Thomas Stephan

Thomas Stephan's Personal Page

Thomas Stephan
Senior Research Associate
The University of Chicago Department of the Geophysical Sciences 5734 South Ellis Avenue Chicago, IL 60637 USA
Office:	HGS 121
Phone: Fax: E-Mail:	+1-773-702-8856 +1-773-702-9505 tstephan "at" uchicago "dot" edu

Research Interests

Dust plays a major role in the universe. Stars form from clouds of gas and dust. At the end of their lives – after they have developed to red giant stars, AGB stars, or during nova and supernova explosions – dust forms in the outflows of dying stars. This dust eventually becomes part of the interstellar medium where new generations of stars develop. 4.6 Ga ago, our solar system formed from such a cloud of gas and dust. Remnants of preceding stars can be found as so-called presolar grains in primitive meteorites. They still provide information about nucleosynthetic processes in individual stars these dust grains come from. Another source of information about the early solar system are interplanetary dust particles – dust that originate in our solar system from asteroids and comets and that is collected in the stratosphere. Especially cometary material is of special interest since comets are considered the most primitive bodies in the solar system. In 2006, the Stardust spacecraft has returned dust from comet Wild 2. These samples provide information about processes in the outer solar system, especially the Kuiper belt where Wild 2 originated.

I have used time-of-flight secondary ion mass spectrometry (TOF-SIMS) to study mainly the chemical composition of meteorites and all kinds of available cosmic dust samples: interplanetary dust, presolar dust, and samples from the Stardust mission.

In a joint University of Chicago-Argonne National Laboratory project, we are now developing the next generation of instruments based on microbeam laser resonance ionization mass spectrometry that will be used to measure isotopic and chemical compositions of various dust samples. CHILI – the Chicago Instrument for Laser Ionization – is nearing completion.

Selected Publications

Rost D., Stephan T., Greshake A., Fritz J., Weber I., Jessberger E. K., and Stöffler D. (2009) A combined ToF-SIMS and EMP/SEM study of a three-phase symplectite in the Los Angeles basaltic shergottite. Meteorit. Planet. Sci. 44, 1225–1237. [PDF]
Stephan T., Flynn G. J., Sandford S. A., and Zolensky M. E. (2008) TOF-SIMS analysis of cometary particles extracted from Stardust aerogel. Meteorit. Planet. Sci. 43, 285–298. [PDF]
Stephan T., Rost D., Vicenzi E. P., Bullock E. S., MacPherson G. J., Westphal A. J., Snead C. J., Flynn G. J., Sandford S. A., and Zolensky M. E. (2008) TOF-SIMS analysis of cometary matter in Stardust aerogel tracks. Meteorit. Planet. Sci. 43, 233–246. [PDF]
Leitner J., Stephan T., Kearsley A. T., Hörz F., Flynn G. J., and Sandford S. A. (2008) TOF-SIMS analysis of crater residues from Wild 2 cometary particles on Stardust aluminum foil. Meteorit. Planet. Sci. 43, 161–185. [PDF]
Stephan T. (2008) Assessing the element composition of comet 81P/Wild 2 by analyzing dust collected by Stardust. Space Sci. Rev., 138, 247–258. [PDF]
Stephan T., Jessberger E. K., Heiss C. H., and Rost D. (2003) TOF-SIMS analysis of polycyclic aromatic hydrocarbons in Allan Hills 84001. Meteorit. Planet. Sci. 38, 109–116. [PDF]
Stephan T. (2001) TOF-SIMS in cosmochemistry. Planet. Space Sci. 49, 859–906. [PDF]

Book Chapter

Jessberger E. K., Stephan T., Rost D., Arndt P., Maetz M., Stadermann F. J., Brownlee D. E., Bradley J. P., and Kurat G. (2001) Properties of Interplanetary Dust: Information from Collected Samples. In Interplanetary Dust (eds. E. Grün, B. Å. S. Gustafson, S. F. Dermott, and H. Fechtig), pp. 253–294. Springer-Verlag, Berlin, Heidelberg, New York. [PDF]

Popular Science

Stephan T. (2005) Stardust Memories – Kosmischer Staub und die Methoden seiner Erforschung. In Staub – Spiegel der Umwelt (eds. J. Soentgen and K. Völzke), pp. 72–82. oekom verlag, München. [PDF]
Stephan T. (1998) Sternenstaub und Marsmikroben – Planetologie, eine interdisziplinäre Wissenschaft. Forschungsjournal der Westfälischen Wilhelms-Universität Münster 7(1), 44–46. [html]

Article about Scientists in Germany

Stephan T. (2008) Plötzlich vor dem Nichts – Ein erfolgreicher Wissenschaftler wird arbeitslos. Forschung und Lehre 15, 464–466. [PDF]

Selected Posters

Stephan T. et al. (2003) Time-of-Flight Secondary Ion Mass Spectrometric Analysis of Residues from Fluid Inclusions in Terrestrial Glass and their Possible Connection to Cometary Interplanetary Dust. Presented at the 66th Annual Meeting of the Meteoritical Society, Münster, Germany. [PDF – 9.3 MB]