Letters of Intent received in 2013

LoI 2015-178
Focus Meeting: Water throughout the universe

Topics

- Basic water chemistry
- Water in nearby and high-redshift galaxies
- Galactic ISM and evolved stars
- Water transport and processing in disks
- Solar system bodies
- Exoplanetary atmospheres
- Isotopic ratios and spin statistics
- Laboratory studies of interstellar water ice analogues
- Water delivery to terrestrial planets

Rationale

The presence of water on a planet is universally accepted as essential for its potential habitability. Water in gaseous form acts as a coolant that allows interstellar gas clouds to collapse to form stars, whereas water ice facilitates the sticking of small dust particles that eventually must grow to planetesimals and planets. Its many excitation modes (vibrational/rotation) lead to its widespread use as an astrophysical probe of the gas physics and water content. On the surface of our planet the evelopement of life requires liquid water and even the most primitive cellular life consists primarily of water. Water assists many biological chemical reactions leading to complexity by acting as an effective solvent. It shapes the geology and climate on rocky planets, and is a major or primary constituent of the solid bodies of the outer solar system.

Results from recent space missions, in particular Spitzer and Herschel, have lead to significant progress in our understanding of the formation and transport of water from clouds to disks, planetesimals, and planets. This has been aided by new work on the laboratory study of the relevant phases of water. More broadly, water vapor has also been detected in local galaxies, and in the high-redshift universe up to z=5.6. In the local neighborhood the characterization of extra-solar planetary systems has also become a major focus of astronomical study. The question of the presence/absence of water in the giant planet atmosphere or as a constituent of a rocky world is becoming a central theme. Each of these fields, star/planetary birth, the local/distant universe, and exoplanetary systems are expected to explode as ALMA reaches its full potential and new observatories come online.

The goal of the proposed focus meeting is to synthesize and highlight the growing cross-IAU division connections and tremendous progress in the study of water. Thus we will include the recent observational and laboratory advances that allow the use of water as a probe in our galaxy to the high-redshift universe. Here a major focus will be a cross-pollination of understanding of the physics and chemistry of water on all scales. On the scale of planetary systems we will include a discussion of the water formation in space, its transport to a forming disk, its evolution in the planet-forming disk, its delivery to forming terrestrial planets, and incorporation into giant planet atmospheres. Clear connections exist in this area with the dynamical evolution of young forming planetary systems. Here we will highlight growing evidence that the early solar system was highly chaotic and the architecture of extra-solar planetary systems leaves strong hints of dynamical interactions; these strongly influence the water content of forming rocky and gaseous worlds. In this regard, the statistics and overall architecture of exoplanetary systems must be viewed as grounding information on these processes. Measurements of the isotopic ratios, in particular D/H, in various bodies provide perhaps the best data points to chemically constrain this evolution in our solar system. Additional advances include growing knowledge of the composition of atmospheres of extra-solar gas giants, which may be influenced by the variable phases of water in the protoplanetary disk.

In sum, a focus meeting at the GA in 2015 will be the time to capitalize on the vast gains in our understanding of water in the universe and promulgate this information across field boundaries.