Habitable Zones & Global Climate: February 2019

The aim of our study is to explore the possible existence of Earth-mass planets in the habitable zone of 55~Cancri, an effort pursued based on detailed orbital stability simulations.

The habitable zone (HZ) is defined as the range of distances from a host star within which liquid water, a key requirement for life, may exist at a planet's surface. Substantially more CO2 than present in Earth's modern atmosphere is required to maintain clement temperatures for most of the HZ, with concentrations of several bars required at the outer edge.

A new astronomical spectrograph built by a Penn State-led team of scientists provides the highest precision measurements to date of infrared signals from nearby stars, allowing astronomers to detect planets capable of having liquid water on their surfaces that orbit cool stars outside our solar system.

A major volcanic event could have triggered one of the largest glaciations in Earth's history - the Gaskiers glaciation, which turned the Earth into a giant snowball approximately 580 million years ago.

How good is our universe at making habitable planets? The answer to this depends on which factors are important for life: Does a planet need to be Earth mass? Does it need to be inside the temperate zone?

We report improved masses, radii, and densities for four planets in two bright M-dwarf systems, K2-3 and GJ3470, derived from a combination of new radial velocity and transit observations. Supplementing K2 photometry with follow-up Spitzer transit observations refined the transit ephemerides of K2-3 b, c, and d by over a factor of 10.

The world's oceans could harbor an unpleasant surprise for global warming, based on new research that shows how naturally occurring carbon gases trapped in reservoirs atop the seafloor escaped to superheat the planet in prehistory.

Transit spectroscopy of terrestrial planets around nearby M dwarfs is a primary goal of space missions in coming decades. 3-D climate modeling has shown that slow-synchronous rotating terrestrial planets may develop thick clouds at the substellar point, increasing the albedo.

Earth's solid surface and clement climate may be in part due to a massive star in the birth environment of the Sun. Without its radioactive elements injected into the early solar system, our home planet could be a hostile ocean world covered in global ice sheets.

Recent studies have shown that ocean dynamics can have a significant warming effect on the permanent night sides of 1 to 1 tidally locked terrestrial exoplanets with Earth-like atmospheres and oceans in the middle of the habitable zone.