Introduction and Questions about Asteroid Belt/Jovians

[redwood973]

Good evening, everyone.

My name is Steve, I'm 37 and from a small town called Fort Dodge in Iowa (USA). I have no formal education in Astronomy, but have always loved the topic since I was a child (most likely due to having a cousin who was an engineer for NASA who would send me photos and trinkets in the mail from time to time).

I stumbled upon your forum this afternoon and have been enjoying reading many of the threads since finding my way here . My interests will limit my reading and participation to this General Astronomy section of the forum. I may not be able to contribute much to your group, but I will defiantly be stopping by and reading the threads (a lurker, I believe it’s called).

Through my wondering around here I found myself wondering about the asteroid belt and the gas giants. I believe the accepted theory of the belts formation was the inability of the mass present in the belt to form a planetary body due to the effects of Jupiter’s gravity.

Now I was wondering–if Jupiter where much smaller than its actual 318 Earth masses, say closer to Saturn 95 Earth masses, would there still be an asteroid belt, or would we have another terrestrial planet?

Since Uranus (14 Earth masses) and Neptune (17 Earth masses) are considerably smaller, is it a given that there would be another terrestrial planet occupying the orbit of what would have been the asteroid belt if Jupiter were of their mass rather than the 318 it is?

I look forward to your thoughts on this topic.

 

[Drakkith]

Theres no way to tell for certain, as we cannot go back and time and see everything that was there and that happened when the solar system formed. The current mass of the asteroid belt is very small, only 4% of the moon according to the wikipedia article on the asteroid belt. While its very probably that some of the forming mass was ejected from the belt by Jupiter and other bodies when the belt was forming, I'm not sure there would have been enough mass to form anything larger than a moon sized object.

 

[redwood973]

Hello, Drakkith.

Was there an estimate on how much mass was lost from the belt zone? It's only a guess, but I suspect it would be a considerable amount (based on the guess that the mass present in the belt zone would not have been much different from the mass present in the orbits of each of the four terrestrial planets, had the belt zone mass not been cast out by the giants).

I'm really interested in what effect on the belt Juipiter would have if it were smaller, but still a giant. I suspect that had Juipiter been an ice giant, such as Uranus and Neptune, there would be some planetary body in the belts orbit (due to the smaller size of the ice giants, it's not unreasonable to assume such a body in the belt zone would have been larger than 4% of Luna, as the smaller mass of the giant did not result in a scattering of mass the way superjovian Juipter did). But what of a Saturn-sized body at Juipiter's orbit? Would 95 Earth masses be sizeable enough to disrupt planetary formation? Doubtless it would scatter some mass, but would it inhibit planetary formation?

Anymore thoughts on the topic, or any source material anyone knows of?

 

[Drakkith]

Sorry Redwood, I don't know any details on this. I would definitely think a lower mass Jupiter would have caused less mass to be ejected from the asteroid belt. But I don't know how much was there originally or how much was predicted to have been lost.

 

[qraal]

Good evening, everyone.

My name is Steve, I'm 37 and from a small town called Fort Dodge in Iowa (USA). I have no formal education in Astronomy, but have always loved the topic since I was a child (most likely due to having a cousin who was an engineer for NASA who would send me photos and trinkets in the mail from time to time).

I stumbled upon your forum this afternoon and have been enjoying reading many of the threads since finding my way here . My interests will limit my reading and participation to this General Astronomy section of the forum. I may not be able to contribute much to your group, but I will defiantly be stopping by and reading the threads (a lurker, I believe it’s called).

Through my wondering around here I found myself wondering about the asteroid belt and the gas giants. I believe the accepted theory of the belts formation was the inability of the mass present in the belt to form a planetary body due to the effects of Jupiter’s gravity.

Now I was wondering–if Jupiter where much smaller than its actual 318 Earth masses, say closer to Saturn 95 Earth masses, would there still be an asteroid belt, or would we have another terrestrial planet?

Since Uranus (14 Earth masses) and Neptune (17 Earth masses) are considerably smaller, is it a given that there would be another terrestrial planet occupying the orbit of what would have been the asteroid belt if Jupiter were of their mass rather than the 318 it is?

I look forward to your thoughts on this topic.

Hi redwood973

There's a paper which discussed modelling of these very scenarios, but I can't remember the reference. Do a search of either the Internet PrePrint Archive...

http://arxiv.org/"

...or Google or try NASA's Astrophysical Database Server...

http://adsabs.harvard.edu/abstract_service.html"

...all very good reference tools.

 

[redwood973]

Hello, qrall and thanks!

Very good reference indeed! Just need to refine my search a bit--first searched turned up 527,000 hits, but I've gotten it down to about 8,000 (using SAO/NASA). Just a little more fine tuning to go.

 

[Chronos]

My guess is Jupiter, being very massive, inhibited formation of what would have been the fourth planet orbiting the sun. What remains is the asteroid belt.