Tuesday, 01 December 2009 00:00    E-mail
The beauty of our galaxy: Hubble Telescope captures amazing images

Thumbnail image EO-1209-Hubble_Telescope.pdf

Earlier this year the Hubble Space Telescope received its final “tune-up,” which was more like an extreme makeover that made the telescope more powerful than ever.

The new instruments are more sensitive to light and, therefore, will improve Hubble’s observing efficiency significantly. It is able to complete observations in a fraction of the time that was needed with prior generations of Hubble instruments.

Hubble is now expected to perform until at least 2014, when its successor, the James Webb Space Telescope (JWST), is due to be launched. The Hubble Space Telescope was launched in 1990. Initially, its giant lens was defective, but a Shuttle repair mission corrected the lens and Hubble began returning some of the most stunning images ever captured by science.

Ten amazing photographs from Hubble are featured here. These images illustrate the strange beauty of our universe. All images are courtesy of the National Aeronautics and Space Administration.

Thumbnail image1. NASA’s Hubble Space Telescope has trained its razor-sharp eye on one of the universe’s most stately and photogenic galaxies, the Sombrero galaxy, Messier 104 (M104). The galaxy’s hallmark is a brilliant white, bulbous core encircled by the thick dust lanes comprising the spiral structure of the galaxy. This brilliant galaxy was named the Sombrero because of its resemblance to the broad rim and high-topped Mexican hat.  At a relatively bright magnitude of +8, M104 is just beyond the limit of naked-eye visibility and is easily seen through small telescopes.

The Sombrero lies at the southern edge of the rich Virgo cluster of galaxies and is one of the most massive objects in that group, equivalent to 800 billion suns. The galaxy is 50,000 light-years across and is located 28 million light-years from Earth.

The Hubble Heritage Team took six pictures of the galaxy and then stitched them together to create the final composite image.  Images were taken in three filters (red, green, and blue) to yield a natural-color image, one of the largest Hubble mosaics ever assembled.

Thumbnail image2. From ground-based telescopes, the so-called “ant nebula” (Menzel 3, or Mz 3) resembles the head and thorax of a garden-variety ant. This dramatic NASA/ESA Hubble Space Telescope image, showing 10 times more detail, reveals the “ant’s” body as a pair of fiery lobes protruding from a dying, Sun-like star.

The Hubble images directly challenge old ideas about the last stages in the lives of stars.  By observing Sun-like stars as they approach their deaths, the Hubble Heritage image of Mz 3—along with pictures of other planetary nebulae—shows that our Sun’s fate probably will be more interesting, complex and striking than astronomers imagined just a few years ago.

Though approaching the violence of an explosion, the ejection of gas from the dying star at the center of Mz 3 has intriguing symmetrical patterns unlike the chaotic patterns expected from an ordinary explosion.  This intriguing image, which is a composite of several filters from each of the two datasets, was created by the Hubble Heritage Team.

Thumbnail image3. This stellar relic, first spied by William Herschel in 1787, is nicknamed the “Eskimo” Nebula (NGC 2392) because, when viewed through ground-based telescopes, it resembles a face surrounded by a fur parka. In this Hubble telescope image, the “parka” is really a disk of material embellished with a ring of comet-shaped objects, with their tails streaming away from the central, dying star.

The Eskimo’s “face” also contains some fascinating details. Although this bright central region resembles a ball of twine, it is, in reality, a bubble of material being blown into space by the central star’s intense “wind” of high-speed material.

The planetary nebula began forming about 10,000 years ago, when the dying star began flinging material into space. The nebula is composed of two elliptically shaped lobes of matter streaming above and below the dying star. In this photo, one bubble lies in front of the other, obscuring part of the second lobe.

Scientists believe that a ring of dense material around the star’s equator, ejected during its red giant phase, created the nebula’s shape.  This dense waist of material is plodding along at 72,000 miles per hour, preventing high-velocity stellar winds from pushing matter along the equator.

The Eskimo Nebula is about 5,000 lightyears from Earth in the constellation Gemini.  The picture was taken Jan. 10 and 11, 2000.  The nebula’s glowing gases produce the colors in this image: nitrogen (red), hydrogen (green), oxygen (blue) and helium (violet).

Thumbnail image4. In this detailed view from NASA’s Hubble Space Telescope, the so-called Cat’s Eye Nebula looks like the penetrating eye of the disembodied sorcerer Sauron from the film adaptation of “The Lord of the Rings.” The nebula, formally cataloged NGC 6543, is every bit as inscrutable as the J.R.R.  Tolkien phantom character. Though the Cat’s Eye Nebula was one of the first planetary nebulae to be discovered, it is one of the most complex such nebulae seen in space.

A planetary nebula forms when Sun-like stars gently eject their outer gaseous layers that form bright nebulae with amazing and confounding shapes.

As if the Cat’s Eye itself isn’t spectacular enough, this image reveals the full beauty of a bull’s eye pattern of 11 or even more concentric rings, or shells, around the Cat’s Eye.  Each “ring” is actually the edge of a spherical bubble seen projected onto the sky—that’s why it appears bright along its outer edge.

Observations suggest the star ejected its mass in a series of pulses at 1,500-year intervals.  These convulsions created dust shells, each of which contain as much mass as all of the planets in our solar system combined (still only 1 percent of the Sun’s mass). These concentric shells make a layered, onion-skin structure around the dying star. The view from Hubble is like seeing an onion cut in half, where each skin layer is discernible.

Thumbnail image5. This is an image of MyCn18, a young planetary nebula located about 8,000 light-years away. This Hubble image reveals the true shape of MyCn18 to be an hourglass with an intricate pattern of “etchings” in its walls. This picture is composed of three separate images taken in the light of ionized nitrogen (represented by red), hydrogen (green) and doubly-ionized oxygen (blue). The results are of great interest because they shed new light on the poorly understood ejection of stellar matter that accompanies the slow death of Sun-like stars. In previous ground-based images, MyCn18 appeared to be a pair of large outer rings with a smaller central one, but the fine details cannot be seen.

According to one theory for the formation of planetary nebulae, the hourglass shape is produced by the expansion of a fast stellar wind within a slowly expanding cloud that is more dense near its equator than near its poles. What appears as a bright elliptical ring in the center, and at first sight might be mistaken for an equatorially dense region, is seen on closer inspection to be a potato shaped structure with a symmetry axis dramatically different from that of the larger hourglass.

Hubble has revealed other features in MyCn18 which are completely new and unexpected. For example, there is a pair of intersecting elliptical rings in the central region that appear to be the rims of a smaller hourglass.

There are the intricate patterns of the etchings on the hourglass walls. The arc-like etchings could be the remnants of discrete shells ejected from the star when it was younger (e.g., as seen in the Egg Nebula), flow instabilities, or could result from the action of a narrow beam of matter impinging on the hourglass walls. An unseen companion star and accompanying gravitational effects may well be necessary in order to explain the structure of MyCn18.

Thumbnail image6. Resembling a nightmarish beast rearing its head from a crimson sea, this monstrous object is actually an innocuous pillar of gas and dust. Called the Cone Nebula (NGC 2264)—so named because, in ground-based images, it has a conical shape—this giant pillar resides in a turbulent star-forming region.

This picture shows the upper 2.5 lightyears of the nebula, a height that equals 23 million roundtrips to the Moon. The entire nebula is 7 light-years long. The Cone Nebula resides 2,500 light-years away in the constellation Monoceros.

Radiation from hot, young stars—located beyond the top of the image—has slowly eroded the nebula over millions of years.  Ultraviolet light heats the edges of the dark cloud, releasing gas into the relatively empty region of surrounding space. There, additional ultraviolet radiation causes the hydrogen gas to glow, which produces the red halo of light seen around the pillar. The blue-white light from surrounding stars is reflected by dust. Background stars can be seen peeking through the evaporating tendrils of gas, while the turbulent base is pockmarked with stars reddened by dust.

Over time, only the densest regions of the Cone will be left. Inside these regions, stars and planets may form. This color image is constructed from three separate images taken in blue, near-infrared and hydrogen-alpha filters.

Thumbnail image7. Resembling the fury of a raging sea, this image actually shows a bubbly ocean of glowing hydrogen gas and small amounts of other elements such as oxygen and sulfur.  The photograph captures a small region within M17, a hotbed of star formation.

M17, also known as the Omega or Swan Nebula, is located about 5,500 light-years away in the constellation Sagittarius.  The wave-like patterns of gas have been sculpted and illuminated by a torrent of ultraviolet radiation from young, massive stars, which lie outside the picture to the upper left.

The glow of these patterns accentuates the three-dimensional structure of the gases. The ultraviolet radiation is carving and heating the surfaces of cold hydrogen gas clouds. The warmed surfaces glow orange and red in this photograph. The intense heat and pressure cause some material to stream away from those surfaces, creating the glowing veil of even hotter greenish gas that masks background structures.

The pressure on the tips of the waves may trigger new star formation within them.  The image, roughly 3 light-years across, was taken May 29-30, 1999, with the Wide Field Planetary Camera 2. The colors in the image represent various gases. Red represents sulfur; green, hydrogen and blue, oxygen.

Thumbnail image8. This image, complete with never-before-seen spirals of dust swirling across trillions of miles of interstellar space, was obtained with the Advanced Camera for Surveys on Feb. 8, 2004. This is a view of an expanding halo of light around a distant star, named V838 Monocerotis (V838 Mon). The illumination of interstellar dust comes from the red supergiant star at the middle of the image. V838 Mon is located about 20,000 light-years away from Earth in the direction of the constellation Monoceros, placing the star at the outer edge of our Milky Way galaxy.

Called a light echo, the expanding illumination of a dusty cloud around the star has been revealing remarkable structures.  Though Hubble has followed the light echo in several snapshots, this image shows swirls or eddies in the dusty cloud for the first time.  These eddies are probably caused by turbulence in the dust and gas around the star as they slowly expand away.

The detailed behavior of V838 Mon, in particular its extremely red color, has been completely different from any previously known nova. This structure will continue to change its appearance in coming years as the light from the stellar outburst continues to propagate outward and bounce off more distant black clouds of dust. Astronomers expect the echoes to remain visible for at least the rest of the current decade.

Thumbnail image9. This NASA Hubble Space Telescope image of the Trifid Nebula reveals a stellar nursery being torn apart by radiation from a nearby, massive star. The picture also provides a peek at embryonic stars forming within an ill-fated cloud of dust and gas, which is destined to be eaten away by the glare from the massive neighbor. This stellar activity is a beautiful example of how the life cycles of stars like our Sun is intimately connected with their more powerful siblings.

A stellar jet—the thin, wispy object pointing to the upper left—protrudes from the head of a dense cloud and extends threequarters of a light-year into the nebula. The jet’s source is a very young stellar object that lies buried within the cloud. Jets such as this are the exhaust gases of star formation. Radiation from the massive star at the center of the nebula is making the gas in the jet glow, just as it causes the rest of the nebula to glow.

The images were taken Sept. 8, 1997, through filters that isolate emission from hydrogen atoms, ionized sulfur atoms and doubly ionized oxygen atoms. The images were combined in a single color composite picture.  While the resulting picture is not true color, it is suggestive of what a human eye might see.

Thumbnail image10. In the direction of the constellation Canis Major, two spiral galaxies pass by each other like majestic ships in the night.  The near-collision has been caught in images taken by NASA’s Hubble Space Telescope and its Wide Field Planetary Camera 2.  The larger and more massive galaxy is cataloged as NGC 2207 (on the left) and the smaller one on the right is IC 2163. Strong tidal forces from NGC 2207 have distorted the shape of IC 2163, flinging out stars and gas into long streamers stretching out 100,000 light-years toward the right-hand edge of the image.