Modeling of various atmospheric pressures shows that Exo earths could have life friendly atmospheres across a broader range of orbital distances than our thin aired original. Since we are ‘seeing’ a lot of big worlds out there this is promising, though of course too much of a good thing is bad, as our sister world Venus shows.
A figure from Vladilo’s paper summarizing the general findings. The area of the circles is proportional to their habitability. The bottom axis shows the virtual worlds’ distance from their Sun-like star, with 1 AU (astronomical unit) representing the average Sun-Earth distance of approximately 150 million kilometers (93 million miles). The top axis (insolation) shows solar radiation (in watts) received on a unit area (a square meter). Surface pressure is on the y axis to the left. Credit: Vladilo et al. 2013, ApJ, 767, 65; http://wwwuser.oats.inaf.it/astrobiology/planhab/
Read more at: http://phys.org/news/2013-05-pressure-density-exoplanets-atmospheres-odds.html#jCp
Eyeball Earths…Red or Brown Dwarf Life Worlds?
Artist’s concept of a planet where one side always faces its star, with the dark side covered in ice. Credit: Beau.TheConsortium
Red dwarfs are small, faint stars about one-fifth as massive as the Sun and up to 50 times dimmer. They are the most common stars in the galaxy and make up to 70 percent of the stars in the universe, vast numbers that potentially make them valuable places to look for extraterrestrial life. Indeed, the latest results from NASA’s Kepler space observatory reveal that at least half of these stars host rocky planets that are half to four times the mass of Earth.
Read more at: http://phys.org/news/2013-05-eyeball-earths.html#jCp
New phase of water could dominate the interiors of Uranus and Neptune : phys.org: by Lisa Zyga
Structure of superionic ice in (left) the bcc phase and (right) the newly discovered and more stable fcc phase. Credit: Hugh F. Wilson, et al. ©2013 American Physical Society
Read more at: http://phys.org/news/2013-04-phase-dominate-interiors-uranus-neptune.html/
Although superionic ice doesn’t exist under normal conditions on Earth, the high pressures and temperatures where it is thought to exist are very similar to the predicted conditions in the interiors of Uranus and Neptune.
“Uranus and Neptune are called ice giants because their interiors consist primarily of water, along with ammonia and methane,” Wilson said. “Since the pressure and temperature conditions of the predicted new phase just happen to line up with the pressure and temperature conditions of the interiors of these planets, our new fcc superionic phase may very well be the single most prevalent component of these planets.”
The researchers predict that understanding superionic ice—particularly the stable fcc phase—will offer insight into these ice giants.
“Uranus and Neptune remain very poorly understood at this stage, and their interiors are deeply mysterious,” Wilson said. “The observations we have are very limited—every other planet in the solar system we’ve visited multiple times, but Uranus and Neptune we’ve just done brief flybys with Voyager 2. What we do know is that they have bizarre non-axisymmetric non-dipolar magnetic fields, totally unlike any other planet in our solar system. We also know that they’re extremely similar in mass, density and composition, yet somehow fundamentally different, because Neptune has a significant internal heat source and Uranus hardly emits any heat at all.”
It’s possible that the predicted bcc-to-fcc phase transition may explain the planets’ unusual magnetic fields, although more research is needed in this area.
“Our results imply that Uranus’s and Neptune’s interiors are a bit denser and have an electrical conductivity that is slightly reduced compared to previous models,” Militzer added.
Understanding Uranus and Neptune’s interiors could have implications far beyond our solar system, as well.
“One thing we’re learning from the Kepler mission is that Uranus-like or Neptune-like exoplanets are extremely common,” Wilson said. “They appear to be more common than Jupiter-like gas giants. So understanding our local ice giants is important, because they’re an archetypal example for a huge class of planets out there in the universe.”