Second-Closest Earth-Like Planet Discovered

www.popularmechanics.com ^ | 11/15/2017 | By Jay Bennett

[Red Badger]

About 11 light-years away, Ross 128 b is closer to the solar system than any known exoplanet save Proxima b.

First there was Proxima b, the Earth-sized planet orbiting the closest star to us, Proxima Centauri. Then came the seven Earth-sized worlds orbiting TRAPPIST-1, a star 39 light-years away, three of which are in the habitable zone. Now we welcome a new tantalizing exoplanet to the group, the second closest we know of, also Earth-sized and temperate, orbiting a calm red dwarf star: Ross 128 b.

Ross 128 is an old, inactive red dwarf star that sits 11 light-years away. Proxima Centauri is only 4.2 light-years away. However, Ross 128 is moving toward us, and it will become the closest star to the sun in just 79,000 years, towing the planet Ross 128 b along with it. Considering the oldest human remains are thought to be hundreds of thousands or even millions of years old, it's not crazy to think our species could still be roaming the Earth when Ross 128 b becomes the closest exoplanet to our home world.

The new planet was discovered by an international team of astronomers using the European Southern Observatory's (ESO) High Accuracy Radial velocity Planet Searcher (HARPS) at the La Silla Observatory in the high desert of Chile. Unlike most exoplanet discoveries, Ross 128 b was not detected during a transit when the planet moves in front of the host star from our perspective, allowing astronomers to detect the reduction in light from the star.

"HARPS is a spectrograph specially designed to measure the radial velocity of the stars," Nicola Astudillo-Defru, an astronomer with the Geneva Observatory in Switzerland and a member of the team that made the discovery, told Popular Mechanics in an e-mail. "With radial velocity we are able to detect the periodic stellar wobble produced by the planet (gravitational interaction), so we do not require a transit to make the detection."

In other words, the planet makes the star wobble as it rotates, astronomers were able to measure the wobble with HARPS, and that measurement revealed some key information about the planet, such as its mass and how far away it is from the host star. The discovery is outlined in a paper titled "A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs" published today in the journal Astronomy and Astrophysics.

The exoplanet around Ross 128 orbits about 20 times closer to its host star than the Earth to the sun, making a trip around the star every 9.9 days. However, Ross 128 is a particularly calm and cool dwarf star, only about 20 percent the diameter of the sun with a little more than half the sun's surface temperature. The temperatures on the planet Ross 128 b could therefore be comparable to those on Earth, estimated at at -60 to 20 degrees Celsius (-76 to 68°F). Follow-up observations are needed to determine whether Ross 128 b orbits within or near the habitable zone where liquid water could exist on the planet's surface.

If Ross 128 b has an atmosphere, it could be an even better place to search for life than Proxima b or the TRAPPIST-1 planets. "The main disadvantage of these two stars [Proxima Centauri and TRAPPIST-1] is their frequent and strong flares," says Astudillo-Defru. "This kind of stellar activity can erode the planetary atmosphere or even completely blow it away, and additionally the high-energy radiation can even sterilize the surface of the planets. This is where Ross 128 has a big advantage, the star is much quieter. ... I think Ross 128 b is more comfortable to the development of life."

While stellar flares are known to erupt from red dwarf stars and shower any orbiting planets in deadly ultraviolet and X-ray radiation, Ross 128 b is estimated to receive only 1.38 times the radiation as Earth from its quiet host star. The inactivity of Ross 128 prompted the ESO to say the star "may be the closest known comfortable abode for possible life."

To find out for sure, however, astronomers will need to probe the atmosphere of Ross 128 b (assuming it has one) for biomarkers. An example of a biomarker would be abundant oxygen, which only exists on Earth due to photosynthetic life. To search for these clues, astronomers need bigger telescopes, and fortunately multiple giant scopes coming online in the 2020s should be up to the task, such as the Giant Magellan Telescope (GMT) and the Extremely Large Telescope (ELT).

"Although Ross 128 b does not transit its host star, with forthcoming giant telescopes we expect to directly observe the planet, allowing us to characterize its atmosphere, and search for biomarkers!" says Astudillo-Defru.

With telescopes discovering new exoplanets all the time, particularly around red dwarf stars due to their abundance, astronomers are eagerly preparing to use future giant telescopes to search for extraterrestrial life. Perhaps that life is on Ross 128 b right now, drifting toward us in the cosmic void, destined to be the closest planet to Earth that doesn't orbit the sun in less than 100,000 years. Perhaps humanity will even be here still to greet that life if it comes.

[pgkdan]

If each light year translates to 5.88 trillion miles we are looking at a 64.68 trllion mile journey. We better bring snacks! :-)

Make sure everyone pees before they leave!

[SunkenCiv]

Thanks Red Badger.

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[jmacusa]

A single light year is about 6 trillion miles. So..... doing the old math that’s ...66 trillion miles?

[jmacusa]

Yes, make sure everyone goes to the bathroom and please, you kids in the back seat no fighting or I swear I’ll pull over. Do you want me to PULL OVER? NOT another word outta you two or so help me I’ll pull this spaceship over right now!:-)

[minnesota_bound]

I read the article and think there are red dwarfs living on the planet.

[Boogieman]

“it will become the closest star to the sun in just 79,000 years”

Oh, JUST 79,000 years... only almost 15 times as long as human civilization has existed. No problem!