The Habitable Zone: Intended Applications, Controversial Misapplications, and Needed Improvements
Abstract
This presentation will review the intended purpose of the Habitable Zone, recent work on the Habitable Zone, and critical areas of work that are needed to improve the Habitable Zone.
The Habitable Zone is a concept designed to help us 1) design future direct telescopes and instrumentation whose goals include confirming habitability and/or searching for biosignatures; and 2) prioritize targets with a high likelihood of habitability when using those assets. Because of these intended purposes, the habitable zone has been centered around identifying regions around a star for which planets could sustain global surface liquid water over geological timescales. Such planets have the highest likelihood of being not only habitable but also supporting robust biospheres that are detectable with telescopes across interstellar space. However, it is not meant to be a theoretical consideration of the range of conditions over which a planet might harbor habitable environments. It is also focuses on factors based on or inferred from past measurements. There are three things that control the Habitable Zone's central criterion, the sustainability of global liquid water: the temperature of the environment, the pressure of the environment, and the presence of water molecules in the environment. In the past, research on the Habitable Zone has focused almost exclusively on the first of these environmental control factors. And while more a ever-more complete consideration of climate feedbacks can improve our understanding of temperature controls on habitability, future work should focus the effects of atmospheric pressure and water abundance on habitability. Specifically, we need to understand what controls the presence/absence of rocky planet atmospheres. This will require incorporation of expertise from space physics, astrophysics, and deep-Earth/planet geology. By combining such expertise in the future, we will improve our ability to assess habitability of exoplanets on a global scale, by considering both their potential climates, and also controls on the availability of the materials that constitute planetary oceans and the atmospheres that keep them in a liquid state. Such improvements have the potential for major impacts on the Habitable Zone's intended purpose: considerations of future space telescopes and their targets.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.P31C3734D
- Keywords:
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- 2740 Magnetospheric configuration and dynamics;
- MAGNETOSPHERIC PHYSICSDE: 5210 Planetary atmospheres;
- clouds;
- and hazes;
- PLANETARY SCIENCES: ASTROBIOLOGYDE: 5215 Origin of life;
- PLANETARY SCIENCES: ASTROBIOLOGYDE: 5225 Early environment of Earth;
- PLANETARY SCIENCES: ASTROBIOLOGY