To bring us back to pressure and density:
Eric Walker wrote:
"In the Physics Forums thread you started, there was a reply that suggested that electron screening contributes a small amount to the overall rate. Did the paper cited mention electrons confined to one dimension? I'm going to guess that it did not."
Longview then wrote:
"At a stellar core density (about 150 g/cc), the opportunity for screening may be quite enhanced. Whether it becomes an important factor.... ?
Another speculative contribution: Muonic CF works because the greater muonic mass means the muonic orbital is about 1/207 of an electron. At a solar core density of 150 times water-- 1 g/cc at stp v. H2 0.0708 g/cc at stp-- 150/0.0708 at such a pressure suggests a volumetric compression factor of over 2100 times is likely. The cube root of 2100 is about 12.5 giving a mean estimate of the effect of solar core pressure on hydride radii of 1/12.5 or 8% of that for liquid H2 at normal stp. For comparison, a Teller-Ulam thermonuclear device relies to great extent on compression of say lithium deuteride to 1000th of the volume at stp, that is an implied radius contraction to 10% of that at stp.