Object name: HindsVarNb NGC1555
NGC 1555 is one I imaged before but in a short exposure. It's known as Hind's Variable Nebula. It is lit by T Tauri, a variable star surrounded by dust clouds. Some of the variability is due to these obscuring the star though most are due to the star itself. But these clouds also can shadow NGC 1555 causing part or all of it to dim and brighten.
Related Designation(s):HindsVarNb NGC1555,