Star Formation

Through advancing science, mankind has become able to look beyond the reaches of its own galaxy and following spectral signatures, observe the birth of stars. Of course, considering that information often takes ten thousand light years of travel or more before observation on Earth, what scientists are seeing is an event that took place long, long ago.

A Look at Star Formation

One might think that studying how the Sun came to be would answer all the general questions about Star Formation, as the Sun is an average, or Main Sequence, star. However this is not the case; there are a few uncertainties how some stars are formed, specifically those over a certain mass.

In general, there are two kinds of star formation catalysts; Spontaneous star formation, and Triggered star formation. In spontaneous star formation it is believed that huge molecular clouds become unstable and begin to collapse, falling inward towards a centre that would eventually become a protostar (the object that is the official beginnings of a star.) For triggered star formation the results are roughly the same- material is drawn together to form a protostar, but the impetus of this process is the effect of nearby supernova that force the molecular cloud to collapse.

Protostar, and Then…

Whatever the catalyst, it is what happens next that is the building blocks of the star formation. As the centre of the process loses gravitational pull, that lost energy is transformed into heat, sort of priming the pump for the protostar. A flat disc of debris and energy is formed around the protostar, into which is dumped material from accretion, where energy and matter is passed from the edge of the disk into the protostar. Eventually the density and temperatures reach the point where hydrogen fusion occurs, that nuclear process that fuels the energy production of the star. What was once a protostar is now a star, a process that can take some ten thousand years.

Low Mass vs. High Mass

One way to express mass in astronomy is by the unit of “solar mass”, which is equal to the mass of the Sun (more than three hundred times the mass of the Earth.) For star formation up to around eight solar masses, the above theories of star formation hold sway; for those over eight solar masses, however, there are a few uncertainties.

It has long been thought that a massive protostar would put off so much radiation that it would slow the accretion process, preventing enough energy and material to fall onto the protostar to achieve star status. A recent theory suggests that multiple low mass protostars combine together to form a high mass protostar.

Final Thoughts

Because the formation of a star from a protostar takes around ten thousand years, there is no record of real time observation of the star formation process. There are, however, observations of different parts of the process, which put together to make a reasonable whole. Some examples include the youngest main sequence star ever observed, around three and half million years old, and a protostar younger than 10,000 years old.

Related Articles in the 'The Stars' Category...

• How Big Are the Stars?
• How Far Away are the Stars?
• Main Sequence Life of Stars
• Pioneer Plaques
• The Death of Stars
• The Milky Way
• Types of Star
• Using Constellations to Find Other Constellations
• What Are Star Remnants?
• What's Inside a Star