The researchers calculated that the process of Hawking radiation theoretically also applies to other objects with a gravitational field
but: doesn't this only apply if these objects if they have some sort of decay process going on? There are nuclides that have never been observed decaying. I would expect a white dwarf to burn out, go through radioactive decay (unstable nuclides -> stable ones) and end up as inert rock (stable nuclides) at background temperature.
The whole point of Hawking radiation is that a thing which famously shouldn't have a decay process (a black hole) in fact does have a decay process due to the interaction of gravity and quantum mechanics.
Hawking radiation doesn't require decay. Pairs of particles appear spontaneously. One falls into the gravitational field, losing energy.
The net energy loss comes from the gravitational field of the object, and its mass decreases. We don't have details on just what that means at a Standard Model level, but the net loss of energy means something is going to disappear even without any kind of previously understood decay.
>here are nuclides that have never been observed decaying
Aren't we pretty sure due to things like quantum tunneling that the probability of any quantum particle existing trends to zero given a long enough time?
Regular "stable nuclides" stuff which falls into a black hole gets spit out as Hawking radiation, so no, this is a gravitational process, radioactive decay is a standard model one.
