Sequence of Astronomical Objects in Infrared Light
Description
This figure shows an artist's rendition comparing brown dwarfs to stars and planets. All objects are plotted to the same scale. On the far left is the limb of the Sun. To its right is shown a very low mass star (a so-called "late-M dwarf"), a couple of brown dwarfs (a hotter "L dwarf" and a cooler "T dwarf"), and the planet Jupiter. These objects have masses ranging from 1050 times that of Jupiter (for the Sun) through 75, 65, 30, and 1 Jupiter mass for the late-M dwarf, L dwarf, T dwarf, and Jupiter, respectively. The colors of the brown dwarfs are chosen to match an age of 1 billion years. Despite the range in mass, all four of the low-mass objects are approximately the same size, ten times smaller than the diameter of the Sun. The infrared-light shows the same objects as they might appear to eyes sensitive to near-infrared light. Here the M and L dwarfs are slightly orange or red compared to the Sun, but the T dwarf is distinctly blue due to a lack of light in the "green" and "red" caused by absorption from methane. Methane is also abundant in the atmosphere of Jupiter and this, along with the clouds and bands of other complex molecules, gives it alternating patches of pink and blue.
Multiwavelength M81
Title
Multiwavelength M81
Description
This beautiful galaxy is tilted at an oblique angle on to our line of sight, giving a "birds-eye view" of the spiral structure. The galaxy is similar to our Milky Way, but our favorable view provides a better picture of the typical architecture of spiral galaxies. M81 may be undergoing a surge of star formation along the spiral arms due to a close encounter it may have had with its nearby spiral galaxy NGC 3077 and a nearby starburst galaxy (M82) about 300 million years ago. M81 is one of the brightest galaxies that can be seen from the Earth. It is high in the northern sky in the circumpolar constellation Ursa Major, the Great Bear. At an apparent magnitude of 6.8 it is just at the limit of naked-eye visibility. The galaxy's angular size is about the same as that of the Full Moon. This image combines data from the Hubble Space Telescope, the Spitzer Space Telescope, and the Galaxy Evolution Explorer (GALEX) missions. The GALEX ultraviolet data were from the far-UV portion of the spectrum (135 to 175 nanometers). The Spitzer infrared data were taken with the IRAC 4 detector (8 microns). The Hubble data were taken at the blue portion of the spectrum.
A Planet in a Different Ligh
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Title
A Planet in a Different Light
Description
This artist's animation shows first what a fiery hot star and its close-knit planetary companion might look like close up in visible light, then switches to infrared views. 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 stars 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. In this animation, the colors represent real differences between the visible and infrared views of the system. The initial visible view 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 second half of the animation, 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.
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