Atmosphere Loss by Aerial Bursts

Abstract

We present a simple analytic description of atmospheric mass loss by aerial bursts and demonstrate that mass loss from aerial bursts becomes significant when the maximum impactor size that leads to an aerial burst rather than a ground explosion, $r_o$, is larger than the minimum impactor size needed to achieve atmospheric loss, $r_{min}$. For vertical trajectories, which give the most stringent limit, this condition is approximately satisfied when ${\rho }_o/{\rho }_i\gtrsim 0.4v_e/v_{\infty }$, which implies atmospheric densities need to be comparable to impactor densities for impactor velocities that are a few times the escape velocity of the planet. The range of impactor radii resulting in aerial burst-induced mass loss, $r_o-r_{min}$, increases with the ratio of the atmosphere to the impactor density and with the trajectory angle of the impactor. The range of impactor radii that result in aerial burst-induced mass loss and the atmospheric mass lost is larger in adiabatic atmospheres than isothermal atmospheres of equivalent total mass, scale height, and atmospheric surface density. Our results imply that aerial bursts are not expected to significantly contribute to the atmospheric mass-loss history of Earth, but are expected to play an important role for planets and exoplanets similar to Neptune with significant atmospheres. For Neptune-like atmospheres, the atmospheric mass ejected per impactor mass by aerial bursts is comparable to that lost by ground explosions, which implies that, for impactors following a Dohnanyi size distribution, overall loss by aerial busts is expected to exceed that by ground explosions by a factor of $(r_{ground}/r_{aerial}{)}^{0.5}$.

arXiv comment10 pages, 9 figures

References in corpus (9)

• Kepler planets: a tale of evaporation
• Core-powered mass loss and the radius distribution of small exoplanets
• Sculpting the Valley in the Radius Distribution of Small Exoplanets as a by-product of Planet Formation: The Core-Powered Mass-Loss Mechanism
• Super-Earth Atmospheres: Self-Consistent Gas Accretion and Retention
• Atmospheric Mass Loss During Planet Formation: The Importance of Planetesimal Impacts
• Origin and Loss of nebula-captured hydrogen envelopes from "sub"- to "super-Earths" in the habitable zone of Sun-like stars
• The Dual Origin of the Terrestrial Atmosphere
• Susceptibility of planetary atmospheres to mass loss and growth by planetesimal impacts: the impact shoreline
• Evolution of the Earth's Atmosphere during Late Veneer Accretion