So those galaxies are literally more than halfway across the universe. When Spitzer looks back to a z of 6, for example, it is not only looking to an epoch when the universe was 15 percent of its current size; it is also looking back to within about million years of the Big Bang. By observing galaxies both at such great redshifts and also as close as our nearest extragalactic neighbors—the Magellanic Clouds and the Andromeda Nebula—Spitzer has uncovered many of the features of galaxy evolution.
Clusters of galaxies, which can have masses of about a quadrillion or a million billion times that of the Sun, are the largest structures in the known universe.
The same survey that yielded the brown-dwarf census is producing an equally exciting census of clusters of galaxies in the early universe.
Spitzer sees these distant clusters quite readily because their optical starlight is shifted into the infrared.
The observations have led to the identification of more than clusters of galaxies at redshifts greater than 1 in this one area of sky, many more than had been identified over the entire sky by all previous observations.
The number and properties of high-redshift clusters of galaxies hold clues to the way those structures formed and grew in the early universe. We know from observations of the microwave background radiation still present in the cosmos that the early universe was remarkably smooth and uniform, with minute density and temperature fluctuations superimposed on a uniform background.
With time, these fluctuations grew, driven largely by gravitational forces, into the rich variety of structures we see in the universe around us today. It also could elucidate the roles and perhaps the nature of the mysterious dark matter and dark energy that apparently make up most of the material in the universe. Studying galaxies at high redshift can also provide clues to their chemical evolution. Spitzer, following up on previous results from IRAS and ISO, has shown that the mid-infrared emission from the interstellar medium in our galaxy and, indeed, from entire galaxies, is dominated by molecules called polycyclic aromatic hydrocarbons PAHs.
These planar hydrocarbon molecules consist of hexagonal carbon rings and their associated hydrogen atoms. PAHs are very familiar on Earth as combustion products; they have been extensively studied by chemists and have also been detected in meteorites.
The result suggests that this constituent of the interstellar medium was in place just a few billion years after the Big Bang. Controversial but tantalizing Spitzer results suggest extremely massive galaxies may be present at redshifts higher than 6.
This result, if confirmed, would represent a major challenge to the theoretical framework of galaxy formation that has been built over the past decade. The Warm Spitzer Mission, using these arrays, will operate for at least two additional years, through mid, with the possibility of an extension for two or three years beyond that before Spitzer drifts out of easy communication range. The cloud DR22 shows dust in blue and hot gas in orange left.
The galaxy NGC above right is relatively calm, showing little star-forming activity. A dying star, or planetary nebula, called NGC bottom right is unusual because it has four jets of ejecting material instead of two, indicating it could be a twin set of stars instead of a single one.
Much of the time available for observations during the first two years of the warm mission has been awarded competitively to scientific teams that will carry out large programs of broad general interest. Some of the topics covered will be familiar: galactic structure, clusters of galaxies and the distant universe.
In these areas, Warm Spitzer will extend the results of the cryogenic mission. In the dynamic area of exoplanet research, Warm Spitzer provides a much-needed capability to follow up on the additional discoveries that will undoubtedly be announced in the coming months, including those from the Kepler Mission, which will employ the first NASA spacecraft devoted to exoplanet studies.
Some totally new programs will also take place, such as monitoring the variability of young and forming stars as a means of studying both the stars and their planet-forming disks, and measurements of hundreds of Near Earth Objects asteroids and extinct comets to determine their sizes and to help in the assessment of the hazards these populations might pose to Earth. Other missions in addition to Warm Spitzer will be supporting the infrared exploration of the universe in the coming years.
Herschel will extend the work of Spitzer to longer wavelengths, looking at cooler and perhaps more distant objects. Its spectrometers will study interstellar atoms and molecules with unprecedented precision.
The WISE mission mentioned earlier will launch in late to carry out a highly sensitive survey of the entire sky at infrared wavelengths.
As an airborne observatory, SOFIA will also support the development and deployment of novel instruments as preludes to their use in space. Finally in the middle of the next decade the James Webb Space Telescope, with 50 times the telescope area of Spitzer, will extend the work of its predecessors to unprecedented depths.
Skip to main content. Login Register. Page DOI: Bibliography Gehrz, R. Review of Scientific Instruments Knutson, H. A map of the day-night contrast of the extrasolar planet HD b. Nature — Rieke, G. Tuscon: University of Arizona Press. Soifer, B. Helou and M. The Spitzer view of the extragalactic universe. Annual Review of Astronomy and Astrophysics — Werner, M.
Fazio, G. Rieke, T. Roellig and D. First fruits of the Spitzer Space Telescope: Galactic and solar system studies. American Scientist Comment Policy Stay on topic. Be respectful. We reserve the right to remove comments. Please read our Comment Policy before commenting. All Topics More in Astronomy. About JPL. Engage With JPL. Mission Statistics. Launch Date Aug 25, Target Stars and Galaxies. About the mission. Though it took decades to get to launch, along the way the mission incorporated lessons learned by IRAS and other space-based infrared telescopes.
When it launched, Spitzer had higher sensitivity, larger detector arrays, and better precision pointing — critical for studying small, distant objects, including exoplanets — than any of its predecessors. It remains the most sensitive infrared observatory ever operated in the 3 to 40 micron range.
Throughout its lifetime, it has combined its powerful capabilities with those of other observatories to provide even deeper insights into our universe. Space-based infrared telescopes come with another major advantage: They get away from the substantial amount of infrared light produced by Earth's atmosphere and can be cooled to such low temperatures they produce very little infrared light themselves.
Just as the light from the Sun makes it impossible to see the stars during the day, these sources of ambient infrared light overwhelm faint sources in the night sky. A warm telescope on the ground looks at the heavens through a bright haze of infrared radiation, but for a cold telescope in space, this haze disappears and the universe can be seen in all its infrared glory.
Thus Spitzer — with a mirror only 33 inches 85 cm in diameter about the size of a hula-hoop — is much more sensitive than even the largest ground-based telescopes which are up to 33 feet or 10 meters in diameter at the infrared wavelengths where Spitzer operates. During its subsequent "warm" mission to , Spitzer observed in 3. Spitzer is the most sensitive IR telescope in history in these wavelengths. Spitzer is also helping to lay the groundwork for future telescopes that will observe the universe in infrared wavelengths.
The James Webb Space Telescope , set to launch in , will observe in wavelengths that overlap the ones Spitzer observes. Webb will observe from 0.
Click on a thumbnail to view a larger version, and then save the file to your computer. These images have been optimized to work with Zoom virtual backgrounds. Jet Propulsion Laboratory. California Institute of Technology.
Mission Lyman Spitzer Jr. Mission Overview Technology History Science. May 3rd, December 18th, Solar System. January 13th, Planet Formation. January 10th, July 24th, Stars and Nebulae. July 22nd,
0コメント