It’s all about the pebbles.

https://newatlas.com/meteorites-jupiter-childhood/56128/

PermeateFree said:

It’s all about the pebbles.

https://newatlas.com/meteorites-jupiter-childhood/56128/

I’ve done a bit of research on the pebbles in the early solar system, in particular how the pebbles grow by accumulating spherical surface layers.

https://www.nature.com/articles/s41550-018-0557-2

> The standard model for giant planet formation is based on the accretion of solids by a growing planetary embryo, followed by rapid gas accretion once the planet exceeds a so-called critical mass. However, the dominant size of the accreted solids (‘pebbles’ of the order of centimetres or ‘planetesimals’ of the order of kilometres to hundreds of kilometres) is unknown.

Yep.

> Recently, high-precision measurements of isotopes in meteorites have provided evidence for the existence of two reservoirs of small bodies in the early Solar System (Reference 3). These reservoirs remained separated from ~1 Myr until ~3 Myr after the Solar System started to form.

3 million years is a startlingly short time for a planet like Jupiter to form from gas and dust.

We need to follow this up by finding reference 3.

• Kruijer, T. S., Burkhardt, C., Budde, G. & Kleine, T. Age of Jupiter inferred from the distinct genetics and formation times of meteorites. Proc. Natl Acad. Sci. USA 114, 6712–6716 (2017).
  Here it is: http://www.pnas.org/content/114/26/6712.full

> Here, using molybdenum and tungsten isotope measurements on iron meteorites, we demonstrate that meteorites derive from two genetically distinct nebular reservoirs that coexisted and remained spatially separated between ∼1 My and ∼3–4 My after Solar System formation.

I hope they’ve taken into account that the iron meteorites formed really late in the scheme of things. Nanodiamonds formed first, then CAIs (calcium aluminate inclusions), then forsterite and chondrules, then primitive carbonaceous chondrite meteorites, then heat-modified carbonaceous chondrite meteorites, then ordinary chondrites, then stony irons, and lastly iron meteorites. But even so, given that Al-26 has a half-life of only about 730,000 years, that’s well within the timespan we’re talking about. So OK, we can still use iron meteorites to talk about times as short as ~1 My.

> To address these issues and to ultimately determine the timescale of Jupiter’s formation, we obtained W and Mo isotopic data for iron meteorites. These samples are fragments of the metallic cores from some of the earliest-formed planetesimals

Good. Yes.

> CC and NC Iron Meteorites …

I’ll leave it to you to read from here on.