3 ms·

Do we actually know what would happen to 73 earth masses of rock? Maybe common elements become more dense under immense gravitational pressure.

by p1mrx 3y ago

dredmorbius 3y ago
That's what I'm wondering, and it's well past my competence level. I would like to see what people who do know what they're talking about think might be the case, and what experimental / observational basis they have for thinking that. Based on understanding of the Earth's inner core, which is thought to be comprised of iron-nickel, at a density of ~13 g/cm^3 at its centre, under 330--360 GPa (3.3 -- 3.6 million atmospheres). Iron and nickel have densities of 7.8 and 8.9 g/cm^3 at STP. I'm not sure what NiFe's STP density is, but suspect it's well below 13 g/cm^3, which would suggest density roughly doubles at those pressures. How much further solid matter compresses with 73x greater mass (so ... 73x greater pressure? Are we talking 24,000 -- 26,000 GPa?), I don't know. There's also the question of other phase-changes. TFA discusses water as "a high-pressure solid". If I'm reading this phase-diagram correctly, probably as Ice X, "Proton-ordered symmetric ice": <https://en.wikipedia.org/wiki/Ice#/media/File:Phase_diagram_of_water.svg https://en.wikipedia.org/wiki/Ice#/media/File:Phase_diagram_...> <https://en.wikipedia.org/wiki/Ice#Phases https://en.wikipedia.org/wiki/Ice#Phases> Wikipedia's high-pressure physics article notes that diamond anvils are good to about 1,000 GPa (approaching the range of interest here), and that shockwaves have registered over 100,000 GPa. So we could in theory recreate conditions near TOI-1853 b's core, at least momentarily. <https://en.wikipedia.org/wiki/High_pressure https://en.wikipedia.org/wiki/High_pressure> Another limit I'm aware of is electron degeneracy, where atoms are compressed beyond the limits of their electron shells. This occurs in white dwarfs, up to the Chandrasekhar limit (1.44 solar masses). What I don't know is that the minimum pressure required is, though I suspect 73 Earth masses is insufficient. The Wikipedia article discusses Fermi temperature rather than pressure: <https://en.wikipedia.org/wiki/Electron_degeneracy_pressure https://en.wikipedia.org/wiki/Electron_degeneracy_pressure> More on that: <https://en.wikipedia.org/wiki/Fermi_energy#White_dwarfs https://en.wikipedia.org/wiki/Fermi_energy#White_dwarfs> (I know some of the words, I don't really follow the discussion however.)

Do we actually know what would happen to 73 earth masses of rock? Maybe common elements become more dense under immense gravitational pressure.

by p1mrx 3y ago

Do we actually know what would happen to 73 earth masses of rock? Maybe common elements become more dense under immense gravitational pressure.

dredmorbius 3y ago

That's what I'm wondering, and it's well past my competence level. I would like to see what people who do know what they're talking about think might be the case, and what experimental / observational basis they have for thinking that. Based on understanding of the Earth's inner core, which is thought to be comprised of iron-nickel, at a density of ~13 g/cm^3 at its centre, under 330--360 GPa (3.3 -- 3.6 million atmospheres). Iron and nickel have densities of 7.8 and 8.9 g/cm^3 at STP. I'm not sure what NiFe's STP density is, but suspect it's well below 13 g/cm^3, which would suggest density roughly doubles at those pressures. How much further solid matter compresses with 73x greater mass (so ... 73x greater pressure? Are we talking 24,000 -- 26,000 GPa?), I don't know. There's also the question of other phase-changes. TFA discusses water as "a high-pressure solid". If I'm reading this phase-diagram correctly, probably as Ice X, "Proton-ordered symmetric ice": <https://en.wikipedia.org/wiki/Ice#/media/File:Phase_diagram_of_water.svg https://en.wikipedia.org/wiki/Ice#/media/File:Phase_diagram_...> <https://en.wikipedia.org/wiki/Ice#Phases https://en.wikipedia.org/wiki/Ice#Phases> Wikipedia's high-pressure physics article notes that diamond anvils are good to about 1,000 GPa (approaching the range of interest here), and that shockwaves have registered over 100,000 GPa. So we could in theory recreate conditions near TOI-1853 b's core, at least momentarily. <https://en.wikipedia.org/wiki/High_pressure https://en.wikipedia.org/wiki/High_pressure> Another limit I'm aware of is electron degeneracy, where atoms are compressed beyond the limits of their electron shells. This occurs in white dwarfs, up to the Chandrasekhar limit (1.44 solar masses). What I don't know is that the minimum pressure required is, though I suspect 73 Earth masses is insufficient. The Wikipedia article discusses Fermi temperature rather than pressure: <https://en.wikipedia.org/wiki/Electron_degeneracy_pressure https://en.wikipedia.org/wiki/Electron_degeneracy_pressure> More on that: <https://en.wikipedia.org/wiki/Fermi_energy#White_dwarfs https://en.wikipedia.org/wiki/Fermi_energy#White_dwarfs> (I know some of the words, I don't really follow the discussion however.)