Argon hydride or ArH (which is unstable on earth) is called “argonium” in cosmology. It is common despite argon being supposedly ‘inert’.
At least in interstellar space, the widespread presence of argonium proves that argon is not inert under the proper conditions, and preferentially binds to hydrogen. Ordinarily, the ArH molecule decays in milliseconds in the environment of earth. But ‘dense hydrogen’ availability in Space is an unknown factor, given that most hydrogen from a supernova should be dense to begin with (according to Mills), assuming that electrons are more tightly bound in dense hydrogen with increased stability. Almost all of Mills early papers used argon as a co-catalyst. There is a fair chance that the hydrino (dense hydrogen) will bind to argon more readily than normal hydrogen, and that this stability as a gaseous molecule will be a useful way to collect and store dense hydrogen for later use. Spectral line surveys of galaxies, especially younger ones, find a strong absorption feature at 617.5 GHz, which is attributed to ArH. https://www.aanda.org/articles/aa/full_html/2014/06/aa23727-14/aa23727-14.html Ubiquitous argonium (ArH+) in the diffuse interstellar medium… By P. Schilke et al. The situation with helium is somewhat similar in that a species known as “helium-like hydrogen” has been studied. https://en.wikipedia.org/wiki/Two-electron_atom BTW – a stable muon replacing an electron in hydrogen would provide an alternative explanation for many phenomena, including the identity of dense hydrogen itself.
