Circumstellar matter surrounding the luminous blue variable star AG Carinae is seen in this HST image. Because the nebulosity is so much fainter than the star, the overexposed central bright image is occulted by the circular black disk. The long vertical white column is an artifact because of the over-exposure in the brightest part of the image. Likewise, the white rayed structure extending from the edge of the black disk is an artifact, not a real stellar feature.
This image is much sharper than previous views through telescopes on the ground. Those had shown the brighter nebulosity extending to the left from AG Carinae as a relatively featureless `jet'. The `jet' and other circumstellar nebulosities are here revealed as a complex mix resembling bubbles, filaments, and arches. The nebulosities are gas clouds that contain microscopic dust. They shine because the light from AG Carinae is reflected by the dust particles. The nebulosities are probably shaped by the stellar wind from AG Carinae and swept outwards in its flow.
A luminous blue variable is a supergiant star in an unstable state in which it may change noticeably in brightness and lose much mass. AG Carinae is one of the brightest and most massive stars in the Milky Way, and is located about 21,000 light years from the Sun.
Camera: WFPC2
Technical: This image artistically enhanced.
Credit: A. Nota, M. Clampin, and C. Leitherer (STScI), and NASA
