POSTED 5 MAY 2005
Visible light is not the only type of electromagnetic signal coming from stars and galaxies. In the past few years, orbiting telescopes that read X-rays, ultraviolet and infrared light have been launched. Spitzer Space Telescope, named for Lyman Spitzer, Jr., the astronomer who first suggested putting giant telescopes in space, reads infrared, the kind of radiation given off by cool objects, like dust.
Spitzer can look at:
Brown dwarfs: These "failed stars," between Jupiter and the sun in mass, are hard to see, but they may be extremely common.
Circumstellar disks: The whirling gas and dust surrounding stars carries hints about the early universe.
Clouds of hydrogen: These giant clouds, which can coalesce into stars, give off no visible light, but plenty of infrared
Seeing the invisible
To see what your eyes are missing, compare the visible-light picture of the Trifid Nebula to the false-color infrared views. The Trifid Nebula is a giant cloud of gas and dust 5,400 light-years distant. While dusty regions in the visible-light image suggest locations where stars might be forming, the infrared image allows astronomers to actually count star embryos: 30 massive embryonic stars a-borning, and 120 smaller newbies. Ten of the big embryos appear in four dark cores called stellar "incubators."
The driving force in this nebula is a gargantuan explosion of a massive "type O" star (the remains are that faint white spot at the center). Type O's, the most massive stars, live fast and die young, in an explosive supernova.
See the Spitzer slide show.
What can you learn from X-rays?
Megan Anderson, project assistant; Terry Devitt, editor; S.V. Medaris, designer/illustrator; David Tenenbaum, feature writer; Amy Toburen, content development executive