AASTCS 5: Radio Exploration of Planetary Habitability

Synopsis

AASTCS 5
Radio Exploration of Planetary Habitability
Palm Spring, CA
7 – 12 May 2017

Low-mass stars have been regarded as very exciting targets for planet searches, because of their abundance compared to the Sun-like stars, and their desirable properties from the standpoint of sensitivity of radial velocity and transit surveys. The ongoing and upcoming searches, such as CARMENES, the Habitable Planet Finder, and space missions like K2, TESS, and Gaia, are expected to deliver a large number of potentially habitable planets. As such planets must be located close to their parent stars, these developments have created a growing need to investigate stellar activity and its influence on habitability of possible planetary companions.

The recent, spectacular results from the MAVEN spacecraft has provided persuasive evidence that it was the activity of the young Sun that has stripped Mars of its original atmosphere. This very clearly indicates that, in addition to low-mass stars, investigations of magnetic activity must be extended to young, solar-type stars.

Research on planetary habitability must also include detection of exoplanetary magnetic fields across the entire range of planet masses and ages. This encompasses a range of possibilities, including magnetic, kinetic and unipolar star-planet interactions that may generate detectable radio emission, and radio detection of young, hot planets discovered by direct imaging.

Searches for close-in planets orbiting in habitable zones of very low-mass stars, by detecting bursts of radio emission generated by the unipolar (Jupiter-Io) mechanism, represent a very exciting complement to the radial velocity and transit surveys at the optical and near-infrared wavelengths. This includes detection of planets around brown dwarfs, white dwarfs and moons around gas giants.

Radio observations using the new generation, broadband receivers and the high time/frequency resolution data acquisition hardware, offer unique tools for detailed investigations of the phenomena that are relevant to the topics listed above. This is especially true in the case of the lowest mass stars, brown dwarfs, and exoplanets. In fact, one can reasonably predict that radio measurements of stellar activity that have become possible with the new technology may lead to a substantial reformulation of the concept of planetary habitability.

Of course, all the above issues cannot be properly addressed without further theoretical and observational
developments in the areas of magnetic field generation in fully convective stars, stellar magnetic activity and CME
generation versus planetary habitability, and a number of related topics.

This meeting has been motivated by a highly timely nature and the anticipated increasing importance of studies
related to planetary habitability, and the potential impact of radio astronomy, especially the existing and the planned,
large radio telescopes, in this type of research.

List of Topics

1. Stellar activity and planetary habitability

  • Radio detection (Type-II like bursts; CME-induced O/IR maser variability; VLBI imaging) of coronal mass ejections on nearby active stars and their implications for habitability.
  • Direct detection of stellar winds (via free-free emission) on nearby active stars.
  • Magnetic activity of young, solar-type stars
  • Magnetic activity of M-dwarfs, especially those targeted by the upcoming transit and NIR radial velocity surveys
  • The radio – optical - X-ray connection related topics
  • Radio exploration of the coolest/low-mass brown dwarf - giant planet interface

2. Detection of planets and planetary magnetic fields

  • Young, giant planets around young stars
  • Detection of planets/planetary magnetic fields at low radio frequencies, star-planet interaction
  • Searching for planets in HZs of low-mass stars, brown dwarfs, moons around gas giants, and white dwarfs (star - planet unipolar mechanism)
  • Radio-astrometric planet searches
  • SETI surveys

3. Theory

  • Planetary radio emission and application to exoplanets
  • Planetary magnetic fields and habitability
  • Star – planet plasma interaction
  • Fully convective objects: structure, magnetic field generation
  • Stellar activity and CME generation
  • Planet formation around VLMs