The Scorpius Centaurus association is the OB association nearest to the Sun. It contains several hundred B stars which concentrate in the three subgroups Upper Scorpius, Upper Centaurus Lupus, and Lower Centaurus Crux. Upper Scorpius is the youngest subgroup, Upper Centaurus Lupus the oldest subgroup of the association.
The next image shows the Scorpius Centaurus association and its surrounding in X-rays. The field of view is about 100 times 100 square-degrees. The color images is a true color X-ray image constructed from the data of the ROSAT All Sky Survey Background maps. The yellow dots mark the positions of bright X-ray sources detected in the ROSAT All Sky Survey (note that we hav plotted only the about 10% brightest X-ray sources). The blue circles mark the three subgroups Upper Scorpius, Upper Centaurus Lupus, and Lower Centaurus Crux (from left to right). One can see a clear enhancement in the density of X-ray sources associated with these three subgroups of the association. The association is embedded in a large roughly circular structure; this is a huge bubble of hot gas created by the stellar winds of the numerous massive stars in the association and by several super-nova explosions, which happened in the Scorpius Centaurus association during the last few million years.
Some very nice IRAS infrared images of the Scorpius Centaurus association can be found here