August 24, 2013
With incredibly sharp images provided by Atacama Large Millimeter/submillimeter Array (ALMA), astronomers are able to detect new features in the Herbig-Haro 46/47 object – an object created by the material ejected from young stars into surrounding gas.
Herbig-Haro 46/47 combined out of images from ALMA and ESO's New Technology Telescope.
The Atacama Large Millimeter/submillimeter Array is an array of 66 radio telescopes, located in Atacama desert in Chile. It began observations in 2011 and is fully operational since March 2013. During the early phase, while it was still under construction, it has been targeting the Herbig-Haro 46/47 object. A Herbig-Haro object is a cloud of gas and dust with a star forming inside it. Young stars eject the material while forming and this material reaches speeds up to 1 million km/h. When the material hits the surrounding gas, it glows, creating a Herbig-Haro object. The Herbig-Haro 46/47 observed by the ALMA is 1400 light years away from Earth, in the constellation Vela.
There are two jets of material emitted by the forming star – one directed toward Earth and the other one away from it. The latter was almost invisible in earlier observations which used the visible range of the electromagnetic spectrum – light. This was due to the dust around the star blocking the light. ALMA has provided sharper images than previous telescopes (and in just five hours of observation), but more than that, it made it possible to obtain much more accurate measurements regarding the speed of these material jets. The material is being ejected by the star at much higher speeds than previously thought i.e. it carries more energy and momentum than we thought. Furthermore, ALMA has detected what appears to be another object, with lower mass than the young star, carving its own path in the surrounding cloud and creating a secondary material outflow at almost 90 degree angle to the main flow.
"ALMA's exquisite sensitivity allows the detection of previously unseen features in this source, like this very fast outflow. It also seems to be a textbook example of a simple model where the molecular outflow is generated by a wide-angle wind from the young star," the team leader Héctor Arce from Yale University in New Haven, USA said. "ALMA has made it possible to detect features in the observed outflow much more clearly than previous studies. This shows that there will certainly be many surprises and fascinating discoveries to be made with the full array. ALMA will certainly revolutionize the field of star formation!"
"The detail in the Herbig-Haro 46/47 images is stunning. Perhaps more stunning is the fact that, for these types of observations, we really are still in the early days. In the future, ALMA will provide even better images than this in a fraction of the time," said Stuartt Corder from the Joint ALMA Observatory in Chile.