Gamma-ray bursts and other sources of giant lightning discharges in protoplanetary systems

Abstract

Abstract. Lightning in the solar nebula is considered to be one of the probable sources for producing the chondrules that are found in meteorites. Gamma-ray bursts (GRBs) provide a large flux of γ-rays that Compton scatter and create a charge separation in the gas because the electrons are displaced from the positive ions. The electric field easily exceeds the breakdown value of ≈1 V m −1 over distances of order 0.1 AU. The energy in a giant lightning discharge exceeds a terrestrial lightning flash by a factor of ∼1012 . The predicted post-burst emission of γ-rays from accretion into the newly formed black hole or spin-down of the magnetar is sufficiently intense to cause a lightning storm in the nebula that lasts for days and is more probable than the GRB because the radiation is beamed into a larger solid angle. The giant outbursts from nearby soft gamma-ray repeater sources (SGRs) are also capable of causing giant lightning discharges. The total amount of chondrules produced is in reasonable agreement with the observations of meteorites. Furthermore in the case of GRBs most chondrules were produced in a few major melting events by nearby GRBs and lightning occurred at effectively the same time over the whole nebula, and provide accurate time markers to the formation of chondrules and evolution of the solar nebula. This model provides a reasonable explanation for the delay between the formation of calcium aluminium inclusions (CAIs) and chondrules.

Shapes of chondrules determined from the petrofabric of the CR2 chondrite NWA 801

“…; McBreen et al. ), irradiation from the Sun (Shu et al. , ), turbulent heating by current sheets (Ryan Joung et al.…”

“…Possible mechanisms responsible for melting include shockwaves (Wood 1963;Hood and Horanyi 1991;Ciesla and Hood 2002;Ciesla et al 2004;Boss and Durisen 2005;Desch et al 2005; Morris and Desch 2010;Hood and Weidenschilling 2012;Morris et al 2012;Boley et al 2013), lightning discharge (Pilipp et al 1992(Pilipp et al , 1998Desch and Cuzzi 2000), gamma-ray bursts from nearby supernovae (McBreen and Hanlon 1999;Duggan et al 2003;McBreen et al 2005), irradiation from the Sun (Shu et al 1996(Shu et al , 2001, turbulent heating by current sheets (Ryan Joung et al 2004), impact melting or volcanism , and planetesimal collisions (Asphaug et al 2011;Wakita et al 2017).…”

Astrophysics in 2005

“…We caught during the year four very localized heat sources that might have done the melting. McBreen et al (2005) suggest lightning due to a nearby gamma ray burst; Boss & Durisen (2005) favor shocks when planets are formed by the gravitational instability mechanism; Krot et al (2005) make their planets by the accretion mechanism and melt chondrules when planetesimals collide; and Aleon et al (2005) use high energy particles from the young Sun. It is not obvious that they cannot all be right (unlike multiple hypotheses for, say, the formation of the Moon).…”

Gamma-ray bursts and giant lightning discharges in protoplanetary systems

“…This mechanism can produce a large amount of chondrules in the nebula (∼ 30 Earth masses) but it has a low probability of occurrence (< 0.1%). The effect of this new process is to induce giant lightning discharges over the whole nebula [10]. The model of McBreen et al (1999) [7] did not include lightning caused by Compton scattering of γ-rays by the gas in the nebula or the γ-rays from post-burst emission.…”