The Oort cloud as rival to the sun ?

[billslugg]

1.9 times the mass of the Earth with an order of magnitude uncertainty is essentially the same as 5 times.
Both are trivial compared to the mass of the Sun.
Late heavy bombardment was possibly due to a gas giant migrating through an asteroid belt. Perhaps a star passing through the Oort cloud.

 

[Catastrophe]

Both are trivial compared to the mass of the Sun.

Yes, as I stated. Glad you agree.

I thought we were discussing the Oort cloud today - not 3.8 billion years ago?

Cat

 

[billslugg]

No, the original post postulated the existance of the Oort Cloud and its influence on the planets during the formation of the Solar System.

 

[Catastrophe]

the original post postulated the existance of the Oort Cloud and its influence on the planets during the formation of the Solar System.

We have no way of knowing about that. Please advise any contra evidence. Especially in relation to coincident time frames.

Cat

 

[billslugg]

What we have are three groups of objects, the Oort Cloud the Scattered Disc Objects and the Kuiper Belt. The three groups lie at different distances and have different inclinations. Modelling by Levison (2020) suggests 90% of the Oort Cloud is made of comets captured by the Sun while it was still in its birth cluster. More recent modelling, Siraj/Loeb (2020), shows how capturing from other stars addresses the observed ratio of the number of objects in the Oort Cloud and the Scattered Disc Objects.

 

[Catastrophe]

With respect, it is all Modelling . . . Modelling . . . Modelling.

All maths and no observations (in the presumed Oort cloud).

Yes, we see the comets when they get 'here', but never in their assumed home land.

Why not just settle for "there are many bodies at great distances from the Sun. Some are diverted to appear to us as comets".

Would you not agree that the division into short term and long term is somewhat arbitrary?

Cat

 

[Catastrophe]

Short-period comets take less than 200 years, and long-period comets take over 200 years, with some taking 100,000 to 1 million years to orbit the Sun. The short-period comets are found near the ecliptic, which means they are orbiting the Sun in same plane as the planets.
Comets, the Kuiper Belt and the Oort Cloud

The short-period comets are found near the ecliptic, which means they are orbiting the Sun in same plane as the planets. The short-period comets are thought to originate in the Kuiper Belt, an area outside Neptune's orbit (from about 30 to 50 AU) that has many icy comet-like objects. The long-period comets tend to have orbits that are randomly oriented, and not necessarily anywhere near the ecliptic. They are thought to originate in the Oort cloud. The Oort cloud has never been observed, but is believed to have at least 10^12 icy objects located between 3000 AU and 100,000 AU in a spherical distribution around the Sun.

The Oort cloud has never been observed . . . but is believed to . . .

Cat

 

[billslugg]

I did not make any statements of fact. I said it is "suggested" that such and such is/was the case. Until we can get better data, modelling is the best we've got.
The division between short term and long term is not arbitrary. Short Term comets reside in the ecliptic while Long Term comets are distributed spherically.

 

[Catastrophe]

I was referring to:

short-period comets take less than 200 years, and long-period comets take over 200 years,

Bold in original. not mine.

For the rest, please see post #32 which already contained such elaboration.

Cat

 

[Catastrophe]

This is the title: The Oort cloud as rival to the sun ?

This is my point:

The Oort cloud has never been observed . . . but is believed to . . .

I submit that the answer to OP's question is: No. The Sun has been observed and measured - the Oort cloud (if it exists at all} has not.

Cat

 

[billslugg]

Yes, Oort Cloud is only assumed to be there, but we have very good evidence given the number of objects that fall from it.

 

[Catastrophe]

Yes, Oort Cloud is only assumed to be there, but we have very good evidence given the number of objects that fall from it.

Bill, I understand what you are saying. I would rather express it as:
A number of objects are diverted to our region of the Solar System, from its furthermost regions.
Many of these objects are termed comets, as they develop a tail when nearing the Sun.

Cat

 

[billslugg]

I don't understand your reluctance to call it a cloud. There are a certain number of objects coming from some sort of reservoir, this cannot be disputed. In order to produce the observed flux there must be a certain number out there. They cannot develop out of the vacuum. They cannot be coming from interstellar space as their orbits are not hyperbolic. What other alternate possibilities are there that "cloud" does not allow for?

 

[Catastrophe]

Bill, a cloud implies some sort of boundary. I see more an uneven random distribution. Certainly nothing like a puffy white 'thing'. Again, reservoir implies some sort of boundary. Since we have never seen any of these objects in situ, how can you possibly deny a random distribution.
You may have seen the suggestion that Oort 'clouds' can overlap, especially where stars are relatively close (as in galaxy centres). I see random distributions easier to merge than 'clouds'.

This takes care of the rest of your post, the tone of which I do find rather overbearing. I am sure that this was not your intention.

Cat

cloud
noun

1. a visible mass of condensed watery vapour floating in the atmosphere, typically high above the general level of the ground.
"the sun had disappeared behind a cloud
2. used to refer to a state or cause of gloom, suspicion, trouble, or worry.
"the only cloud on the immediate horizon is raising a mortgage"

reservoir
noun
a place for storing liquid, especially a natural or artificial lake providing water for a city or other area

 

[Catastrophe]

I rather like this description:

Might the better description be: The "Oort cloud" is (perhaps) a very loose aggregation of objects which exist at great, even (perhaps) immeasurable distances from the Sun. The "Oort cloud" has never been observed, but is inferred from the sporadic appearance of comets. In some cases, "Oort clouds" of different stars may even overlap.

Cat

 

[Wolfshadw]

I think this thread has gone far enough.
Thank to all who have contributed.

Wolfshadw
Moderator