Seeing Red: A cool revival of Hubble’s infrared camera

After 3 years of blindness, the Hubble Space Telescope’s near-infrared vision has been restored. Prematurely running out of its nitrogen-ice coolant in 1999, Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) was brought back to life in March when astronauts installed a neon-gas refrigerator (SN: 3/16/02, p. 163: Telescope Tuned Up: Back to work for orbiting observatory).

PENETRATING VIEWS. A four-galaxy collision shows infrared glow (yellow) from dust absorbing light from newborn stars. The blue regions surrounding the core represent the ultraviolet glow of new stars that haven’t produced enough dust to absorb the radiation. NASA, NICMOS Group (STScI, ESA), and NICMOS Science Team (Univ. of Ariz.)
A galaxy with a ring of stars (arrow) at its center. NASA, NICMOS Group (STScI, ESA), and NICMOS Science Team (Univ. of Ariz.)

Cooled to a temperature that gives the detector 10 to 30 times greater sensitivity than before, NICMOS is once again peering through dust-shrouded regions that can’t be seen in visible and ultraviolet light. It can also scan for objects so distant that cosmic expansion has shifted their light out of the range of every other detector on Hubble.

The rejuvenated NICMOS teamed with Hubble’s newly installed Advanced Camera for Surveys to observe a four-galaxy collision a billion light-years from Earth. The infrared-bright regions at the collision’s center produce the equivalent of 200 new suns each year, 100 times more than the Milky Way’s output. Although new stars primarily radiate ultraviolet light, the dust they generate absorbs that light and reemits it in the near-infrared.

In another study, NICMOS peered through the dusty disk of the spiral galaxy NGC 4013 to discover what appears to be a ring of newborn stars at the galaxy’s core. Such rings are relatively common in spiral galaxies, but this is the first time a telescope has found one by looking through dust in a galaxy with an edge-on orientation, says Daniela Calzetti of the Space Telescope Science Institute in Baltimore.

Calzetti and her colleagues unveiled the images this week at a meeting of the American Astronomical Society in Albuquerque.

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