Letters of Intent received in 2015

LoI 2017-293
Magnetic Fields, Planetary Climates and Habitability

Topics

1. How do solar and stellar flares form and evolve during stellar evolution? What is the maximum flare energy the Sun and stars can produce?
2. What characterizes space weather around solar-type stars at various phases of their evolution?
3. Does solar analogy work for all solar-like stars? (magnetic fields, activity, eruptive events, high-energy output, winds, etc)
4. How do we extrapolate solar flare and CME statistical relationships to stellar events?
5. What are the cumulative steady-state and transient effects of stellar winds, CMEs and SEPs on solar & stellar magnetospheres, atmospheric erosion, chemistry, climate and planetary habitability over geologically significant time periods?
6. How does XUV quiescent and flare ionizing radiation affect atmospheric erosion, chemistry, climate and planetary habitability?
7. What are the impacts of severe space weather on early and current Earth’s magnetosphere and chemistry of the atmosphere?
8. Can magnetic geodynamo models be extrapolated to model terrestrial (exo)planets?
9. What are the effects of planetary magnetic field reversals on planetary habitability?
10.How do global planetary parameters such as rotation, metallicity and mass affect its dynamo-generated magnetic field?

Rationale

As the number of observed exoplanets skyrockets, the field of exoplanetary science is still searching for a better understanding of whether or when life may have begun on those planets – or how long they could remain viable habitats for life. Presently, we have only a superficial notion of where to look for habitable planets. The principal cause of this uncertainty is the lack of understanding of the interaction between planets and their host stars as they age, the dynamical evolution of planetary systems and their atmospheres. Currently, knowledge of a planet’s mass, orbital distance from its host star, and the host star’s mass are used to infer the probability that an exoplanet may be habitable – i.e. that is may be Earth-sized with liquid water at its surface, which defines the habitable zone (HZ). The landscape of exoplanetary science has changed considerably with the great success of the Kepler mission, which has discovered thousands of transit candidates and hundreds of confirmed exoplanets around stars of widely different spectral classes (masses) and a few planets within HZ’s. Kepler also revealed thousands of superflares on hundreds of solar-type stars, which may suggest that host stars may have profound effects on the physical and chemical evolution of exoplanetary atmospheres. These observations provide a new look at our own Sun’s and other stars early evolution and how it might have affected the early evolution of climates of terrestrial planets, possibly setting the stage for the origin of life. During early phases of stellar evolution, stellar fluxes specified by the level of a star’s magnetic activity may provide a critical input to exoplanetary atmospheres and surfaces and thus set the stage for life, beyond merely providing thermal conditions that support liquid water. Changes in the solar forcing would have had a dramatic effect on the histories of atmospheric loss, atmospheric chemical speciation, and climatic energy inputs. Thus, there is a need to use sophisticated models (and validated for the current Earth’s atmospheric loss) of atmospheric loss to address the following critical questions: What is the role of the solar forcing in long-term evolution of climate on Venus and Mars? What is the role of the stellar forcing in habitability and climates on exoplanets around active F, K, G and M dwarfs? What is the role of planetary magnetic fields in their climate and habitability?
The observations and emerging theoretical models of solar and stellar winds and various forms of magnetic activity have opened new perspectives for understanding of the physical mechanisms of the impact of stellar activity on physics and chemistry of planetary atmospheres. The assessment of the impacts of hosts stars on climate and habitability of terrestrial (exo)planets may significantly modify the current definition of the habitability zone and provide new avenues for searching for signatures of life.