Magnetic flaring in the young
Sun and implications for solar nebula solids
E. Feigelson, G. Garmire, Y. Tsuboi(Penn State) S. Pravdo (JPL),
Abstract
To address the role of energetic processes in the solar nebula, we
provide a detailed characterization of magnetic flaring in stellar
analogs of the pre-main sequence Sun based on two 0.5-day observations
of analogs of the young Sun in the Orion Nebula Cluster obtained with
the Chandra X-ray Observatory. The sample consists of 41 stars with
masses 0.7-1.4 M
and ages <1 to
Myr. We find the
X-ray luminosities are strongly elevated over main sequence levels, and
decline during the pre-main sequence phase according to
,
where Lx is in erg s-1 measured
in the 2-8 keV band and t is in years. The X-ray emission is
strongly variable in time in most solar analogs; about 20 flares with
erg s-1 on timescales from 0.5 to
>12 hours are seen during the Chandra observations. The ubiquity of
the strong, hard and variable X-ray emission in this sample is strong
evidence that the early Sun exhibited similar enhanced magnetic
activity.
Comparison to the contemporary Sun shows that, at an age of 1 Myr, the Sun exhibited long duration events (LDE) with 102 higher peak X-ray luminosities occurring 102 times more frequently than the most powerful LDE flares seen today. MeV proton fluxes are inferred to have been 105.5 times greater than current levels. The results support a local flare origin of various properties of pristine meteorites. The particles and shocks produced by the magnetic reconnection flares may have flash melted meteoritic chondrules, produced correlated excess 22Ne and particle tracks in free-floating meteoritic grains, and generated at least some of the short-lived nuclides found in CAI inclusions by spallogenic nuclear reactions.
CATEGORY: SOLAR SYSTEM AND MISC