Series of astronomy articles

I need a series of high quality articles on astronomy topics. The topics would be: "why do stars twinkle?" "What is a supernova?" "What is a neutron star and what is a plusar" "what is a red giant?" "What is a white dwarf?" "What is a black dwarf?" "What is a black hole?" "How old and how big is the universe?" All articles should be a minimum of 300-500 words or more, depending on what is needed to deliver a concise explanation. As illustration, all articles should contain a few pictures from the public domain or with copyright regulations allowing to post them on a commercial web site and must be copyscape proof! The content should be delivered as valid html.