Contrary to our Sun, the majority of stars in the Milky Way are significantly smaller and cooler, possessing half the mass at most. These common stars host billions of orbiting planets in our galaxy. To maintain habitable temperatures, these planets must be situated near their smaller stars, making them vulnerable to extreme tidal forces.
In a recent analysis using updated data, University of Florida astronomers discovered that two-thirds of planets surrounding these smaller stars could be rendered uninhabitable due to intense tidal forces. However, this leaves one-third of the planets, amounting to hundreds of millions across the galaxy, which could reside within the 'Goldilocks' orbit—close enough to maintain liquid water and potentially support life. Researchers measured the eccentricity of over 150 planets orbiting M dwarf stars, approximately the size of Jupiter. The more oval an orbit, the greater its eccentricity. If a planet orbits close to its star, similar to Mercury's orbit around the Sun, an eccentric orbit could subject it to tidal heating, which could eventually eliminate any possibility of liquid water.
The data originates from NASA's Kepler telescope, which records information on exoplanets as they pass in front of their host stars. To measure the planets' orbits, researchers focused on the time it took for the planets to transit their stars. Their study also incorporated new data from the Gaia telescope, which has measured distances to billions of stars within our galaxy. The astronomers found that stars with multiple planets were more likely to exhibit circular orbits, allowing them to maintain liquid water. Conversely, stars with only one planet typically exhibit more eccentric orbits, rendering them unsuitable for life. Given that one-third of planets in this small sample possessed orbits potentially capable of harboring liquid water, the Milky Way may contain hundreds of millions of promising candidates for extraterrestrial life exploration.
Source: scitechdaily
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