The secrets of the Orion A molecular cloud revealed by the VISTA telescope

Global view of the Orion A molecular cloud (Image ESO/VISION survey)
Global view of the Orion A molecular cloud (Image ESO/VISION survey)

An article published in the journal “Astronomy & Astrophysics” describes the most detailed view of the molecular cloud called Orion A, one of the two giant molecular clouds in the Orion molecular cloud complex. A team of researchers created it by putting together infrared images obtained from the VISION (Vienna Survey in Orion) survey with ESO’s VISTA telescope revealing many young stars and other objects normally hidden within dust clouds.

The Orion molecular cloud complex, also known simply as the Orion complex, is one of the most active star formation regions so its molecular clouds are the subject of various studies. The molecular cloud known as the Orion A is the one that appears from Earth near the part of the constellation of Orion known as the sword. The molecular cloud known as Orion B is close to the part known as the belt.

Research on the Orion A molecular cloud was possible because the VISTA (Visible and Infrared Survey Telescope for Astronomy) telescope sees at infrareds and at those frequencies it’s possible to detected much more than at visible light, blocked by the dust present in the cloud. The remarkable VISTA sensitivity also allowed to capture high quality images and identify young stars that were previously invisible and more.

The VISION survey focused precisely on that area of ​​space also detecting ten possible galactic clusters. However, they’re millions if not billions of light years away and will be studied separately. The most important objects were the ones inside the Orion A molecular cloud, far from Earth “only” about 1,350 light years. These are stars, big and small, disks of materials that could be pre-stellar disks from which other stars will be born in the future, but also Herbig-Haro objects, which are emission nebulae associated with newborn stars.

This research provides new information about star formation processes because in molecular clouds, where hydrogen atoms have reached such levels of temperature and density that they combine into molecules, there are the conditions for those processes to occur. In the Orion A molecular cloud those processes are in various stages so astronomers can see a series of moments of the evolution of that type of cloud from the formation of disks of dust and gas to very young stars.

For these reasons, the completion of the VISION survey represents only the end of one phase of the research. Now a new phase can start with the specific study of the objects discovered and their characteristics while the VISTA telescope will be used for new similar surveys of other areas of the sky.

Small areas within the Orion A molecular cloud (Image ESO/VISION survey)
Small areas within the Orion A molecular cloud (Image ESO/VISION survey)

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