Wonderful topic, and one I wish I had a day to contribute and read comments thoughtfully. Great work by the OP and the recent information, although
tenuous in our exact understanding due to SAG Deg being discovered in 1994, is the reality we now see that we are in a relationship with an interloper
I did a lot of illustration for different astronomy orgs and publications before the discovery was confirmed and accepted, so all my work eventually
became obsolete, which is a good thing. It shows our understanding and observational is evolving.
Below is an illustration of our local group with delineated distances. We did not see SagDEG behind the Sagittarius stellar density of our galactic
core, and still cannot see it clearly due to this, so it is not in this illustration, but would be like the Magellanic clouds, (LMC SMC), but closer,
smaller and more diffuse. The arms so diffuse you can only see remnants in star density imaging from our location.
You can see how larger galactic structures attract smaller ones in this. SagDEG has been absorbed mostly, but has been orbiting the Milky Way for many
orbits, It's closest at about 50,00 LY from SagA, the center of our galactic Core.
It is hard then to speculate on and if our particular stellar cluster was from SagDEG originally. Such an event would be hundreds of millions of years
past, and long since become a "naturalized" citizen of the milky way.
Ancient Sanskrit texts in India, largely found to be accurate in its numbers, volumes and distances thousands of years before modern astronomy, tell
of our solar systems orbit of the core several times.
Called the "Yugas", they outline ages of our planetary life in many hundreds of thousands of years, and tell us also of an eccentricity where in our
Aphelion and Perihelion, or closest and furthest point to the center, we experience a different awareness. Orbital eccentricity is the off center
point of orbit also.
Apsides 1) Apoapsis; 2) Periapsis; 3) Focus
We are in the Kali Yuga, the apsis, or the point of greatest distance of the foci of the elliptical orbit. We are moving in to the Dwapara Yuga,
inbound and now getting closer. Point being, if the record from ancients predating our current cycle of civilization on this planet is accurate, we
might be original, and not from SagDEG. The Hopi say we are 4th world moving to 5th. Maybe they have the records deep in their sacred repository to
back this up too?
As far as our position on a theoretical plane of the galaxy, we are always moving away and towards and pass up and over, under and up the plain every
few thousand years. In this illustration we can see how we would look if our planetary track was lit as we oscillate in our orbit. Notice the very
slight curve of the sun? That would be the oscillatory point weaving up and down along the orbit.
Everything is a sine wave. Amplitude and frequency determining by the mass and speed and relationship to the larger mass. In this case the Milky Way
core. This might show in visual terms how all objects move in a stationary relationship to each other while also being influenced by other nearby
masses and solar and other particle space winds, gases and forms of space "friction". All effects all.
I would like to illustrate and animate in 3D the SagDEG interloping event to current and project forward. I wish someone would give me a grant to do
that. You can do that on small systems now. No super Cray is needed.
The stretched arms of a galaxy being ripped by larger galaxies when exposed, are called Rat Tail galaxies. In this illustration, you can see some
galaxies arms being ripped and stretched, then absorbed into the larger galaxies. Timothy Ferris has a great picture book called Galaxies, that
explains and shows how that dynamic effect works. We get very interesting galactic formations from such events.
It is a common event in galactic evolution. Galaxies attract, then absorb, or can actually decimate one another completely, like a car wreck, throwing
fractions and gravitationally cohesive strings of debris millions of light years from an event. Flung into the intergalactic abyss. The LMC and SMC
might be stabilized crumbs left over from other impacts or just smaller attracted entities to the Milky Way.
The Andromeda Galaxy, thought to have been the biggest in our local group, is now thought to be smaller than our Milky Way, and is moving towards us
and will impact us in 3-4 billion years.
Science has waffled about such events, saying that component distribution of one galaxy and another are so far apart that nothing will touch as they
pass through one another. Others then said otherwise, and again back to the dispersion being too great. OK in theory, but it is misleading because
there are gravitational and other fields that will impact as well. Collisions of stars and planets are not out of the realm of possibility. We have
observed as much in other galactic events. Even core impacts. THAT would be a show of shows. Remote view that however if you know whats good for you.
Thanks again to the OP. I eat this stuff for lunch