Speaker | Talk Date | Talk Series |
---|---|---|
Suzanne Aigrain | 29 July 2014 | Across HR 2014 Talks |
The past few years have seem something of an explosion in the rate of discovery exoplanet around main-sequence stars, driven in large part by the Kepler transit-search mission, but also by a steady improvement in the sensitivity of radial velocity, microlensing, direct imaging and ground-based transit surveys. These larger samples, together with careful evaluation of observational biases, allow for an increasingly detailed investigation of the demographics of the exoplanet population, over a wide range of host star spectral type (A to M) and planet types (Jupiters to Earths). The first order result is that planets are very common: the average number of planets per star (integrated across the full parameter space accessible to current studies) ranges from ~25% (for Sun-like stars) to 50% or more (for M-stars). Small planets (R<2.5 R_earth, M<10 M_earth) in short-period orbits (a<0.5 AU) make up the bulk of this population, and tend to be found in compact, multi-planet systems. Several recent studies have estimated eta_earth -- the frequency of Earth-size planets in the habitable zone of their host star -- though for Sun-like stars this still involves extrapolation.
I will give an overview of recent population studies based on Kepler and other datasets, highlighting the most important trends, discussing the main methodological differences and challenges along the way. I will also compare the results of different surveys to each other and discuss, in very broad terms, their implications for planet formation and evolution models. Finally, I will highlight areas of parameter space where we may expect interesting developments over the next few years.