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| Figure 1: Visible Panel | Figure 2: Infrared Panel |
This artist's concept shows what a fiery hot star and its close-knit
planetary companion might look close up if viewed in visible (figure 1)
and infrared light (figure 2). In visible light, a star shines
brilliantly, overwhelming the little light that is reflected by its
planet. In infrared, a star is less blinding, and its planet perks up
with a fiery glow.
Astronomers using NASA's Spitzer Space Telescope took advantage of this
fact to directly capture the infrared light of two previously detected
planets orbiting outside our solar system. Their findings revealed the
temperatures and orbits of the planets. Upcoming Spitzer observations
using a variety of infrared wavelengths may provide more information
about the planets' winds and atmospheric compositions.
These colors represent real differences between the visible and infrared
views of the system. The visible panel shows what our eyes would see if
we could witness the system close up. The hot star is yellow because,
like our Sun, it is brightest in yellow wavelengths. The warm planet, on
the other hand, is brightest in infrared light, which we can't see.
Instead, we would see the glimmer of star light that the planet reflects.
In the infrared panel, the colors reflect what our eyes might see if we
could retune them to the invisible, infrared portion of the light
spectrum. The hot star is less bright in infrared light than in visible
and appears fainter. The warm planet peaks in infrared light, so is shown
brighter. Their hues represent relative differences in temperature.
Because the star is hotter than the planet, and because hotter objects
give off more blue light than red, the star is depicted in blue, and the
planet, red.
The overall look of the planet is inspired by theoretical models of hot,
gas giant planets. These "hot Jupiters" are similar to Jupiter in
composition and mass, but are expected to look quite different at such
high temperatures. The models are courtesy of Drs. Curtis Cooper and Adam
Showman of the University of Arizona, Tucson.
