SOLAR MAGNETIC HELICITY INJECTED INTO THE HELIOSPHERE: MAGNITUDE, BALANCE, AND PERIODICITIES OVER SOLAR CYCLE 23
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States)
- National Solar Observatory, Sacramento Peak, Sunspot, NM 88349 (United States)
- National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)
Relying purely on solar photospheric magnetic field measurements that cover most of solar cycle 23 (1996-2005), we calculate the total relative magnetic helicity injected into the solar atmosphere, and eventually shed into the heliosphere, over the latest cycle. Large active regions dominate the helicity injection process with approx5.7 x 10{sup 45} Mx{sup 2} of total injected helicity. The net helicity injected is approx<1% of the above output. Peculiar active-region plasma flows account for approx80% of this helicity; the remaining approx20% is due to solar differential rotation. The typical helicity per active-region CME ranges between (1.8-7) x 10{sup 42} Mx{sup 2} depending on the CME velocity. Accounting for various minor underestimation factors, we estimate a maximum helicity injection of approx6.6 x 10{sup 45} Mx{sup 2} for solar cycle 23. Although no significant net helicity exists over both solar hemispheres, we recover the well-known hemispheric helicity preference, which is significantly enhanced by the solar differential rotation. We also find that helicity injection in the solar atmosphere is an inherently disorganized, impulsive, and aperiodic process.
- OSTI ID:
- 21378389
- Journal Information:
- Astrophysical Journal (Online), Vol. 705, Issue 1; Other Information: DOI: 10.1088/0004-637X/705/1/L48; ISSN 1538-4357
- Country of Publication:
- United States
- Language:
- English
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