Of course we can discuss that Hydrogen with no electron becomes H+ and that is commonly known as simple "proton", not more hydrogen, the chemical element. But discussing this will derail the main subject of this thread, about Jupiter. Lets keep focus.
What is the evidence of a dense substance between Sun and Jupiter that change its visible size?
Some people may confuse the word "evidence" with something written in a paper.
I can write "John is the assassin" and deliver the paper to the judge to incriminate John, that is not considered evidence, except if I can disclose where John hide the body or the weapon with his incriminatory fingerprints. Evidence and proof is when you can duplicate the experiment, replay several times and obtain the same results, or, when the byproduct of the experience is a non contestable situation, non prima-facie. For example, empty beer bottles inside your car is not evidence that you are driving under influence, but enough evidence to give authority to the officer to conduct a sobriety test. A letter delivered to the police saying that someone saw empty bottles inside your car, will not dispatch a cruiser to intercept you in the street, not enough evidence, a picture of you drinking while driving, maybe. When you read something in a paper, old books, etc, it means nothing, except if you can duplicate that with the correct tools. Paper hold records of said previous experiments, but not evidence at all about the truth of those experiments, and the scientific validity of it.
What scientific experiments one can do at a lab or at kitchen table and obtain results to prove this very dense substance between Sun and Jupiter?