Magnetic flaring in the pre-main-sequence Sun and implications for the early solar system

Eric D. Feigelson, Gordon P. Garmire, Steven H. Pravdo

Research output: Contribution to journalArticle

126 Citations (Scopus)

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 the Orion Nebula cluster obtained with the Chandra X-Ray Observatory. The sample consists of 43 stars with masses between 0.7 and 1.4 M and ages from less than 0.3 to ≃ 10 Myr. We find that the X-ray luminosities measured in the 0.5-8 keV band are strongly elevated over main-sequence levels with an average 〈log Lx〉 = 30.3 ergs s-1 and 〈log Lx/L*〉 = -3.9. The X-ray emission is strongly variable within our exposures in nearly all solar analogs; about 30 flares with 29.0 ergs s-1 < log Lx (peak) < 31.5 ergs s-1 on timescales from 0.5 to more than 12 hr are seen during the Chandra observations. Analogs of the ≤1 Myr old premain-sequence Sun exhibited X-ray flares that are 101.5 times more powerful and 102.5 times more frequent than the most powerful flares seen on the contemporary Sun. Radio observations indicate that acceleration of particles to relativistic energies is efficient in young stellar flares. Extrapolating the solar relationship between X-ray luminosity and proton fluence, we infer that the young Sun exhibited a 105-fold enhancement in energetic protons compared to contemporary levels. Unless the flare geometries are unfavorable, this inferred proton flux on the disk is sufficient to produce the observed meteoritic abundances of several important short-lived radioactive isotopes. Our study thus strengthens the astronomical foundation for local proton spallation models of isotopic anomalies in carbonaceous chondritic meteorites. The radiation, particles, and shocks produced by the magnetic reconnection flares seen with Chandra may also have flash-melted meteoritic chondrules and produce excess 21Ne seen in meteoritic grains.

Original languageEnglish (US)
Pages (from-to)335-349
Number of pages15
JournalAstrophysical Journal
Volume572
Issue number1 I
DOIs
StatePublished - Jun 10 2002

Fingerprint

solar system
flares
sun
erg
protons
analogs
x rays
energetics
carbonaceous meteorites
luminosity
stellar flares
Orion nebula
chondrule
solar nebula
radio observation
spallation
meteorite
radioactive isotopes
flash
observatories

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Feigelson, Eric D. ; Garmire, Gordon P. ; Pravdo, Steven H. / Magnetic flaring in the pre-main-sequence Sun and implications for the early solar system. In: Astrophysical Journal. 2002 ; Vol. 572, No. 1 I. pp. 335-349.
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Magnetic flaring in the pre-main-sequence Sun and implications for the early solar system. / Feigelson, Eric D.; Garmire, Gordon P.; Pravdo, Steven H.

In: Astrophysical Journal, Vol. 572, No. 1 I, 10.06.2002, p. 335-349.

Research output: Contribution to journalArticle

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