[BUG][FIXED] Earth's axis and argument of obliquity & other quick questions

[cavok84]

I wasn't able to find a thread on this topic, hopefully this isn't a duplicate.

1.) *Possible Bug
 When running the default Solar System simulation, Earth's axis is set to 23.4 degrees obliquity (no problem there) and the argument of obliquity is set to approx. 167 degrees. As earth completes its revolutions around the sun the argument of obliquity does not change but perhaps a degree or two.

When creating my own simulation and placing earth around a parent star, the axis obliquity is still 23.4 d, but the argument of obliquity changes with respect to earth's position in its orbit (it sweeps the entire range of the slider).

Since the definition of argument of obliquity is: where in the orbit the rotation axis points, it's a bit confusing to me which behavior is correct. I suppose it depends to what ' the orbit' is actually referring to (i.e., orbital velocity vector or some planar view of the orbital path giving a coordinate value).

Is there anyway to change the behavior of the axis besides just changing the angle of obliquity? If I wanted to keep Earth's axis at an angle of 23 degrees, but allow the axis to 'swing' with the orbit (the effect being that it would eliminate seasonal change), can I do this by manipulation of the argument of obliquity?

In the initial question, both cases resume their initial behaviors after any manipulation of argument of obliquity (i.e., if I change the value in the Solar System Sim, it remains fixed-- if I change it during a custom sim, it resumes a sweeping change in value).

2.) Is there anyway to increase/decrease the intensity of solar winds experienced by planets around a star?

3.) Any plans to update the kinetics of impactors so that mass and velocity are accurately modeled? Right now even a slow pyramid of Giza causes nation sized craters.
4.) With the super nova visual updates, any plan to more accurately model the differences between type IA, type II as well as the selected yield input. It's difficult to tell if changes to the yield do anything.


I'm still really enjoying the simulation, thanks!

Thanks

cavok

[Jar]

Thanks for the detailed descriptions and good questions!

1) I had to check in with the team on this one. It turns out there is a bug here, but it's a little different than expected. The short version of the story is that the behavior of Argument of Obliquity for objects in the default Solar System (it applies to all, not just Earth) is correct. And you can get this correct behavior with placed objects if you just increase the eccentricity beyond any 0. The bug lies in an issue with objects given a perfectly circular orbit. So just increase eccentricity and it should be fine. Of course, we're looking into fixing this underlying issue, and also rewording the tooltip (and the property itself) for more clarity and accuracy.

2) You can adjust the magnetic field for a planet, adjust properties of the star, or you should be able to toggle it completely in Sim Settings > Fragment Creation > Volatiles > Solar Wind Loss. That might not be exactly what you're looking for, but those are the current factors.

3) Definitely. Crater size is actually more limited by visual representation than the physics right now, which you can read a bit about here (see section 3): http://universesandbox.com/blog/2017/09/cassini-limitations/

4) In the future, yes. Right now the colors are based on optical images of supernovae, but they are not yet connected to progenitor properties or nova type. These properties are used to determine remnants (and may affect a bit more that I'm not privy to), but the short of this is that we will improve the overall relation here when we have our new stellar evolution model implemented.


Hope this helps!

[cavok84]

Thanks again for the detailed and timely response Jar (I've inflicted these types of questions upon you before)

In response to your explanations:

1.) That is good to know, and clears up something that was causing me quite a bit of confusion, and which led to some late night astronomy research which wasn't fruitful.

2.) That partially helps, but mainly I was wondering if, for example, specific stellar traits within the sim (e.g., luminosity, type of star, star's magnetic field, rotation rate) affect or could be modified to affect the stellar wind strength and rate at which a planet with a given mag field would be eroded.

3.) Thanks

4.) I figured as much, and this probably makes my question moot. But, if I wanted to detonate a supernova near a solar system and observe the heating and erosion effects, it doesn't seem that yield is really affecting anything. This also holds for type1a and type II, which would have substantially different compositions (like one being composed mostly of particulate matter, another being in the EM and neutrino).

I also noticed, with white dwarfs) if you set the star to explode with the tool vs adding hydrogen to the star, you get two different types of super nova (one being correct with no remnant and the other leaving a remnant of higher mass).

I figured this will be addressed in future updates.
thanks

[cavok84]

Jar or whomever,

Was wondering if you could take a look at this quick question. Thanks!

2.) That partially helps, but mainly I was wondering if, for example, specific stellar traits within the sim (e.g., luminosity, type of star, star's magnetic field, rotation rate) affect or could be modified to affect the stellar wind strength and rate at which a planet with a given mag field would be eroded.

[Jar]

Sorry for the long delay! Yes, luminosity/temperature affect the strength of stellar winds.

[cavok84]

Thanks and no problem!