A computer simulation of the dark nebula Barnard 68 suggests the cloud will collapse into a brand new star relatively soon… at least on an astronomical time scale.
Astrophysicist João Alves, director of the Calar Alto Observatory in Spain, and his colleague Andreas Bürkert from the University of Munich, believe the dark cloud Barnard 68 will inevitably collapse and give rise to the new star, according to an article published recently in the April 2009 issue of The Astrophysical Journal.
Barnard 68 (B68) is a dark nebula about 400 light years away in the constellation of Ophiuchus. Such nebulae are interstellar clouds of dust and gas located within the Milky Way which block out the light of the stars and other objects behind them.
Most astronomers believe stars form from giant gas clouds which collapse under their own gravity until high density and temperatures lead to nuclear fusion. Although many details of the process are still not understood, the new study may be able to shed some light on this.
Alves and Bürkert suggest the collision of two gas clouds could be the mechanism that activates the birth of a star. They suggest Barnard 68 is already in an initial unstable state and that it will collapse “soon” – within some 200,000 years.
Images show B68 is a cold gas cloud with a mass equivalent to that of two suns. But there’s a smaller cloud just 1/10 as massive getting close enough to collide with the larger cloud.
In order to prove their theory, the two astrophysicists have simulated the scenario in a supercomputer at the University of Munich. They modelled two globules separated by one light year, with masses and speeds similar to those of Barnard 68 and its “small” companion. By using a numerical algorithm, the researchers showed how these two virtual gas clouds evolved over time.
The results showed that the smaller globule penetrated the larger one after around 1.7 million years at a speed of 370 metres per second. The model also showed that the stability of the initial situation declined over time. At the moment when the two globules merged, enormous densities were generated, making the system collapse and creating the ideal conditions for the formation of a star.
The researchers varied the physical parameters of the globules until they worked out the circumstances in which the merger of two gas clouds will lead to their subsequent collapse. According to Bürkert and Alves’ calculations, a new star system will form from B68 within 200,000 years.
Source: FECYT – Spanish Foundation for Science and Technology