- 16 Αύγ 2020, 21:43
#659627
https://arstechnica.com/science/2020/08 ... e-instead/A series of unlikely events
So, there seems to be mass, but where did it come from? The planet would have to be something like 300-1,000AU from the Sun (for reference, Neptune’s orbit is just 30AU), where there is very little rock or gas. Simply put, a planet could not form out there. One possibility is that the planet formed closer the Sun and was ping-ponged out there by interactions with one or more of the gas giants. However, to stabilize at a distant orbit, a passing star (or something similar) is required, which seems unlikely. The remaining option is that our Sun captured a freely wandering planet.
But wanderers need to have been expelled from their own solar system, meaning that most of them are moving at a fair clip. Hence, the chance of capturing such a planet in the required orbit is low, although not impossible.
The new paper argues that, if we are looking at a low-probability event, why not a primordial black hole? Primordial black holes might have formed shortly after the Big Bang. And, unlike black holes formed from collapsing stars, they could have masses ranging from tiny (10µg) on upwards. That means there should be a few with the right mass range. How many is a matter of speculation.
Drawn in by the idea, the researchers started rolling d20s: they set primordial black holes to an arbitrary low number and then concluded that capturing a black hole is about as likely as capturing a wandering planet.
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