A Decade of Solar Type III Radio Bursts Observed by the Nançay Radioheliograph 1998-2008
Abstract
We present a statistical survey of almost 10,000 radio type III bursts observed by the Nançay Radioheliograph from 1998 to 2008, covering nearly a full solar cycle. In particular, sources sizes, positions, and fluxes were examined. We find an east-west asymmetry in source positions that could be attributed to a 6° ± 1° eastward tilt of the magnetic field, that source FWHM sizes s roughly follow a solar-cycle-averaged distribution (dN/ds) ≈ 14 ν-3.3 s -4 arcmin-1 day-1, and that source fluxes closely follow a solar-cycle-averaged (dN/ds ν) ≈ 0.34 ν-2.9 S -1.7 ν sfu-1 day-1 distribution (when ν is in GHz, s in arcminutes, and S ν in sfu). Fitting a barometric density profile yields a temperature of 0.6 MK, while a solar wind-like (vproph -2) density profile yields a density of 1.2 × 106 cm-3 at an altitude of 1 RS , assuming harmonic emission. Finally, we found that the solar-cycle-averaged radiated type III energy could be similar in magnitude to that radiated by nanoflares via non-thermal bremsstrahlung processes, and we hint at the possibility that escaping electron beams might carry as much energy away from the corona as is introduced into it by accelerated nanoflare electrons.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2013
- DOI:
- 10.1088/0004-637X/762/1/60
- arXiv:
- arXiv:1211.3474
- Bibcode:
- 2013ApJ...762...60S
- Keywords:
-
- acceleration of particles;
- radiation mechanisms: non-thermal;
- Sun: corona;
- Sun: radio radiation;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 22 pages, 18 figures