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My layman-scifi-loving hypothesis is that its not a planet that we are looking for but the remnants of the novae which birthed the solar system. this star core

My layman-scifi-loving hypothesis is that its not a planet that we are looking for but the remnants of the novae which birthed the solar system. this star core is likely mostly iron and other heavier elements, and as such is incredibly dense. It will probably be a super earth only a few times the Earth's radius but with mass over 10x that of earth. While detecting gas giants is easier due to their infrared signature, one such dense star core in (or beyond) the Oort cloud would be practically invisible to us in the infrared searches and using starlight occlusion (due to its much smaller size).

newsbinator 8y ago
What's the best way to detect a massive iron ball in dark space? Can we ping it with radio waves?
aruggirello 8y ago
I'm afraid there are no 'wild star cores' in the Solar System backyard. A supernova remnant would either be a white dwarf, or a city-sized neutron star (possibly a black hole) with a mass larger than that of the Sun. The latter could go undetected, but can be safely excluded since in that case it would be the Solar System actually orbiting it (or anyway being affected by it - the minimum mass for a neutron star is ~1.4 Sol, and a black hole would be even larger), and we already know the Sun's path around the Milky Way to a certain extent. OTOH a white dwarf would likely take billions of years to cool off and we would be able to spot it - so no, only planetary bodies may still be lurking there undetected. Edit - clarification.
- KnightOfWords 8y ago
  > A supernova remnant would either be a white dwarf... A small correction, white dwarfs are not produced by supernovae but by main sequence stars running out of fuel.
kijin 8y ago
You don't even need "a few times the Earth's radius." Assuming identical density, mass is proportional to the cube of radius. Earth already has the highest density of all the large objects in the solar system, at about 70% of the density of solid iron. An object that has the same density as Earth, but with 2x the radius, will have the mass of 8 Earths. If the object was made of solid iron, it will have the mass of over 11 Earths. That's a lot of mass in a small area.

newsbinator 8y ago

What's the best way to detect a massive iron ball in dark space? Can we ping it with radio waves?

aruggirello 8y ago

I'm afraid there are no 'wild star cores' in the Solar System backyard. A supernova remnant would either be a white dwarf, or a city-sized neutron star (possibly a black hole) with a mass larger than that of the Sun. The latter could go undetected, but can be safely excluded since in that case it would be the Solar System actually orbiting it (or anyway being affected by it - the minimum mass for a neutron star is ~1.4 Sol, and a black hole would be even larger), and we already know the Sun's path around the Milky Way to a certain extent. OTOH a white dwarf would likely take billions of years to cool off and we would be able to spot it - so no, only planetary bodies may still be lurking there undetected. Edit - clarification.

KnightOfWords 8y ago
> A supernova remnant would either be a white dwarf... A small correction, white dwarfs are not produced by supernovae but by main sequence stars running out of fuel.

kijin 8y ago

You don't even need "a few times the Earth's radius." Assuming identical density, mass is proportional to the cube of radius. Earth already has the highest density of all the large objects in the solar system, at about 70% of the density of solid iron. An object that has the same density as Earth, but with 2x the radius, will have the mass of 8 Earths. If the object was made of solid iron, it will have the mass of over 11 Earths. That's a lot of mass in a small area.