Magnetic Flaring in the Pre-Main-Sequence Sun and Implications for the Early Solar System

By Eric D. Feigelson, G. Garmire, S. Pravdo. 2002

158 citations recorded by the source corpus.

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 = 30.3 ergs s-1 and = -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 pre-main-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.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/1ed03f8e5937b7467e53fec893403e7a055dafa4

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In Astronomy and Astrophysics

1. M. Gudel
2. K. Luhman
3. L. Hillenbrand
4. Eric D. Feigelson
5. G. Garmire
6. T. Preibisch
7. Eric Mamajek
8. C. Lada

Citations in the corpus

• The Origin of T Tauri X-Ray Emission: New Insights from the Chandra Orion Ultradeep Project (2005, methodology): “The results of two Advanced CCD Imaging Spectrometer observations with a combined exposure time of 23 hr were reported in Garmire et al. (2000) and Feigelson et al. (2002a, 2002b, 2003).”
• The Evolution of X-Ray Emission in Young Stars (2005, background): “…or two-temperature optically thin thermal plasma MEKAL models (Mewe 1991), assuming 0.3 times solar abundances (Imanishi, Koyama, & Tsuboi 2001; Feigelson et al. 2002a) and X-ray absorption according to the atomic cross sections of Morrison & McCammon (1983) with traditional solar abundances…”
• X-ray emission from T Tauri stars and the role of accretion: inferences from the XMM-Newton extended survey of the Taurus molecular cloud (2006, result): “In the ONC, Feigelson et al. (2002) concluded from Chandra observations that the presence of circumstellar disks has no influence on the X-ray emission, whereas Flaccomio et al. (2003a), in another Chandra study of the ONC, found LX and LX/L∗ to be enhanced in WTTS when compared to CTTS.”
• The Sun in Time: Activity and Environment (2007, background): “Although cosmic rays have long been suspected to be an effective disk ionization source (Gammie, 1996), the high-level, hard coronal emission and frequent stellar flares may be more effective ionizing sources (Glassgold et al., 1997; Feigelson et al., 2002b).”
• Origin and evolution of the atmospheres of early Venus, Earth and Mars (2018, background): “On the other hand according to Feigelson et al. (2002) and Halliday et al. (2014, and references therein) noble gases could have also been incorporated into early formed planetesimals by the intense solar wind of the young Sun after the gas disk evaporated.”
• Astrophysics with Extraterrestrial Materials (2016, background): “Irradiation processes in the Solar System: Young stars are prodigious producers of charged particles that will interact with protoplanetary disk materials (Feigelson et al. 2002), and even today, solar wind particles and galactic cosmic rays may interact with small bodies in interplanetary space.”
• Advanced CCD imaging spectrometer (ACIS) instrument on the Chandra X-ray Observatory (2003, unknown): “5 31 solar mass star theta 2A Orionis and several B stars, which is inconsistent with the standard model of the X-rays originating from wind shocks; support for the hypothesis that intermediate-mass mid-B through A type stars do not emit significant X-ray emission; confirmation that low-mass G throu”
• Chandra Orion Ultradeep Project: Observations and Source Lists (2004, methodology): “Counterparts to earlier Einstein, ROSAT , and ASCA sources are given by Feigelson et al. (2002a).”
• A Perspective from Extinct Radionuclides on a Young Stellar Object: The Sun and Its Accretion Disk (2011, background): “Studies of the X-ray activity of low-mass, pre–main sequence stars have revealed that these stars show time-averaged luminosity and power of individual flares that exceed present-day solar values by several orders of magnitude (Feigelson & Montmerle 1999, Feigelson et al. 2002).”
• X-Ray-emitting Young Stars in the Orion Nebula (2002, background): “This issue is discussed further in Feigelson et al. (2002b).”