The Spitzer Infrared Array Camera (IRAC), easily detected the galaxy at longer infrared wavelengths. Spitzer's IRAC is sensitive to the light from older, redder stars which should make up most of the mass in a galaxy. The brightness of the infrared galaxy suggests that it is quite massive.
Object Names: Hubble Ultra Deep Field; HUDF, HUDF-JD2, UDF033238.74-274839.9
Image Type: Astronomical
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