To facilitate studies of exo-Venus candidates, astronomers from the University of California, Riverside, the University of California, Santa Cruz, Brown University and Southwest Research Institute provide a catalog of all confirmed rocky planets in the so-called Venus zone, including transiting and non-transiting worlds.
University of California, Riverside Ph.D. student Colby Ostberg and colleagues began with 317 known rocky exoplanets in the Venus zone, a range of stellar distances where a planet with an initial Earth-like atmosphere could experience a runaway greenhouse effect that transforms it into a Venus-like atmosphere.
The astronomers whittled the list down to the five most likely to resemble Venus in terms of their radii, masses, densities, the shapes of their orbits, and perhaps most significantly, distances from their stars.
They also ranked the most Venus-like planets in terms of the brightness of the stars they orbit, which increases the likelihood that the NASA/ESA/CSA James Webb Space Telescope would get more informative signals regarding the composition of their atmospheres.
Today’s Venus floats in a nest of sulfuric acid clouds, has no water, and features surface temperatures of up to 475 degrees Celsius (900 degrees Fahrenheit) — hot enough to melt lead.
Using Webb to observe these possible Venus analogs, or exo-Venuses, the astronomers hope to learn if things were ever different for our Venus.
“One thing we wonder is if Venus could once have been habitable,” Ostberg said.
“To confirm this, we want to look at the coolest of the planets in the outer edge of the Venus zone, where they get less energy from their stars.”
Finding a planet similar to Venus in terms of planet mass is also important because mass affects how long a planet is able to maintain an active interior, with the movement of rocky plates across its outer shell known as plate tectonics.
“Venus has 20% less mass than Earth, and as a result, scientists believe…
Read the full article here