Dr. Christina Lacey

Assistant Professor of Physics and Astronomy
University of South Carolina

Phone: 803-777-6089
FAX:   803-777-3065

E-mail: lacey at sc dot edu

Classes Spring 2006:


 SCCC 116 Syllabus    Schedule
 ASTR 211 ASTR 211/211A Syllabus

Classes Fall 2005:


 SCCC 115 Syllabus    Revised Schedule 22 Sep. 2005
 ASTR 211 ASTR 211/211A Syllabus


 Astronomy Center  - Information about the self-paced astronomy courses ASTR 111, 111A, 211, 211A, and 311.
 

Research Interests:


My research centers around  the birth and death of massive stars: HII regions (large clouds of ionized hydrogen), which are  stellar nurseries, and supernovae, which occur when massive stars exhaust their  nuclear fuel, inducing  core-collapse events that lead to the destruction of the stars. HII regions are the birthplace of stars and supernovae are the deaths of stars, so this study leads to a better understanding of the life cycle of stars and how the evolution of stars affects the interstellar medium and ultimately, the evolution of galaxies. Supernova remnants are also believed to be the sites of cosmic ray electron acceleration.

In order to investigate these topics, I use a multi-wavelength approach: X-ray, optical, radio, and low-frequency radio. The primary observatory that I use for  observations is the  Very Large Array radio telescope, which is located in New Mexico.  Multi-wavelength observations are necessary to fully investigate the different emission mechanisms that exist in different, complex regions of supernovae and HII regions.  One of my primary research goals is to fully  understand the global picture of supernova remnant evolution in nearby galaxies and how it affects the evolution of the interstellar medium and of the galaxies themselves.

In addition to the above research, I am involved with colleagues on other projects such as astronomy at low frequencies,  3-D imaging techniques, and cosmic ray electron acceleration.

Here are some examples with brief explanations of current projects underway:
 

  • Monitoring of Supernovae at the VLA:  Observations are underway at the VLA  to monitor new supernovae and to track old supernovae at several frequencies.  By studying the evolution of the spectra and "radio light" curves, we can extract information on the progenitor star and its mass-loss history in time.
  • Radio Surveys of Nearby Galaxies for Supernova Remnants: There is  a large sample of supernova remnants in our own Galaxy, but less than 25 Galactic supernova remnants have well-known distances. Samples of supernova remnants and HII regions in nearby galaxies are all equidistant, making inter comparisons possible.  These samples of remnants are used to determine the properties of the galactic environment  and properties of the remnants themselves.  Future work includes making comparisons between galaxies, looking for differences between evolutionary behavior and galactic environment.
  • Radio Surveys of Nearby Galaxies for HII Regions: The motivations for extragalactic samples of  HII regions are similar to those for supernova remnants. HII regions can be used to gauge the amount of extinction (how much internal gas and dust exists in th line of sight).  The properties of gas and dust throughout a galaxy are not well-known. Extinction gradients have been reported in some galaxies but need to be correlated with metallicities or other properties of galaxies.  The HII regions are used to calculate star formation rates and to predict the past and future of stellar evolution in galaxies.
  • Optical and X-ray follow-ups to radio surveys: The radio surveys must be followed with optical spectroscopic confirmation.  The optical spectra also yield information on chemical abundances and different regions of the remnants compared to radio. X-ray information leads to temperature and electron density estimates, which can be used to calculate distances, magnetic fields, and other properties of supernovae.
  • Low Frequency Survey of Galactic Supernova Remnants and Interstellar Medium: This project has just begun and explores a previously unaccessible portion of the radio spectrum.  By studying remnants at these low frequencies, we  can test various models of cosmic ray acceleration in remnants and by using the remnants as background sources, study the interstellar medium in front of the remnants through absorption by the remnant. Preliminary results confirm that we can use this method to study the interstellar medium.

    •  
    In addition to the above projects, I am interested in many other areas of astronomy and would welcome any interested astronomy students who want to pursue other topics.  I am also interested in physics and astronomy education, which are allowable dissertation topics at USC.
    Astronomy is an excellent topic to pursue as a major or dissertation topic. In addition to "out of this world" research, study in astronomy leads to vast computer experience and skills with many operating systems and software packages, being published in refereed journals, and investigations in many areas of physics in astrophysical settings. Modern astronomy relies heavily on computers for analysis, controlling telescopes, interacting with colleagues, and data reduction. But astronomers still have the thrill of pointing the telescope and receiving data, which is then used to test theories to advance our understanding of the Universe.

    Current Graduate Students: Leila Mizouni, Sara Schultz

    You can contact me at:

    Phone: 803-777-6089
    FAX: 803-777-3065

    E-mail: lacey at sc dot edu