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Roger F. Knacke - Origins of Stars and Planets


We are interested in astrophysical problems related to the origins of solar systems and the birth of stars. Using primarily techniques of infrared astronomy, my students, coworkers, and I have studied comets and the atmospheres of the giant planets. We're now concentrating on the environments of young stars and the recently discovered extra-solar planetary systems.

Gas and dust orbit many young and intermediate-age stars. Usually this matter forms a disk or shell surrounding the star. Some disks are almost certainly birthplaces of new planets, while others appear to be generated by breakup of comet or asteroid debris. The disks raise many interesting scientific questions. Is there evidence for planets, or of planet formation, in the disks? What determines disk structure? What is the disk matter made of? Is it similar to Solar System material such as the silicates found in comets, asteroids, and planets? What can extra-solar disks tell us about processes that took place in the solar system when it formed 4.6 billion years ago?

We observe with telescopes on Mauna Kea, Hawaii, Cerro Tololo, Chile, and other observatories. Our research requires the angular resolution and sensitivity of large telescopes to study structure in the disks, and to study their composition. Recent results include thermal infrared observations of the disk surrounding the young (~6 million years old) star, HR 4796 B, and the similar star, HD 141569. Our research is funded by grants from NASA.

HD 4796 - Infrared 18 micron image of the disk surrounding the star. Note the ring-like structure (seen edge-on) that surrounds the center bright region where the star is.
 
 
 
 
 
 
 
 

HR 141569 - Infrared 18-micron contours (thin lines) superimposed on a NICMOS image (black and white picture). Note that the thermal radiation (infrared) originates primarily inside the near-infrared ring.
 
 
 
 
 
 
 
 
 

Today, ground-based and space-based research by astronomers around the world is laying the basis for understanding how solar systems form and evolve. Future projects and facilities in this field include the Keck Interferometer (2002), The Space Infrared Telescope Facility (2002), The Space Interferometer Mission (2005), the Next Generation Space Telescope (~2009), and Terrestrial Planet Finder (~ 2015). These missions promise to make the coming decades an extraordinary period in the exploration of planetary systems, the understanding of the origins of solar systems, and the search for life in the universe.

 

 
 
 


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