How does stellar feedback drive interstellar turbulence and molecular hydrogen formation?

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Stars are formed in the interstellar medium (ISM) in dense and cold regions that are rich in different types of molecules. To understand how stars and planets form, it is essential to understand how their molecules form out of diffuse, neutral ISM gas. Once formed, stars inject energy into the ISM causing turbulence, which shakes and stirs the future stellar birthplaces. Astronomers study the neutral ISM using the 21-cm emission line of atomic hydrogen (HI). The researchers at the University of Wisconsin-Madison will investigate how interstellar turbulence affects the diffuse gas. They will use a new radio telescope in Australia to obtain HI observations of the Magellanic Clouds. The project team will also continue with the development of a comic strip for middle school students, entitled “Galaxy scouts: Spaceventures with Stella and Riley”. This strip features excitement and products of science in daily life, with the key goal of enhancing societal scientific literacy. These materials will be publicly available. By developing the comic strip and three activity books, the group will provide a unique introduction to STEM disciplines for elementary and middle school students.This project has the following objectives. First, to quantify the influence of different astronomical sources on interstellar turbulence, the project will quantify the level of spatial variations of HI turbulent properties across the Magellanic Clouds by using a novel statistical method. Second, to provide direct constraints for numerical simulations of star formation, the exact modes of turbulent motions and scales of operations will be mapped across the Magellanic Clouds. This will constrain the fraction of turbulent energy that shakes, as opposed to stirs, the HI gas. Third, as molecular hydrogen forms from the atomic hydrogen structures affected by turbulent motions, the project will test theories that incorporate turbulence in the molecular hydrogen formation process.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.