By using data collected by NASA's Kepler satellite, researchers from the Australian National University (ANU) and the Niels Bohr Institute (NBI) at the University of Copenhagen have calculated how many of the planets would be in a habitable zone, according to a press release from NBI.
The results are published in the scientific journal, Monthly Notices of the Royal Astronomical Society.
Astronomers have so far found about 1,000 planets around stars in our galaxy as well as 3,000 other potential planets. Many of the host stars have been seen with anywhere from two to six planets in orbit, but there might be more as the Kepler satellite is better equipped at finding larger planets orbiting close to a star.
Planets too close to the host star would be too hot to support liquid water and life, but researchers made calculations based on a 250-year-old method called the Titius-Bode law, which is used to calculate a "missing" planet's position in orbit.
"We decided to use this method to calculate the potential planetary positions in 151 planetary systems, where the Kepler satellite had found between three and six planets," said Steffen Kjær Jacobsen, a PhD student in the research group Astrophysics and Planetary Science at the NBI, according to the press release. "In 124 of the planetary systems, the Titius-Bode law fit with the position of the planets. Using T-B's law we tried to predict where there could be more planets further out in the planetary systems. But we only made calculations for planets where there is a good chance that you can see them with the Kepler satellite."
According to the calculations and the addition of "missing" planets, researchers figured that one to three planets from each system would be in the habitable zone. Out of the 151 planetary systems, 31 had planets either observed by the Kepler satellite in the habitable zone or only needed one extra planet to meet the habitable requirements.
"In these 31 planetary systems that were close to the habitable zone, our calculations showed that there was an average of two planets in the habitable zone," said Jacobsen, according to the press release. "According to the statistics and the indications we have, a good share of the planets in the habitable zone will be solid planets where there might be liquid water and where life could exist."
Reference:
"Using the Inclinations of Kepler Systems to Prioritize New Titius-Bode-Based Exoplanet Predictions," Timothy Bovaird, Charles H. Lineweaver, and Steffen K. Jacobsen, to appear in Monthly Notices of the Royal Astronomical Society.
