Artist's impression of the GX 339-4 black-hole binary system
This artist's impression shows the GX 339-4 binary system, which consists of a 7-solar-mass black hole that accretes mass from its companion, a low-mass star, shown on the left. The process takes place via an accretion disc and also triggers the release of powerful jets of highly-energetic particles.
Different regions in the jets and disc emit radiation at different wavelengths: the base of the jets, closer to the black hole, emit light at shorter wavelengths (infrared, shown here in yellow) than the extremity of the jets, which shine brightly in radio waves (shown here in red). Similarly, the most central part of the disc, closer to the black hole, shines brightly in X-rays (shown here in violet), whereas the outer parts shine most brightly at longer wavelengths (ultraviolet and optical, shown here in blue).
Observations performed using ESA's Herschel space observatory have provided the first view of GX 339-4 at far-infrared wavelengths, allowing astronomers to probe the jets down to their base, where the far-infrared emission originates. This is an important addition to the understanding of black-hole jets and of the physical processes that take place very close to a black hole.