Imagine the Universe!
Imagine Home  |   Ask an Astrophysicist  |  
Ask an Astrophysicist

The Question

(Submitted March 30, 2001)

How are binary star systems formed?

The Answer

This is a very good question and, perhaps much to your surprise, this can be a hot topic for a debate among astronomers.

In essence, a binary-star system emerges out of a cloud of gaseous material collapsing and forming more than a single star at the same time in a small proximity. This type of a collapsing event does not necessarily form only two stars -- it can form more than two, but it all depends on their unique environment in which stars form.

Also it is most unlikely for a single star to capture another star in a typical stellar space. When two stars encounter, they tend to swing by each other and almost never captures one to another by their own gravitational field. We are not going to explain why it is so, but you will need more than two stars (in fact, many stars) to do just that. Some cases of binary-capture may have been seen in a place like globular clusters where a million of stars are found in a very tiny volume of space.

Hope this helps,

Koji & Bish
for "Ask an Astrophysicist"

Previous question
Main topic

Imagine the Universe is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

The Imagine Team
Acting Project Leader: Dr. Barbara Mattson
All material on this site has been created and updated between 1997-2012.

DVD Table of Contents
Educator's Index