'Runaway greenhouse' may be easier to trigger than previously thought
According to a study published July 28 in Nature Geoscience, astronomers at the University of Washington and the University of Victoria say that it may be easier than previously thought for a planet to overheat during the so-called "runaway greenhouse" stage. This discovery does not bode well for some planets that are currently labeled as 'possibly habitable' as their suitability for such consideration may be revoked.
A warmer planetary haven around cool stars, as ice warms rather than cools
In a bit of cosmic irony, planets orbiting cooler stars may be more likely to remain ice-free than planets around hotter stars. This is due to the interaction of a star's light with ice and snow on the planet's surface. It seems logical that the warmth of terrestrial or rocky planets should depend on the amount of light they get from their stars, all other things being equal. But new climate model research led by Aomawa Shields, a doctoral student in the University of Washington astronomy department, has added a surprising new twist to the story: planets orbiting cool stars actually may be much warmer and less icy than their counterparts orbiting much hotter stars, even though they receive the same amount of light.
Super-Earths detected in nearby star system
A team of astronomers, including Rory Barns at the University of Washington, have discovered a nearby star system containing three to five "super-Earths" in its habitable zone. "Super-Earths" are planets up to ten times bigger than Earth and, according to the researchers, this is the first time so many have been detected in one system. "These planets are good candidates to have a solid surface and maybe an atmosphere like the Earth's, not something like Jupiter," said Barnes.
Kepler Stars and Planets are Bigger than Previously Thought
In a new study using the NOAO Kitt Peak National Observatory Mayall 4-meter telescope, observations of a large sample of stars with candidate planets identified by the NASA Kepler Mission have revealed that many of the stars, and hence their planets, are actually somewhat larger than originally thought. In addition, the researchers confirm that planets larger than Neptune are more likely to be found orbiting stars that contain more heavy elements (such as iron) than the Sun. Small planets, however, have been discovered around stars both rich and poor in metals. Over three years ago, Steve B. Howell (NASA Ames Research Center) put together a team to investigate and characterize the stars that the NASA Kepler Mission found to host planets. The team members are Mark Everett and David Silva (both at NOAO) and Paula Szkody (University of Washington).