XZ Tauri System Ejects Gas Bubble . ... WFPC2 , HST , NASA Explanation: Why is the binary star system XZ Tauri emitting a hot bubble of expanding gas? ... The XZ Tauri star system is known to reside in the Taurus star forming region located about 500 light-years away. ... The bubble has been expanding over the past thirty years and now extends to nearly fifteen times the binary separation. ... NASA Web Site Statements, Warnings, and Disclaimers . NASA Official: Jay Norris. ...