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Star Formation Triggered by Colliding Interstellar Clouds

   Cardiff School of Physics and Astronomy

About the Project

CONTEXT. Much of the interstellar gas in a galaxy like the Milky Way is in dense molecular clouds. When these clouds enter a spiral arm, they merge to form larger clouds, and are compressed to higher densities. This leads to enhanced rates of star formation, which is why spiral arms are lit up by the radiation from massive stars; massive stars evolve so fast that they are only visible close to where they form. A key role is played by the gravitational field of the spiral arm, and by the magnetic field, which regulates the dynamics of the gas. The magnetic fields in molecular clouds can now be mapped with increasing resolution and sensitivity, thanks to instruments like SCUBA-2. In combination with dust-continuum and molecular-line observations of the distribution and velocity of gas and dust, these measurements provide vital constraints on the forces and flows that determine the structure and appearance of dense clouds, and the properties of the stars and star clusters that form in them. No theory of star formation or galactic structure can be complete without a theoretical understanding of the role played by the magnetic field in the formation and evolution of star-forming clouds.

PROJECT. This project will use numerical magneto-hydrodynamic simulations to model dense molecular clouds and collisions between them, as a function of cloud mass, collision velocity, impact parameter (how far from head-on the collision is), magnetic field strength and magnetic field orientation. The simulations will start from dynamical initial conditions informed by galactic-scale simulations of the interstellar medium. They will aim to reproduce observed properties of dense clouds, in particular those obtained by the BISTRO project using POL-2 on the James Clerk Maxwell telescope. The project will use the PHANTOM Smoothed Particle Magneto-Hydrodynamics code, with additional modules to treat the thermal and chemical processes that regulate the dynamics. The results will be post-processed using UCLChem, LIME and RADMC-3D to produce molecular-line profiles, line maps and dust-continuum maps, including polarisation.

SKILLS. The student will become expert in interstellar gas dynamics and the associated chemical and radiative processes, triggered star formation, and numerical magneto-hydrodynamics. Once acquired, these skills can be applied to a range of other problems in astrophysics, and many can also be applied in other fields like meteorology.


The typical academic requirement is a minimum of a 2:1 a relevant discipline.

Applicants whose first language is not English are normally expected to meet the minimum University requirements (e.g. 6.5 IELTS) (

How to apply

Applicants should apply to the Doctor of Philosophy in Physics and Astronomy.

Applicants should submit an application for postgraduate study via the Cardiff University webpages ( including:

• your academic CV

• a personal statement/covering letter

• two references, at least one of which should be academic

• Your degree certificates and transcripts to date (with certified translations if these are not in English).

In the "Research Proposal" section of your application, please specify the project title and supervisors of this project.

This project is only available to self-funded students, please can you include your funding source in the "Self-Funding" section.

Funding Notes

Please note that bench fees may be charged in addition to tuition fees for this project. This will be confirmed as part of any formal offer for this project.

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