THE HEAVENS AND THE EARTH...
Okay, need a help with an SMS? A Single Mother System, or CLASSICAL system, like our own, only one Star in the center.
The first thing I recommend is to draft your system in paper, a few lined circles should do the work, feel your system, edit if something doesn't feel right, add a moon aside, up or down the planet, or draw a inclined line across the planet to indicate any ring system you may like it to have...
Like this:
I have decided to keep it rather simple and add no moons for now, but we will do it later.
Now all we have is to name our planets and star:
It seems already good, let's put that to Scale, pick any planet from our Solar System and put it side to side with your planets, from known sizes of real planets we can figure out what sizes are our planets...
Heya, 2021 Valent here, sketching is cool and all, but never mind much about changing stuff as you learn more - it's part of the journey
Alright, everything okay with your planets?
Lets go back to the star, Vol.
Define its mass, and the other formulas will do the rest...
Here are the nominal parameters of Vol
It end up that this star is a G-type like our Sun, which means it's spectrum and composition are pretty similar to our Sun.
How similar? Well that depends quite a bit on the star's metallicity - for the Sun, that's about [Fe/H] ~ 0,0022.
The equation below will give you multiples of this value (1x, 2x, 3x...), based on star mass.
However, it will stop working when the mass is greater than 2,6 solar masses.
(because WHY would you need to go any higher?).
With metallicity in hand, we can start making some estimates for planet's around our star.
The mass of a terrestrial planet around our star can be determined based on Metallicity, Habitable Zone (HZ), and desired orbital distance (a) in AU, by:
If this sounds too much like a seven-headed serpent for you to solve, since Sun-like stars differ little in their mass-budget (as far as we can tell), we can simplify that to be hooked onto the Habitable Zone distance.
Now, for Gaseous planets there is no way to that in a simpler manner than:
For those of you that haven't noticed that yet - the less metallic, ie, the smaller the dust-to-gas ratio, the bigger are the gas planets around the star, and vice-versa.
Characteristics of most G-type stars are weaker Hydrogen lines, Calcium+ ions, ionized & neutral metals.
Bellow is a simulation of the Sun's spectrum:
And Vol's spectrum:
Notice how Vol's spectrum has more darker lines of Iron and Magnesium mostly, I opted for a high metalicity star cause I want very heavy-cored Ice giants along with a metal rich super-earth (Hool) to be explored. Helium lines are also stronger to 27% in contrast to the Sun's 24,85%.
Wanna estimate your star's age based on Hydrogen/Helium proportions?
The Sun currently fuses about 600 million tons of hydrogen into helium every second.
36 billion tons per minute.
2,160 trillion tons an hour.
51,84 trillion per day.
18,91 quadrillion tons a year...
The Sun's mass is 1.988,55 septillion tons... 494,15 septillion tons are Helium...
Theoretically, the sun produced ~87,175 septillion tons of Helium since its birth, 4,6 billion years ago, meaning that it was originally made of ~20,46% Helium.
Change is ~4% per 4,6 billion year.
~ +1% [He] per 1,15 billion years
If our star works at similar rate, and were initially made also of ~80/20... (Close G-type relative)
Change index is ~7%.
Then our star is ~8,05 billion years old, 1,75x older than our Sun.
As it turns out, this star is old enough that any habitable planet around it could have evolved complex life from zero-point TWICE and a half (assuming it takes roughly 3 billion years for that), unfortunately it has only 3,6 billion years left, but it is enough so life could occur a 4th time before Vol becomes a blooming red giant.
(assuming somehow this planet biosphere died every 3 Gyrs ugh < .< ).
STELLAR EVOLUTION EFFECTS?
As we have covered in the last post, stars move through the HR Diagram as they age, our star is predicted to have a MS phase of 11,6 Gyr, being 8,05Gyr old, this takes our star to the far end of it's lifetime.
As such, it's predicted to be slightly cooler and larger than the Sun as it approaches the Red Giant branch.
Aged Vol parameters
Bellow, there is a chart showing both stars...
Which means that planets would have formed much more closer to Vol compared to how far are the Solar System planet's from the Sun.
For instance, gas giants could form at 2,16 AU because of how much close is the T-Tauri Vol's Frost Line - while rocky planets could have formed as close as 0,0723 AU.
Let's plot what those changes would look like:
I have plotted Paart's orbital distance drift based on what seems right in timescales, explicitly calculating the exact path requires radical changes to the model I have already built with my team - HOWEVER, it should be no problem to one that starts with this new knowledge in hand.
We have it's path and stellar evolution such that, by the rise of the complex life, it will drift towards the mean Habitable zone.
What I did for my system back in 2019?
None of that, though it happens to be excusable in my case, if we consider planetary migrations - which I will tackle in a future post about the pre-solar history of the Volar System.
What I did instead at the time - was to use a Keplerian Distribution
If we take a look at our solar system, we will notice how planets are spaced.
Mercury - 0,38 AU
Venus - 0,73 AU
Earth - 1,00 AU
Mars - 1,52 AU
Jupiter - 5,24 AU
Saturn - 9,50 AU
- -
Johannes Kepler when measuring the Solar System, noticed that if we begin a sequence at 0, 3, 6, 12, 24, 48, 96... and so on, added 4 and divided by 10.
4, 7, 10, 16, 28, 52, 100... /10 = 0,4 AU, 0,7 AU, 1 AU, 1,6 AU, 2,8 AU, 5,2 AU, 10 AU...
It matches around the same proportions as the known planet's orbit.
Although, no one had found the planet that lies at 2,8~3,2 AU yet, between Mars and Jupiter, Daniel Titius, another astronomer at the time said "But should the Lord Architect have left that space empty? Not at all."
Since then, many searched the skies for the missing planet of Kepler, as himself wrote “Between Mars and Jupiter, I place a planet"...
After the discovery of Ceres, that orbits in this zone, astronomers could finally set their telescopes down cause they have figured out the solar system...
... BUT ACTUALLY, NOT THOUGH.
They had also found out some of other objects in the same zone as Ceres, at the time, they also included them in map of the Solar System, as this map of 1846 shows:
For reference, Vulcan was still believed to exist due observation of the wobble in Mercury's orbit until Einstein came up with his Special Relativity Theory, Mercury wobble was nothing more than predictable space-time warp by the Sun's mass.
Astronomers dismissed their planets to asteroid-tier (aster = star; oid = similar; asteroid = star-looking), because they were absurdly small, even more than Charon, moon of Pluto.
This orbital proportions are due to orbital resonances and planetary migrations, but that's for other day...
You could come up with values between 0,2x and 2,0x the previous orbit, from innermost to outer planets, that might do the trick as well.
For the Vol System, I came up with 0, 2,5, 5, 10, 20, 40.
For the first, I added 3.
For the others, I added +0.1 point according to each position after the star, and sum the previous orbit value.
And divided everyone by 10.
0+3+0.1, 2,5+0.2, 5+0.3, 10+0.4, 20+0.5, 40+0.6.
/10
0,31 AU
0,58 AU
1,11 AU <- Paart fell inside the Habitable Zone, yay
2,15 AU
4,20 AU
8,26 AU
I have put that comet orbit at 2,15 AU, and made it very elliptical.
Distances to scale, it looks something like this:
And for today that's everything folks, bye.
- M. O. Valent, 20/02/2019
- M. O. Valent, last updated 02/06/2021
