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On the relationship between shock wave and magnetic bottle associated with the solar flare of 4 November 1968
Planet. Space Sci. 1974, Vol. 22, pp. 493 to 494. Persamon Press.
Printed in Northern Ireland
RESEARCH
NOTES
ON THE RELATIONSHIP BETWEEN SHOCK WAVE AND MAGNETIC BOTTLE ASSOCIATED WITH THE SOLAR FLARE OF 4 NOVEMBER 1968 in final form
(Received
22 October 1973)
Abstract-This note discusses the relation between shock wave and magnetic bottle, which were both associated with the solar proton flare of 4 November 1968. In particular, the formation and development of this wave and bottle are described. The solar flare, which occurred at - 0513 UT at the west limb, was associated with type II and type IV radio bursts, interplanetary shock waves and SSC geomagnetic storm. Furthermore, this flare ejected a magnetic bottle into the envelope of the Sun (Schatten, 1970), and produced MeV solar cosmic rays (Solar Geophysical Data). Therefore, we should say that this flare was one of the major flares. A transient Faraday rotation phenomenon was observed from 1600 to 1900 UT on this day in the 2.292 GHz radio wave transmitted from the Pioneer 6 spacecraft (Levy et al., 1969). This phenomenon was produced when the magnetic bottle passed through the region IO-12 solar radii from the Sun, where the above radio wave was passing through (Schatten, 1970). The speed of this bottle was - 200 km set-l. This flare produced a shock wave which was indirectly observed as type II radio bursts in the solar
Jc
PIONEER
8
8. MAGNETIC OF TYPE
INTERPLANETARY
\
SHOCK
BOTTLE ISOURCE lx BURSTS)
WAVE
16 NO”. ,968)
Vu : SPEED OF TYPE Z ASSOClATEO
SHOCK
“s : SPEED
OF MAGNETIC
“1:
SPEED IN INTERPLANETARY
SHOCK
BOTTLE SPACE
FIG. 1. SCHOCK WAVE EXCITING TYPE II BURST, MAGNETIC BOTTLE AND INTERPLANETARY SHOCK WAVE AT THE EARTH’S ORBIT, ALL OF WHICH WERE GENERATED BY THE FLARE 0~ 4 NOVEMBER 1968. Their speeds are indicated by Vrr, V, and VI, respectively. 10
493
494
RESEARCH
NOTES
atmosphere (Sheridan and Smerd, 1973. private communication). Moreover, an interplanetary shock wave associated with this flare was detected by the magnetometer on board the Explorer 33 satellite, and by ground-based magnetometers on the Earth. These magnetic records show that the mean speed of the shock wave was - 650 km se& in interplanetary space. Using the observed record for type II burst, we have estimated the approximate radial speed of the shock wave to be 2000-3000 km set-r in the range 0.072-1.0 solar radii above the photosphere. In doing so, we have assumed the electron density distribution for the solar activity maximum deduced by Van de Hulst (see Stelzried er al., 1970). The difference between the shock speed near the Sun and that in interplanetary space suggests that the shock wave decelerated between the Sun and the Earth during propagation. Since both the shock wave and the magnetic bottle are thought of as being produced simultaneously during the explosive phase of the solar flare (e.g. Sakurai, 1965, 1971), the difference between the speeds of the shock wave and the bottle must be essential in this case. Although both the shock wave and magnetic bottle were produced in this phase, it seems that the mechanisms of their production were different from each other; that is, the shock wave was produced in association with the explosive development of a flare, though the details are not known as yet, whereas the formation must have been closely related to the production of a number of high-energy protons and electrons in the flare region. These particles were first trapped by sunspot magnetic fields near and above the flare region, and later seemed to begin to transport these fields by forming the observed magnetic bottle. Thus the expansion of this bottle was necessarily delayed from that of the shock wave mentioned above. Hence the speed of the bottle was not necessarily equal nor similar to that of the shock wave. It is noted that this bottle is identified as the source of type IV radio bursts at metric frequencies (e.g. Takakura, 1961; Wild, 1962). So far we have considered the observed result and a possible cause for the difference between the speeds of the shock wave and the magnetic bottle associated with the 4 November 1968 flare. This difference may be. essential because the shock wave did not expand together with the magnetic bottle at the same speed. The situations near the Sun a few hr after the onset of the flare and at the Earth’s orbit 2 days after this flare are described in Fig. 1. This figure shows that the shock wave exciting type II bursts moved much faster than the magnetic bottle in the solar atmosphere. While decelerating, this shock wave arrived at the Earth’s orbit on 6 November and its mean speed has been estimated to be - 650 km set-‘. The proton flare of 4 November 1968 has given us an opportunity to examine how both shock wave and magnetic bottle form in the explosive phase of a flare, and then are released into outer space. Furthermore, tvhe result shown above strongly suggests that even major flares generate a magnetic’ bottle moving with a soeed of a few 100 km set’. much lower than that of the local Alfven waves (Sakurai and Chao. 1974). 1 Acknowledgements-We would like to thank Dr. L. F. Burlaga for his critical comment on this work. We are indebted to Drs. K. V. Sheridan and S. F. Smerd for their supply of solar radio data. K. SAKURAI+ J. K. CHAOt
Laboratory for Extraterrestrial Physics, NASA, Goddard Space Flight Cenfer, Greenbelt, Maryland 20771, U.S.A. REFERENCES
LEVY, G. S., SATO, T., SEILXL,B. L., STELZRIED,C. T., ORSON,J. E. and RUSCH, W. V. T. (1969). Science
166, 596. SAKURAI, K. (1965). Rep. Ionosph. Space Res. Japan 19,408. SAKURAI, K. (1971). Solar Phys. 20, 147. SAKURAI, K. and CHAO, J. K. (1974). J. geophys. Res. In press. SCHAITEN, K. H. (1970). Solar Phys. 12,484. SHERIDAN,K. V. and SMERD,S. F. (1973). Private communication. SMERD,S. F. and DULK, G. A. (1971). Solar Magnetic Fields (Ed. R. Howard), p. 616. Reidel, Dordrecht,
Holland. STELZRIED,C. T., LEW, G. S., SATO, T., RUSCH, W. V. T., OLSON, J. E., SCHATTEN,K. H. and WILCOX.
J. M. (1970). Solar Phys. 14, 440. TAKAKURA, T. (1961). Publs astr. Sot. Jupan 13, 166. WILD, J. P. (1962). J. phys. Sot. Japan 17, Suppl. A-II, 249. l Also at the University of Maryland. Lunar and Planetary t Present address: 85721 U.S.A.
Laboratory,
University
of Arizona,
Tucson,
Arizona
Printed in Northern Ireland
RESEARCH
NOTES
ON THE RELATIONSHIP BETWEEN SHOCK WAVE AND MAGNETIC BOTTLE ASSOCIATED WITH THE SOLAR FLARE OF 4 NOVEMBER 1968 in final form
(Received
22 October 1973)
Abstract-This note discusses the relation between shock wave and magnetic bottle, which were both associated with the solar proton flare of 4 November 1968. In particular, the formation and development of this wave and bottle are described. The solar flare, which occurred at - 0513 UT at the west limb, was associated with type II and type IV radio bursts, interplanetary shock waves and SSC geomagnetic storm. Furthermore, this flare ejected a magnetic bottle into the envelope of the Sun (Schatten, 1970), and produced MeV solar cosmic rays (Solar Geophysical Data). Therefore, we should say that this flare was one of the major flares. A transient Faraday rotation phenomenon was observed from 1600 to 1900 UT on this day in the 2.292 GHz radio wave transmitted from the Pioneer 6 spacecraft (Levy et al., 1969). This phenomenon was produced when the magnetic bottle passed through the region IO-12 solar radii from the Sun, where the above radio wave was passing through (Schatten, 1970). The speed of this bottle was - 200 km set-l. This flare produced a shock wave which was indirectly observed as type II radio bursts in the solar
Jc
PIONEER
8
8. MAGNETIC OF TYPE
INTERPLANETARY
\
SHOCK
BOTTLE ISOURCE lx BURSTS)
WAVE
16 NO”. ,968)
Vu : SPEED OF TYPE Z ASSOClATEO
SHOCK
“s : SPEED
OF MAGNETIC
“1:
SPEED IN INTERPLANETARY
SHOCK
BOTTLE SPACE
FIG. 1. SCHOCK WAVE EXCITING TYPE II BURST, MAGNETIC BOTTLE AND INTERPLANETARY SHOCK WAVE AT THE EARTH’S ORBIT, ALL OF WHICH WERE GENERATED BY THE FLARE 0~ 4 NOVEMBER 1968. Their speeds are indicated by Vrr, V, and VI, respectively. 10
493
494
RESEARCH
NOTES
atmosphere (Sheridan and Smerd, 1973. private communication). Moreover, an interplanetary shock wave associated with this flare was detected by the magnetometer on board the Explorer 33 satellite, and by ground-based magnetometers on the Earth. These magnetic records show that the mean speed of the shock wave was - 650 km se& in interplanetary space. Using the observed record for type II burst, we have estimated the approximate radial speed of the shock wave to be 2000-3000 km set-r in the range 0.072-1.0 solar radii above the photosphere. In doing so, we have assumed the electron density distribution for the solar activity maximum deduced by Van de Hulst (see Stelzried er al., 1970). The difference between the shock speed near the Sun and that in interplanetary space suggests that the shock wave decelerated between the Sun and the Earth during propagation. Since both the shock wave and the magnetic bottle are thought of as being produced simultaneously during the explosive phase of the solar flare (e.g. Sakurai, 1965, 1971), the difference between the speeds of the shock wave and the bottle must be essential in this case. Although both the shock wave and magnetic bottle were produced in this phase, it seems that the mechanisms of their production were different from each other; that is, the shock wave was produced in association with the explosive development of a flare, though the details are not known as yet, whereas the formation must have been closely related to the production of a number of high-energy protons and electrons in the flare region. These particles were first trapped by sunspot magnetic fields near and above the flare region, and later seemed to begin to transport these fields by forming the observed magnetic bottle. Thus the expansion of this bottle was necessarily delayed from that of the shock wave mentioned above. Hence the speed of the bottle was not necessarily equal nor similar to that of the shock wave. It is noted that this bottle is identified as the source of type IV radio bursts at metric frequencies (e.g. Takakura, 1961; Wild, 1962). So far we have considered the observed result and a possible cause for the difference between the speeds of the shock wave and the magnetic bottle associated with the 4 November 1968 flare. This difference may be. essential because the shock wave did not expand together with the magnetic bottle at the same speed. The situations near the Sun a few hr after the onset of the flare and at the Earth’s orbit 2 days after this flare are described in Fig. 1. This figure shows that the shock wave exciting type II bursts moved much faster than the magnetic bottle in the solar atmosphere. While decelerating, this shock wave arrived at the Earth’s orbit on 6 November and its mean speed has been estimated to be - 650 km set-‘. The proton flare of 4 November 1968 has given us an opportunity to examine how both shock wave and magnetic bottle form in the explosive phase of a flare, and then are released into outer space. Furthermore, tvhe result shown above strongly suggests that even major flares generate a magnetic’ bottle moving with a soeed of a few 100 km set’. much lower than that of the local Alfven waves (Sakurai and Chao. 1974). 1 Acknowledgements-We would like to thank Dr. L. F. Burlaga for his critical comment on this work. We are indebted to Drs. K. V. Sheridan and S. F. Smerd for their supply of solar radio data. K. SAKURAI+ J. K. CHAOt
Laboratory for Extraterrestrial Physics, NASA, Goddard Space Flight Cenfer, Greenbelt, Maryland 20771, U.S.A. REFERENCES
LEVY, G. S., SATO, T., SEILXL,B. L., STELZRIED,C. T., ORSON,J. E. and RUSCH, W. V. T. (1969). Science
166, 596. SAKURAI, K. (1965). Rep. Ionosph. Space Res. Japan 19,408. SAKURAI, K. (1971). Solar Phys. 20, 147. SAKURAI, K. and CHAO, J. K. (1974). J. geophys. Res. In press. SCHAITEN, K. H. (1970). Solar Phys. 12,484. SHERIDAN,K. V. and SMERD,S. F. (1973). Private communication. SMERD,S. F. and DULK, G. A. (1971). Solar Magnetic Fields (Ed. R. Howard), p. 616. Reidel, Dordrecht,
Holland. STELZRIED,C. T., LEW, G. S., SATO, T., RUSCH, W. V. T., OLSON, J. E., SCHATTEN,K. H. and WILCOX.
J. M. (1970). Solar Phys. 14, 440. TAKAKURA, T. (1961). Publs astr. Sot. Jupan 13, 166. WILD, J. P. (1962). J. phys. Sot. Japan 17, Suppl. A-II, 249. l Also at the University of Maryland. Lunar and Planetary t Present address: 85721 U.S.A.
Laboratory,
University
of Arizona,
Tucson,
Arizona