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rfmcdonaldUniverse Today's Elizabeth Howell writes about a new paper, "On the Frequency of Potential Venus Analogs from Kepler Data", that examines the whole question of stellar Venus zones. Where must Venuses--broadly Earth-like but very hotel planets--be located in their planetary systems?
“We believe the Earth and Venus had similar starts in terms of their atmospheric evolution,” stated lead author Stephen Kane, an astronomer at San Francisco State University. “Something changed at one point, and the obvious difference between the two is proximity to the Sun.”
The habitable region around a star is poorly understood because scientists don’t quite know what conditions are necessary for life. It usually refers to the area where liquid water is possible, although this also depends on the climate of the planet itself. Clouds, terrain and atmospheric composition are just some of the variables that could affect habitability.
To better figure out where potential Venus-like exoplanets lurk, Kane’s team used data from the planet-hunting Kepler Space Telescope and examined solar flux — or how much solar energy a planet gets — to figure out where the Venus zone would be. The zone is then defined between two regions: where a planet could have the “runaway greenhouse effect” seen on Venus, and the spot where the planet is so close to its star that energy would wear away its atmosphere.
The first step would be pinpointing which planets reside within these zones. In future decades, astronomers could then examine the planetary atmospheres with telescopes to learn more about how they are composed — and how similar they are to Earth or Venus. Meanwhile, Kane’s team plans to model if carbon in the planet’s atmosphere could affect the boundaries of the zone.
