Research Interests:

I use the combined techniques of observational spectropolarimetry and three-dimensional numerical radiative transfer modelling to probe the geometrical configurations of gas and dust surrounding these stars. I haves applied these techniques to newly formed protostars, interacting binary systems, evolved mass-losing variable stars, and supernova explosions. My aim is to trace the structure of circumstellar material and the ways it mediates between a star and its environment over the course of the star's life cycle. My most recent project focuses on understanding the commonalities and differences among the members of the heterogeneous category of supernovae called Type IIn, which show signatures of strong interaction between the supernova ejecta and the circumstellar material expelled in pre-supernova mass loss episodes.

Recent Publications:
(Abstracts of some articles are available)

• Winn, J.N., Hamilton, C.M., Herbst, W.J., Hoffman, J.L., Holman, M.J., Johnson, J.A., & Kuchner, M.J. 2006. The Orbit and Occultations of KH 15D. ApJ, vol. 644, p. 510 (DOI: 10.1086/503417)
• Leonard, D.C., Filippenko, A.V., Ganeshalingam, M., Serduke, F.J.D., Li, W., Swift, B.J., Gal-Yam, A., Foley, R.J., Fox, D.B., Park, S., Hoffman, J.L., and Wong, D.S. 2006. Evidence for a Non-Spherical Explosion in SN 2004dj. Nature, vol. 440, p. 505 (DOI: 10.1038/nature04558)
• Hoffman, J.L., Chornock, R., Leonard, D.C., and Filippenko, A.V. 2005. Interstellar Polarization and the Position Angle Orientations of Seyfert 1 Galaxies. Monthly Notices of the Royal Astronomical Society, vol. 363, p. 1241 (DOI: 10.1111/j.1365-2966.2005.09513.x)
• Hoffman, J.L., Whitney, B.A., and Nordsieck, K.H. 2003. The Effect of Multiple Scattering on the Polarization from Binary Star Envelopes. I. Self- and Externally-Illuminated Disks. Astrophysical Journal, vol. 598, p. 572 (DOI: 10.1086/378770)
• Wisniewski, J.P., Morrison, N.D., Bjorkman, K.S., Miroshnichenko, A., Gault, A.C., Hoffman, J.L., Meade, M.R., and Nett, J.M. 2003. Spectroscopic and Spectropolarimetric Observations of V838 Mon. Astrophysical Journal, vol. 588, p. 486 (DOI: 10.1086/373897)
• Meyer, J. M., Nordsieck, K.H., and Hoffman, J.L. 2002. Spectropolarimetric Clues to the Structure and Evolutionary Status of MWC 349A. Astronomical Journal, vol. 123, p. 1639 (DOI: 10.1086/339186)
• Hoffman, J.L., Nordsieck, K.H., and Fox, G.K. 1998. Spectropolarimetric Evidence for a Bipolar Flow in beta Lyrae. Astronomical Journal, vol. 115, p. 1576 (DOI: 10.1086/300274)