Showing posts with label HABITABLE ZONE. Show all posts
Showing posts with label HABITABLE ZONE. Show all posts

Friday, April 28, 2017

Astronomers have discovered a new planet named LHS 1140b with the greatest chances of sustaining life. '' It's the most exciting planet ''

This artist's impression shows the exoplanet LHS 1140b, which orbits a red dwarf star 40 light-years from Earth and may be the new holder of the title 'best place to look for signs of life beyond the Solar System'. Using ESO's HARPS instrument at La Silla, and other telescopes around the world, an international team of astronomers discovered this super-Earth orbiting in the habitable zone around the faint star LHS 1140. This world is a little larger and much more massive than the Earth and has likely retained most of its atmosphere. Credit: ESO/spaceengine.org
An exoplanet orbiting a red dwarf star 40 light-years from Earth may be the new holder of the title 'best place to look for signs of life beyond the solar system.' Using ESO's HARPS instrument, and other telescopes, astronomers discovered a 'super-Earth' orbiting in the habitable zone around the star LHS 1140. This world is larger and more massive than the Earth and has likely retained most of its atmosphere. This makes it one of the most exciting targets for atmospheric studies.

The newly discovered super-Earth LHS 1140b orbits in the habitable zone around a faint red dwarf star named LHS 1140, in the constellation of Cetus (The Sea Monster). Red dwarfs are much smaller and cooler than the Sun and, although LHS 1140b is ten times closer to its star than the Earth is to the Sun, it only receives about half as much sunlight from its star as the Earth and lies in the middle of the habitable zone. The orbit is seen almost edge-on from Earth and as the exoplanet passes in front of the star once per orbit it blocks a little of its light every 25 days.

"This is the most exciting exoplanet I've seen in the past decade," said lead author Jason Dittmann of the Harvard-Smithsonian Center for Astrophysics (Cambridge, USA). "We could hardly hope for a better target to perform one of the biggest quests in science -- searching for evidence of life beyond Earth."

"The present conditions of the red dwarf are particularly favourable -- LHS 1140 spins more slowly and emits less high-energy radiation than other similar low-mass stars," explains team member Nicola Astudillo-Defru from Geneva Observatory, Switzerland.

For life as we know it to exist, a planet must have liquid surface water and retain an atmosphere. When red dwarf stars are young, they are known to emit radiation that can be damaging for the atmospheres of the planets that orbit them. In this case, the planet's large size means that a magma ocean could have existed on its surface for millions of years. This seething ocean of lava could feed steam into the atmosphere long after the star has calmed to its current, steady glow, replenishing the planet with water.

The discovery was initially made with the MEarth facility, which detected the first telltale, characteristic dips in light as the exoplanet passed in front of the star. ESO's HARPS instrument, the High Accuracy Radial velocity Planet Searcher, then made crucial follow-up observations which confirmed the presence of the super-Earth. HARPS also helped pin down the orbital period and allowed the exoplanet's mass and density to be deduced .

The astronomers estimate the age of the planet to be at least five billion years. They also deduced that it has a diameter 1.4 times larger than the Earth -- almost 18,000 kilometres. But with a mass around seven times greater than the Earth, and hence a much higher density, it implies that the exoplanet is probably made of rock with a dense iron core.

This super-Earth may be the best candidate yet for future observations to study and characterise its atmosphere, if one exists. Two of the European members of the team, Xavier Delfosse and Xavier Bonfils both at the CNRS and IPAG in Grenoble, France, conclude: "The LHS 1140 system might prove to be an even more important target for the future characterisation of planets in the habitable zone than Proxima b or TRAPPIST-1. This has been a remarkable year for exoplanet discoveries!" [4,5].

In particular, observations coming up soon with the NASA/ESA Hubble Space Telescope will be able to assess exactly how much high-energy radiation is showered upon LHS 1140b, so that its capacity to support life can be further constrained.

Further into the future -- when new telescopes like ESO's Extremely Large Telescope are operating -- it is likely that we will be able to make detailed observations of the atmospheres of exoplanets, and LHS 1140b is an exceptional candidate for such studies.

Notes

[1] The habitable zone is defined by the range of orbits around a star, for which a planet possesses the appropriate temperature needed for liquid water to exist on the planet's surface.

[2] Although the planet is located in the zone in which life as we know it could potentially exist, it probably did not enter this region until approximately forty million years after the formation of the red dwarf star. During this phase, the exoplanet would have been subjected to the active and volatile past of its host star. A young red dwarf can easily strip away the water from the atmosphere of a planet forming within its vicinity, leading to a runaway similar to that on Venus.

[3] This effort enabled other transit events to be detected by MEarth so that the astronomers could nail down the detection of the exoplanet once and for all.

[4] The planet around Proxima Centauri is much closer to Earth, but it probably does not transit its star, making it very difficult to determine whether it holds an atmosphere.

[5] Unlike the TRAPPIST-1 system, no other exoplanets around LHS 1140 have been found. Multi-planet systems are thought to be common around red dwarfs, so it is possible that additional exoplanets have gone undetected so far because they are too small.


Other articles on the same theme:





Story source: 
 
The above post is reprinted from materials provided by Sciencedaily . Note: Materials may be edited for content and length.

Monday, January 30, 2017

Researchers have found another planet (Wolf 1061c) that can sustain life: Located just 14 light-years away

Credit: The Wolf 1061 system. Credit: UNSW Sydney
An exoplanet with the prime conditions for life could be located just 14 light-years away, scientists report, in one of the closest neighbouring solar systems to our own.

New research suggests that a planet circling the star Wolf 1061 falls within what's called the star's habitable zone - making it one of the most likely neighbouring candidates for a planet that supports life.


This artist's concept illustrates a young, red dwarf star surrounded by three planets. Credit: wikipedia

"The Wolf 1061 system is important, because it is so close, and that gives other opportunities to do follow-up studies to see if it does indeed have life," says lead researcher Stephen Kane from San Francisco State University.

There are three planets orbiting Wolf 1061, but the planet Wolf 1061c is of particular interest.

Discovered in 2015, and with an estimated mass that's more than four times Earth's mass, Wolf 1061c is located right in the middle of Wolf 1061's habitable zone: the region where a planet's distance from its host star makes conditions suitable for liquid water and other life-supporting elements.

Our own Solar System runs by the same rules: conditions on Earth are just right for liquid water, whereas Mars is too cold.

To investigate whether Wolf 1061c might offer the same kind of habitability, the researchers analysed seven years of luminosity data from its host star and ran calculations of the exoplanet's orbit to figure out what the temperature and pressure on the surface could be.


The findings add weight to previous speculation that Wolf 1061c could be habitable – but just because the exoplanet is within a habitable zone, that doesn't necessarily mean it's one like Earth's.

The new data suggest that Wolf 1061c could have an atmosphere similar to what Venus had in its earliest days, meaning that any liquid water on the planet might not stick around for long. 

Previous research has suggested that high temperatures caused excessive water evaporation on Venus, and the newly formed water vapour in the atmosphere increased temperatures even further - a process known as a runaway greenhouse effect.

Now, the team thinks the same thing could be happening on Wolf 1061c, which is "close enough to the star that it's looking suspiciously like a runaway greenhouse", says Kane.

In addition, Wolf 1061c's orbit of its star varies much more quickly than Earth's orbit of the Sun, which would lead to chaotic climate changes such as a rapidly encroaching ice age (or warm phase).

So, is there life on Wolf 1061c?

We don't yet know, and to find out, we'll need more detailed measurements than what we have so far. To that end, Kane says NASA's James Webb telescope is one of the ways we'll be able to learn more about the exoplanet in the future.

Wolf 1061c Credit: Centauri Dreams

The telescope is launching next year, and its advanced optics should be able to reveal the atmospheric conditions on Wolf 1061c, and give us a better idea about whether water (and life) could really exist there.

Meanwhile, scientists from METI - the Messaging Extraterrestrial Intelligence organisation - are also interested in Wolf 1061c, and have been keeping a close eye on the exoplanet as they try to reach out to any alien life that might exist beyond our Solar System.

"I'm not holding my breath that we'll ever find evidence of life on Wolf 1061c," METI president Doug Vakoch told Rae Paoletta at Gizmodo.

"But the fact that there's a roughly Earth-like planet in the habitable zone of a star so close to our own Solar System is a good omen as we continue our search for life on other planets."

Other articles on the same theme:




Story source: 
The above post is reprinted from materials provided by Sciencealert . Note: Materials may be edited for content and length.

Tuesday, July 19, 2016

KEPLER SPOTS 100+ MORE EXOPLANETS, SOME POTENTIALLY HABITABLE WE'VE GOT EXOPLANETS ON EXOPLANETS

















NASA announced today that its Kepler spacecraft has discovered a "crop of more than 100 planets" orbiting the M dwarf star K2-72, 181 light years away from Earth.

Of the 104 planets found outside of our solar system, four seem Earth-sized and rocky, and two of those are within the "habitable zone," with the potential for liquid water on their surfaces. They orbit their star closer than Mercury orbits ours, but because K2-72 is cooler and less than half the size of our sun, it keeps them in the sweet spot for temperature. One is 10 percent warmer than Earth, while the other is 6 percent cooler. All of the planets discovered are 20-50 percent larger than Earth in diameter.


These discoveries come after thousands of exoplanets landed in Kepler's sights, including three dozen planets or planet candidates in the habitable zone. The odds keep getting better for life outside of our own solar system.



The above post is reprinted from materials provided by  POPSCI. Note: Materials may be edited for content and length