Who was the brother of XXX?
François Arago
Dominique François Jean Arago (Catalan: Domènec Francesc Joan Aragó), known simply as François Arago (French: (fʁɑ̃swa aʁaɡo); Catalan: Francesc Aragó, IPA: (fɾənˈsɛsk əɾəˈɣo)) (26 February 1786 -- 2 October 1853), was a French mathematician, physicist, astronomer, freemason, supporter of the carbonari and politician.
Jean Arago