Earth-like planet around Proxima Centauri discovered

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paddoboy

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Earth-like planet around Proxima Centauri discovered
August 15, 2016 by Matt Williams, Universe Today

Artist’s impression of a sunset seen from the surface of an Earth-like exoplanet. Credit: ESO/L. Calçada
The hunt for exoplanets has been heating up in recent years. Since it began its mission in 2009, over four thousand exoplanet candidates have been discovered by the Kepler mission, several hundred of which have been confirmed to be "Earth-like" (i.e. terrestrial). And of these, some 216 planets have been shown to be both terrestrial and located within their parent star's habitable zone (aka. "Goldilocks zone").


But in what may prove to be the most exciting find to date, the German weekly Der Spiegel announced recently that astronomers have discovered an Earth-like planet orbiting Proxima Centauri, just 4.25 light-years away. Yes, in what is an apparent trifecta, this newly-discovered exoplanet is Earth-like, orbits within it's sun's habitable zone, and is within our reach. But is this too good to be true?

For over a century, astronomers have known about Proxima Centauri and believed that it is likely to be part of a trinary star system (along with Alpha Centauri A and B). Located just 0.237 ± 0.011 light years from the binary pair, this low-mass red dwarf star is also 0.12 light years (~7590 AUs) closer to Earth, making it the closest star system to our own.



Read more at: http://phys.org/news/2016-08-earth-like-planet-proxima-centauri.html#jCp
 
This is similar to a previous announcement that of an Earth size rocky planet orbiting Alpha Centauri B. From memory that was labeled Alpha Centauri Bb, and has since been retracted.
Let's hope for better luck and confirmation with this latest possible finding.
 
paddoboy said:
This is similar to a previous announcement that of an Earth size rocky planet orbiting Alpha Centauri B. From memory that was labeled Alpha Centauri Bb, and has since been retracted.
Let's hope for better luck and confirmation with this latest possible finding.
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So what there are billion solar systems in our galaxy an they probably have some planet like ours , why go out of our way to a less reachable place.
 
timojin said:
So what there are billion solar systems in our galaxy an they probably have some planet like ours , why go out of our way to a less reachable place.
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I'm not sure what you are trying to say. The whole fuss and folderol about this new star system is that we don't have to go out of our way. It's right next door.
 
timojin said:
So what there are billion solar systems in our galaxy an they probably have some planet like ours , why go out of our way to a less reachable place.
Click to expand...
We were made to explore and to copy cat a popular truism, go where no man has gone before. ;)
Do you want exploration [for whatever reason] to cease?
 
I don't wanna explain about it but once I believed that alien is available around Proxima Centauri.
And then I worried about that 'no earth like planet around Proxima Centauri is discovered'

But now it's really so interesting to me.
 
Here are three relevant papers on this subject.....

https://arxiv.org/abs/1608.06919

The Habitability of Proxima Centauri b I: Evolutionary Scenarios

We analyze the evolution of the potentially habitable planet Proxima Centauri b to identify environmental factors that affect its long-term habitability. We consider physical processes acting on size scales ranging between the galactic scale, the scale of the stellar system, and the scale of the planet's core. We find that there is a significant probability that Proxima Centauri has had encounters with its companion stars, Alpha Centauri A and B, that are close enough to destabilize Proxima Centauri's planetary system. If the system has an additional planet, as suggested by the discovery data, then it may perturb planet b's eccentricity and inclination, possibly driving those parameters to non-zero values, even in the presence of strong tidal damping. We also model the internal evolution of the planet, evaluating the roles of different radiogenic abundances and tidal heating and find that a planet with chondritic abundance may not generate a magnetic field, but all other models do maintain a magnetic field. We find that if planet b formed in situ, then it experienced ~160 million years in a runaway greenhouse as the star contracted during its formation. This early phase may have permanently desiccated the planet and/or produced a large abiotic oxygen atmosphere. On the other hand, if Proxima Centauri b formed with a thin hydrogen atmosphere (<1% of the planet's mass), then this envelope could have shielded the water long enough for it to be retained before being blown off itself. Through modeling a wide range of Proxima b's evolutionary processes we identify pathways for planet b to be habitable and conclude that water retention is the biggest obstacle for planet b's habitability. These results are all obtained with a new software package called VPLANET.


https://arxiv.org/abs/1608.06827

The habitability of Proxima Centauri b II. Possible climates and Observability

Radial velocity monitoring has found the signature of a Msini=1.3~M⊕ planet located within the Habitable Zone of Proxima Centauri, (Anglada-Escud\'e et al. 2016). Despite a hotter past and an active host star the planet Proxima~b could have retained enough volatiles to sustain surface habitability (Ribas et al. 2016).
Here we use a 3D Global Climate Model to simulate Proxima b's atmosphere and water cycle for its two likely rotation modes (1:1 and 3:2 resonances) while varying the unconstrained surface water inventory and atmospheric greenhouse effect.
We find that a broad range of atmospheric compositions can allow surface liquid water. On a tidally-locked planet with a surface water inventory larger than 0.6 Earth ocean, liquid water is always present, at least in the substellar region. Liquid water covers the whole planet for CO2 partial pressures ≳1~bar. For smaller water inventories, water can be trapped on the night side, forming either glaciers or lakes, depending on the amount of greenhouse gases. With a non-synchronous rotation, a minimum CO2 pressure is required to avoid falling into a completely frozen snowball state if water is abundant. If the planet is dryer, ∼0.5~bar of CO2would suffice to prevent the trapping of any arbitrary small water inventory into polar ice caps. More generally, any low-obliquity planet within the classical habitable zone of its star should be in one of the climate regimes discussed here.
We use our GCM to produce reflection/emission spectra and phase curves. We find that atmospheric characterization will be possible by direct imaging with forthcoming large telescopes thanks to an angular separation of 7λ/D at 1~μm (with the E-ELT) and a contrast of ∼10−7. The magnitude of the planet will allow for high-resolution spectroscopy and the search for molecular signatures.



https://arxiv.org/abs/1608.06813

The habitability of Proxima Centauri b. I. Irradiation, rotation and volatile inventory from formation to the present

Proxima b is a planet with a minimum mass of 1.3 MEarth orbiting within the habitable zone (HZ) of Proxima Centauri, a very low-mass, active star and the Sun's closest neighbor. Here we investigate a number of factors related to the potential habitability of Proxima b and its ability to maintain liquid water on its surface. We set the stage by estimating the current high-energy irradiance of the planet and show that the planet currently receives 30 times more EUV radiation than Earth and 250 times more X-rays. We compute the time evolution of the star's spectrum, which is essential for modeling the flux received over Proxima b's lifetime. We also show that Proxima b's obliquity is likely null and its spin is either synchronous or in a 3:2 spin-orbit resonance, depending on the planet's eccentricity and level of triaxiality. Next we consider the evolution of Proxima b's water inventory. We use our spectral energy distribution to compute the hydrogen loss from the planet with an improved energy-limited escape formalism. Despite the high level of stellar activity we find that Proxima b is likely to have lost less than an Earth ocean's worth of hydrogen before it reached the HZ 100-200 Myr after its formation. The largest uncertainty in our work is the initial water budget, which is not constrained by planet formation models. We conclude that Proxima b is a viable candidate habitable planet.
 
http://phys.org/news/2016-08-discovery-proxima-host-star-habitable.html


New discovery Proxima b is in host star's habitable zone—but could it really be habitable?

The world's attention is now on Proxima Centauri b, a possibly Earth-like planet orbiting the closest star, 4.22 light-years away. The planet's orbit is just right to allow liquid water on its surface, needed for life. But could it in fact be habitable?

If life is possible there, the planet evolved very differently than Earth, say researchers at the University of Washington-based Virtual Planetary Laboratory, where astronomers, geophysicists, climatologists, evolutionary biologists and others team to study how distant planets might host life.

Astronomers at Queen Mary University in London have announced discovery of Proxima Centauri b, a planet orbiting close to a star 4.22 light years away. The find has been called "the biggest exoplanet discovery since the discovery of exoplanets."

Rory Barnes, UW research assistant professor of astronomy, published a blog post about the discovery at palereddot.org, a website dedicated to the search for life around Proxima Centauri. His essay describes research underway through the UW planetary lab—part of the NASA Astrobiology Institute—to answer the question, is life possible on this world?

"The short answer is, 'It's complicated,' Barnes writes. "Our observations are few, and what we do know allows for a dizzying array of possibilities"—and almost as many questions.



Read more at: http://phys.org/news/2016-08-discovery-proxima-host-star-habitable.html#jCp

 
The only "problem" with these studies is that we really don't have the tools (presently) to be able to tell if another planet is "Earth like". Venus and Mars would be considered Earth like given the tools we presently have.

Timojin, this potential planet is in our galaxy and closeby at that, approximately 4 light years away, so I'm unsure of what you are trying to say.
 
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