Abstract
A solar radio burst on 25 August 1999 with fine structures (FS) at 4.5–7.5 GHz is studied in this paper. The FS started about one minute prior to the main burst. The maximum emission took place at 4–5 GHz for the FS, and at 10–11 GHz for the main burst, respectively. The time profiles at 4.5–7.5 GHz coincide very well with those of hard X-rays (from 25 keV to > 300 keV) in both the main burst and the FS, which shows that the same population of accelerated electrons is responsible for both the microwave and hard X-ray bursts. The source of FS is 20 arc sec away from the main source close to a compact dipolar magnetic field, which is confirmed by different time and polarization profiles in the FS and main sources. It is interesting that the FS at 4.5–7.5 GHz are associated with a series of twisted magnetic loops or ropes, which may be modulated by Alfvén waves with a period of 1 s and a spatial wavelength of 103 km in respect to the typical Alfvén velocity of 103 km s−1 in corona. These magnetic ropes may be rooted in the dipole site, which extended into the corona during the event and retracted after the event. Therefore, the FS in this event may show an important signature or precursor for energy release. The magnetic reconnection may be triggered by the interaction of the magnetic ropes at the height corresponding to 5–6 GHz, followed by cascaded energy release close to the foot-point of the magnetic ropes.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Allaart, M. A. F., van Nieuwkoop, J., Slottje, C., Sondaar, L. H.: 1990, Solar Phys. 130, 183.
Aschwaden, M. J.: 1992, Astrophys. J. 401, 736.
Aschwanden, M. J., Dennis, B. R., and Benz, A. O.: 1998, Astrophys. J. 497, 972.
Dulk, G. A.: 1985, Ann. Rev. Astron. Astrophys. 23, 169.
Emonet, T., Moreno-Insertis, F., and Rast, M. P.: 2000, SPD Meeting, American Astronomical Society.
Fishman, G. J., Meegan, C. A., Parnell, T. A., Wilson, R. B., Paciesas, W., Mateson, J. L., Cline, T. L., and Teegarden, B. J.: 1985, 19th Int. Cosmic Ray Conf. 3, 343.
Fleishman, G. D. and Melnikov, V. F.: 2002, Astrophys. J., in press.
Fu, Q. J., Qin, Z. H., Ji, H. R., and Pei, L. B.: 1995, Solar Phys. 160, 97.
Güedel, M. and Benz, A. O.: 1988, Astron. Astrophys. Suppl. 75, 243.
Hu, Y. Q. and Jiang, Y. W.: 2001, Solar Phys. 203, 309.
Hu, Y. Q. and Liu, W.: 2000, Astrophys. J. 540, 1119.
Huang, G. L.: 1987, Solar Phys. 114, 363.
Huang, G. L.: 1998, Astrophys. J. 498, 877.
Huang, G. L. and Wang, D. Y.: 1991, Acta Astrophys. Sinica 11, 352.
Huang, G. L. and Zhou, A. H.: 2000, New Astron. 4, 591.
Huang, G. L., Qin, Z. H., and Yao, Q. J.: 1996, Astrophys. Space Sci. 243, 401.
Huang, G. L., Yang, G., and Liu, Y. Y.: 1998, Astrophys. Space Sci. 259, 317.
Huang, G. L., Fu, Q. J., and Qin, Z. H.: 1999, Astrophys. Space Sci. 266, 389.
Isliker, H. and Benz, A. O.: 1994, Astron. Astrophys. Suppl. 104, 145.
Kaufmann, P., Strauss, M., Opher, R., and Laporte C.: 1980, Astron. Astrphys. 87, 58.
Kosugi, T., Makishima, K., Murakami, T., Sakao, T., Dotani, T., Inda, M., Kai, K., Masuda, S., Nakajima, H., Ogawara, Y., Sawa, M., and Shibasaki, K.: 1991, Solar Phys. 136, 17.
Krall, J., Chen, J., and Santoro, R.: 2000, Astrohpys. J. 539, 964.
Krall, J., Chen, J., Santoro, R., Spicer, D. S., Zalesak, S. T., and Cargill: 1998, Astrophys. J. 500, 992.
Nakajima, H., Hishio, M., Enome, S., Shibasaki, K., Takano, T. et al.: 1994, Proc. of IEEE 82, 705.
Paesold, G., Benz, A. O., Klein, K.-L., and Vilmer, N.: 2001, Astron. Astrophys. 371, 333.
Qin, Z. H. and Huang, G. L.: 1994, Astrophys. Space Sci. 218, 213.
Robinson, P. A. and Benz, A. O.: 2000, Solar Phys. 194, 345.
Scherrer, P. H., Hoeksema, J. T., Bogart, R. S., Walker, A. B. C., Jr., Title, A. M., Tarbell, T. D., Wolfson, C. J., Brown, T. M., Jr., Christensen-Dalsgaard, J., and Gough, D. O.: 1988, The SOHO Mission. Scientific and Technical Aspects of the Instruments, ESA, p. 25.
Sturrock, P. A., Kaufmann, P., Moore, P. L., and Smith, D. F.: 1984, Solar Phys. 94, 341.
Takakura, T.: 1972, Solar Phys. 26, 151.
Wu, D. J., Huang, G. L., and Wang, D. Y.: 1996, Phys. Rev. Lett. 77, 4346.
Zhou, A. H. and Huang, G. L.: 2001, ChAA 1, 365.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Huang, G., Wu, H., Grechnev, V. et al. The radio signature of twisted magnetic ropes and reconnection site in the low corona. Solar Physics 213, 341–358 (2003). https://doi.org/10.1023/A:1023912800896
Issue Date:
DOI: https://doi.org/10.1023/A:1023912800896