SOLAR ENERGETIC PARTICLE EVENTS AND THE KIPLINGER EFFECT

Journal Article · Thu Mar 01 04:00:00 EST 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/747/1/66· OSTI ID:22016274

The Kiplinger effect is an observed association of solar energetic (E > 10 MeV) particle (SEP) events with a 'soft-hard-harder' (SHH) spectral evolution during the extended phases of the associated solar hard (E > 30 keV) X-ray (HXR) flares. Besides its possible use as a space weather predictor of SEP events, the Kiplinger effect has been interpreted as evidence of SEP production in the flare site itself, contradicting the widely accepted view that particles of large SEP events are predominately or entirely accelerated in shocks driven by coronal mass ejections (CMEs). We review earlier work to develop flare soft X-ray (SXR) and HXR spectra as SEP event forecast tools and then examine recent Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) evidence supporting the association of SHH HXR flares with large SEP events. We point out that ad hoc prediction criteria using the CME widths and SXR flare durations of associated RHESSI hard X-ray bursts (HXBs) can yield results comparable to those of the SHH prediction criteria. An examination of the RHESSI dynamic plots reveals several ambiguities in the determination of whether and when the SHH criteria are fulfilled, which must be quantified and applied consistently before an SHH-based predictive tool can be made. A comparative HXR spectral study beginning with the large population of relatively smaller SEP events has yet to be done, and we argue that those events will not be so well predicted by the SHH criteria. SHH HXR flares and CMEs are both components of large eruptive flare events, which accounts for the good connection of the SHH HXR flares with SEP events.

• OSTI ID: 22016274
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 747; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
GAMMA RADIATION
HARD X RADIATION
SOFT X RADIATION
SOLAR CORONA
SOLAR FLARES
SOLAR RADIATION
SOLAR SYSTEM EVOLUTION
SUN