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posted by martyb on Thursday November 16, @07:51AM   Printer-friendly
from the Ross-128?-When-did-Harry-Mudd-join-"Friends"? dept.

Astronomers using the High Accuracy Radial velocity Planet Searcher (HARPS) at the La Silla Observatory in Chile have discovered an Earth-sized exoplanet orbiting a red dwarf in its "habitable zone". The star, Ross 128, is about 10.89 light years away and is less active than Proxima Centauri, possibly boosting the chances of its exoplanet being habitable. Ross 128b has a minimum mass of about 1.35 Earth masses, and is considered by its discoverers to be "the best temperate [exo]planet known to date". The next step will be to determine the atmospheric composition of Ross 128b:

There's still uncertainty about whether Ross 128 b is within its star's habitable zone, but scientists say that with temperatures of between -60 and +20°C, it can be considered temperate.

Next, astronomers want to study the atmospheric composition and chemistry of suitable, nearby worlds like Ross 128 b. The detection of gases such as oxygen could potentially point to biological processes on planets orbiting other stars.

Several gases have already been detected in the atmospheres of exoplanets, but this line of enquiry is expected to be boosted immeasurably when observatories such as the European Southern Observatory's Extremely Large Telescope (E-ELT) and Nasa's James Webb Space Telescope (JWST) come online in the next few years.

Although currently 11 light-years from Earth, the new planet's parent star Ross 128 is moving towards us and is expected to overtake Proxima Centauri as our nearest stellar neighbour in just 79,000 years - a heartbeat on cosmic timescales.

A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs (open, DOI: 10.1051/0004-6361/201731973) (DX)


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  • (Score: 4, Funny) by takyon on Thursday November 16, @10:05AM

    by takyon (881) Subscriber Badge <reversethis-{gro ... s} {ta} {noykat}> on Thursday November 16, @10:05AM (#597632) Journal

    https://en.wikipedia.org/wiki/List_of_nearest_stars [wikipedia.org]
    https://en.wikipedia.org/wiki/File:Near-stars-past-future-en.svg [wikipedia.org]

    Ross 128 will be the closest star in around 70,000 years, but it will be just under 7 light years away, whereas the Centauri system is about 4.24-4.36 light years away today (2.9-2.97 light years away at closest approach in ~28,000 years) and Ross 248 will be 3 light years away in 36,000 years. Gliese 445, Barnard's Star, and Lalande 21185 also come closer before then. Look forward to it.

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  • (Score: 4, Interesting) by StupendousMan on Thursday November 16, @01:21PM (2 children)

    by StupendousMan (103) on Thursday November 16, @01:21PM (#597670)

    The authors of the paper use measurements of the host star's optical spectrum to infer that it doesn't produce a lot of UV emission, and note that it doesn't have frequent optical flares. That's good news for the habitability of the planet around it, as they point out.

    However, they apparently did not note that Ross 128 is a relatively strong X-ray source, as measurements by the ROSAT X-ray satellite show. A colleague of mine worked out the X-ray luminosity of the host star, and it turns out to be not unlike that of the Sun, or even larger. That means that the X-ray flux striking the planet -- which is very close to this host star -- is likely high enough to remove the atmosphere of the planet. No atmosphere means not so interesting a planet, alas.

    • (Score: 3, Informative) by takyon on Thursday November 16, @01:31PM (1 child)

      by takyon (881) Subscriber Badge <reversethis-{gro ... s} {ta} {noykat}> on Thursday November 16, @01:31PM (#597673) Journal

      https://www.nytimes.com/2017/11/15/science/planet-ross-128.html [nytimes.com]

      Vladimir Airapetian, an astrophysicist at the NASA Goddard Space Flight Center in Greenbelt, Md., questioned whether Ross 128 would be such a benign star.

      “Even being quiet, its X-ray to extreme U.V. emission can be 10 times higher than that of the sun,” said Dr. Airapetian. That amount of radiation might be enough to destroy the planet’s atmosphere.

      In an Astrophysical Journal Letters article in February, he and his colleagues noted that radiation from red dwarf stars might strip oxygen from the atmospheres of nearby planets.

      This wrangling can be solved once new telescopes like the JWST and E-ELT are up and running.

      “There is potential for an atmosphere and hence habitability, but it is highly uncertain,” he said. “This is an important discovery and well worth many follow-up studies.”

      The next generation of large terrestrial telescopes, with mirrors 100 feet or more in diameter, should be able to make out the planet circling Ross 128 and possibly identify specific molecules in its atmosphere.

      If the planet has a higher surface gravity than Earth, perhaps it can retain a thick atmosphere despite powerful UV/x-ray emissions.

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      • (Score: 2) by bob_super on Thursday November 16, @06:49PM

        by bob_super (1357) on Thursday November 16, @06:49PM (#597812)

        > That amount of radiation might be enough to destroy the planet’s atmosphere.

        or just mean a different kind of atmosphere from what our narrow-minded models think possible.
        Aliens are gray with black eyes because they photosynthesize and see in the X-ray range.

  • (Score: 1) by ian991 on Thursday November 23, @05:59PM

    by ian991 (6779) on Thursday November 23, @05:59PM (#600735)

    Great discovery..
    It is only 11 light years away! Will we ever make it to travel that long distance?

    After Proxima, this is most Earth-like http://www.evolving-science.com/space/habitable-exoplanet-discovered-close-earth-00495 [evolving-science.com]exoplanet discovered

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