James explores how stars form across the Galaxy.

The Sun is one of 400 billion stars in the Milky Way Galaxy.  Where did all these stars come from?  Between the stars lie vast clouds of dark and cold gas, sometimes up to one million times the mass of our Sun or more.  Stars form when small pockets of these clouds become overdense and collapse from their own gravity.  Lots of questions about this process remain unanswered, however.  For instance, how did these clouds and their dense pockets themselves arise?  Why do many stars form in multiple systems, groups, or clusters?  Why do stars have a wide range of masses, with relatively more lower-mass stars than higher-mass ones?  What is the connection between how much gas is in a cloud and the number and types of stars it creates? Which stars produce planets, and which of those may have life? James’ research looks for answers to these questions.

He studies dark clouds using powerful telescopes around the world that can reveal what’s going on inside.  They are opaque to us because intermixed with the gas are small grains of dust that efficiently absorb visible light.  At wavelengths of light 100 to 1000 times longer, however, the dust and gas themselves are softly glowing in their own way.  With certain telescopes, we can observe and detect such light from these clouds to catch stars as they coalesce out of their surroundings.  I look within clouds of our own Galaxy primarily because here we can see the process unfolding in the greatest detail. Understanding how stars come to be in our own Galaxy will have far-reaching implications. For instance, it will help us understand better how the Milky Way and other galaxies evolve over cosmic time and will inform us about how the very first generation of stars in the universe came to be. 

On this page are some examples of some recent work in which James was involved, images of the long-wavelength emission from dust in clouds relatively close to the Sun taken with the ESA Herschel Space Observatory. Shown are the central parts of the Ophiuchus, Taurus, and Orion B clouds. These are false-colour images where blue denotes warmer dust heated by nearby young stars and red denotes colder dust further away that is only a few 10s of degrees above absolute zero. What’s striking about these images is the prevalence of thin, wispy filaments everywhere. At certain locations in some filaments are compact “bright” objects that are the dense pockets of gas and dust where young stars emerge. Indeed, these images and others revealed that star-forming pockets usually are found within the densest examples of such filaments.

Interested in more? Here are links to James’ short CV, my long CV, and his Publications List. Students interested in working with James, especially those from groups historically under-represented in astronomy, should contact him. He has a lot of ideas!