Milky Way Sidelined in Galactic Tug-of-War, Computer Simulation Shows

Milky Way Sidelined in Galactic Tug-of-War, Computer Simulation Shows

The Magellanic Stream is an arc of hydrogen gas spanning more than 100 degrees of the sky as it trails behind the Milky Way's neighbor galaxies, the Large and Small Magellanic Clouds. Our home galaxy, the Milky Way, has long been thought to be the dominant gravitational force in forming the Stream by pulling gas from the Clouds.

A new computer simulation by Gurtina Besla (Harvard-Smithsonian Center for Astrophysics) and her colleagues now shows, however, that the Magellanic Stream resulted from a past close encounter between these dwarf galaxies rather than effects of the Milky Way.

[atsimg]http://files.abovetopsecret.com/images/member/528f3d49c419.jpg[/atsimg]

This plot shows the simulated gas distribution of the Magellanic System resulting from the tidal encounter between the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) as they orbit our home Milky Way Galaxy.

Here's what the Large and small Magellanic Clouds looks like:

www.sciencedaily.com...
[atsimg]http://files.abovetopsecret.com/images/member/32c589e8c533.jpg[/atsimg]

I read that the Milky Way and Andromeda Galaxies are on a collision course with each other, and will "collide" in maybe about 2 billion years or so.

I have heard of the Large Magellanic Cloud before but what I didn't know is that it's really a dwarf galaxy that seems to have barely avoided a collision with our Milky Way and is now traveling along the length of it as shown in the top image. At one point we thought it was in orbit around the Milky Way but now it appears that the large and small Magellanic clouds are just passing by so wave at them when they go by, we will never see them again after they leave (joking a little, it will take many generations for them to disappear from view).

The interesting part of this simulation is the trail those two "clouds" or dwarf galaxies are leaving in their wake can be formed just by an interaction between the two clouds, confirming the assertion that they're not really in orbit around the Milky Way as previously thought was the cause of the trail.

I read these threads about Nibiru which I've never seen any real evidence for, then I see something like this that shows an entire dwarf galaxy almost collided with the Milky Way, so here is real evidence of a cosmic shooting gallery.

Looking at that top image, I have to wonder if the LMC is yet to collide with the outer part of the Milky way? Will it?

The other thing we have to wonder is, are there other objects like dwarf galaxies that are passing through the milky way and might be heading towards us that we can't see, because they are obscured by all the other material already in the milky way?

So maybe our solar system will have a visitor someday and maybe it won't be Nibiru but something else, like part of one of these dwarf galaxies?

Originally posted by Arbitrageur
So maybe our solar system will have a visitor someday and maybe it won't be Nibiru but something else, like part of one of these dwarf galaxies?

There is a theory that our solar system is actually part of another galaxy. Our position in this galaxy is the product of a collision between the Milky Way and Sagittarius galaxies, as per this theory.

For what it's worth I should point out that I think it has been "scientifically" debunked, as it were, but some questions still go unanswered. Mainly why our solar obliquity is 60° to the galactic plane. This angle of our solar system does appear to match Sagittarius if we factor in the deviation from the Milky Way's rotational motion that pulled us away from our supposed point of induction. Meaning that Sagittarius brought us in, dumped us off and we started orbiting the center of the Milky Way.

here is a link describing this theory.
Scientits Now Know: We're From Sagittarius.

Star & Flag Arbitrageur, with 5 cool points, too. I like learning new stuff, and I find this stuff interesting, thanks.

Originally posted by Arbitrageur
I read that the Milky Way and Andromeda Galaxies are on a collision course with each other, and will "collide" in maybe about 2 billion years or so.

I think it is closer to 4 & 1/2 Billion years when our galaxies will collide (I had to look it up) , but who knows .... the time table could change.

Looking at that top image, I have to wonder if the LMC is yet to collide with the outer part of the Milky way? Will it?

I don't know. Can we do something about it if it is a problem? I don't know.

So maybe our solar system will have a visitor someday and maybe it won't be Nibiru but something else, like part of one of these dwarf galaxies?

I'm not afraid of speculation. Space travel may mean/require time travel. Perhaps there are older races from Andromeda and the Milky Way already swapping ambassadors and representatives planning this merger for the future, for all I know. But, I'm a science fiction buff and love the "what ifs".

thanks again for sharing,
ET

Originally posted by Esoteric Teacher
Star & Flag Arbitrageur, with 5 cool points, too. I like learning new stuff, and I find this stuff interesting, thanks.

Thanks, it's nice to know others find it interesting too!

I think it is closer to 4 & 1/2 Billion years when our galaxies will collide (I had to look it up) , but who knows .... the time table could change.

I think the timetable is known pretty well, at least we think so. That 4.5 billion year number may not be technically wrong but it's very misleading, I wouldn't quote that number to a layperson for that reason.

As that Wiki article points out there is some uncertainty about the collision. But if it happens, 2 billion years is when the milky way will start seeing the effects, as this series of images shows (It's from a Harvard website so it might be more informative than the Wikipedia article):

www.cfa.harvard.edu...
[atsimg]http://files.abovetopsecret.com/images/member/378aee1c0056.png[/atsimg]

The last image (see the link for that one) shows that the merger won't really be mostly complete until about 5.5 billion years but if you Google for simulations of this collision you will see that the galaxies actually do a little dance around each other and 2 billion years is when the dance starts, so to speak, so that's what I was referring to. If you "almost" hit another car with your car, the near miss doesn't count as a collision, but as they say "close" only counts in horseshoes, hand grenades, and nukes....it also counts in galaxies too because the tidal forces from the near miss start drastically deforming the shapes of both galaxies.

Here's another source:
news.nationalgeographic.com...

There's also a small chance that our solar system will be swept from its home in the Milky Way and scooped up by Andromeda during an earlier close encounter, in just three-and-a-half-billion years.

The first close contact between the Milky Way and Andromeda will also come sooner than had previously been thought—just two billion years from now, say model creators T.J. Cox and Avi Loeb. Both scientists work at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

So if our part of the milky way gets flung off into Andromeda in just 3.5 billion years, we don't want to be left thinking the collision wasn't supposed to happen for another billion years, right? The Earth will be too hot to support life by then but hopefully we will be inhabiting at least some nearby star systems by then.

I don't know. Can we do something about it if it is a problem? I don't know.

I don't know this for a fact, however I suspect that many of the galaxies in our local group will end up merging. That link I just posted has a good image of the local group.

The most important thing we can do if we want to survive is spread our civilization off the Earth. First, we should colonize another planet or moon in our solar system, so that if all life on Earth is destroyed, people won't be. Second, we need to colonize another star system.

We are the first species we know of that have the ability to avoid our own extinction, like the dinosaurs experienced. So it would be nice if we actually put that capability to good use instead of just sitting here not colonizing any other places in the universe, waiting for something bad to happen to our home planet.

Originally posted by Devino
There is a theory that our solar system is actually part of another galaxy. Our position in this galaxy is the product of a collision between the Milky Way and Sagittarius galaxies, as per this theory.

Thanks for the post Devino, that's interesting. I hadn't heard that theory, and I don't know about the Sagittarius galaxy claim specifically. But what I do know is that there is lots of evidence to support that many of the modern day spiral galaxies are the result of collisions. Here's a good article about that:

Forming the present-day spiral galaxies

Using data from the NASA/ESA Hubble Space Telescope, astronomers have, for the first time, created a demographic census of galaxy types and shapes from a time before the Earth and the Sun existed, to the present day. The results show that, contrary to contemporary thought, more than half of the present-day spiral galaxies had so-called peculiar shapes only 6 billion years ago, which, if confirmed, highlights the importance of collisions and mergers in the recent past of many galaxies. It also provides clues for the unique status of our own galaxy, the Milky Way....

Although our own Milky Way galaxy is a spiral galaxy, it seems to have been spared much of the teenage drama; its formation history has been rather quiet and it has avoided violent collisions in astronomically recent times. However, the large Andromeda galaxy from our neighbourhood has not been so lucky and fits well into the "spiral rebuilding" scenario. Researchers continue to seek out explanations for this.

I'm not so sure about that last statement saying the Milky Way doesn't show evidence of collisions, we don't have such a great view of our galaxy trying to look at it from the inside. So I'm not as confident as they seem to be that our galaxy isn't also the result of collisions of other galaxies.

For what it's worth I should point out that I think it has been "scientifically" debunked, as it were, but some questions still go unanswered.

Mainly why our solar obliquity is 60° to the galactic plane.

Reading that made me wonder, of the 100+ exoplanets we have discovered, how many of those solar system orbits align with our galactic plane? I don't know!

I wasn't able to find anything definitive yet, just a post from a guy who seems to know what he's talking about saying their orientation is pretty much random and in his next post, that the internet is full of nuts claiming otherwise.

www.physicsforums.com...

I'm going to look into that a little bit more as I have time but that's all I was able to find in a quick search. If the orientation is really random, then we can't read too much into the orientation of the plane of our solar system.

Originally posted by Arbitrageur

As that Wiki article points out there is some uncertainty about the collision. But if it happens, 2 billion years is when the milky way will start seeing the effects, as this series of images shows (It's from a Harvard website so it might be more informative than the Wikipedia article):

Thanks for correcting my previously understood misconceptions Yes, the teacher is also a student

I think the whole word "Collision" may be a tad bit confusing. When we think of things colliding and impacting eachother we usually do not equate a "collision" with taking billions of years.

Thanks again Arbitrageur for Sharing the Harvard stuff,
ET

reply to post by Arbitrageur

I'm not so sure about that last statement saying the Milky Way doesn't show evidence of collisions,

Well, we know that the Milky Way has been involved in galactic collisions, Sagittarius being the evidence of at least one such collision. Your linked article states that the Milky Way has avoided "violent collisions". Does this make all known collisions with the Milky Way non-violent?

Reading that made me wonder, of the 100+ exoplanets we have discovered, how many of those solar system orbits align with our galactic plane? I don't know!

This is something I have also wondered about, all of this talk about GRB yet what are the chances of one pointing towards us?

I wasn't able to find anything definitive yet, just a post from a guy who seems to know what he's talking about saying their orientation is pretty much random and in his next post, that the internet is full of nuts claiming otherwise.
...
I'm going to look into that a little bit more...

I haven't found anything really good neither. If you do find something let me know because I have thought about this for a long time now. As for anyone claiming that these orientations are simply random and anyone claiming otherwise are "full of nuts" I would ask these questions.

• Why do galaxies form orbital planes? They are not spherical as one would think in random occurring events but rather flat and spin as one unit.
  
• Why do solar systems form orbital planes?
  
• Why does our Sun rotate in the same direction as the planets orbit, prograde motions?
  
• What is the cause for angular motion, both rotational and orbital? And please don't settle for the big bang excuse. That has been the only answer I can come up with from astrophysicists and I am far from satisfied with that explanation.

Really what I was attempting to find out is if there is a natural tendency to rotate and/or orbit in one preferred direction. Is there a force that causes rotation.
So, from our perspective the Milky Way spins clockwise. Could we expect that stars born here would also spin clockwise and the same for any orbiting planets around these stars?

Originally posted by Devino
Well, we know that the Milky Way has been involved in galactic collisions, Sagittarius being the evidence of at least one such collision. Your linked article states that the Milky Way has avoided "violent collisions". Does this make all known collisions with the Milky Way non-violent?

My guess is that what they are trying to say is that if a bicycle and a tractor-trailer collide, the tractor trailer won't think of it as a violent collision. If he didn't have his radio turned up too loud, he might wonder that that thump was. Saggitarius is a dwarf galaxy so I'm comparing it to the bicycle and the Milky way to the huge truck. Now when two big trucks collide, that's a violent collision, so I guess there have been collisions but maybe not considered violent if they weren't with anything big.

This is something I have also wondered about, all of this talk about GRB yet what are the chances of one pointing towards us?

Slim for just one, but multiply slim chances for one, times the huge number of potential gamma ray bursters and the slim chances of any one pointing at us, become a lot greater.

I haven't found anything really good neither. If you do find something let me know because I have thought about this for a long time now. As for anyone claiming that these orientations are simply random and anyone claiming otherwise are "full of nuts" I would ask these questions.

If we can truly observe the orientation and determine that it's random (yet to be confirmed by my research), that doesn't mean we would necessarily know the answers to any of those questions. But I'll let you know if I find out anything about that.

Regarding what causes rotation, I think it's objects or gas clouds moving past each other, combined with the effects of gravity. Model two objects or gas clouds experiencing a near miss and even if they were going in a straight line before the near miss, there will be some rotation resulting after the near miss, kind of like the simulation of the collision between the Milky Way and the Andromeda galaxies:



I suspect there are other causes too, but I think near misses or collisions are a big reason for rotation.

Regarding the shape, one reason planets are spherical is because their gravity and density makes them that way if they are larger than a certain mass. This is why we see irregularly shaped asteroids but not irregularly shaped planets.

This formula which applies to planets doesn't apply to giant gas clouds which have a low enough density that their spinning motion, forms a disk shape, not a sphere. Have you ever watched the guys in the Pizzaria hand-toss the pizza dough by spinning it to stretch the disk out wider and wider? That's the kind of force that makes the disk shape of solar systems like ours, I think. And I suspect it had a near miss or a gravitation tug from something else to get it spinning. I don't recall reading that anywhere, but it seems logical to me.

reply to post by Arbitrageur

Regarding what causes rotation, I think it's objects or gas clouds moving past each other, combined with the effects of gravity.

I have a problem with the gravity only explanation. I understand the concept of two objects moving past each other causing rotational motions due to gravitational force but this isn't very realistic.

Gas clouds can be light years across and contain trillions of particles and each particle contains its own momentum.
How can gravity alone explain a unified motion in these clouds?
How can gravity alone explain the formation of accretion disks?
How can gravity alone explain the unified rotational motion observed in galaxies?


It's obvious that there is a force present here that is unaccounted for. Call it dark matter/energy, plasma or even Aether but there is something here holding all of this stuff together that gravity alone can not explain. I think that this force might also be the cause of angular motion.

Originally posted by Devino
It's obvious that there is a force present here that is unaccounted for. Call it dark matter/energy, plasma or even Aether but there is something here holding all of this stuff together that gravity alone can not explain. I think that this force might also be the cause of angular motion.

And that is precisely why we are looking for "dark matter", whatever that is.

In fact, what started the idea of dark matter is that the rotation of galaxies isn't explained by what we see and what we think we know. We are assuming the force is gravity and the dark matter is undiscovered mass, but I suppose it's possible there's an as yet undiscovered force other than gravity at work. I think it's occam's razor that makes us lean toward the gravity acting on dark matter explanation, but that doesn't mean it's necessarily correct.

Until we solve the dark matter mystery we have more questions than answers.

Originally posted by Arbitrageur
what started the idea of dark matter is that the rotation of galaxies isn't explained by what we see and what we think we know.

The rotational motions of galaxies are far more complicated than what even dark matter can explain away. The galactic bar in the center rotate at a much faster rate than the spiral arms do and these arms rotate faster than the stars inside do. All of the stars outside of the center rotate at the same rate so all of this stays together. If we imaging this process in motion what we see describes an electric motor, I wish I had an animation to illustrate this. The center propagates energy into the arms which propagate energy into the stars and so on down to the atomic level.

As each of these motions is a different acceleration then each has its own 'inertial mass' and each has its own 'time dilation'. This causes me to think of each of these areas as 'bubbles of time', for lack of a better term. Our solar system is accelerating inside the galaxy and I am sure that this acceleration effect both gravity and time. What happens when we fall outside of the Orion spiral arm spur as it passes us by? As far as I can tell we are on the outer edge of this arm right now.

We are assuming the force is gravity and the dark matter is undiscovered mass,

I guess I have a problem with the whole dark matter/energy thing. The way I understand it is that this was a fabricated element created to try and explain what was being observed. The goal was to explain this in a manner that didn't contradict the known laws of physics yet this explanation has failed to fit the observations. And let's not forget the big question, how does one go about finding invisible matter? Could it be that this unknown force is causing rotational motion and this is what's causing gravity not the other way around.

ADD: Either way we have to come up with a new theory here don't we? Either it is some invisible dark matter or some unknown acceleration/force or something else altogether. Since we must come up with a new theory either way then Ockham's razor doesn't apply here.

I would like to point out the Pioneer anomaly as it is called. I think that this is proof of an unknown force or at least a misunderstanding of the forces that we do know.

well if we collide with Andromeda, then they wont have to travel too far, no?