The Orion Molecular Cloud Complex, sometimes called simply the Orion Complex, consists of multiple bright nebulae, dark clouds, and young stars located in the constellation of Orion. The cloud itself is between 1,500 and 1,600 light-years away from our Solar system and measures hundreds of light-years across. At the same time it is the nearest site where the high-mass stars are being actively formed and this location is considered to be one of the most active regions of stellar formation.
Now it seems that despite its vast size, the Orion Complex is only a part of even larger gaseous structure. An international team of scientists from Germany, the United Kingdom and the United States used a technique of 3D mapping to analyze dust contained in the interstellar medium in the surroundings of Orion to reveal that this complex forms a sub-structure of large ring of space dust and molecular matter.
In their paper published on arXiv.org the scientists explain that the circular morphology or the ring allows for assumption that it was formed as a bubble in the interstellar medium. Such bubbles are common in the universe and range in their size from small ones around planetary nebulae to superbubbles created by clusters of young stars interacting with associated supernovae. The authors note that these structures are an important component of our Universe as they have potential to reshape their environment, by initiating star formation in some locations while slowing down the formation of new stars in others.
In the present study, astronomers focused their attention on a region of sky surrounding the Orion Molecular Complex, well-known for a number of bubble-like interstellar structures. Previously developed two-dimensional dust maps are limited in their practical usefulness for tracing structural features of Orion due to interference with other visible dust structures along the line of sight, the authors say. For this reason, they took advantage of high-quality optical photometry from Pan-STARRS1 to determine the distances and red-shifts of stars.
On the basis of this additional data and previous star surveys it was possible to map an angular structure of the dust. 3D data processing was used to remove the dust visible in the foreground and background of the Orion region. In this numerically developed image a clear ring-like structure was observed spanning 100 pc ring of dust covering the main Orion molecular cloud. The scientists named the newly discovered structure the “Orion dust ring”.
“The maps not only trace the total dust column also seen by Planck, but reveal additionally the distances to these clouds with unprecedented resolution,” the scientists say. They also note that they were not able to identify the energy source driving processes inside the Orion dust ring, so no precise classification can be assigned to this bubble of the interstellar medium yet. The authors hope that the photometry and stellar parallaxes from the recently launched Gaia mission will provide data needed for more accurate 3D dust maps, allowing to perform more precise analysis of the 3D structure of the Orion Molecular Complex itself.
Written by Alius Noreika