From ScienceDaily: One team’s estimate:
Based on their simulations, the researchers estimate that planets very close to Earth in size, from three-quarters to one-and-a-half times the size of earth, with orbital periods ranging from 237 to 500 days, occur around approximately one in four stars. Importantly, their model quantifies the uncertainty in that estimate. They recommend that future planet-finding missions plan for a true rate that ranges from as low about one planet for every 33 stars to as high as nearly one planet for every two stars.
“Knowing how often we should expect to find planets of a given size and orbital period is extremely helpful for optimize surveys for exoplanets and the design of upcoming space missions to maximize their chance of success,” said Ford. “Penn State is a leader in brining state-of-the-art statistical and computational methods to the analysis of astronomical observations to address these sorts of questions. Our Institute for CyberScience (ICS) and Center for Astrostatistics (CASt) provide infrastructure and support that makes these types of projects possible.”
The Center for Exoplanets and Habitable Worlds at Penn State includes faculty and students who are involved in the full spectrum of extrasolar planet research. A Penn State team built the Habitable Zone Planet Finder, an instrument to search for low-mass planets around cool stars, which recently began science operations at the Hobby-Eberly Telescope, of which Penn State is a founding partner. A second Penn State-built spectrograph is in being tested before it begins a complementary survey to discover and measure the masses of low-mass planets around sun-like stars. This study makes predictions for what such planet surveys will find and will help provide context for interpreting their results.Paper. paywall – Danley C. Hsu, Eric B. Ford, Darin Ragozzine, Keir Ashby. Occurrence Rates of Planets Orbiting FGK Stars: Combining Kepler DR25, Gaia DR2, and Bayesian Inference. The Astronomical Journal, 2019; 158 (3): 109 DOI: 10.3847/1538-3881/ab31ab More.
Is this a high-tech Drake Equation or is it a good bet?
See also: Researchers: Toxic Gases Would Slow Emergence Of Life On Exoplanets