Karen S. Bjorkman
(Circumstellar Disks, Polarimetry, and Stellar Winds)
Professor of Astronomy,
& Associate Department Chair
Ph.D. Astrophysics, 1989 - University of Colorado
Personal Homepage
My research interests are in the material around stars
(circumstellar matter) and in the winds from hot stars. Evidence of
circumstellar disks is seen in many types of stars, from the earliest
young stars
to older planetary nebulae, and the presence of disk-like geometries
seems to be ubiquitous in the stellar zoo. Studying such systems can
help
to shed light on the ways that stars are formed, and possibly even on
the development of protoplanetary systems around other stars.
Some questions we ask about winds, disks and circumstellar material
include: What causes disks to form around massive stars? Are
there interactions between stellar winds and circumstellar disks, and
if so what are their consequences? What are the disks like? (are they
thick or thin? hot or cool? high or low density?) How do disks affect
the evolution of the star and the interstellar medium around it? Are
there similarities between the disks observed in pre-main-sequence
(young) stars, which may be the precursors to planetary systems, and
those) observed in main-sequence (older)
stars? In studying these questions, I use several observational
techniques (spectroscopy, spectropolarimetry, and imaging) at multiple
wavelengths (optical, ultraviolet, and infrared). Combining different
types of observations can help develop a consistent picture of the
nature
of circumstellar envelopes and disks. These data are also used for
comparison with models, which allows us to
distinguish between different ideas of how disks form and what their
physical
characteristics are.
Subset of Recent Publications:
(full
bibliography
available online)
Miroshnichenko, A.S., Gray, R.O., Klochkova, V.G., Bjorkman, K.S., Kuratov, K.S.,
2004, “Fundamental parameters and evolutionary state of the
Herbig Ae star candidate HD 35929”, A&A, 427, 937.
Miroshnichenko, A.S., Levato, H., Bjorkman, K.S., Grosso,
M., and Manset, N., 2004, “Properties of Galactic B[e] Supergiants III.
MWC 300”, A&A, 417, 731.
Wisniewski, J.P., Bjorkman, K.S., and Magalhaes, A.M., 2003,
“Evolution of the Inner Circumstellar Envelope of V838 Monocerotis”, ApJ
(Letters), 598, L43.
Miroshnichenko, A.S., Bjorkman, K.S., Morrison, N.D.,
Wisniewski, J.P., Manset, N., Levato, H., Grosso, M., Pollmann, E.,
Buil, C., and Knauth, D.C., “Spectroscopy of the Growing Circumstellar
Disk in the delta Scorpii Be Binary”, 2003, A&A, 408,
305.
Wisniewski, J.P., Morrison, N.D., Bjorkman, K.S.,
Miroshnichenko, A.S., Gault, A.C., Hoffman, J.L., Meade, M.R., and
Nett, J.M., “Spectroscopic and Spectropolarimetric Observations of V838
Mon”, 2003, ApJ, 588, 486.
Miroshnichenko, A.S., Bjorkman, K.S., and Krugov, V.D.,
2002, “High-resolution Spectroscopy of Gamma Cas. Long Term
Variations and Binary Nature”, P.A.S.P., 114, 1226.
Bjorkman, K.S., Miroshnichenko, A.S., McDavid, D., and
Pogrosheva, T.M., 2002, “A Study of Pi Aquarii During a Quasi-Normal
Star Phase: Refined Fundamental Parameters and Evidence for Binarity”, Ap.J.,
573, 812.
Wood, K., Smith, D., Whitney, B., Stassun, K., Kenyon, S., Wolff,
M., and Bjorkman, K.S., 2001, “Scattered Light Models of
Protostellar Envelopes: Multiple Outflow Cavities and Misaligned
Circumstellar Disks”, Ap.J., 561, 299.
E-mail: karen@astro.utoledo.edu
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