Gruffty
SOC-14 1K
Greetings All
I found this whilst surfing:
Arxiv website
The paper focuses on systems containing gas giants, and looks at how the gravitational "reach" of each system's gas giant(s) might effect an Earth-like world located in the habitable zone.
Basically the paper states that gas giants with large enough gravitational reaches (i.e. that extend into the HZ) will "bump" an Earth-like world in the HZ, increasing the Earth-like world's orbital eccentricity and send it zooming out of the HZ. It also shows that Earth-like worlds can exist in the HZ when there are gas giants in the system whose gravitational reach doesn't extend into the HZ. Finally, the papers shows how much of the HZ is available to an Earth-like world where a gas giant's gravitational reach extends into the HZ. The paper does this by showing the % of HZ available for the orbit of the Earth-like world.
From what I can gather, the paper shows that systems with a "configuration" (third column in from right of tables at end of the document) of "1" or "2" have the best chances of an Earth-like world in the HZ. Systems with a "configuration" of "3" or "4" (there are no "5"s in the tables) have a % of the HZ available for an Earth-like world. Systems with a "configuration" of "6" have no chance of an Earth-like world in the HZ.
I think (although I could be wrong) the "configurations" indicate the arrangement of each system's gas giants, i.e., configuration 6 gas giants have gravity reaches that extend all the way across the HZ, thus affecting any Earth-like world that is/was in the HZ. 3 and 4 indicate shorter gas giant gravity reaches, that only extend partially into the HZ. 1 and 2 indicate gas giants that don't have gravity reaches that come anywhere near the HZ.
Whilst it's an entirely scientific paper (and thus contains some weird and wonderful equations) the tables at the end of the document provide us with the following useful information:
Real world star catalog numbers and names;
Their masses;
The Inner and Outer edge distances of each star's Habitable Zone;
Whether the system is habitable today;
The number of gas giants in the system.
Here are some examples from the tables at the end of the document:
</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> p Cor Borealis G0 V (mass = 0.95 sol)
Inner HZ edge = 1.094 Au
Outer HZ edge = 2.175 Au
Planets = b (i.e. p Cor Borealis b, a gas giant)
a/Au = 0.22 Au
e = 0.04 (= orbital eccentricity of the GG)
Configuration = 2 (i.e. good!)
System Habitability Today = Yes
Sustained Habitability = Yes</pre>[/QUOTE]I read the above as showing that the GG orbits a G0 V star at 0.22 Au with an orbital eccentricity of 0.04. This is well inside the HZ Inner edge at 1.094 Au - the GG's gravity reach doesn't extend into the HZ, so our little Earth-like world can exist there.
Here's a more dodgy example:
</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> HD 11964 G5 V (mass = 1.125 sol)
Inner HZ edge = 1.562 Au
Outer HZ edge = 3.077 Au
Planets = b
a/Au = 0.229 Au
e = 0.15
Planets = c
a/Au = 3.167 Au
e = 0.3
Configuration = 3
System Habitability Today = 10%
Sustained Habitability = No</pre>[/QUOTE](Please note: I've left out a lot of the more technical data from the tables in the above examples.)
I read the above as showing a G5 V primary with 2 GGs orbiting it, one at 0.229 Au, the other at 3.167 Au. The outer GG's gravitational reach extends back towards the primary star through the HZ's Outer edge at 3.077 Au. This leaves only 10% of the HZ available for our little Earth-like world. I'm pretty sure the Earthlike world would be located close to the Inner edge of the HZ:
</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Inner HZ edge = 1.562 Au
less
Outer HZ edge = 3.077 Au
= width of HZ = 1.515 Au
10% of 1.515 = 0.1515 Au
+
Inner HZ edge = 1.562 Au
= 1.6665 Au</pre>[/QUOTE]So our little Earth-like world is squeezed into an orbit between 1.562 Au and 1.6665 Au from its primary star, as a direct result of the gravitational reach of the outer GG.
Whilst I appreciate the above is very math heavy, the tables at the end of the document are extremely useful for those of us who haven't got the time, resources or inclination to sit and do the math.
"You want to know how far the Mainworld is from the F9 V primary? It orbits at [pick a distance between 1.021 and 2.08 Au] Au and there's a gas giant orbiting the primary at 0.104 Au. Go fill 'er up for free, boys!"
Hopefully useful stuff, and it's all RealWorld (TM) too...
I found this whilst surfing:
Arxiv website
The paper focuses on systems containing gas giants, and looks at how the gravitational "reach" of each system's gas giant(s) might effect an Earth-like world located in the habitable zone.
Basically the paper states that gas giants with large enough gravitational reaches (i.e. that extend into the HZ) will "bump" an Earth-like world in the HZ, increasing the Earth-like world's orbital eccentricity and send it zooming out of the HZ. It also shows that Earth-like worlds can exist in the HZ when there are gas giants in the system whose gravitational reach doesn't extend into the HZ. Finally, the papers shows how much of the HZ is available to an Earth-like world where a gas giant's gravitational reach extends into the HZ. The paper does this by showing the % of HZ available for the orbit of the Earth-like world.
From what I can gather, the paper shows that systems with a "configuration" (third column in from right of tables at end of the document) of "1" or "2" have the best chances of an Earth-like world in the HZ. Systems with a "configuration" of "3" or "4" (there are no "5"s in the tables) have a % of the HZ available for an Earth-like world. Systems with a "configuration" of "6" have no chance of an Earth-like world in the HZ.
I think (although I could be wrong) the "configurations" indicate the arrangement of each system's gas giants, i.e., configuration 6 gas giants have gravity reaches that extend all the way across the HZ, thus affecting any Earth-like world that is/was in the HZ. 3 and 4 indicate shorter gas giant gravity reaches, that only extend partially into the HZ. 1 and 2 indicate gas giants that don't have gravity reaches that come anywhere near the HZ.
Whilst it's an entirely scientific paper (and thus contains some weird and wonderful equations) the tables at the end of the document provide us with the following useful information:
Real world star catalog numbers and names;
Their masses;
The Inner and Outer edge distances of each star's Habitable Zone;
Whether the system is habitable today;
The number of gas giants in the system.
Here are some examples from the tables at the end of the document:
</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> p Cor Borealis G0 V (mass = 0.95 sol)
Inner HZ edge = 1.094 Au
Outer HZ edge = 2.175 Au
Planets = b (i.e. p Cor Borealis b, a gas giant)
a/Au = 0.22 Au
e = 0.04 (= orbital eccentricity of the GG)
Configuration = 2 (i.e. good!)
System Habitability Today = Yes
Sustained Habitability = Yes</pre>[/QUOTE]I read the above as showing that the GG orbits a G0 V star at 0.22 Au with an orbital eccentricity of 0.04. This is well inside the HZ Inner edge at 1.094 Au - the GG's gravity reach doesn't extend into the HZ, so our little Earth-like world can exist there.
Here's a more dodgy example:
</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> HD 11964 G5 V (mass = 1.125 sol)
Inner HZ edge = 1.562 Au
Outer HZ edge = 3.077 Au
Planets = b
a/Au = 0.229 Au
e = 0.15
Planets = c
a/Au = 3.167 Au
e = 0.3
Configuration = 3
System Habitability Today = 10%
Sustained Habitability = No</pre>[/QUOTE](Please note: I've left out a lot of the more technical data from the tables in the above examples.)
I read the above as showing a G5 V primary with 2 GGs orbiting it, one at 0.229 Au, the other at 3.167 Au. The outer GG's gravitational reach extends back towards the primary star through the HZ's Outer edge at 3.077 Au. This leaves only 10% of the HZ available for our little Earth-like world. I'm pretty sure the Earthlike world would be located close to the Inner edge of the HZ:
</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Inner HZ edge = 1.562 Au
less
Outer HZ edge = 3.077 Au
= width of HZ = 1.515 Au
10% of 1.515 = 0.1515 Au
+
Inner HZ edge = 1.562 Au
= 1.6665 Au</pre>[/QUOTE]So our little Earth-like world is squeezed into an orbit between 1.562 Au and 1.6665 Au from its primary star, as a direct result of the gravitational reach of the outer GG.
Whilst I appreciate the above is very math heavy, the tables at the end of the document are extremely useful for those of us who haven't got the time, resources or inclination to sit and do the math.
"You want to know how far the Mainworld is from the F9 V primary? It orbits at [pick a distance between 1.021 and 2.08 Au] Au and there's a gas giant orbiting the primary at 0.104 Au. Go fill 'er up for free, boys!"
Hopefully useful stuff, and it's all RealWorld (TM) too...
