Planet in Proxima Centauri's habitable zone

[CountDeMoney]

[Eddie Teach]

I like Tim and I like his posts. I learn a lot on different subjects that sometimes end up fascinating.

Keep doing you, Timmay.

Tim is one of South Korea's national Treasures.

[jimmy olsen]

http://www.nature.com/nature/journal/v536/n7617/full/nature19106.html

At a distance of 1.295 parsecs1, the red dwarf Proxima Centauri (α Centauri C, GL 551, HIP 70890 or simply Proxima) is the Sun's closest stellar neighbour and one of the best-studied low-mass stars. It has an effective temperature of only around 3,050 kelvin, a luminosity of 0.15 per cent of that of the Sun, a measured radius of 14 per cent of the radius of the Sun2 and a mass of about 12 per cent of the mass of the Sun. Although Proxima is considered a moderately active star, its rotation period is about 83 days (ref. 3) and its quiescent activity levels and X-ray luminosity4 are comparable to those of the Sun. Here we report observations that reveal the presence of a small planet with a minimum mass of about 1.3 Earth masses orbiting Proxima with a period of approximately 11.2 days at a semi-major-axis distance of around 0.05 astronomical units. Its equilibrium temperature is within the range where water could be liquid on its surface5.

Video about the discovery by The European Southern Observatory

https://www.youtube.com/watch?v=lysJduOqads

[jimmy olsen]

Awesomeness! 

Exploring plausible formation scenarios for the planet candidate orbiting Proxima Centauri
http://arxiv.org/pdf/1608.06908v1.pdf

ABSTRACT
We present a study of four dierent formation scenarios that may be able to explain
the origin of the recently announced planet (`Proxima b') orbiting the star Proxima
Centauri. The aim is to examine how the formation scenarios dier in their predic-
tions for the multiplicity of the Proxima planetary system, the water/volatile content
of Proxima b and its orbital eccentricity, so that these can be tested by future obser-
vations.

A scenario of in situ formation via giant impacts from a locally enhanced disc
of planetary embryos and planetesimals, after dispersal of the gaseous protoplanetary
disc, predicts that Proxima b will be a member of a multiplanet system with a mea-
surably nite value of orbital eccentricity. Assuming that the local solid enhancement
needed to form a Proxima b analogue with minimum mass 1:3M arises because of
the inwards drift of solids in the form of small planetesimals/boulders that arose dur-
ing earlier phases, this scenario also likely results in Proxima b analogues that are
moderately endowed with water/volatiles, arising from the dynamical diusion of icy
planetesimals from beyond the snowline during planetary assembly .

A scenario in which multiple embryos form, migrate and mutually collide within a gaseous proto-
planetary disc also results in Proxima b being a member of a multiple system, but
where the constituent members are Ocean planets due to accretion occurring mainly
outside of the snowline, possibly within mean motion resonances. A scenario in which
a single accreting embryo forms at large distance from the star, and migrates inwards
while accreting either planetesimals or pebbles results in Proxima b being an isolated
Ocean planet on a circular orbit.

A scenario in which Proxima b formed via pebble accretion interior to the snowline produces a dry planet on a circular orbit. Future observations that characterise the physical and orbital properties of Proxima b, and any additional planets in the system, will provide valuable insight into the formation history of this neighbouring planetary system.

The habitability of Proxima Centauri b II. Possible climates and Observability
http://arxiv.org/pdf/1608.06827v1.pdf

ABSTRACT
Radial velocity monitoring has found the signature of a Msin i = 1:3 M planet located within the Habitable Zone of Proxima Centauri, the Sun's closest neighbor (Anglada-Escudé 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 (GCM) to simulate Proxima b's atmosphere and water cycle for its two likely rotation modes (the 1:1 and 3:2 spin-orbit resonances) while varying the unconstrained surface water inventory and atmospheric greenhouse eect (represented here with a CO2-N2 atmosphere.)

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 (assuming 1 bar of N2), 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 of  10 mbar (assuming 1 bar of N2) is required to avoid falling into a completely frozen snowball state if water is abundant. If the planet is dryer, 0.5 bar of CO2 would suce 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 for the diffrent rotations and surface volatile inventories. We find that atmospheric characterization will be possible by direct imaging with forthcoming large telescopes thanks to an angular separation of 7=D at 1 m (with the E-ELT) and a contrast of  107. The magnitude of the planet will allow for high-resolution spectroscopy and the search for molecular signatures, including H2O, O2, and CO2. The observation of thermal phase curves, although challenging, can be attempted with JWST, thanks to a contrast of 2105 at 10 m. Proxima b will also be an exceptional target for future IR interferometers. Within a decade it will be possible to image Proxima b and possibly determine whether this exoplanet's surface is habitable.

[Josquius]

Been reported on bbc news today. 
They say it takes 20 years to get there

[Hamilcar]

Been reported on bbc news today. 
They say it takes 20 years to get there

Breakthrough starshot, google it.

[HVC]

Been reported on bbc news today. 
They say it takes 20 years to get there

Breakthrough starshot, google it.

so they've read a mote in gods eye

[Monoriu]

Been reported on bbc news today. 
They say it takes 20 years to get there

That's quite fast.  The system is like four light years away from Earth.  If one can get there in 20 years, that means the travelling speed is like 20% of light speed.  That's really fast. 

[jimmy olsen]

Been reported on bbc news today. 
They say it takes 20 years to get there

Breakthrough starshot, google it.

Weren't you bashing them when they announced their ambitions?

Why the change of heart? You being paid a consulting fee?

[Grinning_Colossus]

11.5 days means tidally locked.

[jimmy olsen]

11.5 days means tidally locked.

If it has an atmosphere the heat could be equally distributed by the winds.

It's the atmosphere that's the sticking point. The radiation from the star might have stripped it off.

[Grinning_Colossus]

11.5 days means tidally locked.

If it has an atmosphere the heat could be equally distributed by the winds.

It's the atmosphere that's the sticking point. The radiation from the star might have stripped it off.

The temperature differential between the light and dark sides means that any winds would probably be insanely strong.

[Ed Anger]

Ed's plan:

Send Tim.
Blow up spaceship halfway there.

[Martinus]

Ed's plan:

Send Tim.
Blow up spaceship halfway there.

Better yet blow up the "spaceship" still on Earth. Much cheaper.

[Ed Anger]

Ed's plan:

Send Tim.
Blow up spaceship halfway there.

Better yet blow up the "spaceship" still on Earth. Much cheaper.

Let him get one last thrill. I'm a nice guy.