Cool as a Stellar Cucumber
Jet Propulsion Laboratory https://www.jpl.nasa.gov/ June 24, 2010
This image shows what astronomers think is one of the coldest brown dwarfs discovered so far (red dot in middle of frame). The object, called SDWFS J143524.44+335334.6, is one of 14 such brown dwarfs found by NASA's Spitzer Space Telescope using infrared light. Follow-up observations are required to nail down this "failed" star's temperature, but rough estimates put this particular object at about 600 Kelvin (620 degrees Fahrenheit).
In this image, infrared light with a wavelength of 3.6 microns is color-coded blue; 4.5-micron light is red. The brown dwarf shows up prominently in red because methane is absorbing the 3.6-micron, or blue-coded, light.