Project Nebula – Novae Debris

A binary system that contains a main sequence star, like Sol, and a White Dwarf can create a cataclysmic x-ray binary. Matter from the main sequence star can be transferred to the white dwarf companion. This matter builds on the surface of the White Dwarf until it passes a critical level and a burst of fusion in the White Dwarf’s outer layer. The fusion is similar to what occurs in the cores of main sequence stars, i.e. isotopes of hydrogen being fused to create helium. Unlike in main sequence stars however this fusion occurs in the outermost layer of the White Dwarf and can only be maintained for a short time as the supply of hydrogen is quickly depleted. This burst of thermonuclear fusion creates a massive outflow of energy this allows the outer layers to overcome the star’s significant gravity and blast into space, this event is known as a Nova after the ancient Greek for new as they were believed to be the births of new stars. Despite this upheaval both the stars survive the explosion and over a period of time the system returns to its normal configuration with more matter being sucked onto the White Dwarf. The outer layers blown off in the Nova form a shell around the binary system. This can be classed as a type of nebulosity.

The nebula contains mostly hydrogen and helium. An example of such of an event is Nova Cygni 1992. As its name suggests it was located in 1992 within the constellation Cygnus – The Swan.

This time lapsed image shows the event shortly after the initial outburst (left ) with the second image (right) taken 13 months after the event. The image shows the expansion on the debris as time passes. It is however important to note that the camera had been repaired and improved between the two images.

The initial explosive force from the nova can propel the debris many thousands of kilometres across at speeds of many hundred of kilometres per second. Whilst not as powerful as the more well known supernovae, the cycle of matter build up and thermonuclear reaction can occur many times and can occur in very regular cycles making them very interesting objects to study.