Understanding the lives and deaths of stars

University of Toronto astronomer Marten van Kerkwijk is the recipient of a 2013 John Simon Guggenheim Memorial Fellowship.

It's a distinction awarded each year to a select group of leaders in mid-career, on the basis of exceptional scholarship or creativity in the arts. The prestigious honour was designed to help academics and artists focus on individual projects.

More than 100 Guggenheim fellows have gone on to become Nobel laureates, while 35 have become poet laureates and eight have received the Fields medal.

U of T News asked Professor van Kerkwijk to share some thoughts about his work and the opportunities the Guggenheim will bring.

Tell us about your research

I have two main interests. One is to try to understand the lives and deaths of stars, and in particular the odd turns these can take if a star has a binary companion -- including what one could call rejuvenation, reincarnation, transmutation, and annihilation. The other is to learn about what happens under the extreme conditions found in stellar remnants, where densities range from roughly a million times that of water (a tonne per cubic centimeter) in white dwarfs to nearly a quadrillion times that of water in neutron stars (a density at which all of humanity would fit in a cubic centimeter). Under such conditions, physical processes are very different -- for some, I keep being amazed that we can understand something at all.

With the support of the Guggenheim fellowship, I hope to tackle a long-standing question for white dwarfs, which is how to rekindle nuclear fire, start a nuclear runaway, and get an explosion. We know this happens sometimes -- the results are the so-called type Ia supernovae, the type used to show that the expansion of the Universe is, most surprisingly, accelerating (2011 Nobel prize in physics) -- but the standard mechanism usually invoked has serious problems in reproducing the observed rates and properties. During my last sabbatical, I discussed these issues at length with two colleagues, and we concluded that the standard scenario was untenable. We suggested an alternative mechanism and in the coming year I hope to find out whether this withstands full scrutiny.

What drew you to this field - and to this particular focus?

My interest in astronomy goes back to popular science magazines (a Dutch magazine called Kijk or Look), which had fascinating descriptions of the onion-like structure massive stars attain late in their lives. Strangely, perhaps, I was not all that interested in looking through telescopes at the time, though that changed when as a third-year student I overheard my superviser, Prof. Ed van den Heuvel, mention on the phone something along the lines of `yes, we could use any extra telescope time, and, yes, we will be able to find someone to go to the observatory' -- after he hung up, I immediately volunteered (the trip, to Calar Alto in Spain, made a big impression; it also ended up in a promotional video for the University of Amsterdam). Maybe partly because of this, I now work somewhat on the interface of observations and theory. 

The above also shows an early interest in stars, which was strengthened at the University of Amsterdam. My interest in neutron stars similarly started there, although I also soon learned that for that topic, as for most I guess, it is wise not to expect plans to pan out, but rather be ready for the unexpected: I feel I learned relatively little about neutron stars, but am quite happy about what I managed to learn from their companions about other types of stars.

What kind of impact could your research have for society?

Hmm, hard to pass up the chance to quote Socrates' response in a similar situation (this is part of my first lecture in AST 101). It is from Plato's Republic, where Socrates and his disciples are discussing what topics to study (they have already decided on arithmatic and plane geometry):

(Socrates) And suppose we make astronomy the third -- What do you say?
(Glaucon) I am strongly inclined to it; the observation of the seasons and of months and years is as essential to the general as it is to the farmer or sailor.
(Socrates) I am amused at your fear of the world, which makes you guard against the appearance of insisting upon useless studies; and I quite admit the difficulty of believing that in every man there is an eye of the soul which, when by other pursuits lost and dimmed, is by these purified and re-illumined...

I should add that Socrates later doubts the use of actually observing the sky to learn about astronomy, although a more positive interpretation of his arguments is that observations are of little use unless one tries to understand the underlying patterns.

Which brings me to a somewhat less facetious response, which is that, like most astronomers, I find it hard to argue for more than an indirect impact on society, but I do hope my research will in its small way "illumine eyes of the soul'' by uncovering the workings of the heavens. For my specific project, insight into these thermonuclear supernovae should help improve our understanding of the origin of the elements (these supernovae are responsible for iron and nickel in particular), allow us to make better use of them as tracers of the expansion history of the Universe, and open up new avenues in our quest to understand the often bizarre lives and deaths of stars.

Why U of T?

I came to U of T in 2003, from a faculty position at Utrecht University (in The Netherlands). I moved partly so I could live together with my wife, but as we had multiple offers, the choice was made consciously. Beyond being marvellous scientifically (having not just a great Department of Astronomy & Astrophysics, but also the Canadian Institute of Theoretical Astrophyics), what appealed to me was that at all levels of the university, from students to the president, there seemed to be a happiness of being where one was as well as a genuine interest in improving it further. I continue to feel this way, to the extent that when, e.g., negotiations are described in somewhat adversarial terms, I wonder whether people fully realize how easily it is to destroy the general dedication now present, and how much less effective and efficient the university would be without it. (I feel somewhat similar about city, province and country, except that I'd wish even more strongly that what is good was taken less for granted.)

What advice would you give to a student just starting out in this field?

My main advice would be to try to make use of the opportunities to do research -- it is such fun to try to answer some question -- even a tiny one -- which really has not been answered before. The summer research positions, both NSERC's USRA and U of T's UTEA, are marvellous. They're also highly competitive, so come with good course preparation. At the same time, ensure you have enough time to think about what you are learning, and discuss with your professors and with others (in and out of class; e.g., in the Astronomy and Space Exploration society -- ASX).