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Paper: X-Ray Flares of Sun-like Young Stellar Objects and Their Effects on Protoplanetary Disks
Volume: 341, Chondrites and the Protoplanetary Disk
Page: 165
Authors: Glassgold, A.E.; Feigelson, E.D.; Montmerle, T.; Wolk, S.
Abstract: Astronomical observations of flares from analogs of the early Sun have the potential to give critical insights into the high energy irradiation environment of protoplanetary disks. Solar-mass young stellar objects are significantly more X-ray luminous than the typical low-mass T Tauri star. They undergo frequent strong flaring on a several day time scale. Very powerful flares also occur, but on a longer time frame. The hard X-ray spectrum of these stars become even harder during flaring. The X-rays from these Sun-like young stellar objects have the potential to ionize circumstellar material at a level greater than galactic cosmic rays out to distances ~ 104 AU. Their characteristic hard spectra imply that, on encountering this material, they penetrate to fairly large surface densities of the order of 1 g cm−2 or more. Three specific illustrations are given of the effects of the X-rays: The physics and chemistry of the atmospheres of the inner accretion disks; the ionization level at the disk midplane, important for the viability of the magnetorotational instability; and the nuclear fluence in the irradiation zone just interior to the inner edge of the disk, important in local irradiation scenarios for producing the short-lived radionuclides found in meteorites.
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