Dusty star nurseries, clusters and emission nebulae can be seen in this composite image from ESO’s VLT Survey Telescope at Paranal Observatory, Chile.
This image shows a section of the Ara OB1 stellar association: in the center of the image is the young open cluster NGC 6193, and to the right is the emission nebula NGC 6188, illuminated by the ionizing radiation emitted by the brightest nearby stars. Image credit: ESO.
This region lies approximately 4,000 light-years away in the southern constellation Ara.
At its center is the open star cluster NGC 6193, containing 27 bright stars. The cluster is embedded in a region of dense gas clouds and comprises the core of the Ara OB1 association with its scorching young stars.
Intense UV light streams from the hottest stars in NGC 6193 – two closely spaced O-type stars, known as HD 150135 and HD 150136 – heating up and illuminating their gaseous surroundings, and thus making it shine brightly. Some of these binary systems engage in extremely violent behavior, at least in terms of radiation production, as the powerful stellar winds from these tightly bound stars collide and produce energetic X-ray emissions.
Together, these bright stars provide the main source of illumination for the nearby emission nebula NGC 6188, also known as the Rim Nebula, which is visible to the right of the cluster.
This nebula is the prominent wall of dark and bright clouds marking the boundary between an active star-forming region within the molecular cloud, known as RCW 108, and the rest of the Ara OB1 association.
The area around RCW 108 is made up of mostly hydrogen – the primary ingredient in star formation. Such areas are also known as H II regions.
As RCW 108 creates new stars, it is simultaneously being eroded by the winds and radiation emitted by previous stars, and by violent supernova explosions. In this way, such star-forming H II regions tend to have a lifespan of just a few million years.
Star formation is a very inefficient process, with only about 10 percent of the available material contributing to the process – the rest is blown off into space.
NGC 6188 also shows signs of being in the early phase of pillar formation, meaning that in the future it could end up looking similar to other well-known star-forming regions, such as the Eagle Nebula and the Cone Nebula.
This single spectacular image was actually created from more than 500 individual pictures taken through four different color filters with the VLT Survey Telescope. The total exposure time was more than 56 hours. It is the most detailed view of this region yet achieved.
