Jet Of Molecular Hydrogen Arising From A Forming High-mass Star

While astronomers now understand the overall process of low-mass star formation very well, the formation process of massive stars is still very much under debate. Recent astronomical observations suggest that high-mass stars could form through accretion processes, just like low-mass stars do. For instance, in 2004, European astronomers discovered a large accretion disk that probably surrounds a forming high-mass star, in the star-forming region M17, also known as the Omega nebula and located at a distance of about 7000 light years.

Looking again at M17 with the new spectrograph SINFONI at the ESO-VLT, the same European group report discovering a jet of molecular hydrogen (H₂) that apparently arises from the forming high-mass star. The picture below illustrates this discovery, which is being published in Astronomy & Astrophysics.

The ejection of material through a jet or an outflow is always linked to accretion of gas and dust, either onto the circumstellar disk or onto the central protostar. The detection of the H₂ jet thus provides evidence that ongoing accretion processes occur in the M17 disk. The team also estimates the mass outflow and mass accretion rates, which suggest that a star of high mass is forming within the M17 disk. This is an additional clue that high-mass stars form in a similar way to lower mass stars.