Saturday, 03 June 2017 08:46

Closest potentially habitable planet to our solar system found

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(CNN)In a discovery that has been years in the making, researchers have confirmed the existence of a rocky planet named Proxima b orbiting Proxima Centauri, the closest star to our sun, according to a new study. It is the closest exoplanet to us in the universe.

Given the fact that Proxima b is within the habitable zone of its star, meaning liquid water could exist on the surface, it may also be the closest possible home for life outside of our solar system, the researchers said.
 
 
Because of its location, the researchers hope it provides an opportunity for possible "robotic exploration in the coming centuries."
 
"The good news is that it is so close," study author Ansgar Reiners said. "It is not only nice for having it in our neighborhood, but it's a dream come true for astronomers if we think about follow-up observation."
Proxima Centauri coexists with a binary star in Alpha Centauri, a well-studied star system that serves as a neighbor to our sun.
 
Proxima b is a mere 4.2 light-years away from our solar system, or 266,000 times the distance between the Earth and the sun, which are 92.96 million miles apart. Previous rocky exoplanet discoveries, like those orbiting ultracool red dwarf star TRAPPIST-1, were previously described as "close" at 40 light-years away.
 
"It's not only the closest terrestrial planet found, it's probably the closest planet outside our solar system that will ever be found because there is no star closer to the solar system than this one," said lead study author Guillem Anglada-Escudé.
 
"The only thing you can hope to find between that is Planet Nine, but that would (require) a solar system object or a brown dwarf that hasn't been discovered," researcher Pedro Amado added.
 
Here is what we know about the planet, as well as the questions that researchers hope to be able to answer.
 
This artist's concept shows OGLE-2016-BLG-1195Lb, a planet orbiting an incredibly faint star 13,000 light-years away from us. It is an "iceball" planet with temperatures reaching minus-400 degrees Fahrenheit.
Photos: Weird and wonderful planets beyond our solar system
This artist's concept shows OGLE-2016-BLG-1195Lb, a planet orbiting an incredibly faint star 13,000 light-years away from us. It is an "iceball" planet with temperatures reaching minus-400 degrees Fahrenheit.
 
LHS 1140b is located in the liquid water habitable zone surrounding its host star, a small, faint red star named LHS 1140. The planet weighs about 6.6 times the mass of Earth and is shown passing in front of LHS 1140. Depicted in blue is the atmosphere the planet may have retained.
Photos: Weird and wonderful planets beyond our solar system
LHS 1140b is located in the liquid water habitable zone surrounding its host star, a small, faint red star named LHS 1140. The planet weighs about 6.6 times the mass of Earth and is shown passing in front of LHS 1140. Depicted in blue is the atmosphere the planet may have retained.
An artist's concept image of the surface of the exoplanet TRAPPIST-1f. Of the seven exoplanets discovered orbiting the ultracool dwarf star TRAPPIST-1, this one may be the most suitable for life. It is similar in size to Earth, is a little cooler than Earth's temperature and is in the habitable zone of the star, meaning liquid water (and even oceans) could be on the surface. The proximity of the star gives the sky a salmon hue, and the other planets are so close that they appear in the sky, much like our own moon.
Photos: Weird and wonderful planets beyond our solar system
An artist's concept image of the surface of the exoplanet TRAPPIST-1f. Of the seven exoplanets discovered orbiting the ultracool dwarf star TRAPPIST-1, this one may be the most suitable for life. It is similar in size to Earth, is a little cooler than Earth's temperature and is in the habitable zone of the star, meaning liquid water (and even oceans) could be on the surface. The proximity of the star gives the sky a salmon hue, and the other planets are so close that they appear in the sky, much like our own moon.
Artist's conception of the binary system with three giant planets discovered, where one star hosts two planets and the other hosts the third. The system represents the smallest-separation binary in which both stars host planets that has ever been observed.
Photos: Weird and wonderful planets beyond our solar system
Artist's conception of the binary system with three giant planets discovered, where one star hosts two planets and the other hosts the third. The system represents the smallest-separation binary in which both stars host planets that has ever been observed.
This artist's impression shows the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to our solar system.
Photos: Weird and wonderful planets beyond our solar system
This artist's impression shows the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to our solar system.
This artist's impression shows a view of the surface of the planet Proxima b.
Photos: Weird and wonderful planets beyond our solar system
This artist's impression shows a view of the surface of the planet Proxima b.
An artist's rendering shows Earth-sized exoplanets TRAPPIST-1b and 1c in a rare double transit event as they pass in front of their ultracool red dwarf star, which allowed Hubble to take a peek at at their atmospheres.
Photos: Weird and wonderful planets beyond our solar system
An artist's rendering shows Earth-sized exoplanets TRAPPIST-1b and 1c in a rare double transit event as they pass in front of their ultracool red dwarf star, which allowed Hubble to take a peek at at their atmospheres.
Out of a new discovery of 104 exoplanets, astronomers found four similar in size to Earth that are orbiting a dwarf star. Two of them have the potential to support life. The craft depicted in this illustration is the NASA Kepler Space Telescope, which has helped confirm the existence of thousands of exoplanets.
Photos: Weird and wonderful planets beyond our solar system
Out of a new discovery of 104 exoplanets, astronomers found four similar in size to Earth that are orbiting a dwarf star. Two of them have the potential to support life. The craft depicted in this illustration is the NASA Kepler Space Telescope, which has helped confirm the existence of thousands of exoplanets.
This artist's impression shows a view of the triple-star system HD 131399 from close to the giant planet orbiting in the system. Located about 320 light-years from Earth, the planet is about 16 million years old, making it also one of the youngest exoplanets discovered to date.
Photos: Weird and wonderful planets beyond our solar system
This artist's impression shows a view of the triple-star system HD 131399 from close to the giant planet orbiting in the system. Located about 320 light-years from Earth, the planet is about 16 million years old, making it also one of the youngest exoplanets discovered to date.
An artistic impression of the planet Kepler-1647b, which is nearly identical to Jupiter in both size and mass. The planet is expected to be roughly similar in appearance. But it is much warmer: Kepler-1647b is in the habitable zone. Photos: Weird and wonderful planets beyond our solar system
An artistic impression of the planet Kepler-1647b, which is nearly identical to Jupiter in both size and mass. The planet is expected to be roughly similar in appearance. But it is much warmer: Kepler-1647b is in the habitable zone.
HD-106906b is a gaseous planet 11 times more massive than Jupiter. The planet is believed to have formed in the center of its solar system, before being sent flying out to the edges of the region by a violent gravitational event.
Photos: Weird and wonderful planets beyond our solar system
HD-106906b is a gaseous planet 11 times more massive than Jupiter. The planet is believed to have formed in the center of its solar system, before being sent flying out to the edges of the region by a violent gravitational event.
Kepler-10b orbits at a distance more than 20 times closer to its star than Mercury is to our own sun. Daytime temperatures exceed 1,300 degrees Celsius (2,500 degrees Fahrenheit), which is hotter than lava flows on Earth.
Photos: Weird and wonderful planets beyond our solar system
Kepler-10b orbits at a distance more than 20 times closer to its star than Mercury is to our own sun. Daytime temperatures exceed 1,300 degrees Celsius (2,500 degrees Fahrenheit), which is hotter than lava flows on Earth.
This Jupiter-like planet in the HD-188753 system, 149 light-years from Earth, has three suns. The main star is similar in mass to our own Sun. The system has been compared to Luke Skywalker's home planet Tatooine in "Star Wars."
Photos: Weird and wonderful planets beyond our solar system
This Jupiter-like planet in the HD-188753 system, 149 light-years from Earth, has three suns. The main star is similar in mass to our own Sun. The system has been compared to Luke Skywalker's home planet Tatooine in "Star Wars."
Kepler-421b is a Uranus-sized transiting exoplanet with the longest known year, as it circles its star once every 704 days. The planet orbits an orange, K-type star that is cooler and dimmer than our Sun and is located about 1,000 light-years from Earth in the constellation Lyra.
Photos: Weird and wonderful planets beyond our solar system
Kepler-421b is a Uranus-sized transiting exoplanet with the longest known year, as it circles its star once every 704 days. The planet orbits an orange, K-type star that is cooler and dimmer than our Sun and is located about 1,000 light-years from Earth in the constellation Lyra.
Astronomers discovered two planets less than three times the size of Earth orbiting sun-like stars in a crowded stellar cluster approximately 3,000 light-years from Earth in the constellation Cygnus.
Photos: Weird and wonderful planets beyond our solar system
Astronomers discovered two planets less than three times the size of Earth orbiting sun-like stars in a crowded stellar cluster approximately 3,000 light-years from Earth in the constellation Cygnus.
This artist's conception shows a hypothetical planet with two moons orbiting in the habitable zone of a red dwarf star. The majority of the sun's closest stellar neighbors are red dwarfs.
Photos: Weird and wonderful planets beyond our solar system
This artist's conception shows a hypothetical planet with two moons orbiting in the habitable zone of a red dwarf star. The majority of the sun's closest stellar neighbors are red dwarfs.
Kepler-186f was the first validated Earth-sized planet to be found orbiting a distant star in the habitable zone. This zone a range of distance from a star where liquid water might pool on the planet's surface.
Photos: Weird and wonderful planets beyond our solar system
Kepler-186f was the first validated Earth-sized planet to be found orbiting a distant star in the habitable zone. This zone a range of distance from a star where liquid water might pool on the planet's surface.
Kepler-69c is a super-Earth-size planet similar to Venus. The planet is found in the habitable zone of a star like our sun, approximately 2,700 light years from Earth in the constellation Cygnus.
Photos: Weird and wonderful planets beyond our solar system
Kepler-69c is a super-Earth-size planet similar to Venus. The planet is found in the habitable zone of a star like our sun, approximately 2,700 light years from Earth in the constellation Cygnus.
The Kepler-444 system formed when the Milky Way was just 2 billion years old. The tightly packed system is home to five planets that range in size, the smallest is comparable to the size of Mercury and the largest to Venus, orbiting their sun in less than 10 days.
Photos: Weird and wonderful planets beyond our solar system
The Kepler-444 system formed when the Milky Way was just 2 billion years old. The tightly packed system is home to five planets that range in size, the smallest is comparable to the size of Mercury and the largest to Venus, orbiting their sun in less than 10 days.
This artistic concept image compares Earth, left, with Kepler-452b, which is about 60% larger. Both planets orbit a G2-type star of about the same temperature; however, the star hosting Kepler-452b is 6 billion years old -- 1.5 billion years older than our sun.
Photos: Weird and wonderful planets beyond our solar system
This artistic concept image compares Earth, left, with Kepler-452b, which is about 60% larger. Both planets orbit a G2-type star of about the same temperature; however, the star hosting Kepler-452b is 6 billion years old -- 1.5 billion years older than our sun.

Meet Proxima b

Proxima b is a rocky, terrestrial planet with a surface -- unlike a gas giant, such as Jupiter -- that is 1.3 times the size of Earth and orbits its star every 11.2 days. It is in a close orbit of Proxima Centauri: only 5% of the distance between the Earth and the sun. They are even closer together than Mercury and the sun. But because its star is much cooler and fainter than our sun, Proxima b has a temperature that is suitable for liquid water to exist on the surface without evaporating.
 
Researchers estimate that if the planet has an atmosphere, which could be assumed but isn't known, it may be between 86 to 104 degrees Fahrenheit (31 to 40 degrees Celsius) on the surface. Without an atmosphere, it could be -22 to -40 degrees Fahrenheit (-30 to -40 degrees Celsius). To put that in perspective, Earth would be -4 degrees (-20 degrees Celsius) if it didn't have an atmosphere, Reiners said.
 
Given the proximity to its star, Proxima b is also subject to less pleasant factors like ultraviolet and X-ray flares that are 100 times the intensity of what Earth receives from the sun. In the paper, researchers estimated it to be 400 times the intensity, but recent research has caused them to create a new estimate, they said. If there is life on the planet, it would be affected by this radiation, but it is pure speculation as to what kind of effect.
 
This infographic compares the orbit of the planet around Proxima Centauri (Proxima b) with the same region of the Solar System.
 
This infographic compares the orbit of the planet around Proxima Centauri (Proxima b) with the same region of the Solar System.

What took so long?

If the Alpha Centauri system is well-studied and Proxima Centauri is our sun's cozy star neighbor in the universe, why did it take so long to find Proxima b?
It comes down to an understanding of the star this planet orbits, as well as how data collection has evolved during the last 16 years.
Proxima Centauri is a low-mass red dwarf star, known as an M-class dwarf, that happens to be close to the bright binary star Alpha Centauri AB, which outshines its cool stepbrother, so to speak. All of these stars are within the faint Centaurus constellation, which can't be seen with the unaided eye.
M-class dwarves are not well understood in comparison with other types of stars, Reiners said. Because of that, researchers don't know much about the history of these stars or their radiation in the early days.
 
"But within the field of exoplants, [researchers] have recently realized that looking for planets around M dwarves is what is going to be the most spectacular, because you can find these plants in the liquid water zone more easily than other stars," Reiners said.
 
Because it's an active star, Proxima Centauri can behave in varied ways that mimic the presence of a planet, according to the study. Researchers wanted to observe it for a long period of time, so for the first half of this year, telescopes around the world were pointed at Proxima Centauri. The researchers looked for a "Doppler wobble," or back and forth wobble of Proxima Centauri that would be caused by the gravitational pull of a planet in orbit.
This was combined with research, data and published studies of Proxima Centauri dating to 2000.
"The significance of the detection went sky high," Anglada-Escudé said. "Statistically, there was no doubt. We have found a planet around Proxima
The research around Proxima b will continue, and the researchers have more questions they want to answer. They don't know whether there is water on the surface or if the planet has an atmosphere, although both are likely. They also don't know whether, like Earth, the planet has a protective magnetic field to help with some of the radiation it receives.
 
Perhaps one of the biggest questions includes the history of the star and the planet. How did they form?
"What happened during the formation?" Reiners asked. "Was the star more active than the sun is today, and where during that phase was Proxima b located?"
 
This would indicate whether the plant was rich with water in its early days or started out dry, as well as whether there was any high-energy radiation that could have blasted away an atmosphere during formation of the planet.
A view of the southern skies over the ESO 3.6-meter telescope at La Silla Observatory in Chile with images of the stars Proxima Centauri (lower right) and the double star Alpha Centauri AB (lower left).
A view of the southern skies over the ESO 3.6-meter telescope at La Silla Observatory in Chile with images of the stars Proxima Centauri (lower right) and the double star Alpha Centauri AB (lower left).
There is also some debate over whether this planet is Earth-like, which comes with some connotations. Depending on its formation, perhaps it could be like Venus.
 
Learning the answers to these questions about formation are possible with research. The habitability of a planet like Proxima b is also "a matter of intense debate," according to the study, due to arguments against it: tidal locking, strong stellar magnetic fields, strong flares, and high ultraviolet and X-ray fluxes. But, as they point out, none of those has been proved definitive, either.

Growing excitement

Researchers have long looked to Alpha Centauri for study. Now, they want us to go there.
Programs like Mission Centaur intend to design and build a space mission with a small telescope to point at the star system. It would look for exoplanets by imaging or other techniques that could find more of them around these three stars. Given how long it took us to confirm Proxima b and the fact that the researchers encountered a puzzling extra signal in some of their data and models, it's entirely possible that there are more planets to be found.
It is also the target of the Starshot project, which aims to create and send ultra-fast light-driven nanocraft that would reach the system 20 years after launch and beam home images. This is on the list of Breakthrough initiatives,an effort whose board includes Stephen Hawking and Mark Zuckerberg.
Join the conversation
 
Because Proxima b exists outside our solar system, it doesn't change our well-known roster of planets (and we know some of you are still rather upset over Pluto). But it does add to the field of exoplanet research that's underway, some of which hopes to identify Earth-like planets that future telescopes, such as the James Webb Space Telescope and the European Extremely Large Telescope, can use for observation.
Many researchers hope that we can actually image these planets in the future, getting an idea of their atmospheric makeup and surface composition, and strive to answer the question of "Are we alone in the universe?"
"We know that there are terrestrial planets around stars. The excitement is because it's the nearest one, and we expect to characterize it and maybe visit in a couple of centuries," Anglada-Escudé said.
Centauri."
Source: This article was published edition.cnn.com By Ashley Strickland

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