After the momentous passing of Senator Edward Kennedy from brain cancer on Tuesday, attention now turns to his estate -- and who will get his untold fortune?

With Kennedy's real estate, stocks and even an autobiography worth millions in question, ET talks to author Herb Nass, the author of Wills of the Rich and Famous.

"Ted Kennedy died a very wealthy man," says Nass. "America has no idea how wealthy this family really is. He inherited a lot of money from his parents, from the family trusts that had been established."

A report from 2007 indicates Kennedy amassed a fortune estimated somewhere between $43 million to $163 million. But just last year Ted's reported net worth dropped to an estimated $15 million. It could have been the economy, or perhaps knowing that he was suffering from brain cancer, the senator shifted his wealth into trusts for his children and wife Victoria. Could his ex-wife Joan cash in on the Camelot connection?

"I would be surprised if she's still in his will," says Nass of Joan, who divorced Kennedy in 1982. "Unless their divorce agreement provided that she needed to be [in the will], but usually that doesn't happen. She probably received a substantial settlement at the time of the divorce."

As for wife Victoria, Nass says, "I don't know if there was a prenuptial agreement, but we'll find out. I suspect his children will be a very important part of his estate."

Watch ET for more with Herb Nass and details of Ted Kennedy's estate.