That mostly depends on the agreement between the artist and the author, I think. The artist will own the copyright over the artwork unless they give the actual copyright to the author, and vice versa. What you create is originally copyrighted to you automatically, and only you can decide whether to share or give away the copyright to it.
So, yeah, it depends on the artist's and author's agreement.
He is a published author.
Richard Williamson Ellis has written: 'Book illustration' -- subject(s): Illustration of books, Illustrators, History
the average age for a published author is eleven or older
An author card typically includes the author's name, contact information, biography, photo, and a list of their published works. It serves as a professional introduction to the author and their body of work, helping readers and industry professionals learn more about the author and their literary contributions.
Arlene M. Jackson has written: 'Illustration and the novels of Thomas Hardy' -- subject(s): Illustrations, Illustration of books
Siriol Sherlock has written: 'Botanical Illustration' -- subject(s): Botanical illustration, Flowers in art, Technique, Watercolor painting
Franklin Noble has written: 'Sermons in illustration'
Lother Lang has written: 'Expressionist book illustration in Germany, 1907-1927' -- subject(s): Expressionism (Art), Illustration of books
Saverio Simeone has written: 'Cesare Majoli' -- subject(s): Botanical illustration, Natural history illustration, Naturalists, Biography, History
Thomas George Hill has written: 'The essentials of illustration' -- subject(s): Engraving, Illustration of books, Printing, Photomechanical processes
A posthumous book is one published after the author has died.
R. Herrlinger has written: 'History of medical illustration'