A Tour of Cyg X-3's Little Friend

Narrator (April Hobart, CXC): The story of how stars are born and eventually die can be a complicated one. After all, the life and death of stars is determined by many factors including its mass and environment. Take, for example, Cygnus X-3. For decades, astronomers have studied this object and determined that it is a so-called X-ray binary. This means that it is, in fact, a pair of objects. One of the objects is a compact source - either a neutron star or black hole that was produced by the death of a massive star - that is pulling material away from the other object, a living companion star.

In 2003, astronomers noticed something else when observing Cygnus X-3 with Chandra. They saw another source very close to Cygnus X-3 on the sky. Thanks to Chandra's unparalleled X-ray vision, they were able to resolve this source even though it was a mere 16 arcseconds away on the sky. To put it another way, the separation of Cygnus X-3 and this new source is equivalent to the width of a penny about 800 feet away. Astronomers nicknamed this new object the "Little Friend."

Recently, a team of astronomers has combined Chandra data with radio data from the Submillimeter Array to learn more about both Cygnus X-3 and the Little Friend. They determined that the Little Friend is a Bok globule, which is a small, dense, very cold cloud. The radio data shows that the Little Friend is producing jets, indicating that a new star is forming inside. This unusual configuration of an X-ray binary so close to a Bok globule provides astronomers with a new way of studying how stars - or at least some of them - form.