TOKYO, Oct 9 (Reuters) - Japan's Nikkei share average recovered from a five-week low and gained 1 percent on Wednesday, helped by news that President Barack Obama has tapped Federal Reserve Vice Chair Janet Yellen to head the U.S. central bank. The news removed some uncertainty hanging over the market and helped risk appetite, weakening the yen against the dollar. That triggered futures buying and bargain hunting in exporters that were weaker in early trade, traders said. The Nikkei closed up at 14,037.84, after falling as low as 13,751.85 in the morning session. That was just above a five-week low of 13,748.94 hit on Tuesday. The broader Topix gained 1.5 percent to 1,166.90.