LExEn: Stochastic Photochemistry and Stochastic Photobiology in the Galactic Environment

建议编号：AST-9907582“Lexen：银河环境中的随机光化学和光生物学”本项目旨在了解一种新型极端环境影响的重要性和含义，这种极端环境影响应该影响大多数行星和卫星系统中微生物生命的发展：频繁的短暂高能光子和粒子的震动，这是银河环境的必然结果。这些事件包括与超新星、新星、伽马射线爆发和超新星余震有关的各种现象。该项目将通过将估计的源通量与太阳背景和生物活动的最低水平进行比较，证明这些事件是否能够推动行星和卫星大气层中的非平衡光化学。对于有或没有臭氧等紫外线屏蔽的星球上的微生物来说，它们也可能是生物变化的一个强有力的间歇性来源。正在解决的具体问题包括：(1)这些不同的高能辐射源超过从太阳接收到的背景通量的概率；(2)天文学源中的流体动力学和辐射传输，特别是在超新星的早期激波爆发阶段；(3)发射的光谱能量分布在通过模型的益生、太古代和臭氧后大气传播时的变化；(4)太阳系外天体如土卫六中的非平衡光化学；以及(5)计算的表面通量和由于大气化学变化引起的恒星通量变化对微生物的生物效应。该项目是NSF极端环境生命(LEXEN)计划的一部分。基金由NSF天文科学部门恒星天文学与天体物理学(SAA)计划和NSF分子与细胞生物科学部门(MCB)提供。

ABSTRACTP.I.: Wheeler, J. Craig Proposal Number: AST-9907582"LExEn: Stochastic Photochemistry and Photobiology in the Galactic Environment"This project seeks to understand the importance and implications of a new type of extreme environmental influence that should affect the development of microbial life in most planetary and satellite systems: frequent short-lived jolts of high-energy photons and particles that are an inevitable consequence of the Galactic environment. These events include various phenomena associated with supernovae, novae, gamma ray bursts, and supernova remnant shocks. The project will demonstrate, by comparing the estimated source fluxes with the solar background and minimum levels for biological activity, whether these events can drive non-equilibrium photochemistry in the atmospheres of planets and satellites. They may also be a potent intermittent source of biological alteration for microorganisms on planets with or without ultraviolet shields like ozone. Specific problems that are being addressed include: (1) the probability that these various sources of high energy radiation exceed the background flux received from the Sun; (2) hydrodynamics and radiative transfer in the astronomical sources, especially in the early shock breakout stage of supernovae; (3) transformation of the emitted spectral energy distributions as they propagate through the model prebiotic, Archean, and post-ozone atmospheres; (4) non-equilibrium photochemistry in outer Solar system bodies like Titan; and (5) biological effect of both the calculated surface fluxes and the variation in stellar flux due to changes in atmospheric chemistry on microorganisms.This project is part of the NSF Life in Extreme Environments (LExEn) program.Funding is provided by the NSF Division of Astronomical Sciences StellarAstronomy & Astrophysics (SAA) program and the NSF Division of Molecular& Cellular Biosciences (MCB).