(Paper) Evidence of a Jovian Mass Solar Companion in the Oort Cloud? Options

[Greg Hullender]

Presuming 20,000 AU, to get there in twenty years would require an average speed of 4740 km/s.

Note that 10,000 AU is about two light-months, and 30,000 AU is about half a light-year.

We're talking really, really far here.

--Greg

[Stu]

Great, something ELSE to add on to our Solar System Scale Model... !

[PFK]

Great, something ELSE to add on to our Solar System Scale Model... !

At your scale, 20k AU = 340km. According to GoogleEarth, Kendal Castle to Wembley Stadium 348km. Bingo!

[Stu]

Brilliant! Thanks PFK, you just scribbled one item off my To Do list for me!

[Big_Gazza]

Not wanting to inject controversy into this thread but if Tyche does indeed exist, would the current IAU "rules" result in this object being considered a planet or a "dwarf"? Its a good assumption to believe the object will have reached hydrostatic equilibrium and be a spheroid, but has it cleared its neighbourhood of debris and minor objects?

Wouldn't it be ironic (hilarious) if Sols largest companion was classified by IAU as a dwarf planet due to a technicality?

[brellis]

Wouldn't Jupiter have to be upgraded to "Failed Star"?

[Hungry4info]

I interpret the rule to mean that the object has to gravitationally dominate its region of space. Thus Earth, Jupiter, and Neptune are still planets, as would be "Tyche."

[Vultur]

What is the total mass of the Oort Cloud? I'm pretty sure it is vastly less than 1 Jupiter mass (as supposedly Jupiter outweighs everything else in the System combined, except the Sun) in which case this object would (as I understand it) be considered dominant in its region, as it outweighed all the debris in its orbit (as, say, Ceres doesn't.)

[nprev]

I wouldn't be surprised it's vastly less than an Earth mass...probably less than even that of the Moon. Lotta snowballs out there, not much rock.

[Greg Hullender]

I see it estimated anywhere from 40 Earth masses to as little as 1.

Lots of Oort, not so much cloud. ;-)

--Greg

[brellis]

It gets a little confusing to hear about the Voyagers approaching one type of solar system boundary, while the Oorties are so much further out there!

[dmuller]

What's the Hillsphere of the Sun?

[centsworth_II]

What's the Hillsphere of the Sun?

From this quick Google grab:
"If it is agreed to assume a Hill sphere for the boundaries of the solar system [230,000au],
it is found that these boundaries extend to the nearest stars. However, stable motion of the
planets (with direct motion) probably is possible only within the solar gravitational sphere. [4500au]"

[nprev]

I was going to ask why the radius of the Sun's Hill sphere would have to be "assumed", but then I found this calculator to approximate it. Since it involves the masses of two bodies, I guess that a sufficiently massive planet could be in solar orbit at a considerable distance (much greater than I'd thought possible).

[centsworth_II]

Looking back to the previous page (621) to the page I link (622), It looks like the two bodies used are the sun and the whole galaxy. The major assumptions are the mass of the galaxy and assuming that mass to be concentrated at the center of the galaxy. I wonder if more recent calculations deviate much from this one.