Erratum: Three's a crowd

In Alan P. Boss's article “Three's a crowd” ( Nature 405, 405–407; 2000), the source L1551 IRS5 was said to be a member of a triple system, like T Tauri. The text should have been corrected to state that L1551 IRS5 is known to be a binary protostar, whereas T Tauri itself may be one of a system of four stars.