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Dutch astrophysicist awarded NASA fellowship to study data from 
orbiting observatory with Cornell instrument team

FOR RELEASE:  Feb. 26, 2003

Contact:  David Brand
         Cornell University
Office:  607-255-3651
E-mail:  deb27{at}cornell.edu


ITHACA, N.Y. -- This summer, NASA will sponsor four young scientists 
who will work on analyzing data from the largest infrared telescope to 
be sent into space. The telescope, called SIRTF, for Space Infrared 
Telescope Facility, is scheduled for launch on April 15 and will 
circle the sun in an orbit that trails just behind the Earth's.

One of the SIRTF fellows, Henrik Spoon, an astrophysicist at the 
University of Groningen in the Netherlands, will work at Cornell 
University as a postdoctoral researcher with James Houck, the K.A. 
Wallace Professor of Astronomy.

Houck is the principal investigator on the infrared spectrograph, one 
of three instruments to be carried aboard the orbiting observatory. 
With data from SIRTF, Spoon will study the nature of heavily obscured 
power sources in ultraluminous infrared galaxies (ULIGs), which are 
many times brighter that most known galaxies at infrared wavelengths.

Spoon's fellowship comes with a precious commodity: 10 hours on the 
new telescope dedicated solely to his research. He is excited, he 
says, "to be part of the team of dedicated astronomers and engineers 
pushing the limits of infrared astronomy, to chart the unknown 
infrared universe beyond what previous infrared satellites could see."

The three other researchers to receive SIRTF fellowships are Michael 
Cushing of the University of Hawaii, who will work at NASA-Ames 
Research Center on the chemistry of low-mass stars and brown dwarfs; 
Sarah Gallagher of Pennsylvania State University, who will work at the 
University of California-Los Angeles on broad absorption line quasars; 
and Jacqueline Kessler of the California Institute of Technology 
(Caltech), who will do research at the University of Texas on the 
evolution of grains and ices in low-mass stars. The fellowships were 
awarded by the SIRTF Science Center at Caltech.

The ULIGs that Spoon will study were discovered in the early 1980s 
with NASA's first infrared telescope, the Infrared Astronomical 
Satellite (a mission in which Cornell astronomers played a key role). 
Later, the European Space Agency's Infrared Space Observatory (ISO) 
yielded a more detailed map of about a dozen of the galaxies, which 
were found to be colliding galaxies. The source of their enormous 
luminosity could be due to star formation or to the accretion of gas 
onto a massive central black hole, hidden behind the thick layers of 
enshrouding gas.

  "There are a couple of ways that these things can produce their 
energy, and hence their luminosity," says Houck. "One of them is to 
form stars very rapidly -- maybe 1,000 times faster than our galaxy. 
Another is to harbor a large black hole in the center of the galaxy 
that shreds stars as it swallows them. The gravitational energy that 
these shredded stars release is converted into infrared light, and 
that makes them luminous."

Still other ULIGs, says Houck, might be hybrids, fueled by a 
combination of both black holes and superintense star formation. And, 
since only a handful of the galaxies have been observed in detail, 
there could be unknown processes driving still more types of bright 
galaxies.

SIRTF's infrared detectors are 100 times more sensitive than those of 
its predecessor, ISO. Spoon observes that until the 1950s astronomers 
were able to observe the universe only in visible light. Now they can 
conduct their surveys in "invisible colors" as well, including the 
infrared and ultraviolet. But in order to study the universe in most 
infrared colors, a telescope needs to be taken above the atmosphere. 
"The SIRTF satellite will allow me to study the ULIGs in a very broad 
range of infrared colors, without any missing color in between," says 
Spoon. These colors could turn out to be critically important to 
understanding the true nature of the ULIGs, he notes.

Houck says that trying to observe objects in deep space in the 
infrared from a telescope on Earth is akin to "trying to look at a 
distant mountain with a pair of binoculars that are on fire. That's 
very close to what the situation is -- there's so much light from the 
flaming binoculars, you can't see the mountain. The other problem is 
that the Earth's atmosphere is opaque to almost all wavelengths of 
infrared light."

SIRTF will be the fourth and last in NASA's Great Observatories 
Program, joining the Hubble Space Telescope, the Compton Gamma Ray 
Observatory and the Chandra X-Ray Observatory. The mission is managed 
by NASA's Jet Propulsion Laboratory, and other participating 
institutions include Caltech, the Smithsonian Astrophysical 
Observatory and the University of Arizona.

This release was prepared by Lissa Harris, a Cornell graduate student 
and Cornell News Service science-writing intern.


	Related World Wide Web sites:  The following site provide 
additional information on this news release.  It is not part of the 
Cornell University community, and Cornell has no control over their 
content or availability.

	o SIRTF: http://sirtf.caltech.edu

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