UNSW: Nearby Star Hosts Closest Alien Planet in the "Habitable Zone"

[bystander]

Nearby Star Hosts Closest Alien Planet in the "Habitable Zone"
University of New South Wales | 2015 Dec 16

Click to play embedded YouTube video.

UNSW Australia astronomers have discovered the closest potentially habitable planet found outside our solar system so far, orbiting a star just 14 light years away.

The planet, more than four times the mass of the Earth, is one of three that the team detected around a red dwarf star called Wolf 1061.

“It is a particularly exciting find because all three planets are of low enough mass to be potentially rocky and have a solid surface, and the middle planet, Wolf 1061c, sits within the ‘Goldilocks’ zone where it might be possible for liquid water – and maybe even life — to exist,” says lead study author UNSW’s Dr Duncan Wright.

“It is fascinating to look out at the vastness of space and think a star so very close to us – a near neighbour – could host a habitable planet. ...

[Nitpicker]

Just 14 light years ... so close and yet so far. (And its star, Wolf 1061 [aka HIP 80824] is even visible in most telescopes, between Antares and the Celestial Equator, at magnitude 10.)

I don't suppose much is known with great certainty, of planets with four times the mass of Earth, given that we have nothing remotely like that in the Solar System. I'm not sure if the average density would be typically higher or lower than Earth's (which is the most dense thing of any size in the Solar System).

Regardless, I just whipped up this table, which I thought was interesting:

[neufer]

I don't suppose much is known with great certainty, of planets with four times the mass of Earth, given that we have nothing remotely like that in the Solar System. I'm not sure if the average density would be typically higher or lower than Earth's (which is the most dense thing of any size in the Solar System).

Regardless, I just whipped up this table, which I thought was interesting:

[b][size=150][color=#40BF00]Ozmodiar from Wolf 1061c[/color][/size][/b]

---

An Earth sized Wolf 1061c with
a mean density of 22.056 g/cm³ doesn't smell right

<<Osmium (from Greek osme (ὀσμή) meaning "smell") is a chemical element with symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mostly in platinum ores. Osmium is the densest naturally occurring element, with a density of 22.59 g/cm³.

[Nitpicker]

I quite agree, neufer. But one of the points of the table, was to show what the density and surface gravity of Wolf 1061c would need to be, if it was the same size as Earth.

I'll further note that the density of iron under standard conditions is about 7,900 kg/m3. Yet the density of the Earth's core (which is about 90% iron and under a lotta pressure) is more than 11,000 kg/m3. The core of Earth contributes only about a third of its total mass. The remaining two thirds of the mass (which is almost all mantle with a little bit of crust) is comprised mainly of oxides of silicon and magnesium (and surprisingly little iron).

I wonder what the density of iron would be, within the core of a ferrous/rocky planet four times more massive than Earth?

And here is another interesting table:

earth_composition.PNG (11.69 KiB) Viewed 721 times

(By the way, the -0.2% Nickel in the Mantle/Crust, is a numerical anomaly caused by using different sources. I decided not to worry too much about it.)

[Nitpicker]

I've just read here: http://newt.phys.unsw.edu.au/~duncanw/Wolf1061.pdf, that the authors from UNSW (rah, rah), used the statistically derived "mass-radius relation of Weiss & Marcy (2014)": http://arxiv.org/pdf/1312.0936v4.pdf.

... to estimate a rough radius of 1.64 Earth radii, for Wolf 1061c, which yields a surface gravity of about 1.6g and a density similar to Earth.

According to Weiss & Marcy, the average density of planets reaches a maximum of about 7600 kg/m3, when the radius is about 1.4 to 1.5 Earth radii. But there is a fairly large scatter in the data on which their relation is based, so the 1.64 figure is pretty speculative.