The Red Rectangle, AFGL 915
author: Anglo-Australian Observatory/David Malin Images/Novapix
reference: a-nep98-00082
Image Size 300 DPI: 40 * 51 cm
This surprising object is one of an unusual class of nebulae surrounding mature, sun-like stars that are about to turn into planetary nebulae. Not all pre-planetary nebulae have outbursts like this, and in those that do, the nebula lasts only a few thousand years, hence the rarity. The central star has a thick belt of dust like a girdle around its equator which restricts outflow in that direction. Instead, the star ejects material in a kind of cone from each of its poles. The spectrum of the nebula shows unusual, strong red lines from hydrogen bonded to grains of carbon, however there is sufficient light reflected from the embedded star to dilute the strong red spectrum to the deep yellow we see here.