I am a theoretical astrophysicist and my research focuses on star and planet formation. I completed my undergraduate studies at UBC in mathematics and physics. I then moved to the University of Toronto for my M. Sc. (in theoretical physics). I returned to UBC to do my Ph.D. in astrophysics under the supervision of Greg Fahlman, completing it in 1980. I took up an NSERC Postdoctoral Fellowship at the Institute of Astronomy in Cambridge (England). I went on to further postdoctoral research with Chris McKee and Jon Arons at the Astronomy Dept. at Berkeley, and with Colin Norman at the Johns Hopkins University. I joined the faculty at McMaster in 1986. Research Leaves and Fellowships over the subsequent years have taken me to many outstanding research centres including the Observatoire de Grenoble (1988, 1992), the Max-Planck Inst. for Astronomy in Heidelberg (1993), the Harvard-Smithsonian Center for Astrophysics (1993), the Max-Planck Institute for Astrophysics in Munich (1997), the Canadian Institute for Theoretical Astrophysics (CITA) in Toronto (1990 and 1997), Caltech (2001), and the Kavli Institute for Theoretical Physics (KITP) in Santa Barbara (2007/08).
I have been involved in many aspects of Canadian as well as international astronomy and astrophysics, having served on Time Allocation Committees (CFHT and JCMT), NRC Science Advisory Committees (Gemini, JWST), Visiting Committees (U.S. NRAO), Advisory Boards (HIA, CITA Council), and review committees. I chaired Canada's decadal survey of Astronomy and Astrophysics - the NRC-NSERC Long Range Planning Panel (1998/2000) - and was the principal author of the LRP report; "The Origins of Structure in the Universe". The LRP is playing the central role in guiding the development of Canadian astronomy in this decade and beyond, having involved Canada in ALMA, JWST, TMT, SKA, and several other important space and ground based telescopes and observatories.
Most recently, I spear-headed and am the founding (2004) Director of McMaster's Origins Institute (OI). Its scientific mission is to engage in fundamental transdisciplinary research on the origin of structure and life in the cosmos. The scientific themes of the OI cover 6 broad themes in science: the origin of space and time (cosmology, early universe), structure in the universe (planets, stars and galaxies), the elements, life (astrobiology), species and biodiversity, and humanity. In addition to its research foci, the OI has developed a novel OI Undergraduate Research specialization. The OI is committed to public outreach and education through its award winning OI Public Lecture series and played an important role in the creation of the McMaster 3D theatre. The OI has also run major international annual scientific conferences on some of the most important questions in contemporary science.
Star formation, planet formation, astrobiology
Department of Physics and Astronomy
I have taught a wide variety of undergraduate as well as graduate courses, in both astrophysics and physics. I have often taught graduate courses on Star Formation (Physics 778), the Interstellar Medium (Physics 785) and Galactic Dynamics (Physics 781). In the undergraduate program, I have often taught the Introductory Astronomy and Astrophysics course (Astron 1F03), first year physics, and upper level courses such Galaxies and Cosmology (Astron 3X03), and Stellar Structure (Astron 3Y03).
I have worked extensively with my OI collaborators, Jonathon Stone and Alison Sills, to create and realize a new concept for teaching transdisciplinary courses in fundamental science. We designed the Origins Undergraduate Research Specialization to take students into the heart of 6 of the most fundamental streams of research in 21st century science. These subjects transcend the traditional subjects in science calendars, since these fields are often highly transdisciplinary. Our philosophy is to insure that students that are deeply trained in a particular field (hence requirement to be registered in a traditional Honours Science Program), are at the same time sufficiently immersed in the broad set of fundamental science themes that are emphasized in the OI programs.
This approach is accomplished by first having our students go through a set of survey courses in their first year of the program (e.g. Big Questions). Their interests are then sharpened in the second year of the program through a selection of courses centred on each of the 6 basic themes. All the while, we expose students to the fundamental literature and new scientific results in these fields by means of highly interactive seminars (Origins 2S03 and 3S03). The first of these is designed to take the students through the basic literature, guided by OI faculty. The 2nd year seminar exposes students to visiting scientists and their colloquia as part of the OI colloquium series. The capstone of the program is the OI undergraduate thesis, taken in the 3rd and final year of the program. Here the student is encouraged to work in any area that they have taken an interest in, and to seek appropriate OI supervisors. Our OI students are invited to meet with OI Public Lecturers to broaden their exposure to outstanding scientists at a very early stage in their careers.
I have personally developed and taught, in collaboration with Paul Higgs, the Origins of Life (Astrobiology - Origins 3D03) course. The OI is building a strong research presence in this field, and students participate in this very exciting, emergent new science.
CBC Story on our paper in the Proceeding of the National Academy of Science (PNAS, 2017; Pearce, Pudritz, Semenov, and Henning: “Origin of the RNA world: the fate of nucleobases in warm little ponds”. Link to article: "Origin of the RNA world: The fate of nucleobases in warm little ponds"Origin of the RNA world: The fate of nucleobases in warm little ponds"
Origins of Life Laboratory funded (2016) :
Canadian Astronomical Society (CASCA) Executive Award (2016)
Lecture at Harvard’s Origins of Life Initiative (2011)
McMaster professor to join JHU Society of Scholars (2009)
My Publications- listed on Google Scholar: https://scholar.google.co.jp/citations?user=14hIVDwAAAAJ&hl=ja
Department of Physics & Astronomy
Dear Prospective Research Students:
My research focuses on the theoretical and computational study of star and planet formation, and astrophysical and planetary aspects of the origin of life including experimental work in our Origins of Life Lab. Star formation impacts a huge range of astophysics - from planet formation to galaxy formation and evolution and cosmology. Stars and planets form in protostellar disks and there are very deep connections between these subjects through them. The discovery of over 4000 exoplanets is driving a major revolution in astrophysics as we try to develop new theoretical models that can explain the wealth of new data and planetary populations – such as the dominant SuperEarths. The characterization of the composition of the atmospheres of rocky exoplanets is one of the main drivers for our search for life in the universe. Members of my group perform a wide range of state of the art, high performance computing simulations of star formation – from galaxy scales down to individual stars forming in their protostellar disks; planet formation and the properties of exosolar planets and their atmospheres; and work on early Earth and prebiotic physics and chemistry that lead to the origins of RNA. We connect our work with exciting observations from new observatories such as the James Webb Space Telescope, as well as the ALMA millimeter observatory https://www.eso.org/public/teles-instr/alma/ allow us to connect the work with new observations. I am also the Co-Investigator for our Origins of Life Laboratory in McMaster’s Origins Institute https://origins.mcmaster.ca/research/origins-of-life-laboratory/
There are many exciting research opportunities in my group. In addition to individual meetings, I have regular group meetings every week in which everyone discusses their results and ideas. Students and postdocs at all levels are well connected to one another as well as with the many external collaborators across the world, that we work with.
Research topics in my group:
Star Formation explores a wide range of interconnected problems starting from the scale of the formation of molecular clouds in galaxies, down to filamentary structure of molecular clouds, to the formation of star clusters within them, to the collapse of individual gas “cores” within such clustered environments (to form single or binary stars), and on down to the physics of protostellar disks through which gas accretes onto their central stars and from which highly collimated jets are launched. Much of the research involves state of the art 3D numerical simulations, most recently using the RAMSES Adaptive Mesh Refinement code. We are currently using RAMSES for multiscale galaxy simulations that allow us to trace star formation in magnetized galaxies all the way from cloud formation on many kpc scales, through to star clusters and over the next year or two – down to the 100 AU scales needed to study massive star formation in clusters. See recent articles:
-Star formation in filamentary molecular clouds and a new paradigm for star formation: see our review Andrè et al, (2014): https://arxiv.org/pdf/1312.6232.pdf
- The formation of massive stars: Klassen, Pudritz et al (2016):
- The formation of star clusters: Howard, Pudritz, & Harris ( 2018):
-Theory and simulations of protostellar jets and outflows: see review Pudritz and Ray (2019):
Planet Formation: is arguably one of the hottest topics in astrophysics, and indeed science, today. In my group we are investigating all aspects of planet formation, connection how planets form in protostellar disks, to their final orbits and chemical compositions. This “end-to-end” approach can be used to predict the composition of exoplanet atmospheres, which will be observed for the first time with JWST. This research involves theoretical work, as well as extensive use of astrochemistry codes and population synthesis simulations. Some recent papers in my group include:
- • A theory for planet traps and the migration of forming planets in disks (2011): https://arxiv.org/pdf/1105.4015.pdf
• Linking the composition of atmospheres to planet formation (2016): https://arxiv.org/pdf/1605.09407.pdf
• The combined effects of disk winds and turbulence for planet formation and composition (2022): https://arxiv.org/pdf/2207.01626.pdf
• Bifurcation of planet formation histories (2022): https://arxiv.org/pdf/2111.01798.pdf
Origins of life: focuses on the connection between protostellar disks, and the properties of pre-biotic chemistry on newly formed habitable planets. Nucleobases, amino acids, and fatty acids are found in meteorites and can be synthesized in 100 km parent bodies – planetesimals – which are also the building blocks of terrestrial planets. We have done calculations to show how these molecules are synthesized within planetesimals. Recent work focuses on understanding how meteoritic delivered biomolecules evolve on early planetary conditions, to result in the formation of RNA polymers – the first genetic materials. See our recent article:
• Fate of nucleobases in warm little ponds, upon delivery by meteorites to the Early Earth, see our Cozzarrelli prize paper; (2017): https://arxiv.org/pdf/1710.00434.pdf
• HCN synthesis in early Earth atmospheres leading to biomolecule formation (2022): https://arxiv.org/pdf/2201.00829.pdf
I have many interesting research projects within this broad set of themes. I will be happy to discuss these with you. If you are interested, please send me e-mail at email@example.com or consult my departmental home page. I look forward to hearing from you!
With best wishes,