# Solar System limits and zones

## Solar System limits and zones

Looking for help on calculating the distance for the following:

Tidal Locking // where the planet becomes tidally lock, will probably determine on mass as well.
Vapor Line // are areas that are too close to the sun that will prevent a planet from holding on to an atmosphere.
Ice Line // for water!
Heliosheath limit // where the star's solar wind starts to diminish.
Soot line // probably not correct, but speculated to be where the carbon limit to form carbonaceous asteroids begin.

For stars:
Late-M Dwarf (M6.5 later)
Young M Dwarf (K7-M5)
Old M Dwarf (K7-M5)
K Dwarf (K2)
G Dwarf (G2)
Dimmer G Dwarf (G8)
F Dwarf
Fp Dwarf (probably the same)
A Dwarf

Thanks,
CarpD (^_^)

PS - I'll try to dig up some information on it as well.

_________________
Thanks,
CarpD (^_^)

marasama
SuperEarth

Number of posts : 215
Location : Earth
Registration date : 2008-04-22

## Re: Solar System limits and zones

Here I try posting an attempt.

Let's take a solar analogue (G2V, 1 Solar mass, 1 Solar radius, HZ=1 AU)

1) Tidal locking between <<0.1 and 0.4 AUs

2) Vapor Zone between <0.5 and <0.7 AUs

3) Ice Zone between <0.8 AUs and <2 AUs (a bit forced outer limit)

4) Helios-Heath Limit between <<3 AUs and 6 AUs (?)

5) Soot Line >>9 AUs

I think.

Now, such limits should be easily calculated accounting other star's habitable zones.

For Example, a M0 dwarf like AD Leonis has got a (putative) luminosity of 0.048 that of Sun, thus HZ=0.22 AUs (even accounting flaring events).
Here how limits should shift:

1) Tidal locking between <<0.022 and 0.09 AUs

2) Vapor Zone between <0.11 and <0.15 AUs

3) Ice Zone between <0.17 AUs and <0.44 AUs (a bit forced outer limit)

4) Helios-Heath Limit between <<0.66 AUs and 1.3 AUs (?)

5) Soot Line >>2 AUs

Similar method may be applied to a brighter star alike F5 subgiant Procyon, for example (which actually I don't think it may host any kind of stable planet except innermost barren ones). Procyon has 7.3 times more luminous than Sun, thus HZ=2.7 AUs. Here how data rearrange:

1) Tidal locking between <<0.27 and 1.1 AUs

2) Vapor Zone between <1.35 and <1.9 AUs

3) Ice Zone between <2.1 AUs and <5.4 AUs (a bit forced outer limit)

4) Helios-Heath Limit between <<8.1 AUs and 16.2 AUs (?)

5) Soot Line >>24 AUs

Obviously such limits for Procyon are disrupted, but they're a nice example.
Had fun with colours too
I hope it helps

Edasich
dM star

Number of posts : 1565
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

## Re: Solar System limits and zones

Actually, the projected soot line in our Solar System is within the Asteroid belt. It is possibly the separation between the metallic and carbonaceous asteroids. As for the heliosheath it is about the distance where the Voyager probes are at as of now (2008).

_________________
Thanks,
CarpD (^_^)

marasama
SuperEarth

Number of posts : 215
Location : Earth
Registration date : 2008-04-22

## Re: Solar System limits and zones

I don't know the mathematics of it, but I'll share what thoughts I have.

For tidal locking, it's probably dependent on the orbital period of the planet and/or it's distance from the star, perhaps the mass and radius of the planet, and the mass and radius of the star.

For the vapour line, I'm not sure such a line exists, in my honest opinion. I think it would depend on the mass of the planet, the temperature and solar wind output of the star, the radius of the star, radius of the planet, magnetic field properties of the planet, atmospheric density of the planet, and such. The Hot Jupiter planets still have atmospheres. But then again, Mars is losing its atmosphere, as is Venus and Mercury (though Mercury's seems to be replenished through various methods). The big difference between Mars and Venus, to Earth, is the magnetic field. So I think the magnetic field will play a huge role in the timescale involved in a planet losing it's atmosphere. To this end, I would state my conjecture to say that there's no well defiend "vapour line".

For the ice line, I'm sure it's as simple as calculating the habitable zone, but solve using temperature Temp = 272.15 K. (freezing point of water)

Heliosheath limit probably depends on solar wind output, interstellar medium density and velocity vector, and perhaps galactic magnetic field flux. I think this one would be the hardest to actually calculate.

Soot line... goodness I don't know. I've not heard of it until today. I would guess it's probably similar to calculating the habitable zone.

Well, I don't know how much any of this helps.

Edasich wrote:Had fun with colours too
Yes... a very colourful post .

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Caps Lock: Cruise control for 'Cool'!

Sirius_Alpha

Number of posts : 3816
Location : Earth
Registration date : 2008-04-06

## Re: Solar System limits and zones

Sirius_Alpha wrote:For the ice line, I'm sure it's as simple as calculating the habitable zone, but solve using temperature Temp = 272.15 K. (freezing point of water)
What you want is the sublimation point of water in vacuum which is somewhere around 175 K...

Lazarus
dF star

Number of posts : 3074
Registration date : 2008-06-12

## Re: Solar System limits and zones

I'll have to find the vapor line AJ paper. That's where I got that term from. As for the soot line, it is possible that it is old. But that term still creeps up, just because in the Solar System, the metallic and carbonaceous asteroids seem to nearly form a border line in the main Asteroid Belt.

I'm starting to get the feeling that the border lines will be an equation, rather than a simple AU amount.

_________________
Thanks,
CarpD (^_^)

marasama
SuperEarth

Number of posts : 215
Location : Earth
Registration date : 2008-04-22

## Re: Solar System limits and zones

marasama wrote:I'm starting to get the feeling that the border lines will be an equation, rather than a simple AU amount.
This was more-or-less one of the main points of my earlier post.

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Sirius_Alpha

Number of posts : 3816
Location : Earth
Registration date : 2008-04-06

## Re: Solar System limits and zones

I heard somewhere that later K type stars and anything smaller will tidally lock there planets to them if there in the stars HZ. I saw this somewhere on the OA websites planet classification list so I think that might be a lower boundary for planets in the HZ at least.

As for ones that are closer I have noooooooo idea. I do suspect however that this boundary might be useful for figuring these things out. Also if the people there could figure that out then they might know more on this than we would. Unless they heard this from a paper of some sort.

Darkness nova
Asteroid

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## Re: Solar System limits and zones

WesastKunanlley
Hydrogen Atom

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