Galactic orphans.

[vk3ukf]

Hello people,
I am looking to see if it is possible to deduce some constants here, and do a calculation.

Preamble: It seems to be a logical assumption that during the existance of our Solar system, a number of objects would have been ejected from the system, never to return, through close encounters with other bodies.

It would also be logical to assume that any other star systems that had developed planetary systems would also have ejected a number of objects into a galactic orbit.

Sizes of these objects would have to cover a large range, from boulders to Jupiters.

I'm only wanting to consider objects in our own Galaxy, I'm not sure how to think about things being ejected from a Galaxy, or even if it is possible to occur naturally. (I guess it's possible).

So, I have to assume that if this has been stated as having happened in our own Solar system, it has happened to others.
So, the obvious conclusion is, there are in fact a lot of Galactic Orphans floating around, going on a tour of the Galaxy, not gravitationally attached to any particluar star.

A Galactic Orphan passing through our systems Oort cloud, is probably what throws comets into the inner Solar system, or least responsible for the occasional course change.

In my opinion, the idea of a "Rogue Planet" is entirely feasible.

Values required:

Number of objects above 100 km that have been ejected from our own system in its history.

Number of star systems in our Galaxy that would have formed a planetary system. (This value seems to be getting revised up and up recently).

Whatever you can think of that would be pertinent in such a calculation that I haven't thought of and mentioned.

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If an object was thrown out of a system in a direction perpendicular to the Galactic plane it would eventually slow and come back down through the Galactic plane, out the other side, and oscillate back and forth until is was pretty happy staying in the Galactic plane again. The speed of the object as it travelled through the plane would be somewhat astounding.

In short, we (at current levels of detection, keeping 2007 WD7 and other asteroids not found until AFTER they passed us, in mind), wouldn't even see it coming, until it was looming in the sky.

I suspect this is reminding a lot of you about Velikovsky and his book, "Worlds in collision".

I never thought that much about it when I read the book, but now I am.
It just seems to be a logical outcome to what I think I know. :-)

[R.A.F.]

Please state the nature of your conspiracy.

[vk3ukf]

Hello R.A.F.
well, the title on this forum mentions,

Conspiracy Theories (9 Viewing)
Is NASA hiding something? (no) Are there aliens on Mars? (no) Are there rogue planets that will kill us all? (no) Disagree? Post here!

It was this bit that caused me to post here.
Are there rogue planets that will kill us all? (no) Disagree?

I do disagree.

[Swift]

I think the rogue planet part of the conspiracy theories refers to the Planet X nonsense and to the idea that the government knew Planet X was coming and hid this information.

I don't think your idea is such a conspiracy. It might be better to discuss this in Astronomy, you might ask a mod to move it.

As to your idea, I suspect there are "orphans" out there. But, the flip side is space is very big, so I suspect the odds of one coming through our solar system are very small. I don't know the math or data well enough to calculate them.

[vk3ukf]

Roger that folks, I do agree.

I'll ask for it to be moved as you suggest.

[Tinaa]

Moved per OP request. No conspiracy here.

[vk3ukf]

Hi swift,
yes this is true that space IS very big, but I feel this a bit like trying to predict the density of radiation in certain nuclear reations.
Occassionally in a flux an electron gets knocked out of orbit.
Same goes for Solar systems.
There are values for the questions.
How often does a ?? "walk-about" occur?
Have there been "walk-abouts" occur in our lifetimes gone undetected, because we wern't looking?.
Sooner or later, one will be found.
Flying in, "Hellooooo, Sol system, goodbye, Sol system" Wheeeeee.
Sorry. Ha ha.

Just hoping it's a small thing at a distance, and not some lost gas giant.
K.

[01101001]

How often does a ?? "walk-about" occur?
Have there been "walk-abouts" occur in our lifetimes gone undetected, because we wern't looking?.

I think you'll have to define "walk-about" before we can estimate statistics? Is it any-sized body passing anywhere through our solar system? Is it a planet-sized body passing through our neighborhood of the solar system? Is it just a large body? A killer?

Certainly, for instance, if a Jupiter-like gas giant happened to wander near, oh, Venus, or had gobbled up Mars, we would have noticed. If a breadbox-sized object entered our system and passed through Uranus's rings, we probably didn't notice -- or care so much.

Sooner or later, one will be found.

Later probably, much later, for anything that could affect humanity. But, it depends on what you mean. Can you define your question rigorously so someone might give it a shot?

[vk3ukf]

Hi 01101001,
I am trying to concentrate on objects 100km and over.
Anything from 100km to a brown dwarf. If anyone wants to throw in a singularity or two, naked or not, feel free.

How many objects this size and over, may have been ejected by our Solar system?

I used the term "walk-about" loosely to define an object travelling through our system but not gravitationally attached to our Sun. A better term is probably required. Anyone got a nice name invented ready for this?

Now I want to know is the amount of objects over 100km in diameter similar for all systems, or is it going to vary a large amount with the type of system. (I would guess at yes) High metallicity (as discussed elswhere here) stars having more gas giants, and low metallicity having more terrestrial planets.

I would think that the amount of planets formed in the system would have a lot to do with any ejections.

I might not be very good at forming the right questions in one go.
I may have to thrash this out with you all.

We have seen much and been astounded beyond belief in our lifetimes. If someone had told me when I was watching Neil and Buzz, that I would in the near future, see a comet slam into Jupiter, observe Mars with a microscope from several rovers, see the surface of Titan, etc, I wouldn't have believed them.

I predict in the future the sky will be under complete automatic high resolution surveilance. There won't be much getting past us then. I think we need some more telescopes then.
K.

[Matthew]

I would think that the amount of planets formed in the system would have a lot to do with any ejections.

Why? While I would postulate that there would be a level of correlation between the amount of ejected matter and the remaining orbital matter (because more initial matter means more final and more ejected), it is more an indirect correlation than a direct one. Unless I am missing something here?

[NEOWatcher]

I would think that the amount of planets formed in the system would have a lot to do with any ejections.
I wouldn't.

The heavier the object, the less likely it will be ejected, and any ejections will most likely be cataclysmic for the entire solar system.

Plus; a solar system is created from material already in orbit in a galaxy, so it has already settled into it's own isolation.

And; the material forming the planets have been orbiting long before making the planet.


Now; let's take a look at some numbers, and a amateuristic WAG at some of the factors. And, in a very simplistic manner (like the MW in 2d)
Let's say an object of your thinking happens once per solar system.
The avg density of the MW is around 1 star per 25 sq LY's, or 1 per (around) 4 Billion sq AU.
Now, the heliopause contains about 10,000 sq AU. So now we are talking about a 1/400,000 chance of an encounter with a solar system.
The Kuiper belt... 2500 sq AU, or 1/1.6 Million chance.

And this is also making a huge assumption that the average lifetime of the object in deep space is about the average lifespan of a solar system. This was made to keep time and speed out of the equation.

Now; Experts please chime in... this is purely a thought experiment on my part.


I predict in the future the sky will be under complete automatic high resolution surveilance. There won't be much getting past us then. I think we need some more telescopes then.
I would say that is a pretty safe prediction since we keep advancing in those areas now.
Now; When, and with what resolution? That's the difference between dream (ie. "some day") and prediction.

[vk3ukf]

The heavier the object, the less likely it will be ejected, and any ejections will most likely be cataclysmic for the entire solar system.

Agreed, but that doesn't mean that your scenario could not ever have happened either, somewhere.

Is there any knowledge of any star that has been detected as "going against the flow" not in general unison as regard to direction of travel with surrounding stars. That may indicate that it was ejected from a system of peers.

And this is also making a huge assumption that the average lifetime of the object in deep space is about the average lifespan of a solar system.


I would like to also include any earlier star system lifetimes, ours was obviously not included in the first batches, due to the amount of metals we have been supplied with. As to Galactic evolution and its play on the scenario, I would like to leave that out. I don't know much about the reasons between elipticals and spirals and the difference in star ages and metallicities.
Just the Milky Way spiral.


(like the MW in 2d)

I didn't immediately understand this reference, but the sentence afterwards did put it into context, sort of.

I believe that the densities of star systems is very variable and that would also have a big play in matters, our place in space seems a little voidish.

[NEOWatcher]

Agreed, but that doesn't mean that your scenario could not ever have happened either, somewhere.
But; You stated the relationship of likelyhood which is what I was responding to. And; I responded to likelyhood. I did not say it wasn't possible.
Is there any knowledge of any star that has been detected as "going against the flow" not in general unison as regard to direction of travel with surrounding stars. That may indicate that it was ejected from a system of peers.
I would probably use a much stronger statement than "may". Considering the MY has been around so long, I'm sure anything going against the flow would have been re-aligned, or destroyed by now.
I didn't immediately understand this reference, but the sentence afterwards did put it into context, sort of.
Yep; I have a visual, and don't have the technical background, so I was hopeful that someone to fill in the holes. (thus the "thought experiment" comment)

[neilzero]

If there are a million stray objects, with a diameter over 100 kilometers per cubic light year, average in our part of the galaxy: then their average spacing is about 100 billion kilometers. An object traveling a billion kilometers per year with respect to our sun, will take 100 years to cross the average spacing. If so, we are likely past due to have one pass though our inner solar system. We likely would have guessed wrong on what we saw 200 years ago, and those not much over 100 k would likely have not been observed at all at a distance of 1/4 billion kilometers, which could be considered in the inner solar system. If one pased though 200 years ago, it is now about 200 billion kilometers away and has possibly not been detected yet if it is a cold brown dwarf. It will however eventuatly ocult a star and be detected, if we keep analyzing stars that get occulted.
If you think a million per cubic light year is a few too many, you can add in cold neutron stars and cold black holes = negligible accreation disk. While these are less than 100 kilometers, their passage though the inner solar system would seriously perturb at least one planet.
At an average speed of one billion kilometers per year, it would take two billion years to cross our galaxy, so most of them are likely not far outside the galaxy or still in the galaxy. Of course some would be faster and some slower. Neil

[Kaptain K]

1) The universe is not old enough to contain cold neutron stars or cold brown dwarfs.
2) The minimum mass for a brown dwarf is 13 Jupiter masses. The minimum mass for a neutron star is 1.44 solar masses. The minimum mass of a black hole is 3.2 solar masses. If any of those objects came through the inner solar system there wouldn't be an inner solar system and we wouldn't be here to discuss this.