Dwarf irregular galaxy Leo A
In 2004, an international team of astronomers imaged the dwarf irregular galaxy Leo A with the Subaru Telescope in Hawaii. The galaxy, which is a member of the Local Group of galaxies that includes the Milky Way, lies about 2.6 million light-years away. The astronomers discovered an extended halo of stars with a sharp cutoff, effectively doubling Leo A's size to about 6,000 light-years across. The discovery challenges current scenarios of galaxy formation: Instead of being the preservers of pristine building blocks that combined to form larger galaxies, dwarf irregular galaxies have their own construction history. Subaru Telescope, NAOJ
Interstellar bubble N44F
The Hubble Space Telescope captured this image of a 35-light-year-wide bubble blown by radiation from a hot young star. Known as N44F, the bubble lies 160,000 light years away in a neighboring galaxy known as the Large Magellanic Cloud. A torrent of fast-moving particles — called a stellar wind — streams from an exceptionally hot star once buried inside a cold dense cloud. The central star of N44F ejects 100 million times more mass per second — and at speeds more than four times faster — than does our Sun, which is also losing mass through its own solar wind. The stream of particles sweeps up the gas and dust around the star, pushing it together and inflating it into this enormous interstellar bubble. This image was taken with Hubble's Wide Field Planetary Camera 2 in March 2002. NASA, ESA, Y. Naze (University of Liege, Belgium) and Y.
The Red Rectangle
Discovered in the early 1970s as a strong source of infrared radiation, the Red Rectangle lies about 2,300 light-years from Earth in the constellation Monoceros. Its central stars, which form a binary pair, are embedded in a disk of dust, but their interaction funnels dust and gas up and away, forming the X-shaped structure. NASA, ESA, H. Van Winckel and M. Cohen作者: 卢平α 时间: 2006-4-15 12:43
Great Observatories portrait of Cas A
This stunning portrait of supernova remnant Cassiopeia A (Cas A) is made from images taken by three of NASA's Great Observatories. Warm dust seen by the Spitzer Space Telescope is red; visible filaments of hot gas seen by the Hubble Space Telescope are yellow; and extremely hot, X-ray-emitting gas seen by the Chandra X-ray Observatory is shown in green and blue. Located 11,000 light-years away in the northern constellation Cassiopeia, Cas A is the remnant of a once massive star that died in a violent explosion 325 years ago. It consists of a central remnant called a neutron star and a surrounding shell of material blasted off the star as it died. Cas A, site of our galaxy's most recent supernova, is one of the most studied objects in the sky. NASA / JPL-Caltech / O. Krause, Steward Observatory
NGC 1316
More than 100 million years ago, the giant elliptical galaxy NGC 1316 (center) began snacking on its small northern neighbor. Gas stripped from the smaller galaxy feeds a black hole at NGC 1316's center and helps power a bipolar jet of high-energy particles. This flow is essentially undetectable until it crashes into tenuous gas 500,000 light-years from the galaxy, where it produces radio emission (orange) in two large lobes, each 600,000 light-years across. NRAO/AUI作者: 卢平α 时间: 2006-4-15 12:47
火星表面
The grabens of Claritas Fossae
This Mars Express image shows the meeting of two martian terrains: rugged Claritas Fossae on the left, smoother Solis Planum on the right. We're looking north, toward a diffuse blue-white haze — thin clouds or aerosols — hovering over the plains. Linear, trough-like features called grabens run mainly to the northwest in Claritas Fossae, toward the enormous Tharsis shield volcanoes hundreds of miles away. This is a perspective view generated from a Mars Express image returned June 13, 2004. ESA / DLR / FU Berlin, G. Neukum
月亮
Radar image of Mare Orientale
This is a radar image of the Orientale impact basin, on the western edge of the Moon's Earth-facing side. To make the image, the Arecibo Observatory in Puerto Rico bounced radio signals off the Moon; these echoes were then received by the Green Bank Telescope in West Virginia. The radar signal's wavelength of 2.3 feet (70 cm) penetrated several meters into the lunar surface. Bright areas have more rocks at the surface and subsurface, or have slopes facing the incident radar beam (such as crater walls or mountains). Dark areas are typically associated with smooth lava flows that fill large craters and basins on the Moon. Because the Moon wobbles slightly as it orbits the Earth, this image covers up to 7° of the Moon's far side. NRAO/AUI and Bruce作者: 卢平α 时间: 2006-4-15 12:52
(这个可能有过了...)
UV rings
As the spacecraft swung into orbit on June 30, 2004, scientists imaged the rings in ultraviolet light to study their composition. Thisimage shows Saturn's rings from the inside out: The Cassini Division is at left (faint red), followed by the A ring in its entirety. The A ring begins with a reddish interior, indicating a greater proportion of dirt, followed by more turquoise — ice — at greater distances from the planet. The red band roughly three-fourths of the way outward in the A ring is known as the Encke Gap. NASA / Univ. Colorado, LASP
NGC 5128
NGC 5128 is a type E0 peculiar elliptical galaxy that lies some 13 million light-years away in the constellation Centaurus. One of the most luminous and massive galaxies known, it is a strong radio and X-ray source and is one of the most studied objects in the southern sky. The dark, dusty band spanning the galaxy's disk is thought to be the remains of a spiral galaxy NGC 5128 absorbed in the past few billion years. The core of NGC 5128 is the smallest extragalactic radio source known — only 10 light-days across — and probably contains a supermassive black hole with a mass of about 100 million Suns. ESO作者: 卢平α 时间: 2006-4-15 12:55
Globular cluster NGC 6397
NGC 6397, located 7,200 light-years away in the southern constellation Ara, is one of the nearest globular star clusters. It contains about 400,000 stars and has undergone a "core collapse," which makes its central area very dense. Globular clusters, so named for their spheroidal appearance, hold clues about the onset of star formation in our galaxy. Recent work suggests that NGC 6397 was born just a few hundred million years after the Milky Way's first stars formed. ESO作者: 夜猫子 时间: 2006-4-15 13:49
呵呵，不错！3楼的火星表面和月亮本版没发过。
