES X-ray and H, Yohkoh SXT and EIT-EUV data, we attempt to answer the following questions: (i) if there really were no X-ray flares associated with the above 23 type IIs of groups I and II; (ii) whether they can be regarded as backside events whose X-ray emission might have been occulted. From this analysis, we have found that two factors, flare background intensity and flare location, play important roles in the complete reports about flare–type II–CME associations. In the above 23 cases, for more than 50% of the cases in total, the X-ray flares were not noticed and reported, because the background intensity of X-ray flux was high. In the remaining cases, the X-ray intensity might be greatly reduced due to occultation. From the H flare data, Yohkoh SXT data and EIT-EUV data, we found that ten cases out of 23 might be frontside events, and the remaining are backside events. While the flare–type II association is found to be nearly 90%, the type II–CME association is roughly around 75%. This analysis might be useful to reduce some ambiguities regarding the association among type IIs, flares and CMEs.  相似文献   

The X-ray signature of solar coronal mass ejections     

R. A. Harrison  P. W. Waggett  R. D. Bentley  K. J. H. Phillips  M. Bruner  M. Dryer  G. M. Simnett 《Solar physics》1985,97(2):387-400

The coronal response to six solar X-ray flares has been investigated. At a time coincident with the projected onset of the white-light coronal mass ejection associated with each flare, there is a small, discrete soft X-ray enhancement. These enhancements (precursors) precede by typically 20 m the impulsive phase of the solar flare which is dominant by the time the coronal mass ejection has reached an altitude above 0.5 R . We identify motions of hot X-ray emitting plasma, during the precursors, which may well be a signature of the mass ejection onsets. Further investigations have also revealed a second class of X-ray coronal transient, during the main phase of the flare. These appear to be associated with magnetic reconnection above post-flare loop systems.NCAR is sponsored by the National Science Foundation.  相似文献   

Study of travelling interplanetary phenomena report     

Murray Dryer 《Solar physics》1987,114(2):407-411

Scientific progress on the topic of energy, mass, and momentum transport from the Sun into the heliosphere is contingent upon interdisciplinary and international cooperative efforts on the part of many workers. Summarized here is a report of some highlights of research carried out during the SMY/SMA by the STIP (Study of Travelling Interplanetary Phenomena) Project that included solar and interplanetary scientists around the world. These highlights are concerned with coronal mass ejections from solar flares or erupting prominences (sometimes together); their large-scale consequences in interplanetary space (such as shocks and magnetic bubbles); and energetic particles and their relationship to these large-scale structures. It is concluded that future progress is contingent upon similar international programs assisted by real-time (or near-real-time) warnings of solar activity by cooperating agencies along the lines experienced during the SMY/SMA.  相似文献