Dr. Harrison's main research interest is cataclysmic variables (CVs), concentrating on their fundamental properties: distances, component masses, luminosities and abundances. He has led or participated in several astrometric projects to measure the distances to cataclysmic variables (and other astrophysically important stars, such as Cepheid and RR Lyr variables, very low metallicity stars, and planetary nebulae) using the Fine Guidance Sensors (FGS) on the Hubble Space Telescope. Dr. Harrison specializes in infrared observations, and has obtained infrared spectra of cataclysmic variable stars using the IRTF, Keck, and Gemini. These data reveal that the secondary stars are peculiar with highly unusual abundance patterns. This suggests that their evolutionary history must be different from the currently accepted paradigm.

Another prominent research area is magnetic cataclysmic variables. As cited below, we have used the Spitzer Observatory to examine the mid-infrared spectra of Intermediate Polars (systems where B < 10 MG on the primary white dwarfs), finding that synchrotron emission is probably an important process in these objects.

In addition, Dr. Harrison is also part of two large HST projects that are using the FGSs to measure the masses of explanets, and determine whether their orbits are co-planar. Other research interests include X-ray, infrared and radio observations of Low Mass X-ray Binaries (with Jillian Bornak), and the automated indentification of variable stars (with recent graduate Doug Hoffman).

Instrumentation

With Professor Holtzman, Harrison has obtained an NSF grant under the PREST program to help revitalize the NMSU 1m telescope. Included in the upgrades is a new instrument, the NMSU High Speed Photometer. This instrument employs Avalanche Photodiode detectors that have greatly improved quantum efficiency over the older photomultiplier tube-type detectors. This instrument can obtain high speed photometry simultaneously in UBVRI. One of the goals is to obtain light curves for transiting exoplanets, along with a variety of projects on CVs and pulsating stars. The instrument was designed and built by undergraduate students, and several such students continue to be employed in the deployment and calibration phase of the project.

Teaching

Dr. Harrison currently oversees the Astronomy 110 laboratories which includes the development of new labs, as well as maintenance of the campus observing facilities (two Meade 12" telescopes). He has taught "Introduction to Astronomy" [ASTR-110], "Revolutionary Ideas in Science" [ASTR-301], and "Into the Final Frontier" [ASTR-308]. He also supervised the graduate seminar for Spring 2004 [ASTR-500].

Publications

Cyclotron Modeling Phase-Resolved Infrared Spectroscopy of Polars. I. EF Eridani
Campbell, R. K., Harrison, T. E., Schwope, A. D., & Howell, Steve B. 2008, ApJ, 672, 531

Spitzer IRS Spectroscopy of Intermediate Polars: Constraints on Mid-Infrared Cyclotron Emission
Harrison, T.E., Cambell, R. K., Howell, S. B., Cordova, F.A., & Schwope, A. D. 2007, ApJ, 656, 444

The Nature of the Secondary Star in the Black Hole X-Ray Transient V616 Mon
Harrison, T.E., Howell, S. B., Szkody, P., & Cordova, F.A. 2007, AJ, 133, 162

Why Are the Secondary Stars in Polars So Normal?
Harrison, T.E., Howell, S. B., Szkody, P., & Cordova, F.A. 2005, ApJ, 632, L123

The Detection of Abundance Anomalies in the Infrared Spectra of Cataclysmic Variables: Shorter Period Systems
Harrison, T.E., Osborne, H.L., & Howell, S. B. 2005, AJ, 129, 240

Phase-Resolved Infrared H- and K-Band Spectroscopy of EF Eridani
Harrison, T.E., Howell, S. B., Szkody, P., Homeier, D., Johnson, J.J., & Osborne, H.L. 2004, ApJ, 614, 947

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