We can scarcely view the nighttime sky without becoming curious about celestial phenomena and about connections that may exist between the cosmic and the terrestrial. Modern astrophysics addresses this ancient curiosity and in so doing forges links between the physics of the universe and the nature of our earthly environment. Such progress has been possible through careful observation of electromagnetic radiation from the cosmos and application of physical principles to understand the nature of the stars, nebulae, and other objects that emit this radiation.
Professor Thomas Troland
The astrophysics group at the University of Kentucky combines astronomical observations with physical theory to study a variety of phenomena from the origin of the chemical elements to large scale structure of the universe. These efforts provide research opportunities for faculty and graduate students alike, and they make use of high performance computing facilities at Kentucky as well as national observatories like the Hubble Space Telescope (HST) and the Very Large Array radio telescope.
Consider, for example, the origin of the chemical elements. The lightest of them, hydrogen and helium, most likely arose with the universe itself. But the heavier elements, essential to life and to other interesting physical phenomena, must have a different origin. Most of these heavier elements are now thought to have formed by nuclear reactions in the very earliest generations of stars. As these stars aged, they cast much of their mass back into interstellar space. This material, enriched in heavier elements, formed later generations of stars and planets like the Sun and the Earth. Applying computational tools to data from the HST and from other observatories, researchers at Kentucky infer the abundance of heavy elements in our own galaxy and in others. From this analysis, they seek to understand the rising concentration of heavy elements over the history of the universe.
Related issues concern the origins of stars, and physical nature some of the intriguing phenomena associated with their births and deaths. Stars form from gravitational collapse of vast clouds of gas and dust in interstellar space. Yet many details of this process remain obscure. One is the role of interstellar magnetic fields. Observations of radio frequency radiation from interstellar clouds yield estimates of magnetic field strengths in these regions. From these estimates come indications of the role of the magnetic field in the star formation process. Kentucky researchers carry out these observations using radio telescopes in the U.S. and abroad. Data analysis occurs at home, using university-wide and departmental computing facilities.
Closely related to stellar birth (and death) is the phenomenon of interstellar masers. The radio frequency analogs of laboratory lasers, these powerful sources of radio radiation arise naturally near young and aged stars. Interstellar masers present challenging problems in theoretical physics involving the interaction of matter and radiation in space. Using computer simulations and analytical mathematics, UK researchers seek to understand the propagation of radiation through interstellar masers and through other astrophysical environments as well.
Much larger in scale than stars are the galaxies that fill space to the very limits of the observable universe. At the centers of some galaxies lie intense sources of radiation of non-stellar origin. Such ``active'' galaxies include galactic neighbors as well as the enigmatic quasars, the most powerful and distant objects known in the universe. The power of an active galaxy is now thought to arise from matter approaching a massive black hole near the galaxy center. From numerical simulations and analytical techniques, UK researchers seek a better understanding of the active galaxy phenomenon and of other dynamical processes that affect the large scale structure of galaxies.
On the largest scale of all is the universe itself and the galaxy clusters that inhabit it. When galaxy positions are plotted on maps of the sky, they trace out gossamer filaments hundreds of millions of light years long. Are these filaments real or do they represent the eye's natural inclination to find order amid chaos? Statistical studies of the distribution of galaxies in the universe, carried out by researchers at Kentucky, seek to answer this question. It is one of crucial importance. The spread of galaxies throughout the universe today offers clues to the momentous processes that spawned the universe more than ten billion years ago.
Faculty and Research Staff