Solar Physics

, 292:21 | Cite as

Spectral Trends of Solar Bursts at Sub-THz Frequencies

  • L. O. T. Fernandes
  • P. Kaufmann
  • E. Correia
  • C. G. Giménez de Castro
  • A. S. Kudaka
  • A. Marun
  • P. Pereyra
  • J.-P. Raulin
  • A. B. M. Valio


Previous sub-THz studies were derived from single-event observations. We here analyze for the first time spectral trends for a larger collection of sub-THz bursts. The collection consists of a set of 16 moderate to small impulsive solar radio bursts observed at 0.2 and 0.4 THz by the Solar Submillimeter-wave Telescope (SST) in 2012 – 2014 at El Leoncito, in the Argentinean Andes. The peak burst spectra included data from new solar patrol radio telescopes (45 and 90 GHz), and were completed with microwave data obtained by the Radio Solar Telescope Network, when available. We critically evaluate errors and uncertainties in sub-THz flux estimates caused by calibration techniques and the corrections for atmospheric transmission, and introduce a new method to obtain a uniform flux scale criterion for all events. The sub-THz bursts were searched during reported GOES soft X-ray events of class C or larger, for periods common to SST observations. Seven out of 16 events exhibit spectral maxima in the range 5 – 40 GHz with fluxes decaying at sub-THz frequencies (three of them associated to GOES class X, and four to class M). Nine out of 16 events exhibited the sub-THz spectral component. In five of these events, the sub-THz emission fluxes increased with a separate frequency from that of the microwave spectral component (two classified as X and three as M), and four events have only been detected at sub-THz frequencies (three classified as M and one as C). The results suggest that the THz component might be present throughout, with the minimum turnover frequency increasing as a function of the energy of the emitting electrons. The peculiar nature of many sub-THz burst events requires further investigations of bursts that are examined from SST observations alone to better understand these phenomena.


Solar flares Sub-THz bursts Sub-THz atmospheric transmission Radio-bursts spectra 



The authors are grateful to the anonymous referee for helpful comments. This research was partially supported by the Brazilian agencies FAPESP (contract No. 2013/24155-3), CNPq, INCT Namitec, Mackpesquisa, US AFOSR, and Argentina CONICET.

Disclosure of Potential Conflicts of Interest

The authors declare that they have no conflicts of interest.


  1. Akabane, K., Nakajima, H., Ohki, K., Moriyama, F., Miyaji, T.: 1973, Solar Phys. 33, 431. ADSGoogle Scholar
  2. Bastian, T.S., Benz, A.O., Gary, D.E.: 1998, Annu. Rev. Astron. Astrophys. 36, 131. ADSCrossRefGoogle Scholar
  3. Benz, A.O.: 2009, In: Trumper, J.E. (ed.) Landot-Bornstein – Group IV Astronomy and Astrophysics, Numerical Data and Evolutional Relationships in Science and Technology, Solar System, 4B, Springer, Berlin, 103. Google Scholar
  4. Croom, D.L.: 1971, In: Abrami, A. (ed.) CESRA-2, Committee of European Solar Radio Astronomers 2, 85. Google Scholar
  5. Fleishman, G.D., Kontar, E.P.: 2010, Astrophys. J. 709, L127. ADSCrossRefGoogle Scholar
  6. Georges, C.B., Schaal, R., Costa, J.R., Kaufmann, P., Magun, A.: 1989, In: Proc. SBMO Inte. Microwave Symp., São Paulo, 24 – 27 July 1989, IEEE Cat. No. 89TH0260-0 II, 447. Google Scholar
  7. Gezari, D.Y., Joyce, R.R., Simon, M.: 1973, Astron. Astrophys. 26, 409. ADSGoogle Scholar
  8. Giménez de Castro, C.G., Raulin, J.-P., Makhmutov, V.S., Kaufmann, P., Costa, J.E.R.: 1999, Astron. Astrophys. 140, 373. ADSGoogle Scholar
  9. Guidice, D.A.: 1979 In: Bulletin of the American Astronomical Society 11, 311. Google Scholar
  10. Kaufmann, P., Correia, E., Costa, J.E.R., Vaz, A.M.Z., Dennis, B.R.: 1985, Nature 313, 380. ADSCrossRefGoogle Scholar
  11. Kaufmann, P., Costa, J.E.R., Gimenez de Castro, C.G., Hadano, Y.R., Kingsley, J.S., Kingsley, R.K., Levato, H., Marun, A., Raulin, J.-P., Rovira, M., Correia, E., Silva, A.V.R.: 2001, In: Proc. SBMO Inte. Microwave Symp., Belem, 6 – 10 August 2001, IEEE Cat. No. 01TH8568, 439. Google Scholar
  12. Kaufmann, P., Raulin, J.-P., Gimenez de Castro, C.G., Levato, H., Gary, D.E., Costa, J.E.R., Marun, A., Pereyra, P., Silva, A.V.R., Correia, E.: 2004, Astrophys. J. 603, L121. ADSCrossRefGoogle Scholar
  13. Kaufmann, P., Raulin, J.P.: 2006, Phys. Plasmas 13, 070701. ADSCrossRefGoogle Scholar
  14. Kaufmann, P., Levato, H., Cassiano, M.M., Correia, E., Costa, J.E.R., Gimenez de Castro, C.G., Godoy, R., Kingsley, R.K., Kingsley, J.S., Kudaka, A.S., Marcon, R., Martin, R., Marun, A., Melo, A.M., Pereyra, P., Raulin, J.-P., Rose, T., Silva Valio, A., Walber, A., Wallace, P., Yakubovich, A., Zakia, M.B.: 2008, Proc. SPIE 7012, 70120L. ADSCrossRefGoogle Scholar
  15. Kaufmann, P., Trottet, G., Giménez de Castro, C.G., Raulin, J.-P., Krücker, S., Shih, A.Y., Levato, H.: 2009, Solar Phys. 255, 31.  DOI. CrossRefGoogle Scholar
  16. Kaufmann, P., Marcon, R., Giménez de Castro, C.G., White, S.M., Raulin, J.-P., Correia, E., Olavo Fernandes, L., de Souza, R.V., Godoy, R., Marun, A., Pereyra, P.: 2011, Astrophys. J. 742, 106. ADSCrossRefGoogle Scholar
  17. Kaufmann, P., White, S.M., Freeland, S.L., Marcon, R., Fernandes, L.O.T., Kudaka, A.S., de Souza, R.V., Aballay, J.L., Fernandez, G., Godoy, R., Marun, A., Valio, A., Raulin, J.-P., Giménez de Castro, C.G.: 2013, Astrophys. J. 768, 134. ADSCrossRefGoogle Scholar
  18. Kaufmann, P., Abrantes, A., Bortolucci, E.C., Fernandes, L.O.T., Kropotov, G., Kudaka, A.S., Machado, N., Marcon, R., Nicolaev, V., Timofeevsky, A.: 2015a, In: 26th Intl. Symp. Space THz Technology, Cambridge, MA, 16 – 18 March 2015, paper M1-5. Google Scholar
  19. Kaufmann, P., White, S.M., Marcon, R., Kudaka, A.S., Cabezas, D.P., Cassiano, M.M., Francile, C., Fernandes, L.O.T., Hidalgo Ramirez, R.F., Luoni, M., Marun, A., Pereyra, P., Souza, R.V.: 2015b, J. Geophys. Res. 120, 4155. arXiv. CrossRefGoogle Scholar
  20. Kaufmann, P., Abrantes, A., Bortolucci, E., Caspi, A., Fernandes, L.O.T., Kropotov, G., Kudaka, A., Laurent, G.T., Machado, N., Marcon, R., Marun, A., Nicolaev, V., Hidalgo Ramirez, R.F., Raulin, J.-P., Saint-Hilaire, P., Shih, A., Silva, C., Timofeevsky, A.: 2016, Am. Astron. Soc., SPD meeting #47, id. 6.11. Google Scholar
  21. Klopf, J.M., Kaufmann, P., Raulin, J.-P., Szpigel, S.: 2014, Astrophys. J. 791, 31. ADSCrossRefGoogle Scholar
  22. Krücker, S., Giménez de Castro, C.G., Hudson, H.S., Trottet, G., Bastian, T.S., Hales, A.S., Kasparová, J., Klein, K.-L., Kretzschmar, M., Lüthi, T., Mackinnon, A., White, S.M.: 2013, Astron. Astrophys. Rev. 21, 58.  DOI. ADSCrossRefGoogle Scholar
  23. Melo, A.M., Kaufmann, P., Gimenez de Castro, C.G., Raulin, J.-P., Levato, H., Marun, A., Giuliani, J.L., Pereyra, P.: 2005, IEEE Trans. Antennas Propag. 53, 1528. ADSCrossRefGoogle Scholar
  24. Penn, M., Krücker, S., Hudson, H., Murzy, J., Jennings, D., Lunsford, A., Kaufmann, P.: 2016, Astrophys. J. Lett. 819, L30.  DOI. ADSCrossRefGoogle Scholar
  25. Ramaty, R., Lingerfelter, R.E.: 1969, J. Geophys. Res. 72, 879. ADSCrossRefGoogle Scholar
  26. Roy, J.-R.: 1979, Solar Phys. 64, 143. ADSCrossRefGoogle Scholar
  27. Sakai, J.I., Nagasugi, Y., Saito, S., Kaufmann, P.: 2006, Astron. Astrophys. 457, 313. ADSCrossRefGoogle Scholar
  28. Shibasaki, K., Alissandrakis, C.E., Pohjolainen, S.: 2011, Solar Phys. 273, 309.  DOI. ADSCrossRefGoogle Scholar
  29. Shimabukuro, F.I.: 1970, Solar Phys. 15, 424. ADSCrossRefGoogle Scholar
  30. Silva, A.V.R., Share, G.H., Murphy, R.J., Costa, J.E.R., de Castro, C.G.G., Raulin, J.-P., Kaufmann, P.: 2007, Solar Phys. 245, 311.  DOI. ADSCrossRefGoogle Scholar
  31. Tremblin, P., Schneider, N., Minier, V., Durand, G.A., Urban, J.: 2012, Astron. Astrophys. 548, A65. ADSCrossRefGoogle Scholar
  32. Trottet, G., Raulin, J–P., Mackinnon, A., Gimenez de Castro, G., Simoes, P., Cabeças, D., Luz, V., Luoni, M., Kaufmann, P.: 2015, Solar Phys. 290, 2809.  DOI. ADSCrossRefGoogle Scholar
  33. Turner, D.D., Mlawer, E.J., Bianchini, G., Cadeddu, M.P., Crewell, S., Delamere, J.S., Knuteson, R.O., Maschwitz, G., Mlynczak, M., Paine, S., Palchetti, L., Tobin, D.C.: 2012, Geophys. Res. Lett. 39, L10801. ADSGoogle Scholar
  34. Valio, A., Kaufmann, P., Giménez de Castro, C.G., Raulin, J.-P., Fernandes, L.O.T., Marun, A.: 2013, Solar Phys. 283, 651. ADSCrossRefGoogle Scholar
  35. White, S.M., Kundu, M.R., Bastian, T.S., Gary, D.E., Hurford, G.J., Kucera, T., Bieging, J.H.: 1992, Astrophys. J. 384, 656. ADSCrossRefGoogle Scholar
  36. Zirin, H., Tanaka, K.: 1973, Solar Phys. 32, 173. ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2017

Authors and Affiliations

  • L. O. T. Fernandes
    • 1
  • P. Kaufmann
    • 1
    • 2
  • E. Correia
    • 1
    • 3
  • C. G. Giménez de Castro
    • 1
  • A. S. Kudaka
    • 1
  • A. Marun
    • 4
  • P. Pereyra
    • 5
  • J.-P. Raulin
    • 1
  • A. B. M. Valio
    • 1
  1. 1.Centro de Rádio Astronomia e Astrofísica Mackenzie, Escola de EngenhariaUniversidade Presbiteriana MackenzieSão PauloBrazil
  2. 2.Centro de Componentes SemicondutoresUniversidade Estadual de CampinasCampinasBrazil
  3. 3.Instituto Nacional de Pesquisa Espacial (INPE)São José dos CamposBrazil
  4. 4.Instituto de Ciencias Astronómicas, de la Tierra y del Espacio (CONICET)San JuanArgentina
  5. 5.Complejo Astronômico El Leoncito (CONICET)San JuanArgentina

Personalised recommendations