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ALMA Telescope’s Views of Herbig-Haro Object HH 46/47


Some astronomers using ALMA (Atacama Large Millimeter Array) have got a vivid image to close the material flowing from a newborn star.  Observing the luminescence produced by carbon monoxide molecules in an object known as Herbig-Haro 46/47, they have discovered that the jets from these products are even more energetic than previously thought so far.  The new, highly detailed images, also unveiled an unknown Jet that points in a completely different direction.

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 Source: www.jpl.nasa.gov

Young stars are violent objects which eject material at high speeds, up to one million kilometers per hour. Astronomers George Herbig and Guillermo Haro were not the first that see one of those strange objects that now bear their name, but were the first to study the spectra in detail.  They understood that they were not only clumps of gas and dust that reflect light or glow under the influence of ultraviolet light of young stars, but a new class of objects associated with the shockwaves created by nearly all high speed material from star-forming regions.  A spectacular example of this class is Herbig-Haro 46/47, approximately 1400 light-years away in the constellation Vela, object of study with ALMA during “Early Science”, when the telescope was still under construction and the array of antennas far from being completed. The new images reveal for details in two jets, one that points toward the Earth and the other running.  The Jet out was almost invisible in the previous photography obtained in the optical band, due to obscuring dust clouds surrounding the rising star.  ALMA has provided much sharper images than previous telescopes and also allowed astronomers to measure the speed at which the glowing material moves through space. These new observations of Herbig-Haro 46/47 showed that part of ejected gas has a much greater speed than previous measures.  This means that the gas jets carry much more energy and momentum than previously thought. The head of the team and lead author of the new research, Hector Arce (Yale University, USA), explains that “the exquisite sensitivity of ALMA will reveal details invisible before this spring, as this discharge so fast.  Also seems a textbook example of a simple model where molecular flow is generated by a wind produced by the young star at large angles “. The remarks were obtained in just five hours of observation time with ALMA – even though ALMA was still under construction at the time – observations of similar quality to other telescopes would require ten times as much.

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 Source: www.jpl.nasa.gov

This image from ESO’s New Technology Telescope at the La Silla Observatory in Chile shows the Herbig-Haro object HH 46/47 as jets emerging from a star-forming dark cloud. This object was the target of a study using ALMA during the Early Science phase. “The details of the image of Herbig-Haro 46/47 are amazing.  Perhaps even more surprising is the fact that, for this type of observations, we are really just beginning.  In the future ALMA will provide even better images in even shorter time, “adds Stuartt Corder (Joint ALMA Observatory, Chile), one of the co-authors of the article. Diego Mardones (University of Chile), another co-author, stresses that “this system is similar to most isolated low-mass stars during the formation and birth.  But it is also unusual because the outgoing stream hits the cloud directly from one side of the young star and escapes from the cloud on the other.  This makes it an excellent system to study the impact of stellar winds on the mother cloud that is forming the young star “. The sharpness and sensitivity achieved by these observations of ALMA have allowed the team to discover an unexpected outflow component, which seems to come from a lower mass companion young star.  This secondary flow is nearly at right angles to the main object and apparently is digging a hole in the surrounding cloud. Arce concludes that “ALMA has identified a particular outgoing flow from the star more clearly than earlier studies. This shows that the full array will give us surely many surprises and fascinating discoveries.  ALMA certainly will revolutionize the field of stellar formation! “.

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