PLANETARY MODEL | PART 8 | A MORE DETAILED APPROACH TO PLATE TECTONICS - II

FIGURING OUT A PLANET'S INTERNAL STRUCTURE

Let's first look at what we DO know about the terrestrial planets - with the exception on Earth - all planet's Iron Oxide x Iron Sulfide content seems to follow a power law:

FeO ratio ~ 1,75 * 0,9^(core/planet mass ratio)

And the further you are from the Sun, the more iron oxides you're likely find - the Earth and the Moon are an special case, being outliers to the trend much probably to the Theia Collision event, a planet with different make-up would have mashed against Earth and changed it's composition ever so slightly - giving it a bigger core with more iron oxides.

The default density of Paart as of our Planet Classification Guide points out - would be of 3,06 g/cm³ up to 3,39 g/cm³, Paart is already slightly so heavy with 3,8 g/cm³, a thing we can explain with the Taaf event of birth, when two protoplanets did collide nearby, and Paart accreted their material, mainly metals, accounting for 5% of the planet's current mass (or about 0,04 Me), what did not accrete or was ejected, accreted into the moon Taaf.

The core ratio of a planet in the terrestrial planets seems to follow:

C ratio = 0,28^(AU) * star mass

In a way that,

FeO ratio ~ 1,75 * 0,9^(100 * (star mass * 0,28^(AU)))

We get Paart would have a core that's at least 19% Paart's mass and 26% at most - and iron oxide levels comparable to that of Mars, about 15,7% or twice as Earth's.

Earth's core is about 32,5% of the planet's mass for perspective, the inner core is smaller at about 1,6% of the planet's mass.

Paart's inner core about 1/60th that of it's mass as well, we may have an inner core that's 1274km in radius. While it's outer core would be 3185,5km in radius, with respective densities of 11,47g/cm³ and 9,85g/cm³.

So what do we have? Composition, highlighted green and red what Paart has more or less than Earth.
O 38%; Si 20% ; Bi 14%; Al 9%; Fe 8%; Ti 5%; Ca 3%; 2% K, 0,5% Zn, Na, Mg and other trace elements ~0,5%.

Earth is 46% Oxygen, ~28% silicon, 8% aluminum and 5% iron, mainly. Paart seems to be actually more dense than Earth, for some reason I didn't pay any attention to that.

The composition alone of the elements of Paart sum to a density of about 3,56g/cm³, which is laughable, but remember, we have switched some of the oxygen by bismuth metal, which when combined with sulfur, creates bismuthinite, which has a density of ~7g/cm³.

While on Earth much of it's interior is made of Olivine, which takes up Magnesium and Iron, both less dense than bismuth, but magnesium is rarer on Paart, so we are left with Iron-olivine, and bismuth silicates such as Sillénite, which is monstrously dense with 9,2g/cm³. The most common mineral in the mantle would be bismite, with a density of 8,9g/cm³, along with some small amounts of bismuth and iron sulfides (6,78g/cm³ and 4,84g/cm³).

For the mantle, we have 37% SiO2, 28,7% Fe2SiO4, 15,7% FeO, 5% Bi2O3, 4,5% Al2O3, 2,8% CaO, 2% Bi12SiO20, 2% TiO, 1% Bi2S3, 0,5% FeS, 0,5% ZnS, and 0,3% NiO - with a density of 4,28g/cm³.

The overall density of the planet would then go up to 5,55g/cm³, so...

Correcting for Mass, we would go from 0,798, to 1,167 Earth masses - or for Diameter, from 13.450km to 11.786km. In the first we have a gravity of 10,37m/s², while in the later we have a gravity of 9,14m/s².

FUTURE of PROJECT PAART

The crew has decided to make it smaller - there is three main consequences to that:

1. The Earth-like gravity suggests creatures would be under Earth-like biomechanical constraints, ie, have similar sized animals for certain roles, of course - that depends a lot on other factors too, but it is a big one.
2. The Earth-like gravity also implies a greater atmospheric pressure, initially 2,29atm - now, 2,94atm, that can mess a bit with animal respiration.
   
3. The increased atmospheric pressure does increase the temperatures too, from initially 18,5°C to 30,8°C - which ends up being optimal for bacterial growth, particularly cyanobacteria as we know it.
   

Compared to the terrestrial planets, Paart's structures looks like this:

Besides having lot's of text to correct by next few days regarding these factors - I'm alleviated to have noticed this in it's early phases - otherwise, we would actually have to halt the project right here.

Funfact - is probable that most if not - a good portion - of Paart's bismuth is on the upper mantle, because bismuth is diamagnetic, which means that it wants to flee from magnetic fields, the compounds would have ease arising from the convection currents but resist being dragged back into the planet's core due to the dynamo effect. So, lava flows would also spill out beautiful bismuth crystals, glasses, and metallic daubréeites.

- M.O. Valent, 02/10/2020