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.

Milky Way Astrophysics from Wide Field Surveys - Part I

The entrance to the Royal Astronomical Society's
headquarters at Burlington House in London
(Credit: Wikimedia Commons)

This week I'm at a conference in London at the headquarters of the Royal Astronomical Society where we're discussing scientific results from recent wide field surveys of the Milky Way. Wide field surveys is just another name for surveys that cover a large area of space, and there are many surveys these days that fit that category, including a few that I work on.

Because these surveys cover such a large area of space they allow many different types of astronomical objects to be studied, from young stars to old stars, individual objects to the entire galaxy. So a conference like this is a great opportunity to stay in touch with a wide array of scientific results.

Today's talks have mostly been given by the leaders of the surveys, who have been telling us about their surveys, how we can get the data from the surveys, and highlighting some of the scientific results. This is a good opportunity to learn about new survey data and to think about how this data might be useful to solve some of the problems I'm trying to address.

The Milky Way - home of many many surveys! (Credit: ESO)

I've been really impressed with the surveys presented today. They've covered (almost) every part of the electromagnetic spectrum, from radio waves through the infrared and up to the optical part of the spectrum, and they've offered up a huge range of possibilities for future work. They also have some amazing names, including such gems as e-MERLIN and UWISH - astronomers really love acronyms!

The highlight of the day for me was probably a presentation about a sub-mm survey called ATLASGAL. The sub-mm part of the electromagnetic spectrum is between the infrared and the microwave parts of the spectrum. One of the advantages of observing in this part of the electromagnetic spectrum is that it is not absorbed by dust and so can be used to study objects across our entire galaxy, even on the far side of our galaxy that would normally be obscured and inaccessible to us.

Part of the Galactic Plane of our galaxy seen by the ATLASGAL survey showing a number of prominent
star forming regions, including Messier 20, The Triffid Nebula (Credit: ESO/ATLASGAL)

The survey data has been used by a team of astronomers to survey the majority of our galaxy in the sub-mm part of the spectrum and identify hundreds of dense clumps of molecular gas where massive stars are forming. Sub-mm emission is one of the most reliable and efficient methods to identify dense star forming regions. It's an exciting project and I'm looking forward to seeing more results from the survey in the future.