Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.585 IF 1.585
  • IF 5-year value: 1.698 IF 5-year
    1.698
  • CiteScore value: 1.62 CiteScore
    1.62
  • SNIP value: 0.820 SNIP 0.820
  • IPP value: 1.52 IPP 1.52
  • SJR value: 0.781 SJR 0.781
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 83 Scimago H
    index 83
  • h5-index value: 24 h5-index 24
Volume 30, issue 8
Ann. Geophys., 30, 1129–1141, 2012
https://doi.org/10.5194/angeo-30-1129-2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 30, 1129–1141, 2012
https://doi.org/10.5194/angeo-30-1129-2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.

Regular paper 09 Aug 2012

Regular paper | 09 Aug 2012

Solar flares as proxy for the young Sun: satellite observed thermosphere response to an X17.2 flare of Earth's upper atmosphere

S. Krauss1, B. Fichtinger2, H. Lammer3, W. Hausleitner1, Yu. N. Kulikov4, I. Ribas5, V. I. Shematovich6, D. Bisikalo6, H. I. M. Lichtenegger7, T. V. Zaqarashvili3, M. L. Khodachenko3, and A. Hanslmeier2 S. Krauss et al.
  • 1Space Research Institute, Dept. of Satellite Geodesy, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria
  • 2University of Graz, Institute of Physics, Dept. of Astrophysics, Geophysics and Meteorology, Universitätsplatz 5/II, 8010 Graz, Austria
  • 3Space Research Institute, Dept. of Extraterrestrial Physics, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria
  • 4Polar Geophysical Institute, Russian Academy of Sciences, Khalturina Str. 15, 183010 Murmansk, Russian Federation
  • 5Institut d'Estudis Espacials de Catalunya/CSIC, Campus UAB, Facultat de Ciències, Torre C5-parell-2a planta, 08193 Bellaterra, Spain
  • 6Institute of Astronomy, Russian Academy of Sciences, 48 Pyatnitskaya Str., 119017 Moscow, Russian Federation
  • 7Space Research Institute, Dept. Experimental Space Research, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria

Abstract. We analyzed the measured thermospheric response of an extreme solar X17.2 flare that irradiated the Earth's upper atmosphere during the so-called Halloween events in late October/early November 2003. We suggest that such events can serve as proxies for the intense electromagnetic and corpuscular radiation environment of the Sun or other stars during their early phases of evolution. We applied and compared empirical thermosphere models with satellite drag measurements from the GRACE satellites and found that the Jacchia-Bowman 2008 model can reproduce the drag measurements very well during undisturbed solar conditions but gets worse during extreme solar events. By analyzing the peak of the X17.2 flare spectra and comparing it with spectra of young solar proxies, our results indicate that the peak flare radiation flux corresponds to a hypothetical Sun-like star or the Sun at the age of approximately 2.3 Gyr. This implies that the peak extreme ultraviolet (EUV) radiation is enhanced by a factor of about 2.5 times compared to today's Sun. On the assumption that the Sun emitted an EUV flux of that magnitude and by modifying the activity indices in the Jacchia-Bowman 2008 model, we obtain an average exobase temperature of 1950 K, which corresponds with previous theoretical studies related to thermospheric heating and expansion caused by the solar EUV flux.

Publications Copernicus
Download
Citation