[X] My Assistant

[ustrax]

Tomorrow at DPS Patryk Lykawka will make a presentation where he points out to the existence of a planet with the diameter of the Earth at 100AU.

I received his answers regarding the work done yesterday, here's some of it (the rest is you know where...):

"This massive planetesimal would be, now, at this moment in the history of the Solar System, orbiting the Sun at a distance of, at least, 100 AU, or, simplifying, 3 to 4 times more distant from our star than Pluto.
A far, massive, transplutonian planet in the Lykawka’s description who remarks the importance that the orbital evolution of this planet may be the key to answer several unexplained enigmas of the Kuiper Belt, among which he points out a few…:
The excitation actually observed in the region between 40 and 50 AU is one, another are the populations of different types of objects in the Belt and their orbital characteristics.
Another two pieces of the puzzle can also be put into place under Patrik work: the Belt’s truncated region in the 48 AU region and its small total mass."

What's your opinion regarding this?...
According to him this is not like Planet X, his study even erases Planet X from the map...

EDITED: "Aernus" is the name I'm using, it was the divinity of the Zoelae, a pre-historic tribe that lived in the most remote corner of my country...

[Greg Hullender]

MSNBC is running a story on this today:

http://harbor.scitec.kobe-u.ac.jp/~patryk/...a-Planetoid.pdf

Apparently Patryk has a new paper in the Astrophysical Journal today, although I can't find a link to it on his site:

http://harbor.scitec.kobe-u.ac.jp/~patryk/index-en.html

My biggest question, though, is why he thinks it would only be a "plutoid," since he seems to be describing a very large (Earth-diameter, but 1/3 mass) object well outside the Kuiper Belt -- something that almost certainly would have cleared its orbit.

--Greg

[Alan Stern]

MSNBC is running a story on this today:

http://harbor.scitec.kobe-u.ac.jp/~patryk/...a-Planetoid.pdf

Apparently Patryk has a new paper in the Astrophysical Journal today, although I can't find a link to it on his site:

http://harbor.scitec.kobe-u.ac.jp/~patryk/index-en.html

My biggest question, though, is why he thinks it would only be a "plutoid," since he seems to be describing a very large (Earth-diameter, but 1/3 mass) object well outside the Kuiper Belt -- something that almost certainly would have cleared its orbit.

--Greg

At Pluto's orbit, Earth would not be a planet by IAU standards. Silly, I know. At 100 AU, a several Earth mass object would be disqualified. This is a consequence of the zone clearing criteria which biases what is and is not a planet by distance-- so that objects that are planets at 1 AU like Earth are not planets at 30 AU. You know what I think of this. Now for a prediction: It shall fall before NH reaches Pluto. Too many people are figuring it out. Google "Great Planet Debate."

-Alan

[Greg Hullender]

At 100 AU, a several Earth mass object would be disqualified. This is a consequence of the zone clearing criteria which biases what is and is not a planet by distance

But the Kuiper Belt ends at 55 AU, right? Why wouldn't an Earth-sized object at 100 AU be a planet, provided it orbited in splendid isolation?

Now for a prediction: It shall fall before NH reaches Pluto.

I wouldn't be surprised if results from Pan-STARRS and/or LSST will force a radical rethink, and I note first light for LSST is scheduled for about the same time as N reaches Pluto.

But the real reason I posted here was to see a) if anyone has a link to the actual paper and how serious one ought to take it.

--Greg

[JRehling]

But the Kuiper Belt ends at 55 AU, right? Why wouldn't an Earth-sized object at 100 AU be a planet, provided it orbited in splendid isolation?

I guess the thought would be that that can't happen. For an Earth-sized object to be at 100 AU, the stuff for it to accrete out of has to be out there at about 100 AU. It couldn't have formed somewhere else and then made its way out there and just stopped unless there were something bigger out there. (A highly felicitous impact that significantly changed its orbit could do so, providing it didn't blast enough stuff off to once again reject the axiom.)

The period of an object at 100 AU is 1000 years. The volume of space around its orbit proportional to that of Earth is a million times as great. I'm certain the Earth hadn't cleared its orbit in 4.5 million years (the impacts on the Moon make that clear -- not by a long shot). So there's no reason to suspect that the "Early Heavy Bombardment" would even be over at that distance. Unless there wasn't enough stuff there for an Earth-sized object to accrete.

[Alan Stern]

I guess the thought would be that that can't happen. For an Earth-sized object to be at 100 AU, the stuff for it to accrete out of has to be out there at about 100 AU. It couldn't have formed somewhere else and then made its way out there and just stopped unless there were something bigger out there. (A highly felicitous impact that significantly changed its orbit could do so, providing it didn't blast enough stuff off to once again reject the axiom.)

The period of an object at 100 AU is 1000 years. The volume of space around its orbit proportional to that of Earth is a million times as great. I'm certain the Earth hadn't cleared its orbit in 4.5 million years (the impacts on the Moon make that clear -- not by a long shot). So there's no reason to suspect that the "Early Heavy Bombardment" would even be over at that distance. Unless there wasn't enough stuff there for an Earth-sized object to accrete.

..Simpler than that. The IAU definition is about whether the object *has* cleared its zone. At 100 AU, in fact, even at 30 AU, an object of Earth's mass cannot do the job in the age of the solar system. It's just physics. It can't. Therefore, in the IAU's view, an Earth mass object at 30, 50, 100, or farther out is not a planet. And with that absurdity alone (never mind the trash orbiting with planets, never mind Pluto crossing Neptune's orbit, never mind the "voting" by 4% of the IAU, etc etc.), the IAU planet definition fails the most basic test-the one that keep people from laughing at it.

-Alan

[dvandorn]

..Simpler than that. The IAU definition is about whether the object *has* cleared its zone. At 100 AU, in fact, even at 30 AU, an object of Earth's mass cannot do the job in the age of the solar system. It's just physics. It can't.

Glad I finished reading the thread before responding, 'cause that's the exact point I was going to make.

You have to remember, everybody, that the Kuiper Belt is a (likely spherical) shell of bodies, not the remains of the originally super-flat accretion disk. We're out past the disk, where accretion followed different rules, and may still be occurring.

That volume of space contains so many bodies in so many trajectories that don't cross each other for billions of years at a crack, that even a gas giant would have a hard time clearing it all out in the 4.5 billion years the Solar System has existed, much less an Earth-sized planet. It's simply a function of volume -- correct me if I'm wrong, someone, but doesn't the volume of the Kuiper Belt exceed the volume of the entire Solar System from Neptune on in? And unlike the "main" system, which occupies a pretty flat plane (thereby limiting its useful volume when discussing neighborhood-clearing), the more spherical nature of the Kuiper Belt increases the volume to be cleared -- well, literally astronomically.



-the other Doug