John Landstreet's Home Page

[ Physical Processes in the Solar System ]

The cover of my intermediate level textbook on the Solar System. The beautiful comet image is the work of Dominique Dierick of Gent, Belgium.

MY SOLAR SYSTEM TEXTBOOK

I have published an undergraduate textbook, "Physical Processes in the Solar System". The book has been adopted at more than a dozen universities. However, it is now out of print.

Links to class and course notes

  1. Problem sets for Kippenhahn and Weigert's Stellar Structure and Evolution
  2. Lecture slides from a set of lectures on spectropolarimetry that I gave in September 2007 at the annual Ecole d'Aussois in France
  3. Lecture notes from a course on atoms and radiation, molecules, and nulear physics that I gave a few years ago

Thumbnail Biography

I grew up mainly in the US, where I went to university (Reed College, in Portland, Oregon) and graduate school (Columbia University, in New York City, where I was in the Physics Department but did my thesis under Prof Lodewyk Woltjer, later well known as the long-time Director General of the European Southern Observatory). In 1970 I moved to London, Canada, to a post at the University of Western Ontario (UWO), where I have been (except for three sabbaticals, one at the Institut fuer theoretische Astrophysik of the University of Heidelberg, and two (!) at l'Observatoire Midi-Pyrenees in Toulouse) ever since. I am married to artist Barbara Landstreet, and have two children (David, grown up, and Sarah, a mechanical engineering graduate from McGill University, who has started her own custom packaging business in Kitchener, Ontario).

I am an emeritus/adjunct professor of physics and astronomy at UWO, where I often taught one section of the introductory astronomy course for poets, Astronomy 021. I also taught for some years the second year course in solar system physics (Astronomy 221/231), which I think is a great vehicle for reinforcing basic ideas from first-year physics. I also have taught the graduate level course in stellar interiors, and a number of courses on the physics side of our department. I have taught the third-year physics lab for several years, and various other courses such as fourth-year molecular and nuclear physics. I am now retired from teaching classes, but am still active in research and student supervision. In 2009 I was Leverhulme Visiting Professor at Armagh Observatory in Armagh, Northern Ireland

I have been active in the Canadian and international astronomical communities. I have been a member, Vice-Chair, and Chair of the Scientific Advisory Council of the Canada-France-Hawaii Telescope (1980 - 83), and more recently a member, Secretary, Vice-Chair, and Chair of the Board of Directors of the CFHT (1990 - 1997). I was President of Commission 25 (Photometry and Polarimetry) of the International Astronomical Union (1994 - 1997). I was a member and Chair of the Grant Selection Committee for Space and Astronomy (1980 - 83). I have been a member of the Board of Directors of the Canadian Astronomical Society (1994 - 1998), and served for two years as President. I was President of Commission 36 (Theory of Stellar Atmospheres) of the International Astronomical Union.

In the spring of 2002 I was awarded the C. S. Beals Award of the Canadian Astronomical Society. This is the highest research honour awarded by the Canadian astronomy community.

Research Interests

Early in my career, I worked extensively with Roger Angel on magnetic fields in white dwarf stars. We were involved with Jim Kemp in the discovery of the first of these multi-megagauss fields in Grw +70 8247, and Angel and I did most of the early search and discovery work in this field for the next few years, before we both moved on to other projects.

More recently, I have been interested primarily in physical processes that occur in envelopes and atmospheres of upper main sequence A and B stars, and (again) in white dwarfs. I have searched for and measured magnetic fields in such stars extensively, using both polarimetry and spectroscopy. I have tried to clarify which types of A and B stars have strong, coherent magnetic fields, and which don't. I have also tried to find clues in the magnetic data about how the strong fields of the magnetic A and B stars evolve with time. I have worked on modelling magnetic field geometries using a variety of techniques. Recently I have been modelling both field structure and the distributions of chemical elements over the surfaces of magnetic stars from spectra using my own set of FORTRAN spectrum synthesis programmes for stellar atmospheres permeated by magnetic fields (yes, lots of working scientists actually use FORTRAN, in spite of much editorial comment from colleagues in computer science). An example of this work may be found in Landstreet, Barker, Bohlender and Jewison 1989, The magnetic field and abundance distribution geometry of the peculiar B star HD 215441, Ap. J., 344, 876.

I am an active observer. Over the years, I have used a lot of large telescopes, including the 82" and 107" telescopes at McDonald Observatory, the 84" and 4-m telescopes at Kitt Peak National Observatory, the 60 " and the Big Eye at Palomar Observatory, the 60" and 100" telescopes at Mount Wilson Observatory, the 2.5-m telescope at Las Campanas Observatory, the 2-m telescope at l'Observatoire du Pic-du-Midi and the 152-cm telescope at l'Observatoire de Haute Provence in France, and of course the 3.6-m Canada-France-Hawaii Telescope on Mauna Kea. I have done a lot of photoelectric polarimetry in past years. I am currently doing a lot of (very) high resolution stellar spectropolarimetry at present, much of it using ESPaDOnS at the CFHT.

I have several current research interests. One is participation in a big mapping project to derive detailed maps of magnetic field structure and surface chemical element distributions over the surface of a number of known magnetic Ap stars, using wonderful new data obtained with the Musicos spectropolarimeter at Pic-du-Midi. A second project is to model individual line profiles in a number of very sharp-lined A and B stars, in an effort to detect directly the local line profiles of these stars, using high resolution, high signal-to-noise ratio spectra. This is an effort to see what information can be extracted from such profiles about conditions in the stellar atmosphere, particularly about the weak convection that may be present, and about the adequacy of LTE models to describe line formation in A and late B stars. A third project is an effort to find parametrized magnetic models for a large sample of new Ap star magnetic field measurements by Mathys and his collaborators, and to see what information about Ap magnetic fields is hidden in these data. And of course there are other projects waiting for a little time....

I am fortunate to be associated with (a perceptive person might even say "sustained by") an excellent research group, including one-time UWO undergraduate, now UWO Associate Professor Aaron Sigut. I have some great international collaborations with, for example, former Ph D student, now Professor and Department Head at the Royal Military College, Gregg Wade, and Dr. Stefano Bagnulo at Armagh Observatory, Armagh, Northern Ireland.

A few citations and other links...

Some relevant references to my research are the following:

  1. J. D. Landstreet 1992, Magnetic fields at the surfaces of stars, Astron. Astrophys. Rev., 4, 35-77.

  2. D. A. Bohlender, J. D. Landstreet, and Ian B. Thompson 1993, A study of magnetic fields in Ap Si and He weak stars, Astron. Astrophys., 269, 355-376.

  3. G. M. Hill and J. D. Landstreet 1993, Compositional differences among the A-type stars. I. Six narrow-lined stars, Astron. Astrophys., 276, 142-160.

  4. J. L. Leroy, J. D. Landstreet, and S. Bagnuolo 1993, 49 Camelopardalis: an uncommon magnetic star, Astron. Astrophys., 284, 491-498.

  5. T. A. Ryabchikova, G. M. Hill, J. D. Landstreet, N. Piskunov and T. A. A. Sigut 1994, Astrophysical determination of optical oscillator strengths for Ti II, Mon. Not. R. Astron. Soc., 267, 697-710.

  6. G. Wade et al 1996, The magnetic field and helium variation of the helium-strong star HD 184927, Astron. Astrophys., 320, 172.

  7. J. D. Landstreet 1998, Direct detection of atmospheric velocity fields in A-type stars, Astron. Astrophys, 338, 1041-1056,

  8. J. D. Landstreet, N. Dolez and S. Vauclair 1998, Light elements as probes of weak stellar winds, Astron. Astrophys., 333, 977,

  9. G.A. Wade, J.-F. Donati, J.D. Landstreet, S.L.S. Shorlin, 2000 Spectropolarimetric measurements of magnetic Ap and Bp stars in all four Stokes parameters, MNRAS, 313, 823,

  10. J. D. Landstreet, G. Mathys 2000, Magnetic models of slowly rotating magnetic Ap stars: aligned magnetic and rotation axes, A&A, 359, 213,

  11. J. D. Landstreet 2001, Recent advances in magnetic field diagnosis techniques, in proceedings of the Santiago meeting on "Magnetic Fields across the H-R Diagram", in ASP Conference Proceedings Vol. 248, Edited by G. Mathys, S. K. Solanki, and D. T. Wickramasinghe (San Francisco: Astronomical Society of the Pacific), 277

Some more recent papers are:

  1. J. D. Landstreet et al. 2007, Searching for links between magnetic fields and stellar evolution: II. The evolution of magnetic fields as revealed by observations of Ap stars in open clusters and associations, A&A 470, 685

  2. J. D. Landstreet et al. 2008, Searching for links between magnetic fields and stellar evolution. III. Measurement of magnetic fields in open cluster Ap stars with ESPaDOnS, A&A 481, 465

  3. J. D. Landstreet et al. 2009, Atmospheric velocity fields in tepid main sequence stars, A&A 503, 973

  4. J. D. Landstreet 2011, Abundances of the elements He to Ni in the atmosphere of Sirius A, A&A 528, A132

  5. J. D. Bailey, J. D. Landstreet, S. Bagnulo 2014, Discovery of secular variations in the atmospheric abundances of magnetic Ap stars, A&A 561, A147

  6. J. D. Landstreet, S. Bagnulo, L. Fossati 2014, On the consistency of magnetic field measurements of Ap stars: lessons learned from the FORS1 archive, A&A 572, A113

  7. J. D. Landstreet et al. 2015, A novel and sensitive method for measuring very weak magnetic fields of DA white dwarfs. A search for a magnetic field at the 250 G level in 40 Eridani B, A&A 580, A120

  8. J. D. Landstreet et al. 2016, Discovery of an extremely weak magnetic field in the white dwarf LTT 16093 = WD 2047+372, A&A 591, A80

  9. J. D. Landstreet et al. 2017, Monitoring and modelling of white dwarfs with extremely weak magnetic fields: WD2047+372 and WD2359-434, A&A 607, A92

A few of my former Ph D students have successfully escaped from Western, and lived to create home pages:

  1. Ermanno Borra, a professor in the Dept of Physics at Laval University in Quebec,

  2. Pierre Bastien, a professor in the Dept of Physics at the University of Montreal,

  3. David Bohlender, a staff member at the Canadian Astronomical Data Centre at the DAO, and

  4. Gregg Wade, Assistant Professor at the Royal Military College in Kingston, Ontario (who finally persuaded the Federal Government that even RMC staff should be allowed to live vicariously on the Web...)
And a few more of my former students DID live through the experience, but have never gotten around to those home pages:

  1. Lorence Tomaszewski, still living and working somewhere in deepest Alberta, I think,

  2. Ian Thompson, a staff member at the Observatories of the Carnegie Institute of Washington (i.e. Las Campanas Observatory),

  3. Robert Slawson, a Research Associate at Rochester Institute of Technology in New York State, and

  4. Grant Hill, Instrument Scientist at the W. M. Keck Observatory in Hawaii.

In my spare time I play clarinet and saxophone in a traditional jazz group, the Dixie Five.

Dr. John D. Landstreet
Department of Physics & Astronomy
University of Western Ontario
London, ON N6G 1P7, Canada

Telephone: +1 519 473 4174
Mobile: +44 (0)77 9071 2606
E-mail:jlandstr@uwo.ca

Last modified (somewhat): 2018 February 5