Total Page Views of Dil Se Desi Blog by
Visitors w.e.f. 12.30 Hrs IST 16/04/11

Recent Topics on Dil Se Desi Blog

Sunday, August 28, 2011

Hubble Space Telescope Imagery - 1/2

Hubble Space Telescope Imagery



DilSeDesiGroup


This remarkable picture from the Advanced Camera for Surveys on the NASA/ESA Hubble Space Telescope shows one of the most perfect geometrical forms created in space. It captures the formation of an unusual pre-planetary nebula, known as IRAS 23166+1655, around the star LL Pegasi in the constellation of Pegasus. The image shows what appears to be a thin spiral pattern of astonishingly regularity winding around the star, which is itself hidden behind thick dust. The spiral pattern suggests a regular periodic origin for the nebula's shape. The material forming the spiral is moving outwards a speed of about 50 000 km/hour and, by combining this speed with the distance between layers, astronomers calculate that the shells are each separated by about 800 years. The spiral is thought to arise because LL Pegasi is a binary system, with the star that is losing material and a companion star orbiting each other.


This turbulent cosmic pinnacle lies within a stellar nursery called the Carina Nebula, located 7,500 light-years away in the southern constellation of Carina. Scorching radiation and fast winds (streams of charged particles) from super-hot newborn stars in the nebula are shaping and compressing the pillar, causing new stars to form within it. Streamers of hot ionised gas can be seen flowing off the ridges of the structure, and wispy veils of gas and dust, illuminated by starlight, float around its towering peaks. The denser parts of the pillar are resisting being eroded by radiation. Nestled inside this dense mountain are fledgling stars. Long streamers of gas can be seen shooting in opposite directions from the pedestal at the top of the image. Another pair of jets is visible at another peak near the centre of the image. These jets, (known as HH 901 and HH 902, respectively), are signposts for new star birth and are launched by swirling gas and dust discs around the young stars, which allow material to slowly accrete onto the stellar surfaces. Hubble's Wide Field Camera 3 observed the pillar on 1-2 February 2010.

This is a NASA/ESA Hubble Space Telescope picture a comet-like object called P/2010 A2, which was first discovered by the LINEAR (Lincoln Near-Earth Asteroid Research program) sky survey on January 6th, 2010. The object has a complex structure - a pattern of filamentary structures near the point-like nucleus of the object and trailing streamers of dust - that suggests it is not a comet but instead the product of a head-on collision between two asteroids traveling five times faster than a rifle bullet (5 km per second). Astronomers have long thought that the asteroid belt is being ground down through collisions, but such a smashup has never before been seen. The filaments are made of dust and gravel, presumably recently thrown out of the 140-meter-diameter nucleus. Some of the filaments are swept back by radiation pressure from sunlight to create straight dust streaks. At the time of the Hubble observations, the object was approximately 300 million km from the Sun and 140 million km from Earth.

At first glance, the scatter of pale dots on this NASA/ESA Hubble Space Telescope image looks like a snowstorm in the night sky. But almost every one of these delicate snowflakes is a distant galaxy in the cluster MACS J0717.5+3745 and each is home to billions of stars. The amount of mass in this sea of galaxies is huge, and is great enough to visibly bend the fabric of spacetime. The strange distortion in the shapes of many of the galaxies in this picture, which appear stretched and bent as if they were looked at through a glass bottle, is a result of gravitational lensing, where the gravitational fields around massive objects bend light around them. This picture was created from images taken through near-infrared and yellow filters using the Wide Field Channel of Hubble's Advanced Camera for Surveys.

The star HD 44179 is surrounded by an extraordinary structure known as the Red Rectangle. It acquired its moniker because of its shape and its apparent colour when seen in early images from Earth. This strikingly detailed new Hubble image reveals how, when seen from space, the nebula, rather than being rectangular, is shaped like an X with additional complex structures of spaced lines of glowing gas, a little like the rungs of a ladder. The star at the centre is similar to the Sun, but at the end of its lifetime, pumping out gas and other material to make the nebula, and giving it the distinctive shape. It also appears that the star is a close binary that is surrounded by a dense torus of dust - both of which may help to explain the very curious shape. The Red Rectangle is an unusual example of what is known as a proto-planetary nebula. These are old stars, on their way to becoming planetary nebulae. Once the expulsion of mass is complete a very hot white dwarf star will remain and its brilliant ultraviolet radiation will cause the surrounding gas to glow. The Red Rectangle is found about 2,300 light-years away in the constellation Monoceros (the Unicorn).

The little-known nebula IRAS 05437+2502 billows out among the bright stars and dark dust clouds that surround it in this striking image from the Hubble Space Telescope. It is located in the constellation of Taurus (the Bull), close to the central plane of our Milky Way galaxy. Unlike many of Hubble's targets, this object has not been studied in detail and its exact nature is unclear. At first glance it appears to be a small, rather isolated, region of star formation and one might assume that the effects of fierce ultraviolet radiation from bright young stars probably were the cause of the eye-catching shapes of the gas. However, the bright boomerang-shaped feature may tell a more dramatic tale. The interaction of a high velocity young star and the cloud of gas and dust may have created this unusually sharp-edged bright arc. Such a reckless star would have been ejected from the distant young cluster where it was born and would travel at 200,000 km/hour or more through the nebula. This faint cloud was originally discovered in 1983 by the Infrared Astronomical Satellite (IRAS), the first space telescope to survey the whole sky in the infrared.



In the upper right of this image is part of NGC 4921, an unusual spiral galaxy in the Coma Galaxy Cluster some 320 million light-years from Earth, with a backdrop rich with a variety of much more distant galaxies. The long exposure times and sharp vision of Hubble allowed it to not just image NGC 4921 in fine detail but also to see far beyond into the distant Universe. All around, and even through the galaxy itself, thousands of much more remote galaxies of all shapes, sizes and colours are visible. Many have the spotty and ragged appearance of galaxies at a time before the familiar division into spirals and ellipticals had become established. This image was created from 50 separate exposures through a yellow filter and another 30 exposures through a near-infrared filter using the Wide Field Channel of the Advanced Camera for Surveys on Hubble. The total exposure times were approximately seventeen hours and ten hours respectively.







Two galaxies perform an intricate dance in this new Hubble Space Telescope image. The galaxies, containing a vast number of stars, swing past each other in a graceful performance choreographed by gravity. The pair, known collectively as Arp 87, is one of hundreds of interacting and merging galaxies known in our nearby universe. The two main players comprising Arp 87 are NGC 3808 on the right (the larger of the two galaxies) and its companion NGC 3808A on the left. NGC 3808 is a nearly face-on spiral galaxy with a bright ring of star formation and several prominent dust arms. Stars, gas, and dust flow from NGC 3808, forming an enveloping arm around its companion. NGC 3808A is a spiral galaxy seen edge-on and is surrounded by a rotating ring that contains stars and interstellar gas clouds. The ring is situated perpendicular to the plane of the host galaxy disk and is called a "polar ring." As seen in other mergers similar to Arp 87, the corkscrew shape of the tidal material or bridge of shared matter between the two galaxies suggests that some stars and gas drawn from the larger galaxy have been caught in the gravitational pull of the smaller one. The shapes of both galaxies have been distorted by their gravitational interaction with one another. Arp 87 is in the constellation Leo, approximately 300 million light-years away from Earth.








Barred spiral galaxy NGC 1300 is considered to be prototypical of barred spiral galaxies. Barred spirals differ from normal spiral galaxies in that the arms of the galaxy do not spiral all the way into the center, but are connected to the two ends of a straight bar of stars containing the nucleus at its center. At Hubble's resolution, a myriad of fine details are seen throughout the galaxy's arms, disk, bulge, and nucleus. Blue and red supergiant stars, star clusters, and star-forming regions are well resolved across the spiral arms, and dust lanes trace out fine structures in the disk and bar. Numerous more distant galaxies are visible in the background. In the core of the larger spiral, the nucleus shows its own extraordinary and distinct "grand-design" spiral structure that is about 3,300 light-years long. NGC 1300 lies roughly 69 million light-years away in the direction of the constellation Eridanus.

Look carefully at this animated image. What you see is the Crab pulsar, a rapidly rotating neutron star at the heart of the Crab Nebula, propelling matter and antimatter outward at near the speed of light, seen in 24 sequential images acquired over several months by the Hubble Space Telescope. The Crab pulsar is a tiny, dense remnant of a star that exploded in a supernova, observed here on Earth in the year 1054. It is very small - only about 25 km (15 miles) across, has a mass about 1.5 times our own Sun, and rotates at an amazing rate of 30 times per second. Bright wisps of energetic particles can be seen moving outward from the pulsar at half the speed of light to form an expanding ring. These wisps appear to originate from a shock wave that shows up as an inner X-ray ring. Also, a turbulent jet appears to be spewing material to the left, looking much like steam from a high-pressure boiler - except it's a stream of matter and anti-matter electrons moving at half the speed of light. This little neutron star, some 6,500 light-years away, has been doing this energetic pirouette for the past thousand years, and, undisturbed, will likely continue to do so for billions of years more. One thing I always want to take away from time spent looking at Hubble images: the Universe is a very dynamic place, even if it can often appear static due to vast distances and scales.

DilSeDesiGroup


The spectacular structure of Planetary nebula NGC 2818 contains the outer layers of a star that were expelled into interstellar space. The glowing gaseous shrouds in the nebula were shed by the central star after it ran out of fuel to sustain the nuclear reactions in its core. This Hubble image was taken in November 2008 with the Wide Field Planetary Camera 2. The colors in the image represent a range of emissions coming from the clouds of the nebula: red represents nitrogen, green represents hydrogen, and blue represents oxygen.




Stars burst to life in the chaotic Carina Nebula in this image of a huge pillar taken in visible and in infrared light by NASA's Hubble Space Telescope. Composed of gas and dust, the nebula resides 7,500 light-years away in the southern constellation Carina. This image, taken in visible light, shows the tip of the 3-light-year-long pillar, bathed in the glow of light from hot, massive stars off the top of the image. Scorching radiation and fast winds (streams of charged particles) from these stars are sculpting the pillar and causing new stars to form within it. Streamers of gas and dust can be seen flowing off the top of the structure. Nestled inside this dense structure are fledgling stars. They cannot be seen in this image because they are hidden by a wall of gas and dust. Although the stars themselves are invisible, one of them is providing evidence of its existence. Thin puffs of material can be seen traveling to the left and to the right of a dark notch in the center of the pillar. The matter is part of a jet produced by a young star. Farther away, on the left, the jet is visible as a grouping of small, wispy clouds. A few small clouds are visible at a similar distance on the right side of the jet. Astronomers estimate that the jet is moving at speeds of up to 850,000 miles an hour. The jet's total length is about 10 light-years.



Messier 104 (M104), the Sombrero galaxy. has a brilliant white, bulbous core encircled by the thick dust lanes comprising the spiral structure of the galaxy. As seen from Earth, the galaxy is tilted nearly edge-on. We view it from just six degrees north of its equatorial plane. 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. X-ray emission suggests that there is material falling into the compact core, where a 1-billion-solar-mass black hole resides. In the 19th century, some astronomers speculated that M104 was simply an edge-on disk of luminous gas surrounding a young star, which is prototypical of the genesis of our solar system. But in 1912, astronomer V. M. Slipher discovered that the hat-like object appeared to be rushing away from us at 700 miles per second. This enormous velocity offered some of the earliest clues that the Sombrero was really another galaxy, and that the universe was expanding in all directions.


What resemble dainty butterfly wings are actually roiling cauldrons of gas heated to more than 36,000 degrees Fahrenheit. The gas is tearing across space at more than 600,000 miles an hour - fast enough to travel from Earth to the Moon in 24 minutes! A dying star that was once about five times the mass of the Sun is at the center of this fury. It has ejected its envelope of gases and is now unleashing a stream of ultraviolet radiation that is making the cast-off material glow. The Wide Field Camera 3 (WFC3), installed by NASA astronauts in May 2009, snapped this image of the planetary nebula, catalogued as NGC 6302, which lies within our Milky Way galaxy, roughly 3,800 light-years away in the constellation Scorpius. The glowing gas is the star's outer layers, expelled over about 2,200 years. NGC 6302 was imaged on July 27, 2009, with Hubble's Wide Field Camera 3 in ultraviolet and visible light. Filters that isolate emissions from oxygen, helium, hydrogen, nitrogen, and sulfur from the planetary nebula were used to create this composite image.

An international team of astronomers using the NASA/ESA Hubble Space Telescope has discovered a ghostly ring of dark matter that was formed long ago during a titanic collision between two massive galaxy clusters. It is the first time that a dark matter distribution has been found that differs substantially from the distribution of ordinary matter. This image shows the galaxy cluster Cl 0024+17 (ZwCl 0024+1652) as seen by Hubble's Advanced Camera for Surveys. The image displays faint faraway background galaxies that had their light bent by the cluster's strong gravitational field. By mapping the distorted light and using it to deduce how dark matter is distributed in the cluster, astronomers spotted the ring of dark matter. One of the background galaxies is located about two times further away than the yellow cluster galaxies in the foreground, and has been multiple-imaged into five separate arc-shaped components, seen in blue.


A peculiar system of interacting galaxies known as Arp 194 contains several galaxies, along with a "cosmic fountain" of stars, gas, and dust that stretches over 100,000 light-years. The northern (left) component of Arp 194 appears as a haphazard collection of dusty spiral arms, bright blue star-forming regions, and at least two galaxy nuclei that appear to be connected and in the early stages of merging. A third, relatively normal, spiral galaxy appears off to the right. The southern (lower) component of the galaxy group contains a single large spiral galaxy with its own blue star-forming regions. However, the most striking feature of this galaxy troupe is the impressive blue stream of material extending from the northern component. This "fountain" contains complexes of super star clusters, each one of which may contain dozens of individual young star clusters. The blue color is produced by the hot, massive stars which dominate the light in each cluster. Overall, the "fountain" contains many millions of stars. These young star clusters probably formed as a result of the interactions between the galaxies in the northern component of Arp 194. The compression of gas involved in galaxy interactions can enhance the star-formation rate and give rise to brilliant bursts of star formation in merging systems. Arp 194, located in the constellation Cepheus, resides approximately 600 million light-years away from Earth.

No comments:

Post a Comment

Please Leave Your Precious Comments Here

Related Posts Plugin for WordPress, Blogger...