| |
| Piú viste - The Universe in Super Definition |
Galaxies-HST.jpgGalaxies!54 visiteThese images taken with NASA's Hubble Space Telescope are close-up views of four galaxies from a large survey of nearby galaxies.
The galaxies have very different masses and sizes and showcase the diversity of galaxies found in the ANGST study. Although the galaxies are separated by many light-years, they are presented as if they are all at the same distance to show their relative sizes.
The images, taken with Hubble's Advanced Camera for Surveys, reveal rich detail in the stellar populations and in the interstellar dust scattered between the stars. Hubble's sharp views reveal the colors and brightnesses of individual stars, which astronomers used to derive the history of star formation in each galaxy.
In the composite image at the top, NGC 253 is ablaze with the light from thousands of young, blue stars. The spiral galaxy is undergoing intense star formation. The image demonstrates the sharp "eye" of the Advanced Camera, which resolved individual stars. The dark filaments are clouds of dust and gas. NGC 253 is the dominant galaxy in the Sculptor Group of galaxies and it resides about 13 million light-years from Earth.
In the view of the spiral galaxy NGC 300, second from top, young, blue stars are concentrated in spiral arms that sweep diagonally through the image. The yellow blobs are glowing hot gas that has been heated by radiation from the nearest young, blue stars. NGC 300 is a member of the Sculptor Group of galaxies and it is located 7 million light-years away.
The dark clumps of material scattered around the bright nucleus of NGC 3077, the small, dense galaxy at bottom, left, are pieces of wreckage from the galaxy's interactions with its larger neighbors. NGC 3077 is a member of the M81 group of galaxies and it resides 12.5 million light-years from Earth.
The image at bottom, right, shows a swarm of young, blue stars in the diffuse dwarf irregular galaxy NGC 4163. NGC 4163 is a member of a group of dwarf galaxies near our Milky Way and is located roughly 10 million light-years away.
These galaxies are part of a detailed survey called the ACS Nearby Galaxy Survey Treasury program (ANGST). In the census, Hubble observed roughly 14 million stars in 69 galaxies. The survey explored a region called the "Local Volume," and the galaxy distances ranged from 6.5 million light-years to 13 million light-years from Earth. The Local Volume resides beyond the Local Group of galaxies, an even nearer collection of a few dozen galaxies within about 3 million light-years of our Milky Way Galaxy.
The natural-color images were constructed using observations taken in infrared, visible, and blue light. The observations of NGC 253 and NGC 300 were taken in September 2006; of NGC 3077 in November 2006; and of NGC 4163 in December 2006.
Object Names: NGC 253, NGC 300, NGC 3077, NGC 4163
MareKromium
|
|
NGC-3324-HST.jpgNGC 3324 - Star-forming Region54 visiteThe landmark 10th anniversary of the Hubble Space Telescope's Hubble Heritage Project is being celebrated with a 'landscape' image from the cosmos. Cutting across a nearby star-forming region are the "hills and valleys" of gas and dust displayed in intricate detail. Set amid a backdrop of soft, glowing blue light are wispy tendrils of gas as well as dark trunks of dust that are light-years in height.
The Hubble Heritage Project, which began in October 1998, has released nearly 130 images mined from the Hubble data archive as well as a number of observations taken specifically for the project. By releasing a new, previously unseen Hubble image every month, the team's intent was to showcase some of the most attractive images ever taken by the Hubble telescope, and share them with a wide audience. The Heritage team continues to create aesthetic images that present the universe from an artistic perspective.
This month's three-dimensional-looking Hubble image shows the edge of the giant gaseous cavity within the star-forming region called NGC 3324. The glowing nebula has been carved out by intense ultraviolet radiation and stellar winds from several hot, young stars. A cluster of extremely massive stars, located well outside this image in the center of the nebula, is responsible for the ionization of the nebula and excavation of the cavity.
The image also reveals dramatic dark towers of cool gas and dust that rise above the glowing wall of gas. The dense gas at the top resists the blistering ultraviolet radiation from the central stars, and creates a tower that points in the direction of the energy flow. The high-energy radiation blazing out from the hot, young stars in NGC 3324 is sculpting the wall of the nebula by slowly eroding it away.
Located in the Southern Hemisphere, NGC 3324 is at the northwest corner of the Carina Nebula (NGC 3372), home of the Keyhole Nebula and the active, outbursting star Eta Carinae. The entire Carina Nebula complex is located at a distance of roughly 7,200 light-years, and lies in the constellation Carina.
This image is a composite of data taken with two of Hubble's science instruments. Data taken with the Advanced Camera for Surveys (ACS) in 2006 isolated light emitted by hydrogen. More recent data, taken in 2008 with the Wide Field Planetary Camera 2 (WFPC2), isolated light emitted by sulfur and oxygen gas. To create a color composite, the data from the sulfur filter are represented by red, from the oxygen filter by blue, and from the hydrogen filter by green.
The Heritage project has released images using several of Hubble's optical cameras: the Wide Field Planetary Camera (WF/PC), which was installed when the telescope was first deployed in 1990; WFPC2, which replaced WFPC in 1993 and is still in service today; and ACS, which was added in 2002. After the Hubble Servicing Mission in early 2009, the Hubble Heritage team hopes to continue using ACS as well as the newest of the optical cameras, Wide Field Camera 3.
MareKromium
|
|
NGC-0346-PIA11227.jpgNGC 346 in the Small Magellanic Cloud54 visiteThis painterly portrait of a star-forming cloud, called NGC 346, is a combination of multiwavelength light from NASA's Spitzer Space Telescope (infrared), the European Southern Observatory's New Technology Telescope (visible), and the European Space Agency's XMM-Newton space telescope (X-ray).
The infrared observations highlight cold dust in red, visible data show glowing gas in green, and X-rays show very warm gas in blue. Ordinary stars appear as blue spots with white centers, while young stars enshrouded in dust appear as red spots with white centers.
The colorful picture demonstrates that stars in this region are being created by two different types of triggered star formation — one involving wind, and the other, radiation.
Triggered star formation occurs when massive stars spur new, smaller stars into existence. The first radiation-based mechanism is demonstrated near the center of the cloud. There, radiation from the massive stars is eating away at the surrounding dust cloud, creating shock waves that compress gas and dust into new stars. This compressed material appears as an arc-shaped orange-red filament, while the new stars within this filament are still blanketed with dust and cannot be seen.
The second wind-based mechanism is at play higher up in the cloud. The isolated, pinkish blob of stars at the upper left was triggered by winds from a massive star located to the left of it. This massive star blew up in a supernova explosion 50,000 years ago, but before it died, its winds pushed gas and dust together into new stars. While this massive star cannot be seen in the image, a bubble created when it exploded can be seen near the large, white spot with a blue halo at the upper left (this white spot is actually a collection of three stars).
NGC 346 is the brightest star-forming region in the Small Magellanic Cloud, an irregular dwarf galaxy that orbits our Milky Way galaxy, 210.000 LY away.MareKromium
|
|
NGC-1569.jpgStarburst Galaxy NGC 156954 visiteThis image taken by NASA's Hubble Space Telescope showcases the brilliant core of one of the most active galaxies in our local neighborhood. The entire core is 5,000 light-years wide.
The galaxy, called NGC 1569, sparkles with the light from millions of newly formed young stars. NGC 1569 is pumping out stars at a rate that is 100 times faster than the rate observed in our Milky Way Galaxy. This frenzied pace has been almost continuous for the past 100 million years.
The core's centerpiece is a grouping of three giant star clusters, each containing more than a million stars. (Two of the clusters are so close they appear as one grouping.) The clusters reside in a large, central cavity. The gas in the cavity has been blown out by the multitude of massive, young stars that already exploded as supernovae. These explosions also triggered a violent flow of gas and particles that is sculpting giant gaseous structures. The sculpted structure at lower right is about 3,700 light-years long.
Huge bubbles of gas, such as the two at left, appear like floating islands. The largest bubble is about 378 light-years wide and the smallest 119 light-years wide. They are being illuminated by the radiation from the bright, young stars within them. Some of those stars are peaking through their gaseous cocoons.
The biggest and brightest objects surrounding the core are stars scattered throughout our Milky Way Galaxy. In contrast, the thousands of tiny white dots in the image are stars in the halo of NGC 1569. The galaxy is 11 million light-years from Earth.
A new analysis of NGC 1569 shows that it is one and a half times farther from Earth than astronomers previously thought. The extra distance places the galaxy in the middle of a group of about 10 galaxies centered on the spiral galaxy IC 342. Gravitational interactions among the group's galaxies may be compressing gas in NGC 1569 and igniting the star-birthing frenzy.
MareKromium
|
|
PIA11417.jpgQuartz-like Crystals found in Planetary Disks54 visiteNASA's Spitzer Space Telescope has, for the first time, detected tiny quartz-like crystals sprinkled in young planetary systems. The crystals, which are types of silica minerals called Cristobalite and Tridymite, can be seen close-up in the black-and-white insets (Cristobalite is on the left, and Tridymite on the right). The main picture is an artist's concept of a young star and its swirling disk of planet-forming materials.
Cristobalite and Tridymite are thought to be two of many planet ingredients. On Earth, they are normally found as tiny crystals in volcanic lava flows and meteorites from space. These minerals are both related to quartz. For example, if you were to heat the familiar quartz crystals often sold as mystical tokens, the quartz would transform into Cristobalite and Tridymite.
Because Cristobalite and Tridymite require rapid heating and cooling to form, astronomers say they were most likely generated by shock waves traveling through the planetary disks.
The insets are Scanning Electron Microscope pictures courtesy of George Rossman of the California Institute of Technology, Pasadena, Calif.MareKromium
|
|
Epsilon_Eridani-PIA11376.JPGSolar Systems54 visiteThis artist's diagram compares the Epsilon Eridani System to our own Solar System. The two systems are structured similarly, and both host asteroids (brown), comets (blue) and planets (white dots).
Epsilon Eridani is our closest known planetary system, located about 10 LY away in the constellation Eridanus. Its central star is a younger, fainter version of our Sun, and is about 800 million years old — about the same age of our Solar System when life first took root on Earth.
Observations from NASA's Spitzer Space Telescope show that the System hosts two Asteroid Belts, in addition to previously identified candidate planets and an Outer Comet Ring.
Epsilon Eridani's inner Asteroid Belt is located at about the same position as ours, approximately 3 AU from its star (aone AU is the distance between Earth and Sun). The system's second, denser Belt lies at about the same place where Uranus orbits in our Solar System, or 20 AU from the star.
In the same way that Jupiter lies just outside our Asteroid Belt, shepherding its rocky debris into a ring, Epsilon Eridani is thought to have planets orbiting near the rims of its two Belts. The first of these planets was identified in 2000 via the Radial Velocity Technique.
Called "Epsilon Eridani b", it orbits at an average distance of 3,4 AU — placing it just outside the System's inner Asteroid Belt.
The second planet orbiting near the rim of the outer Asteroid Belt at 20 AU was inferred when Spitzer discovered the belt.
A third planet might orbit in Epsilon Eridani at the inner edge of its outermost Comet Ring, which lies between 35 and 90 AU. This planet was first hinted at in 1998 due to observed lumpiness in the Comet Ring.
The outer Comet Ring around Epsilon Eridani is denser than our Comet Ring, called Kuiper Belt, because the system is younger.
Over time, Epsilon Eridani's ring will become wispier like the Kuiper Belt. Its comets will collide with each other and break up, or get pushed out of the ring by the gravitational influences of the planets. MareKromium
|
|
Cassiopeia_A-PIA11748.jpgSNR Cassiopeia "A"54 visiteFor the first time, a multiwavelength three-dimensional reconstruction of a SuperNova Remnant has been created. This stunning visualization of Cassiopeia A, or Cas A, the result of an explosion approximately 330 years ago, uses data from several telescopes: X-ray data from NASA's Chandra X-ray Observatory, InfraRed data from NASA's Spitzer Space Telescope and optical data from the National Optical Astronomy Observatory 4-meter telescope at Kitt Peak, Ariz., and the Michigan-Dartmouth-MIT 2.4-meter telescope, also at Kitt Peak. In this visualization, the green region is mostly Iron observed in X-rays. The yellow region is a combination of Argon and Silicon seen in X-rays, optical, and infrared — including jets of Silicon — plus outer debris seen in the optical. The red region is cold debris seen in the infrared. Finally, the blue reveals the outer blast wave, most prominently detected in X-rays.
Most of the material shown in this visualization is debris from the explosion that has been heated by a shock moving inwards. The red material interior to the yellow/orange ring has not yet encountered the inward moving shock and so has not yet been heated. These unshocked debris were known to exist because they absorb background radio light, but they were only recently discovered in infrared emission with Spitzer. The blue region is composed of gas surrounding the explosion that was heated when it was struck by the outgoing blast wave, as clearly seen in Chandra images.
To create this visualization, scientists took advantage of both a previously known phenomenon — the Doppler effect — and a new technology that bridges astronomy and medicine. When elements created inside a supernova, such as Iron, Silicon and Argon, are heated they emit light at certain wavelengths. Material moving towards the observer will have shorter wavelengths and material moving away will have longer wavelengths. Since the amount of the wavelength shift is related to the speed of motion, one can determine how fast the debris are moving in either direction.
Because Cas A is the result of an explosion, the stellar debris is expanding radially outwards from the explosion center. Using simple geometry, the scientists were able to construct a 3-D model using all of this information. A program called 3-D Slicer — modified for astronomical use by the Astronomical Medicine Project at Harvard University in Cambridge, Mass. — was used to display and manipulate the 3-D model. Commercial software was then used to create the 3-D fly-through.
The blue filaments defining the blast wave were not mapped using the Doppler Effect because they emit a different kind of light —synchrotron radiation — that does not emit light at discrete wavelengths, but rather in a broad continuum. The blue filaments are only a representation of the actual filaments observed at the blast wave.
This visualization shows that there are two main components to this supernova remnant: a spherical component in the outer parts of the remnant and a flattened (disk-like) component in the inner region. The spherical component consists of the outer layer of the star that exploded, probably made of helium and carbon. These layers drove a spherical blast wave into the diffuse gas surrounding the star.
The flattened component — that astronomers were unable to map into 3-D prior to these Spitzer observations — consists of the inner layers of the star. It is made from various heavier elements, not all shown in the visualization, such as Oxygen, Neon, Silicon, Sulphur, Argon and Iron.
High-velocity plumes, or jets, of this material are shooting out from the explosion in the plane of the disk-like component mentioned above. Plumes of Silicon appear in the North/East and South/West, while those of Iron are seen in the South/East and North. These jets were already known and Doppler velocity measurements have been made for these structures, but their orientation and position with respect to the rest of the debris field had never been mapped before now.
This new insight into the structure of Cas A gained from this 3-D visualization is important for astronomers who build models of supernova explosions. Now, they must consider that the outer layers of the star come off spherically, but the inner layers come out more disk-like with high-velocity jets in multiple directions.MareKromium
|
|
HD-80606b.jpgA Dangerous Summer on HD 80606b54 visiteOn the distant planet HD 80606b, Summers might be dangerous.
Hypothetic life forms floating in HD 080606b's Atmosphere or lurking on one of its (presently hypothetical) moons might fear the 1500 Kelvin Summer heat, which is hot enough not only to melt Lead but also Nickel. Although Summers are defined for Earth by the daily amount of Sunlight, Summers on HD 80606b are more greatly influenced by how close the Planet gets to its Parent Star.
HD 80606b, about 200 LY distant, has the most elliptical orbit of any planet yet discovered. In comparison to the Solar System, the distance to its Parent Star would range from outside the orbit of Venus to well inside the orbit of Mercury.
In this sequence, the night side of HD 80606b is computer simulated as it might glow in infrared light in nearly daily intervals as it passed the closest point in its 111-day orbit around its Parent Star.
The simulation is based on infrared data taken in late 2007 by the Spitzer Space Telescope.
Nota Lunexit (a chi interessa): la Formula di Conversione per le Temperature espresse in Kelvin in Temperature espresse in Celsius è la seguente: T° Celsius = T Kelvin - 273,15
Nel nostro caso di specie, quindi, la temperatura diurna media Estiva di HD 80606b dovrebbe essere pari a circa 1227° C.
Un bel "tepore", davvero...MareKromium
|
|
M-101-PIA11797.jpgM 10154 visiteIn 1609, Galileo improved the newly invented telescope, turned it toward the heavens, and revolutionized our view of the universe. In celebration of the 400th anniversary of this milestone, 2009 has been designated as the International Year of Astronomy.
Today, NASA's Great Observatories are continuing Galileo's legacy with stunning images and breakthrough science from the Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray Observatory.
While Galileo observed the sky using visible light seen by the human eye, technology now allows us to observe in many wavelengths, including Spitzer's infrared view and Chandra's view in X-rays. Each wavelength region shows different aspects of celestial objects and often reveals new objects that could not otherwise be studied.
This image of the spiral galaxy Messier 101 is a composite of views from Spitzer, Hubble, and Chandra.
The red color shows Spitzer's view in infrared light. It highlights the heat emitted by dust lanes in the galaxy where stars can form.
The yellow color is Hubble's view in visible light. Most of this light comes from stars, and they trace the same spiral structure as the dust lanes.
The blue color shows Chandra's view in X-ray light. Sources of X-rays include million-degree gas, exploded stars, and material colliding around black holes.
Such composite images allow astronomers to see how features seen in one wavelength match up with those seen in another wavelength. It's like seeing with a camera, night vision goggles, and X-ray vision all at once.
In the four centuries since Galileo, astronomy has changed dramatically. Yet our curiosity and quest for knowledge remain the same. So, too, does our wonder at the splendor of the universe.
The International Year of Astronomy Great Observatories Image Unveiling is supported by the NASA Science Mission Directorate Astrophysics Division. The project is a collaboration between the Space Telescope Science Institute, the Spitzer Science Center, and the Chandra X-ray Center.
MareKromium
|
|
NGC-6240-PIA11828.jpgNGC 6240 - Colliding Galaxies54 visiteThis image of a pair of colliding galaxies called NGC 6240 shows them in a rare, short-lived phase of their evolution just before they merge into a single, larger galaxy. The prolonged, violent collision has drastically altered the appearance of both galaxies and created huge amounts of heat turning NGC 6240 into an "InfraRed Luminous" Active Galaxy.
A rich variety of active galaxies, with different shapes, luminosities and radiation profiles exist. These galaxies may be related astronomers have suspected that they may represent an evolutionary sequence. By catching different galaxies in different stages of merging, a story emerges as one type of active galaxy changes into another. NGC 6240 provides an important "missing link" in this process.
This image was created from combined data from the infrared array camera of NASA's Spitzer Space Telescope at 3.6 and 8.0 microns (red) and Visible Light from NASA's Hubble Space Telescope (green and blue).MareKromium
|
|
NGC-3242-PIA11968.jpgThe Extended Region around the Planetary Nebula NGC 324254 visiteThe unfortunate name of Planetary Nebula for this class of Celestial Objects is a historical legacy credited to William Herschel during the 18th Century — a time when telescopes where small and objects like these, at least the central region, looked very similar to gas-giant planets such as Saturn and Jupiter. In fact, NGC 3242 has no relation to Jupiter or any other planet.
Telescopes and their detectors have dramatically improved over the past few centuries. Our understanding of what Planetary Nebulae truly are has improved accordingly.
When stars with a mass similar to our Sun approach the end of their lives by exhausting supplies of Hydrogen and Helium fuel in their cores, they swell up into cool red-giant stars. In a last gasp before death, they expel the layers of gas in their Outer Atmosphere. This exposes the core of the dying star, a dense hot ball of Carbon and Oxygen called a "White Dwarf".
The White Dwarf is so hot that it shines very brightly in the UltraViolet Spectrum. The UltraViolet Light from the White Dwarf, in turn, ionizes the gaseous material expelled by the star causing it to glow. A Planetary Nebula is really the death of a low-mass star.
Although low-mass stars like our Sun live for billions of years, Planetary Nebulae only last for about ten thousand years. As the central white dwarf quickly cools and the UltraViolet Light dwindles, the surrounding gas also cools and fades.
In this image of NGC 3242 from the Galaxy Evolution Explorer, the Extended Region around the Planetary Nebula is shown in dramatic detail. The small circular white and blue area at the center of the image is the well-known portion of the famous Planetary Nebula. The precise origin and composition of the extended wispy white features is not known for certain. It is most likely material ejected during the star's red-giant phase before the White Dwarf was exposed.
However, it may be possible that the extended material is simply interstellar gas that, by coincidence, is located close enough to the White Dwarf to be energized by it, and induced to glow with UltraViolet Light.
NGC 3242 is located 1400 to 2500 Light-Years away in the constellation of Hydra. It was discovered by William Herschel in 1785.MareKromium
|
|
M-033-PIA11970.jpgM 33 - Spiral Galaxy54 visiteOne of our closest galactic neighbors shows its awesome beauty in this new image from NASA's Spitzer Space Telescope.
M 33, also known as the "Triangulum Galaxy", is a member of what's known as our Local Group of galaxies. Along with our own Milky Way, this group travels together in the universe, as they are gravitationally bound.
In fact, M 33 is one of the few galaxies that is moving toward the Milky Way despite the fact that space itself is expanding, causing most galaxies in the universe to grow farther and farther apart.
When viewed with Spitzer's InfraRed eyes, this elegant spiral galaxy sparkles with color and detail. Stars appear as glistening blue gems (many of which are actually foreground stars in our own galaxy), while dust in the spiral disk of the galaxy glows pink and red. But not only is this new image beautiful, it also shows M 33 to be surprising large —bigger than its Visible-Light appearance would suggest.
With its ability to detect cold, dark dust, Spitzer can see emission from cooler material well beyond the visible range of M 33's disk. Exactly how this cold material moved outward from the galaxy is still a mystery, but winds from giant stars or supernovas may be responsible.
M 33 is located about 2,9 MLY away in the constellation Triangulum. This composite image was taken by Spitzer's InfraRed Array Camera (a.k.a.: IRAC). The color blue indicates InfraRed Light of 3.6 microns, green shows 4.5-micron light, and red 8.0 microns.MareKromium
|
|
| 157 immagini su 14 pagina(e) |
|
|
|
|
|
9 | |
|
|
|
|
|
|
