Tuesday, 31 March 2015

Milky Way Astrophysics from Wide Field Surveys - Part II

The second day of the Wide Field Surveys meeting has covered a wide range of topics, from the formation of stars, the lives of massive stars, to more evolved stars and even dying stars such as supernovae.

One of the most interesting results presented today came from a sub-mm survey of the Serpens star forming region using the James Clerk Maxwell Telescope in Hawaii. Using this data a group of astronomers have been searching the images for outflows coming from young stars, which is thought to be a common occurrence during the star formation process as a by-product of how stars accrete material from their surroundings.

Outflow coming from the Herbig-Haro object HH47
(Credit: HST/NASA)
After studying these outflows the astronomers were able to calculate the amount of energy that the outflows were injecting into the surrounding molecular cloud. They found that the energy injected from the outflows was as high as 70% of the total turbulent energy within the cloud. Turbulence is the name given to the energetic motions within molecular clouds, and which is thought to be responsible for preventing the molecular cloud from collapsing under its own gravity.

This result suggests that one of the most important mechanisms for preventing molecular clouds from collapsing is the outflows produced by the stars that form within them! Because molecular clouds need to collapse to form stars, outflows are actually limiting the amount of further star formation that these molecular clouds can produce. Astronomers call this feedback, the influence of stars that have already formed on the surrounding molecular cloud, and it's exciting to see it happening in this region.

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