I am not a physicist or astronomer, but I would think detectable levels of trans-iron isotopes would call into question some of the assumptions about heavy elem

I am not a physicist or astronomer, but I would think detectable levels of trans-iron isotopes would call into question some of the assumptions about heavy element production in stars. IIRC anything heavier than iron is not an exothermic nuclear reaction. I speculate the astronomers are trying to figure out how detectable amounts of a very heavy element are in the outer layers of the star where the emission lines can be detected. Later stage stars are layered by the elements produced in fusion. I thought that dwarfs resulted from stars lacking the gravitational pressure to create fusion in the core to reach those elements. So how did they get there at all? And if it's detectable in the halo of the star, that means there is enough in the lower levels (since late-stage stars are basically layers of each atomic number where they are fused) that some of it migrates to somewhere where the lines show up in the star's light emissions? Maybe it's just stuff left over from a previous star's supernova when the star formed? I can't see that resulting in enough that it would appear. Anyway, those are my amateurish questions.