<p>Page 12 of <a href="http://arxiv.org/abs/1601.05438" rel="nofollow">Batygin &amp; Brown (2016)</a> says that a speculative formation scenario can be drawn from recent solar system formation simulations by Bromley &amp; Kenyon and by Izidoro et al. These suggest that the core of a nascent ice giant may have been ejected very early in the solar system's history in order to explain the properties of the observed planets; the formation of Uranus and Neptune was probably accompanied by at least one other ice giant.</p>

<p>The source of the claim you mention is actually an article by <a href="http://www.sciencemag.org/news/2016/01/feature-astronomers-say-neptune-sized-planet-lurks-unseen-solar-system" rel="nofollow">Eric Hand in Science Magazine</a>.  He points out that possibly, to explain why this planet was ejected yet still remains part of the solar system in a much wider orbit, then you need it to have been slowed down by residual gas in the protosolar disk. So I assume the 10 million year is an (uncertain) upper limit on the dispersal of the disk and I would guess the 3 million year lower limit is just how long it takes to form a 10 Earth mass ice giant core at the distance of Neptune.</p>

CC BY-SA 3.0
2016-01-25T22:02:54.097Z
2016-01-26T08:55:57.693Z
2016-01-26T08:55:57.693Z
ProfRob
<p>Konstantin Batygin has estimated that <a href="https://en.wikipedia.org/wiki/Planet_Nine#Origin#Origin" rel="nofollow">if Planet Nine was ejected, it would have been ejected 3-10 million years after the formation of the Solar System</a>.</p>

<p>I'm curious as to how he arrived at this figure. Was it through simulations of the early Solar System, a prediction of the alignments of orbits at that time, or something completely different?</p>

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2016-01-26T07:30:04.010Z
The page you reference appears to be infected with some annoying pop-up/virus. I am unable to locate any source for the statement you are questioning; it does not appear to have been made by Batygin.
ProfRob
CC BY-SA 3.0
2016-01-26T13:13:26.227Z
@RobJeffries I'm so sorry; I thought I had inserted the Wikipedia link, but I must have encountered a  redirect somewhere. Thank you for pointing this out; I should have been more careful.
HDE 226868
<solar-system><9th-planet><estimate>
How did Batygin estimate when Planet Nine was ejected?
HDE 226868
# How did Batygin estimate when Planet Nine was ejected?

(Asked by: username_0 on 2016-01-25)

Konstantin Batygin has estimated that [if Planet Nine was ejected, it would have been ejected 3-10 million years after the formation of the Solar System](https://en.wikipedia.org/wiki/Planet_Nine#Origin#Origin).

I'm curious as to how he arrived at this figure. Was it through simulations of the early Solar System, a prediction of the alignments of orbits at that time, or something completely different?

**Tags:** solar-system, 9th-planet, estimate
> **Comments:**
> **username_1**: The page you reference appears to be infected with some annoying pop-up/virus. I am unable to locate any source for the statement you are questioning; it does not appear to have been made by Batygin.  
> **username_0**: @RobJeffries I'm so sorry; I thought I had inserted the Wikipedia link, but I must have encountered a  redirect somewhere. Thank you for pointing this out; I should have been more careful.  

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## 1 answers

### Answer by username_1 on 2016-01-25. Score: 4 | Accepted answer

Page 12 of [Batygin & Brown (2016)](http://arxiv.org/abs/1601.05438) says that a speculative formation scenario can be drawn from recent solar system formation simulations by Bromley & Kenyon and by Izidoro et al. These suggest that the core of a nascent ice giant may have been ejected very early in the solar system's history in order to explain the properties of the observed planets; the formation of Uranus and Neptune was probably accompanied by at least one other ice giant.

The source of the claim you mention is actually an article by [Eric Hand in Science Magazine](http://www.sciencemag.org/news/2016/01/feature-astronomers-say-neptune-sized-planet-lurks-unseen-solar-system). He points out that possibly, to explain why this planet was ejected yet still remains part of the solar system in a much wider orbit, then you need it to have been slowed down by residual gas in the protosolar disk. So I assume the 10 million year is an (uncertain) upper limit on the dispersal of the disk and I would guess the 3 million year lower limit is just how long it takes to form a 10 Earth mass ice giant core at the distance of Neptune.


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