Tag Archives: habitable zone

Distant Super-Earth Exoplanet Has A Climate Perfect For Simple Life

While astrobiologists are increasingly hoping to find microbial life dwelling on or just beneath the surface of Mars, exoplanet hunters have been continually searching for habitable worlds far from our local corner of the Milky Way. Just recently, three Earth-like planets were discovered hovering 40 light-years away from us, and a new study, published in the journal Astrobiology, may have just described another.

Its roughly 40 percent larger than Earth, and its the outermost of five planets orbiting a star that is both smaller and cooler than our own Sun. Although its a lot further away 1,200 light-years, to be precise this new study suggests that the Kepler-62f may be able to sustain life.

First identified by the mechanical wunderkind that is the Kepler space observatory, little was known about it at the time. A team of researchers from the Universities of California Los Angeles (UCLA) and Washington turned to cutting-edge computer simulations in order to work out what it may be like to wander around on its surface.

We found there are multiple atmospheric compositions that allow it to be warm enough to have surface liquid water, Aomawa Shields, a National Science Foundation astronomy and astrophysics postdoctoral fellow in UCLAs department of physics and astronomy, and the studys lead author, said in a statement. This makes it a strong candidate for a habitable planet.

The relative sizes of recently discovered habitable-zone planets and Earth. From left to right: Kepler-69c, Kepler-62e, this studys Kepler-62f, and our own pale blue dot. NASA/Ames/JPL-Caltech

The shape of the planets orbital path was the first thing that needed to be calculated. To do so, the team used a renowned computer model named HNBody; this was combined with two tried-and-tested climate change models to simulate its possible climate configurations as it orbited its star.

The models assumed the atmosphere of Kepler-62f could be the same thickness as Earths all the way up to 12 times as thick. A variety of concentrations of carbon dioxide in the atmosphere were also considered, ranging from the same as Earths to up to 2,500 times that.

Based on what we know about microbial life, and considering the dimness of the alien star, Kepler-62f would only be completely habitable throughout its entire orbit if its atmosphere was 3 to 5 times thicker than our own, and it was composed entirely of carbon dioxide. This would ensure that a potent greenhouse effect would be in operation, which would warm the planet to habitable levels for microscopic life.

The most likely orbital parameters calculated by the models suggest that the planet would indeed by far away enough from its star to allow carbon dioxide to steadily accumulate in the atmosphere over time, as opposed to being blasted away by powerful solar radiation. Even if there was only an Earth-typical amount of carbon dioxide in the atmosphere, the temperatures would still go above waters freezing point for portions of the year.

The early Earth has a carbon dioxide-rich atmosphere thanks to prolonged volcanic activity. IM_photo/Shutterstock

Wherever you find water on Earth, there is life and such an atmospheric configuration would allow liquid water to be present at the surface. With water and carbon dioxide, photosynthesizing alien life, if it exists there, could one day convert Kepler-62fs atmosphere into one brimming with oxygen.

However, without a strong magnetic field, too much incoming solar radiation may render life at the surface impossible. Still, this somewhat damp and warm planet appears to be in the habitable zone, so thats certainly something worth noting.

Photo Gallery

Read more: http://www.iflscience.com/space/distant-super-earth-exoplanet-has-climate-perfect-simple-life

Kepler Space Telescope Discovers More Potentially Habitable Planets

Yesterday researchers from the NASA’s Kepler Space Telescope announced the discovery of 833 more candidate planets, 104 of which have the potential to harbor life. Included in that 104 in their respective Goldilocks Zones are 10 that are roughly the same size as Earth. As of this announcement, the total number of exoplanets discovered by Kepler since its launch in 2009 is now at 3,538. Its mission is to explore exoplanets and discover which ones are similar in size to Earth and are capable of supporting life. The announcement is coming from Kepler Science Conference, which is hosting over 400 scientists representing 30 countries.

 

According to William Borucki, the principal investigator for Kepler’s science mission, these discoveries “[open] a new era of exploration of our galaxy.” The first potentially habitable planet was announced two years ago, and since astronomers now believe there that most stars in the galaxy have at least one planet there is the possibility of many more potentially life-harboring discoveries to come.

 

This spring, Kepler’s mission was changed when two out of the four wheels used to point the telescope toward its targets broke, and NASA scientists were unable to repair them. Kepler completed its initial mission in 2012, and is currently completing an extended mission. Despite this, there is still a full year’s worth of data that has not been processed yet as Kepler monitored 150,000 stars and recorded data once every half hour for those four operational years. 

 

One analysis of Kepler’s data suggests that around 20% of sun-like stars have an Earth-like planet. So far, there have not been any reports of any such planet that completely mirrors Earth in terms of habitability and revolution length around a star like ours, but astronomers will continue to search. 

Read more: http://www.iflscience.com/space/kepler-space-telescope-discovers-more-potentially-habitable-planets

Exozodiacal Light Could Hinder Direct Imaging of Earth-Like Exoplanets

Finding life on exoplanets in a star’s habitable zone would, arguably, be the biggest event that has ever happened in human history. Unfortunately, an international team of astronomers using the Very Large Telescope discovered exozodiacal light around nearby stars, which would make imaging Earth-like exoplanets in those systems quite difficult. Steve Ertel from ESO and the University of Grenoble in France was lead author of the paper, which was published in the journal Astronomy & Astrophysics

Zodiacal dust can be generated by comet disintegration, collisions between asteroids or small planetary bodies, and through general space weathering of these bodies. When the tiny dust particles reflect sunlight or become heated enough to glow on their own, it produces a faint white light that can be widely seen throughout the solar system. When this phenomenon occurs in solar systems outside of our own, it’s called exozodiacal dust. 

Ertel’s team studied the exozodiacal dust near the habitable zones of 92 nearby stars, including 14 known to have exoplanets. Observations were made in near-infrared wavelengths using the Very Large Telescope’s Interferometer (VLTI). In order to produce a contrast high enough to view the dust, the VLT was given additional light from the four 1.8 meter Auxiliary Telescopes, allowing it to be ten times more powerful than any other similar instrument in the world. 

“If we want to study the evolution of Earth-like planets close to the habitable zone, we need to observe the zodiacal dust in this region around other stars,” Ertel said in a press release. “Detecting and characterizing this kind of dust around other stars is a way to study the architecture and evolution of planetary systems.”

Radiation from the star tends to push the tiny particles of zodiacal dust away, and a disc is formed past the habitable zone. It was assumed that the amount of dust in the clouds would decrease as the star and its system grew older, as there would be fewer asteroids to collide and create the dust. Interestingly, the stars with the brightest exozodiacal light came from older stars.

This blinding exozodiacal light could be problematic for future studies of each star’s potential planetary system. As if the glare from the star’s light wasn’t bad enough, the dust exacerbates that glare, becoming 1000 times brighter than zodiacal light in our solar system. The 14 stars known to have exoplanets all have extremely bright exozodiacal dust near the habitable zone, which will make it very difficult to directly image those planets. Further studies of the dust are needed to better understand its properties. This is necessary to find a way to circumvent it in order to image potential Earth-like planets in the habitable zone.

“The high detection rate found at this bright level suggests that there must be a significant number of systems containing fainter dust, undetectable in our survey, but still much brighter than the Solar System’s zodiacal dust,” adds co-author Olivier Absil from the University of Liège in Belgium. “The presence of such dust in so many systems could therefore become an obstacle for future observations, which aim to make direct images of Earth-like exoplanets.”

Read more: http://www.iflscience.com/space/exozodiacal-light-could-hinder-direct-imaging-earth-exoplanets

Ranking Exoplanets By Their Ability To Support Life

To date, 1,780 planets have been confirmed to exist beyond our solar system. But how many of these hold the potential to support life? National Geographic have compiled the planets discovered so far into a graph, organizing them by mass and temperature, which are two important limiting factors for the potential to support life. The temperature has to be within a range that can maintain any water present in a liquid state, and the mass needs to be within a range that supports a suitable atmosphere.

Of those 1,780 planets, 16 may have the right conditions to support life. Considering how incredibly vast the universe is it’s certainly likely that many more planets will be discovered over time, but this is a pretty encouraging starting figure. The newly discovered Kepler-186f, the first confirmed Earth-size planet orbiting a star in the habitable zone, was included in the list. 

Check out the image below to see the graphic. An interactive version is available on the National Geographic webpage

Read more: http://www.iflscience.com/space/ranking-exoplanets-their-ability-support-life