For those curious, 9.7 g/cm^3 would roughly match the densities of Thulium (9.321), Bismuth (9.807), Moscovium (>9.807), Lutetium (9.84), or Lawrencium (>9.84). Several of those are short-lived radioactive elements, however.
Going up the scale slightly are Actinium (10.07), Molybdenum (10.22), and Silver (10.501).
My suspicion is that there's possibly a core of Lead (11.342) or Thorium (11.72) (both fairly abundant on Earth, and stable), though Mercury (13.5336) and Tungsten (19.25) give some interesting possibilities, surrounded by a crust (or ocean) of less-dense materials.
> There's nothing physically impossible about either of those potential formation mechanisms, but both require a series of unlikely events. The Universe is big, and those things probably happen somewhere…
The universe has so many galaxies, with so many stars, with so many planets, that the odds practically demand these outlier results. We should stop being surprised at them.
Astronomers and astrophysicists need a new law of discovery, something like this: “Every possible astrophysical body already exists somewhere in the universe.”
Going up the scale slightly are Actinium (10.07), Molybdenum (10.22), and Silver (10.501).
My suspicion is that there's possibly a core of Lead (11.342) or Thorium (11.72) (both fairly abundant on Earth, and stable), though Mercury (13.5336) and Tungsten (19.25) give some interesting possibilities, surrounded by a crust (or ocean) of less-dense materials.
Oh, and surface temperature is ~1,200°C.
Quite a conundrum.
Elements listed by density (at standard temperature & pressure: 100 kPa & 0°C): <https://www.thoughtco.com/elements-listed-by-density-606528>