Saturday, 28 January 2017

We're Getting A Lot Better at Looking for Habitable Planets

Good news! If recent events inspire you to look for a way off this planet, we just got a lot better at hunting for another habitable space rock. As researchers are finally starting to directly observe the stars we know have planetary systems, it’s now possible to accurately gauge if their planets' orbits are not too far, but not too close to their stellar parent.

In a study published in Astrophysical Journal, Stephen Kane, associate professor of astronomy at San Francisco State University, focused on the red dwarf star Wolf 1061, located only 14 light-years from Earth. He and his researchers have been able to accumulate enough information to determine the star’s precise habitable zone—that is, the area around a star that harbours conditions conducive for life. What’s even more exciting is that the study confirms suspicions that the second planet in the system is found on the inside edge of this region.

“We understand planets only as well as we understand the star,” Stephen Kane told Motherboard over the phone. Wolf 1061 is a faint star of the M dwarf family. That means that—despite its proximity to our solar system—it’s still very hard to observe and get exact details about it. Kane and his team have measured the luminosity and temperature of Wolf 1061 and also determined the detailed orbits of the star’s three planets. With this data, they can say for sure that Wolf 1061c, the system’s second planet from the star, is situated where scientists believe liquid water could exist on the planet’s surface if there was enough atmosphere to sustain it.

Before now, Wolf 1061’s properties were only approximated through stellar modelling, a process in which a star’s type is used to extrapolate additional data.

“Unfortunately, stellar models do not always give an accurate picture of what these small stars are really like and getting direct measurements has been extraordinarily useful for being able to characterized the system and the planets that are in it,” Kane said.

What we don’t know are the conditions of Wolf 1061c’s atmosphere, or if it even has one. Kane expects that could change with the launch and deployment of space-based telescopes like 2018’s James Webb Space Telescope. Because Wolf 1061 is so close, telescopes would have a good chance of producing a distinguishable image of the planet without it being blotted out by its main star.

Does this mean we should we point our generation sleeper ships at Wolf 1061c? Doubtful. What Kane and his team found is a planetary system with wildly changing Milankovitch cycles. The Milankovitch cycle is how much a planet’s movement through space (like it’s tilt or orbit) affects its climate. Kane explains that the gravity of the other planets in the system influence the orbit of Wolf 1061c to such a degree that its climate could drastically transform over the course of centuries, as opposed to Earth's climate, which changes over tens of thousands of years.

Kane believes we still have a lot to study in our own system before we look outside. There’s still the question of what type of planets develop in habitable zones. Are more planets like Earth, with its temperate atmosphere, or like Venus, wrapped in a completely opaque haze that produces a runaway greenhouse effect?

Kane explained that the early history of Earth and Venus were likely very similar and we need to figure out how they ended up two very distinct planets. “They probably had the same composition in their atmosphere. Now they're completely different, so they diverged dramatically from each other at some point in the past.”

Wolf 1061 is just the first observations of what will be a great hunt, the eventual conclusion of which could be finding a second Earth. Next on Kane’s list is the Proxima Centauri planet Proxima b, which is actually the closest exoplanet to Earth at a mere 4.22 light-years away. It will take time, but with everything happening on this world, I’m glad we’re sorting it out.

from We're Getting A Lot Better at Looking for Habitable Planets

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