The Reflection Nebula
NGC 1999 is a reflection nebula in the constellation Orion. A reflection nebula shines only because the light from an embedded source illuminates its dust; the nebula does not emit any visible light of its own. NGC 1999 is famous in astronomical history because the first Herbig-Haro object was discovered immediately adjacent to it (just outside the image). Herbig-Haro objects are known to be jets of gas ejected from very young stars.
NGC 1999 is illuminated by a bright, recently formed star, visible just to the left of center. This star is cataloged as V380 Orionis, and its white color is due to its high surface temperature of about 10,000 degrees Celsius (nearly twice that of our own Sun). Its mass is estimated to be 3.5 times that of the Sun. The star is so young that it is still surrounded by a cloud of material left over from its formation, here seen as the NGC 1999 reflection nebula.
The image shows a remarkable jet-black, T-shaped cloud near its center. This dark cloud is an example of a "Bok globule," a cold cloud of gas, molecules, and cosmic dust, which is so dense it blocks all of the light behind it. In the Hubble image, the globule is seen silhouetted against the reflection nebula illuminated by V380 Orionis. Astronomers believe that new stars may be forming inside Bok globules, through the contraction of the dust and molecular gas under their own gravity.
CREDIT: NASA and The Hubble Heritage Team (STScI)