... Centaurus A: Young Blue Star Stream . ... Credit: E. Peng and H. Ford ( JHU ), K. Freeman ( ANU ), R. White ( STScI ), CTIO , NOAO , NSF Explanation: Almost lost in this cosmic jumble of stars, gas and dust is a faint but definite blue arc -- a stream of young stars whose formation was probably triggered as a small dwarf galaxy was torn apart approaching the giant elliptical galaxy Centaurus A . ...