The Milky Way contains at least 100 billion planets. And the scientists are interested in finding out which might contain life.
Our galactic neighborhood may be bustling with other worlds, but a new study estimates that only 300 million of those 100 billion planets may have ingredients suitable for life.
And some of them may be closer than we think.
The study, is published on ArXiv’s print server and is accepted for publication in Journal of Astronomy, provides perhaps the most reliable estimate of viability in our galaxy to date
Previous estimates of the habitable Milky Way have ranged between about 40 billion planets and as low as six billion.
But using data from alien hunting missions like Kepler and Gaia, the researchers behind the new study claim that their estimates are much more accurate.
“This is the first time all the pieces have come together to provide a reliable measurement of the number of habitable planets in the galaxy,” said Jeff Coughlin, an exoplanet researcher. at SETI Institute and Director of the Kepler Science Office, and co-author of the new study, said in a statement.
Astronomers have studied three main determinants of viability. First, they estimated the number of exoplanets around the same size as Earth in the Milky Way – these are most likely rocky planets. They then looked at how many stars there are with the same age and temperature as our sun. Finally, they looked at whether the planets had the conditions needed to support liquid water, a key ingredient for life.
Previous studies have only looked at the distance of a planet from its host star to calculate its viability – an overall measurement, the new study shows. Instead, the study also takes into account the amount of light a planet will receive from its star based on distance alone. NASA’s Kepler mission enlarged the stars to see if there are any planets orbiting their habitable zones. Meanwhile, the European Space Agency’s Gaia mission has been measuring the positions, distances, and motions of the stars to get a more accurate estimate of the amount of light – and therefore, heat – they bestowed. for your planet.
Research suggests there may be 300 million habitable planets in the Milky Way. Some are only 30 light-years away from the Sun, data show.
Scientists have confirmed the existence of more than 4,000 exoplanets, although 3,000 suspected exoplanets await confirmation. Some of these planets have already shown signs of viability, but whether or not they have any life will be extremely difficult to determine.
“Knowing how common different types of planets are is extremely valuable for designing upcoming alien search missions,” said Michelle Kunimoto, a member of the Exoplanet Survey Satellite group. planetary at Massachusetts Institute of Technology and co-author of the new study, said in a statement. “Surveys targeting small, potentially habitable planets around stars like the Sun will depend on results like these to maximize their chances of success.”
Abstract: We present the occurrence rates of rocky planets in the habitable zone (HZ) of main sequence dwarfs based on the planetary candidate Kepler DR25 and Gaia-based star properties. We provide the first analysis of the stellar-dependent installed flux, allowing us to track the HZ planets. We define η⊕ as the HZ presence of planets with a radius of 0.5 to 1.5 R orbiting stars with effective temperatures between 4800 K and 6300 K. We found that η⊕ for the conserved HZ is between 0.37 + 0.48−0.21 (reflection error 68 % confidence interval) and 0.60 + 0.90−0.36 planets per while the HZ occurrence rate is optimistic between 0.58 + 0.73−0.33 and 0.88 + 1.28−0.51 planets per star. These limits reflect two extreme assumptions about complete extrapolation beyond the orbital intervals for which DR25 completeness data are available. The great uncertainty is due to the small number of small HZ planets detected. We found similar occurrence rates using both Poisson’s Bayes analysis and approximate Bayes Computation. Our results are calibrated to ensure portfolio completeness and reliability. Both the completeness and the rate of planet appearances depend on the effective temperature of the star. We also provide spawn rates for different star populations and planet size ranges. We estimate with 95% confidence that, on average, the closest HZ planets around dwarfs G and K are about 6 pc away, and that there are about 4 HZ rocky planets around dwarfs G and K that are far from the Sun. 10 pc.