Astronomy and Astrophysics – Astronomy
Scientific paper
May 2001
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001apj...552..340d&link_type=abstract
The Astrophysical Journal, Volume 552, Issue 1, pp. 340-347.
Astronomy and Astrophysics
Astronomy
19
Sun: Activity, Sun: Atmosphere, Sun: Flares
Scientific paper
Fine temporal structures in hard X-ray and microwave emissions of solar flares have been known for many years. Recent observations with high time and spatial resolution revealed that emissions in the wings of Hα could also exhibit fast (subsecond) fluctuations. We argue that such fluctuations are physically related to the small-scale injection of high-energy electrons. We explore this through numerical calculations. The energy equation and the equations for energy-level populations in hydrogen, in particular including the nonthermal collisional excitation and ionization rates, are solved simultaneously for an atmosphere impacted by a short-lived electron beam. We determine the temporal evolution of the atmospheric temperature, the atomic level populations, and the Hα line intensity. We find that although the background Hα wing emission is mainly formed in the photosphere, the fast fluctuations are probably produced in the chromosphere, which is penetrated by ~20 keV electrons. To yield Hα wing fluctuations of amplitude comparable to the observations, a mean energy flux of ~(1-2)×1011 ergs cm-2 s-1 is required for the electron beam, if one adopts a Gaussian macrovelocity of 25 km s-1. Such a burst contains a total energy of 1025-1026 ergs. These parameters are compatible with elementary flare bursts.
Ding Ming-De Ding
Goode Philip. R.
Qiu Jiong
Wang Haimin
No associations
LandOfFree
On the Fast Fluctuations in Solar Flare Hα Blue Wing Emission does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with On the Fast Fluctuations in Solar Flare Hα Blue Wing Emission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the Fast Fluctuations in Solar Flare Hα Blue Wing Emission will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-924272