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Last week, news of the discovery of a potentially habitable "Earth-like" exoplanet orbiting the nearest star to our Sun (Proxima Centauri) leaked to Der Spiegel. Today, the European Southern Observatory confirmed the news about Proxima b:
Astronomers using ESO telescopes and other facilities have found clear evidence of a planet orbiting the closest star to Earth, Proxima Centauri. The long-sought world, designated Proxima b, orbits its cool red parent star every 11 days and has a temperature suitable for liquid water to exist on its surface. This rocky world is a little more massive than the Earth and is the closest exoplanet to us — and it may also be the closest possible abode for life outside the Solar System. A paper describing this milestone finding will be published in the journal Nature on 25 August 2016.
[...] At times Proxima Centauri is approaching Earth at about 5 kilometres per hour — normal human walking pace — and at times receding at the same speed. This regular pattern of changing radial velocities repeats with a period of 11.2 days. Careful analysis of the resulting tiny Doppler shifts showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about 7 million kilometres from Proxima Centauri — only 5% of the Earth-Sun distance.
A note on the press release discusses the potential habitability of Proxima b, given that it is orbiting close to a red dwarf star:
[Continues...]
The actual suitability of this kind of planet to support water and Earth-like life is a matter of intense but mostly theoretical debate. Major concerns that count against the presence of life are related to the closeness of the star. For example gravitational forces probably lock the same side of the planet in perpetual daylight, while the other side is in perpetual night. The planet's atmosphere might also slowly be evaporating or have more complex chemistry than Earth's due to stronger ultraviolet and X-ray radiation, especially during the first billion years of the star's life. However, none of the arguments has been proven conclusively and they are unlikely to be settled without direct observational evidence and characterisation of the planet's atmosphere. Similar factors apply to the planets recently found around TRAPPIST-1.
A terrestrial planet candidate in a temperate orbit around Proxima Centauri (DOI placeholder) (DX)
Two more papers are available (currently in peer review). They discuss the habitability of Proxima b (at a site that appears to be dedicated to the subject).
Related: Internal Temperature of Exoplanets Could Determine Habitability Rather Than "Goldilocks" Distance
Previously: "Earth-Like" Exoplanet Found in Habitable Zone of Proxima Centauri
(Score: 5, Informative) by martyb on Thursday August 25 2016, @05:57PM
No, and Yes. Being a Red Dwarf [wikipedia.org], they generally emit much less radiation that our Sun:
On the other hand Proxima Centauri [wikipedia.org]:
So all is calm and mild, and then it is not.
In case you were thinking how long it would take to get there... by some reports the fastest man-made object is the New Horizons [wikipedia.org] probe which made observations of Pluto:
Which is fast enough to take a lap around the Earth at the equator in under 45 minutes.
Proxima Centauri is 4.25 light-years away, or about 40e+12 km. That implies New Horizons would take about 77,570 years to get there. Space is BIG!
Wit is intellect, dancing.
(Score: 2) by mcgrew on Thursday August 25 2016, @09:00PM
According to the article I read, the exoplanet is getting the same amounts of radiation as the Earth does, in the same frequencies despite its small distance. But that's because a dwarf doesn't radiate much; you can't see it without a telescope from Earth, and it's the nearest star to the sun.
Since it's a... I forgot what they call it, but it flashes, making the prospect of life there pretty bleak. Also consider that there are three planets in the solar system's habitable zone, but only one of them will support life.
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(Score: 2) by takyon on Thursday August 25 2016, @09:13PM
They have assigned this object a minimum mass of 1.3 Earth masses, which could actually enhance its chances of habitability. Hopefully it turns out to be spinning and have a nice magnetosphere.
Here's a comment I wrote on last week's Proxima Centauri article [soylentnews.org].
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(Score: 3, Informative) by deimtee on Friday August 26 2016, @01:21AM
Just a deep enough atmosphere would ameliorate a lot of the radiation from flares. Even Earth's atmosphere is roughly equivalent to 10 metres of water as shielding.
The main benefit of a strong magnetic field is to stop the solar wind stripping the atmosphere.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 2) by takyon on Friday August 26 2016, @02:04AM
Well, the planet supposedly has a minimum mass of 1.27 M⊕, so hopefully it has attracted and held onto a nice thicc atmosphere.
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(Score: 2) by martyb on Friday August 26 2016, @01:00AM
mcgrew (701) wrote:
I doubt it would radiate in the "same frequencies" — as noted in my GP comment, it's a Red Dwarf [wikipedia.org]. I'll quote part of the section on "Habitability":
So, nothing like the same frequencies as our sun, sorry.
Quoting again from the GP comment which already noted:
(More info in Wikipedia's entry on Flare Star [wikipedia.org].)
That said, I'll whole-heartedly agree that the prospect for life there is quite bleak indeed. Though, there is the possibility that instead of being tidally locked with the same face always turned to its star, it might be more like our planet Mercury which, IIRC, is in a 3:2 resonance with the Sun. There's so much we don't know, but one can hope for more information from the huge new optical telescopes which are slated to be completed within the next decade or so.
Wit is intellect, dancing.