Miscellaneous Hubble Wonders

Hubble Reveals Structure of Supernova 1987a Explosion Debris

This Hubble Space Telescope picture shows Supernova 1987A and its neighborhood. The series of four panels shows the evolution of the SN 1987A debris from February 1994 to February 1996. Material from the stellar interior was ejected into space during the supernova explosion in February 1987. The explosion debris is expanding at nearly 6 million miles per hour.

Ten years now after the explosion, this cosmic fireball is large enough —- about one-sixth of a light-year in diameter —- to be resolved from the Earth's orbit with the Hubble Space Telescope. The debris is resolved into two opposing blobs and is dim in the center. The apparent direction of ejection is the same as the short axis of the bright inner ring that surrounds the supernova. This suggests that the explosion is directed out of the plane of the ring. The ring is probably composed of materials lost by the pre-supernova star in the last stages of its evolution.

Supernova 1987A is located 167,000 light-years away from Earth in the Large Magellanic Cloud.

The telescope captured the images with the Wide Field and Planetary Camera 2. The central image of the supernova and the ring system was taken in light emitted by nitrogen gas (658 nanometers) on Sept. 24, 1994. The series of debris images were taken using a visible light filter of wavelength around 550 nanometers taken (from left to right) on Feb. 4, 1994, Sept. 24, 1994, March 5, 1995, and Feb. 6, 1996.

Credit: Chun Shing Jason Pun (NASA/GSFC), Robert P. Kirshner (Harvard-Smithsonian Center for Astrophysics), and NASA

Hubble Captures Merger Between Quasar and Galaxy

This NASA Hubble Space Telescope image shows evidence fo r a merger between a quasar and a companion galaxy. This surprising result might require theorists to rethink their explanations for the nature of quasars, the most energetic objects in the universe.

The bright central object is the quasar itself, located several billion light-years away. The two wisps of material on the (left) of the bright central object are remnants of a bright galaxy that have been disrupted by the mutual gravitational attraction between the quasar and the companion galaxy. This provides clear evidence for a merger between the two objects.

Since their discovery in 1963, quasars (quasi-stellar objects) have been enigmatic because they emit prodigious amounts of energy from a very compact source. The most widely accepted model is that a quasar is powered by a supermassive black hole in the core of a galaxy.

These new observations proved a challenge for theorists as no current models predict the complex quasar interactions unveiled by Hubble.

The image was taken with the Wide Field Planetary Camera-2.

Credit: John Bahcall, Institute for Advanced Study, NASA.

Hubble Observes the Fire and Fury of a Stellar Birth

hese NASA Hubble Space Telescope views of gaseous jets from three newly forming stars show a new level of detail in the star formation process, and are helping to solve decade-old questions about the secrets of star birth. Jets are a common "exhaust product" of the dynamics of star formation. They are blasted away from a disk of gas and dust falling onto an embryonic star.

[upper left] - This view of a protostellar object called HH-30 reveals an edge-on disk of dust encircling a newly forming star. Light from the forming star illuminates the top and bottom surfaces of the disk, making them visible, while the star itself is hidden behind the densest parts of the disk. The reddish jet emanates from the inner region of the disk, and possibly directly from the star itself. Hubble's detailed view shows, for the first time, that the jet expands for several billion miles from the star, but then stays confined to a narrow beam. The protostar is 450 light-years away in the constellation Taurus.

[upper right] - This view of a different and more distant jet in object HH-34 shows a remarkable beaded structure. Once thought to be a hydrodynamic effect (similar to shock diamonds in a jet aircraft exhaust), this structure is actually produced by a machine-gun-like blast of "bullets" of dense gas ejected from the star at speeds of one-half million miles per hour. This structure suggests the star goes through episodic "fits" of construction where chunks of material fall onto the star from a surrounding disk. The protostar is 1,500 light- years away and in the vicinity of the Orion Nebula, a nearby star birth region.

[bottom] - This view of a three trillion mile-long jet called HH-47 reveals a very complicated jet pattern that indicates the star (hidden inside a dust cloud near the left edge of the image) might be wobbling, possibly caused by the gravitational pull of a companion star. Hubble's detailed view shows that the jet has burrowed a cavity through the dense gas cloud and now travels at high speed into interstellar space. Shock waves form when the jet collides with interstellar gas, causing the jet to glow. The white filaments on the left reflect light from the obscured newborn star. The HH-47 system is 1,500 light-years away, and lies at the edge of the Gum Nebula, possibly an ancient supernova remnant which can be seen from Earth's southern hemisphere.

The scale in the bottom left corner of each picture represents 93 billion miles, or 1,000 times the distance between Earth and the Sun. All images were taken with the Wide Field Planetary Camera 2 in visible light. The HH designation stands for "Herbig-Haro" object — the name for bright patches of nebulosity which appear to be moving away from associated protostars.

Upper Left Credit: C. Burrows (STScI & ESA), the WFPC 2 Investigation Definition Team, and NASA

Upper Right Credit: J. Hester (Arizona State University), the WFPC 2 Investigation Definition Team, and NASA

Bottom Credit: J. Morse/STScI, and NASA

Hubble's Close-Up View of a Shockwave from a Stellar Explosion

This image shows a small portion of a nebula called the "Cygnus Loop." Covering a region on the sky six times the diameter of the full Moon, the Cygnus Loop is actually the expanding blastwave from a stellar cataclysm - a supernova explosion - which occurred about 15,000 years ago.

In this image the supernova blast wave, which is moving from left to right across the field of view, has recently hit a cloud of denser than average interstellar gas. This collision drives shock waves into the cloud that heats interstellar gas, causing it to glow.

Just as the microscope revolutionized the study of the human body by revealing the workings of cells, the Hubble Space Telescope is offering astronomers an unprecedented look at fine structure within these shock fronts. Astronomers have been performing calculations of what should go on behind shock fronts for about the last 20 years, but detailed observations have not been possible until Hubble.

This image was taken with Hubble's Wide Field and Planetary Camera 2 (WFPC2). The color is produced by composite of three different images. Blue shows emission from "doubly ionized" oxygen atoms (atoms that have had two electrons stripped away) produced by the heat behind the shock front. Red shows light given off by "singly ionized" sulfur atoms (sulfur atoms that are missing a single electron). This sulfur emission arises well behind the shock front, in gas that has had a chance to cool since the passage of the shock. Green shows light emitted by hydrogen atoms. Much of the hydrogen emission comes from an extremely thin zone (only several times the distance between the Sun and Earth) immediately behind the shock front itself. These thin regions appear as sharp, green, filaments in the image.

This supernova remnant lies 2,500 light-years away in the constellation Cygnus the Swan.

Credit: Jeff Hester (Arizona State University) and NASA

The Slant on Saturn's Rings

This is a series of images of Saturn, as seen at many different wavelengths, when the planet's rings were at a maximum tilt of 27 degrees toward Earth. Saturn experiences seasonal tilts away from and toward the Sun, much the same way Earth does. This happens over the course of its 29.5-year orbit. This means that approximately every 30 years, Earth observers can catch their best glimpse of Saturn's South Pole and the southern side of the planet's rings. Between March and April 2003, researchers took full advantage to study the gas giant at maximum tilt. They used NASA's Hubble Space Telescope to capture detailed images of Saturn's Southern Hemisphere and the southern face of its rings.

The telescope's Wide Field Planetary Camera 2 used 30 filters to snap these images on March 7, 2003. The filters span a range of wavelengths. "The set of 30 selected filters may be the best spectral coverage of Saturn observations ever obtained," says planetary researcher Erich Karkoschka of the University of Arizona. Various wavelengths of light allow researchers to see important characteristics of Saturn's atmosphere. Particles in Saturn's atmosphere reflect different wavelengths of light in discrete ways, causing some bands of gas in the atmosphere to stand out vividly in an image, while other areas will be very dark or dull. One image cannot stand by itself because one feature may have several interpretations. In fact, only by combining and comparing these different images, in a set such as this one, can researchers interpret the data and better understand the planet.

By examining the hazes and clouds present in these images, researchers can learn about the dynamics of Saturn's atmosphere. Scientists gain insight into the structure and gaseous composition of Saturn's clouds via inspection of images such as these taken by the Hubble telescope. Over several wavelength bands, from infrared to ultraviolet, these images reveal the properties and sizes of aerosols in Saturn's gaseous makeup. For example, smaller aerosols are visible only in the ultraviolet image, because they do not scatter or absorb visible or infrared light, which have longer wavelengths. By determining the characteristics of the atmosphere's constituents, researchers can describe the dynamics of cloud formation. At certain visible and infrared wavelengths, light absorption by methane gas blocks all but the uppermost layers of Saturn's atmosphere, which helps researchers discern clouds at different altitudes. In addition, when compared with images of Saturn from seasons past (1991 and 1995), this view of the planet also offers scientists a better comprehension of Saturn's seasonal changes.

Credit: NASA and E. Karkoschka (University of Arizona)

Super Nova Remnant N 49 as captured by HST

Celestial Fireworks

Resembling the puffs of smoke and sparks from a summer fireworks display in this image from NASA's Hubble Space Telescope, these delicate filaments are actually sheets of debris from a stellar explosion in a neighboring galaxy. Hubble's target was a supernova remnant within the Large Magellanic Cloud (LMC), a nearby, small companion galaxy to the Milky Way visible from the southern hemisphere. Denoted N 49, or DEM L 190, this remnant is from a massive star that died in a supernova blast whose light would have reached Earth thousands of years ago. This filamentary material will eventually be recycled into building new generations of stars in the LMC. Our own Sun and planets are constructed from similar debris of supernovae that exploded in the Milky Way billions of years ago. This seemingly gentle structure also harbors a very powerful spinning neutron star that may be the central remnant from the initial blast. It is quite common for the core of an exploded supernova star to become a spinning neutron star (also called a pulsar - because of the regular pulses of energy from the rotational spin) after the immediate shedding of the star's outer layers. In the case of N 49, not only is the neutron star spinning at a rate of once every 8 seconds, it also has a super-strong magnetic field a thousand trillion times stronger than Earth's magnetic field. This places this star into the exclusive class of objects called "magnetars." On March 5, 1979, this neutron star displayed a historic gamma-ray burst episode that was detected by numerous Earth-orbiting satellites. Gamma rays have a million or more times the energy of visible light photons. The Earth's atmosphere protects us by blocking gamma rays that originate from outer space. The neutron star in N 49 has had several subsequent gamma-ray emissions, and is now recognized as a "soft gamma-ray repeater." These objects are a peculiar class of stars producing gamma rays that are less energetic than those emitted by most gamma-ray bursters. The neutron star in N 49 is also emitting X-rays, whose energies are slightly less than that of soft gamma rays. High-resolution X-ray satellites have resolved a point source near the center of N 49, the likely X-ray counterpart of the soft gamma-ray repeater. Diffuse filaments and knots throughout the supernova remnant are also visible in X-ray. The filamentary features visible in the optical image represent the blast wave sweeping through the ambient interstellar medium and nearby dense molecular clouds. Today, N 49 is the target of investigations led by Hubble astronomers You-Hua Chu from the University of Illinois at Urbana-Champaign and Rosa Williams from the University of Massachusetts. Members of this science team are interested in understanding whether small cloudlets in the interstellar medium of the LMC may have a marked effect on the physical structure and evolution of this supernova remnant. The Hubble Heritage image of N 49 is a color representation of data taken in July 2000, with Hubble's Wide Field Planetary Camera 2. Color filters were used to sample light emitted by sulfur ([S II]), oxygen ([O III]), and hydrogen (H-alpha). The color image has been superimposed on a black-and-white image of stars in the same field also taken with Hubble. Image Credit: NASA and The Hubble Heritage Team (STScI/AURA) Acknowledgment: Y.-H. Chu (UIUC), S. Kulkarni (Caltech), and R. Rothschild (UCSD)

The Two Faces of Mars

These two images, taken 11 hours apart with NASA's Hubble Space Telescope, reveal two nearly opposite sides of Mars. Hubble snapped these photos as the red planet was making its closest approach to Earth in almost 60,000 years. Mars completed nearly one half a rotation between the two observations.

The image at left was assembled from a series of exposures taken between 6:20 p.m. and 7:12 p.m. EDT Aug. 26 with Hubble's Wide Field and Planetary Camera 2. Hubble snapped this photo when Mars and Earth were 34,648,840 miles (55,760,220 km) apart.

The prominent Martian features in this photo are Syrtis Major, the "shark-fin" shape on the right and the Hellas impact basin, the circular feature near the center of the image.

The image at right was snapped within minutes of the red planet's close rendezvous with Earth, when the two planets were 34,647,420 miles (55,757,930 km) apart. Mars is a mere 1,400 miles closer to Earth in this picture than in the one taken 11 hours earlier. This photo was assembled from a series of exposures taken between 5:35 a.m. and 6:20 a.m. EDT Aug. 27 with Hubble's Wide Field and Planetary Camera 2.

The striking features in this portrait are Olympus Mons [the oval-shaped object just above center], the largest volcano in the solar system and Solis Lacus, an immense dark marking also known as the "Eye of Mars" [below, right].

Both images show most of the southern polar ice cap. The pictures were taken during the middle of summer in the Southern Hemisphere. During this season the Sun shines continuously on the southern polar ice cap, causing the cap to shrink in size [bottom of image]. The orange streaks are indications of dust activity over the polar cap.

Credit: NASA, J. Bell (Cornell U.) and M. Wolff (SSI)

Additional image processing and analysis support from: K. Noll and A. Lubenow (STScI); M. Hubbard (Cornell U.); R. Morris (NASA/JSC); P. James (U. Toledo); S. Lee (U. Colorado); and T. Clancy, B. Whitney and G. Videen (SSI); and Y. Shkuratov (Kharkov U.)

Hubble Again Views Saturn's Rings Edge-on

Saturn's magnificent ring system is seen tilted edge-on — for the second time this year — in this NASA Hubble Space Telescope picture taken on August 10, 1995, when the planet was 895 million miles (1,440 million kilometers) away. Hubble snapped the image as Earth sped back across Saturn's ring plane to the sunlit side of the rings. Last May 22, Earth dipped below the ring plane, giving observers a brief look at the backlit side of the rings. Ring-plane crossing events occur approximately every 15 years. Earthbound observers won't have as good a view until the year 2038. Several of Saturn's icy moons are visible as tiny starlike objects in or near the ring plane. They are from left to right, Enceladus, Tethys, Dione and Mimas. "The Hubble data shows numerous faint satellites close to the bright rings, but it will take a couple of months to precisely identify them," according to Steve Larson (University of Arizona). During the May ring plane crossing, Hubble detected two, and possibly four, new moons orbiting Saturn. These new observations also provide a better view of the faint E ring, "to help determine the size of particles and whether they will pose a collision hazard to the Cassini spacecraft," said Larson. The picture was taken with Hubble's Wide Field Planetary Camera 2 in wide field mode. This image is a composite view, where a long exposure of the faint rings has been combined with a shorter exposure of Saturn's disk to bring out more detail. When viewed edge-on, the rings are so dim they almost disappear because they are very thin — probably less than a mile thick.

Credit: Phil Nicholson (Cornell University) and NASA

Acknowledgment: A. Cool (SFSU)

Far-Flung Supernovae Shed Light on Dark Universe

Astronomers using the NASA Hubble Space Telescope's Advanced Camera for Surveys (ACS) have found two supernovae that exploded so long ago they provide new clues about the accelerating universe and its mysterious "dark energy." The supernovae are approximately 5 and 8 billion light-years from Earth. The farther one exploded so long ago the universe may still have been decelerating under its own gravity.
"We're trying to fill in a blank region where the universe's rate of expansion switched from deceleration due to gravity to acceleration due to the repulsive force of dark energy," says John Blakeslee, an associate ACS research scientist at Johns Hopkins University, Baltimore, Md., and lead author of a new paper due out in the June Astrophysical Journal. "That's a real challenge, but the ACS is making it very straightforward to find distant supernovae and get detailed information about them."
"This beautifully demonstrates that the ACS is a 'supernova machine' for probing the early universe," says co-investigator Holland Ford, who headed the team that developed the ACS camera that was installed on Hubble in March 2002. According to the Johns Hopkins astronomers, the supernovae they discovered will be just the first of many to be identified with the ACS.
Coupled with Hubble's powerful vision, the ACS can pick out the faint glow of the distant supernovae. The ACS can then dissect their light (by spectroscopy) to measure their distances, study how they fade, and confirm that they are a special type of exploding star that are reliable distance indicators.
In 2001 Hubble astronomers found a supernova even farther away. It offered the first evidence the expanding universe was once decelerating. Astronomers are using Hubble's new camera to go supernova hunting for supporting evidence. "We have enough data on the new supernovae to constrain both their distance and the amount of dust obscuration," says Blakeslee. The filtering effects of interstellar dust can lead to misinterpretation of the cosmic distances unless carefully taken into account.
Type Ia supernovae are believed to be white dwarf stars that pull in gas from an orbiting companion star. The white dwarf siphons off mass until it hits a critical point where a thermonuclear "burning" wave of oxygen, carbon, and heavier elements immolates the star in a few seconds. The physics of the explosions is so similar from star to star that all Type Ia supernovae glow at a predictable peak brightness. This makes them reliable objects for calibrating vast intergalactic distances.
The supernovae were found when ACS team members Daniel Magee (University of California at Santa Cruz) and Zlatan Tsvetanov (Johns Hopkins University) compared earlier Hubble images of the same patch of sky with new ACS images and identified the two supernovae. Follow-up observations were then conducted with ACS and other Hubble instruments to get a detailed fix on their intensities and distances from Earth.
Information from studies of Type Ia supernovae confronted astronomers about five years ago with the stunning, unexpected revelation that galaxies appeared to be moving away from each other at an ever-increasing speed. They've attributed this accelerating expansion to a mysterious factor known as dark energy that is believed to permeate the universe.
Looking farther away into the universe (and, because of the distances involved, further into the past), they've seen evidence that gravity was at that time slowing the expansion of the universe. Astronomers have very little data, though, on the period of transition between these two phases, when the repulsion produced by dark energy began to surpass the tug of gravity.
"Continued studies of supernovae will allow us to uncover the full history of the universal expansion," Blakeslee says. "The sharper images, wider viewing area, and keener sensitivity of ACS should allow astronomers to discover roughly 10 times as many of these cosmic beacons as was possible with Hubble's previous main imaging camera."

The Gravitational Lens G2237 + 0305

The European Space Agency's Faint Object Camera on board NASA's Hubble Space Telescope has provided astronomers with the most detailed image ever taken of the gravitational lens G2237 + 0305—sometimes referred to as the "Einstein Cross". The photograph shows four images of a very distant quasar which has been multiple-imaged by a relatively nearby galaxy acting as a gravitational lens. The angular separation between the upper and lower images is 1.6 arc seconds.
The quasar seen here is at a distance of approximately 8 billion light years, whereas the galaxy at a distance of 400 million light years is 20 times closer. The light from the quasar is bent in its path by the gravitational field of the galaxy. This bending has produced the four bright outer images seen in the photograph. The bright central region of the galaxy is seen as the diffuse central object.
Gravitational lensing occurs when the light from a distant source passes through or close to a massive foreground object. Depending on the detailed alignment of the foreground and background objects with the line of sight to Earth, several images of the background object may be seen. In fact, astronomers expect that a faint fifth image of the quasar should be present near the center of the galaxy in G2237 + 0305. Careful image processing will be needed to determine if the fifth image is actually seen in this FOC exposure.
Gravitational lenses, such as G2237 + 0305, are useful probes of many types of phenomena that occur in the cosmos. For example, it is possible to "weigh" the foreground galaxy by measuring the relative positions and the brightnesses of the different images of the quasar. This should be possible to do more accurately given the resolution of images obtained with the Faint Object Camera. Also, gravitational lenses in genral offer the possibility of determining the elusive "Hubble Constant"—a fundamental measure of the size and age of the universe—by measuring the time delays in changes of the brightness of the lensed images.
Detailed analysis of this fascinating Faint Object Camera image and others to be ob- served later with the Hubble Space Telescope will provide a wealth of information on the details of lensing galaxies, as well as on the process of gravitational lensing itself.

Hubble Probes the Heart of a Nearby Quasar

NASA Hubble Space Telescope's new Advanced Camera for Surveys (ACS) has provided the clearest visible-light view yet of the nearby quasar 3C 273. The ACS' coronagraph was used to block the light from the brilliant central quasar, revealing that the quasar's host galaxy is significantly more complex than had been suggested in previous observations. Features in the surrounding galaxy normally drowned out by the quasar's glow now show up clearly. The ACS reveals a spiral plume wound around the quasar, a red dust lane, and a blue arc and clump in the path of the jet blasted from the quasar. These details had never been seen before. Previously known clumps of hot gas and the inner blue optical jet are now resolved more clearly.
The power of the ACS coronagraph is demonstrated in this picture. The Hubble image on the left, taken with the Wide Field Planetary Camera 2, shows the brilliant quasar but little else. The diffraction spikes demonstrate the quasar is truly a point-source of light (like a star) because the black hole's "central engine" is so compact. Once the blinding "headlight beam" of the quasar is blocked by the ACS (right), the host galaxy pops into view. Note that the ACS' occulting "finger" and other coronagraphic spot are seen in black near the top of the ACS High Resolution Channel image.
Quasars (also known as QSOs — short for quasi-stellar objects) were discovered in the early 1960s, but at least two decades passed before astronomers had observational evidence that they reside in galaxies. They now are commonly accepted to be supermassive black holes accreting infalling gas and dust. Using the ACS, astronomers want to learn what activities in a quasar's host galaxy feed the black hole, allowing it to "turn on" as a quasar.
Credit for WFPC2 image: NASA and J. Bahcall (IAS)
Credit for ACS image: NASA, A. Martel (JHU), H. Ford (JHU), M. Clampin (STScI), G. Hartig (STScI), G. Illingworth (UCO/Lick Observatory), the ACS Science Team and ESA

Hubble Reveals Complex Circumstellar Disk

NASA Hubble Space Telescope's new Advanced Camera for Surveys (ACS) has given astronomers their clearest view yet of the dust disk around a young, 5-million-year-old star. Such disks are expected to be the birthplace of planets. The star, called HD 141569A, lies 320 light-years away in the constellation Libra and appears to be a member of a triple-star system.
The star HD 141569A was first identified as a candidate for a circumstellar disk in 1986, from observations done with the NASA/Netherlands/United Kingdom Infrared Astronomy Satellite (IRAS). An excess of infrared radiation associated with the star provides telltale evidence for the presence of a dust disk. Hubble's Near Infrared Camera and Multi-Object Spectrometer photographed the disk in 1999 and revealed two concentric rings divided by a dark lane. This was interpreted as evidence of dynamical sculpting by one or more planets.

The ACS reveals that the disk's structure is much more complex than previously thought. The disk is actually a tightly wound spiral structure. The outer regions of the disk reveal two diffuse spiral arms, one of which appears to be associated with the nearby double star system (HD 141569BC) seen at the upper left. The apparent connection between the disk and the double star suggest that an interaction with the double star may be responsible for the structures seen in the disk. However, previous mid-IR images of the disk show that it is relatively clear of dust within approximately 2.8 billion miles of the star. This inner region may have been swept clear by one or more unseen planets.
These observations of the disk were obtained with the ACS's High Resolution Camera (HRC) coronagraph. The photo on the left is a processed visible light image. In the photo on the right, the disk has been geometrically altered to simulate a face-on view, and false-color has been applied to enhance the disk structure. The black center marks regions where light from the star has been masked out. These images are the first results of a survey of disks around young main-sequence stars being conducted by the ACS science team.
Credit: NASA, M. Clampin (STScI), H. Ford (JHU), G. Illingworth (UCO/Lick), J. Krist (STScI), D. Ardila (JHU), D. Golimowski (JHU), the ACS Science Team and ESA

Space Movie Reveals Shocking Secrets of the Crab Pulsar

Just when it seemed like the summer movie season had ended, two of NASA's Great Observatories have produced their own action movie. Multiple observations made over several months with NASA's Chandra X-ray Observatory and the Hubble Space Telescope captured the spectacle of matter and antimatter propelled to near the speed of light by the Crab pulsar, a rapidly rotating neutron star the size of Manhattan.

Credits for X-ray Image: NASA/CXC/ASU/J. Hester et al.
Credits for Optical Image: NASA/HST/ASU/J. Hester et al.

Click HERE for more information... then...
Checkout "The Crab" in motion.

Ok... let's add a slight editorial.
This may be the most awesome astronomical display I have ever seen.
Whatever your plans are for the day... make sure that you checkout The Crab in motion.

This movie was made from images capture over the past year by two of the most amazing telescopes mankind has ever assembled. The Hubble Space Telescope captured images at optical wavelength while the Chandra X-Ray Observatory captured images at X-Ray wavelengths. The images were then assembled to produce the accompanying... absolutely spectacular series

The movie shows dynamic rings, wisps and jets of matter and antimatter around the pulsar in the Crab Nebula as observed in X-ray light by Chandra (left, blue) and optical light by Hubble (right, red). .

"X" Marks the Spot: Hubble Sees the Glow of Star Formation in a Neighbor Galaxy

The saying "X" marks the spot holds true in this NASA Hubble Space Telescope (HST) image where Hubble-X marks the location of a dramatic burst of star formation, very much like the Orion Nebula in our Milky Way galaxy, but on a vastly greater scale.
Hubble-X is a glowing gas cloud, one of the most active star-forming regions within galaxy NGC 6822. The name Hubble-X does not refer to the shape of the gas cloud, but rather is derived from a catalog of objects in this particular galaxy. The "X" is actually a Roman numeral designation. The galaxy lies in the constellation Sagittarius at a distance of only 1,630,000 light-years and is one of the Milky Way's closest neighbors. The intense star formation in Hubble-X occurred only about 4 million years ago, a small fraction of the approximate 10 billion year age of the universe.
Giant gas clouds in NGC 6822 have held a special attraction for astronomers since their discovery by the visual observer E. E. Barnard in 1881. Edwin P. Hubble, after whom the HST is named, used the then-new 100-inch telescope at Mount Wilson Observatory in 1925 to make the first detailed photographic investigation of NGC 6822. The Hubble image reveals details too fine to be resolved from telescopes on the ground.
Stars form in groups from enormous clouds of gas and dust called giant molecular clouds. Once star formation begins in a molecular cloud, its rate accelerates until the process is stopped when one or more very massive hot stars are formed. At that point the clouds change from near darkness into the brightly glowing objects such as seen in Hubble-X. It is the intense ultraviolet radiation from the massive stars that causes the residual gas to glow. Radiation and gas outflows, called stellar winds, then cause the gas to disperse, bringing further star formation to an abrupt end.
The Hubble-X image was taken with Hubble's Wide Field Planetary Camera 2 (WFPC2) in September 1997, by astronomers C. Robert O'Dell of Vanderbilt University, Paul W. Hodge of the University of Washington, and R. C. Kennicutt, Jr. of Steward Observatory at the University of Arizona.
The image shows a nearly circular bright cloud at the core of Hubble-X. The cloud's diameter is about 110 light-years, and contains many thousands of newly formed stars in a central cluster. The brightest of these young stars are easily visible in the Hubble image, where they appear as numerous bright white dots.
Hubble-X is many times brighter and larger than the Orion Nebula, the brightest nearby star formation region in our own Milky Way galaxy. In fact, the tiny cloud just below Hubble-X, barely resolved even by HST, has about the same size and brightness as the Orion Nebula.
Image Credit: NASA and The Hubble Heritage Team (STScI/AURA)
Acknowledgment: C. R. O'Dell (Vanderbilt University)

HUBBLE VIEWS ANCIENT STORM IN THE ATMOSPHERE OF JUPITER

When 17th-century astronomers first turned their telescopes to Jupiter, they noted a conspicuous reddish spot on the giant planet. This Great Red Spot is still present in Jupiter's atmosphere, more than 300 years later. It is now known that it is a vast storm, spinning like a cyclone. Unlike a low-pressure hurricane in the Caribbean Sea, however, the Red Spot rotates in a counterclockwise direction in the southern hemisphere, showing that it is a high-pressure system. Winds inside this Jovian storm reach speeds of about 270 mph.
The Red Spot is the largest known storm in the Solar System. With a diameter of 15,400 miles, it is almost twice the size of the entire Earth and one-sixth the diameter of Jupiter itself.
The long lifetime of the Red Spot may be due to the fact that Jupiter is mainly a gaseous planet. It possibly has liquid layers but lacks a solid surface, which would dissipate the storm's energy, much as happens when a hurricane makes landfall on the Earth. However, the Red Spot does change its shape, size, and color, sometimes dramatically. Such changes are demonstrated in high-resolution Wide Field and Planetary Cameras 1 & 2 images of Jupiter obtained by NASA's Hubble Space Telescope, and presented here by the Hubble Heritage Project team. The mosaic presents a series of pictures of the Red Spot obtained by Hubble between 1992 and 1999.
Astronomers study weather phenomena on other planets in order to gain a greater understanding of our own Earth's climate. Lacking a solid surface, Jupiter provides us with a laboratory experiment for observing weather phenomena under very different conditions than those prevailing on Earth. This knowledge can also be applied to places in the Earth's atmosphere that are over deep oceans, making them more similar to Jupiter's deep atmosphere.
The Hubble images were originally collected by Amy Simon (Cornell U.), Reta Beebe (NMSU), Heidi Hammel (Space Science Institute, MIT), and their collaborators, and have been prepared for presentation by the Hubble Heritage Team.
Image Credit: Hubble Heritage Team (STScI/AURA)
Acknowledgment: A. Simon (Cornell U.)

A Change of Seasons on Saturn

Looming like a giant flying saucer in our outer solar system, Saturn puts on a show as the planet and its magnificent ring system nod majestically over the course of its 29-year journey around the Sun. These Hubble Space Telescope images, captured from 1996 to 2000, show Saturn's rings open up from just past edge-on to nearly fully open as it moves from autumn towards winter in its Northern Hemisphere.
Saturn's equator is tilted relative to its orbit by 27 degrees, very similar to the 23-degree tilt of the Earth. As Saturn moves along its orbit, first one hemisphere, then the other is tilted towards the Sun. This cyclical change causes seasons on Saturn, just as the changing orientation of Earth's tilt causes seasons on our planet. The first image in this sequence, on the lower left, was taken soon after the autumnal equinox in Saturn's Northern Hemisphere (which is the same as the spring equinox in its Southern Hemisphere). By the final image in the sequence, on the upper right, the tilt is nearing its extreme, or winter solstice in the Northern Hemisphere (summer solstice in the Southern Hemisphere).
Astronomers are studying this set of images to investigate the detailed variations in the color and brightness of the rings. They hope to learn more about the rings' composition, how they were formed, and how long they might last. Saturn's rings are incredibly thin, with a thickness of only about 30 feet (10 meters). The rings are made of dusty water ice, in the form of boulder-sized and smaller chunks that gently collide with each other as they orbit around Saturn. Saturn's gravitational field constantly disrupts these ice chunks, keeping them spread out and preventing them from combining to form a moon. The rings, as shown here, have a slight pale reddish color due to the presence of organic material mixed with the water ice.
Saturn is about 75,000 miles (120,000 km) across, and is flattened at the poles because of its very rapid rotation. A day is only 10 hours long on Saturn. Strong winds account for the horizontal bands in the atmosphere of this giant gas planet. The delicate color variations in the clouds are due to smog in the upper atmosphere, produced when ultraviolet radiation from the Sun shines on methane gas. Deeper in the atmosphere, the visible clouds and gases merge gradually into hotter and denser gases, with no solid surface for visiting spacecraft to land on.
The Cassini/Huygens spacecraft, launched from Earth in 1997, is well on its way to the Saturn system. It will arrive in 2004 to land a probe on Titan, Saturn's largest moon, and to orbit the planet for four years for a detailed study of the entire Saturn system.
These images of Saturn, taken with the Wide Field Planetary Camera 2 onboard Hubble, were collected by Richard French (Wellesley College), Jeff Cuzzi (NASA/Ames), Luke Dones (SwRI), and Jack Lissauer (NASA/Ames), and have been prepared for presentation by the Hubble Heritage Team.

Image Credit: NASA and The Hubble Heritage Team (STScI/AURA)
Acknowledgment: R.G. French (Wellesley College), J. Cuzzi (NASA/Ames),
L. Dones (SwRI), and J. Lissauer (NASA/Ames)

Hubble Astronomers Feast on an Interstellar Hamburger

Hold the pickles; hold the lettuce. Space is serving up giant hamburgers. NASA's Hubble Space Telescope has snapped a photograph of a strange object that bears an uncanny resemblance to a hamburger. The object, nicknamed Gomez's Hamburger, is a sun-like star nearing the end of its life. It already has expelled large amounts of gas and dust and is on its way to becoming a colorful, glowing planetary nebula.
The ingredients for the giant celestial hamburger are dust and light. The hamburger buns are light reflecting off dust and the patty is the dark band of dust in the middle. The Hubble Heritage image, taken Feb. 22, 2002, with the Wide Field Planetary Camera 2, shows the structure of Gomez's Hamburger with high resolution, particularly the striking dark band of dust that cuts across the middle. The dark band is actually the shadow of a thick disk around the central star, which is seen edge-on from Earth. The star itself, with a surface temperature of approximately 18,000 degrees Fahrenheit (10,000 degrees Celsius), is hidden within this disk. However, light from the star does emerge in the directions perpendicular to the disk and illuminates dust above and below it.
The reason why the star is surrounded by a thick, dusty disk remains somewhat uncertain. It is possible that the central object is actually a pair of stars. If so, then the star that ejected the nebula may be rapidly rotating, expelling material mostly from its equatorial regions.
Stars with masses similar to our Sun's end their lives as planetary nebulae. The star evolves to become a bloated red giant, with a girth about 100 times greater than its original diameter. Then it ejects its outer layers into space, exposing the star's hot core. Ultraviolet radiation from the central core streams out into the surrounding ejected gas, causing it to glow. The glowing gas is called a planetary nebula. The Hubble Space Telescope has provided numerous spectacular images of planetary nebulae over the past several years, including the Ring Nebula and several others that have been released in the Hubble Heritage series.
Less well known are "proto-planetary nebulae," objects like Gomez's Hamburger that are in a state of evolution immediately before the true planetary-nebula stage. Just after the red giant expels its outer layers, the remnant star in the center is still relatively cool. Consequently, it emits ordinary visible light, but very little ultraviolet radiation. Therefore the surrounding gas does not glow. However, the ejected material also contains vast numbers of microscopic dust particles, which can reflect the starlight and make the material visible. This same effect of light scattering produces halos around streetlights on a foggy night.
The lifetime of a proto-planetary nebula is very brief. In less than a thousand years, astronomers expect that the central star will become hot enough to make the dust particles evaporate, thus exposing the star to view. At that time the surrounding gas will glow. Gomez's Hamburger will have become a beautiful, glowing planetary nebula.
Gomez's Hamburger was discovered on sky photographs obtained by Arturo Gomez, an astronomer at the Cerro Tololo Inter-American Observatory in Chile. The photos suggested that there was a dark band across the object, but its exact structure was difficult to determine because of the atmospheric turbulence that hampers all images taken from the ground. Gomez's Hamburger is located roughly 6,500 light-years away in the constellation Sagittarius.
Image Credit: NASA and The Hubble Heritage Team (STScI/AURA)
Acknowledgment: A. Gomez (Cerro Tololo Inter-American Observatory)

Colorful Fireworks Finale Caps a Star's Life

Glowing gaseous streamers of red, white, and blue — as well as green and pink — illuminate the heavens like Fourth of July fireworks. The colorful streamers that float across the sky in this photo taken by NASA's Hubble Space Telescope were created by one of the biggest firecrackers seen to go off in our galaxy in recorded history, the titanic supernova explosion of a massive star. The light from the exploding star reached Earth 320 years ago, nearly a century before our United States celebrated its birth with a bang.
The dead star's shredded remains are called Cassiopeia A, or "Cas A" for short. Cas A is the youngest known supernova remnant in our Milky Way Galaxy and resides 10,000 light-years away in the constellation Cassiopeia, so the star actually blew up 10,000 years before the light reached Earth in the late 1600s.
This stunning Hubble image of Cas A is allowing astronomers to study the supernova's remains with great clarity, showing for the first time that the debris is arranged into thousands of small, cooling knots of gas. This material eventually will be recycled into building new generations of stars and planets. Our own Sun and planets are constructed from the debris of supernovae that exploded billions of years ago.
This photo shows the upper rim of the supernova remnant's expanding shell. Near the top of the image are dozens of tiny clumps of matter. Each small clump, originally just a small fragment of the star, is tens of times larger than the diameter of our solar system. The colors highlight parts of the debris where chemical elements are glowing. The dark blue fragments, for example, are richest in oxygen; the red material is rich in sulfur.
The star that created this colorful show was a big one, about 15 to 25 times more massive than our Sun. Massive stars like the one that created Cas A have short lives. They use up their supply of nuclear fuel in tens of millions of years, 1,000 times faster than our Sun. With their fuel exhausted, heavy stars begin a complex chain of events that lead to the final dramatic explosion. Their cores rapidly collapse, releasing an enormous amount of gravitational energy. This sudden burst of energy reverses the collapse and tosses most of the star's mass into space. The ejected material can travel as fast as 45 million miles per hour (72 million kilometers per hour).
The images were taken with the Wide Field and Planetary Camera 2 in January 2000 and January 2002.
Image Credit: NASA and The Hubble Heritage Team (STScI/AURA)
Acknowledgment: R. Fesen (Dartmouth) and J. Morse (Univ. of Colorado)

Thackeray's Globules in IC 2944

Strangely glowing dark clouds float serenely in this remarkable and beautiful image taken with NASA's Hubble Space Telescope. Another Awesome HST Image

These dense, opaque dust clouds - known as "globules" - are silhouetted against nearby bright stars in the busy star-forming region, IC 2944. These globules were first found in IC 2944 by astronomer A.D. Thackeray in 1950.
Although globules like these have been known since Dutch-American astronomer Bart Bok first drew attention to such objects in 1947, little is still known about their origin and nature, except that they are generally associated with large hydrogen-emitting star-formation regions, called "HII regions" due to their glowing light of hydrogen gas.
The largest of the globules in this image is actually two separate clouds that gently overlap along our line of sight. Each cloud is nearly 1.4 light-years (50 arcseconds) along its longest dimension, and collectively, they contain enough material to equal over 15 solar masses. IC 2944, the surrounding HII region, is filled with gas and dust that is illuminated and heated by a loose cluster of O-type stars. These stars are much hotter and much more massive than our Sun. IC 2944 is relatively close by, located only 5900 light-years (1800 parsecs) away in the constellation Centaurus.
Thanks to the remarkable resolution offered by the Hubble Space Telescope, astronomers can for the first time study the intricate structure of these globules. The globules appear to be heavily fractured, as if major forces were tearing them apart. When radio astronomers observed the faint hiss of molecules within the globules, they realized that the globules are actually in constant, churning motion, moving supersonically among each other. This may be caused by the powerful ultraviolet radiation from the luminous, massive stars, which also heat up the gas in the HII region, causing it to expand and stream against the globules, leading to their destruction. Despite their serene appearance, the globules may actually be likened to clumps of butter put onto a red-hot pan.
It is likely that the globules are dense clumps of gas and dust that existed before the massive O-stars were born. But once these luminous stars began to irradiate and destroy their surroundings, the clumps became visible when their less dense surroundings were eroded away, thus exposing them to the full brunt of the ultraviolet radiation and the expanding HII region. The new images catch a glimpse of the process of destruction. Had the appearance of the luminous O-stars been a bit delayed, it is likely that the clumps would actually have collapsed to form several more low-mass stars like the Sun. Instead they are now being toasted and torn apart.
The hydrogen-emission image that clearly shows the outline of the dark globules was taken in February 1999 with Hubble's Wide Field Planetary Camera 2 (WFPC2) by Bo Reipurth (University of Hawaii) and collaborators. Additional broadband images that helped to establish the true color of the stars in the field were taken by the Hubble Heritage Team in February 2001. The composite result is a four-color image of the red, green, blue and H-alpha filters.
Image Credit: NASA and The Hubble Heritage Team (STScI/AURA) Acknowledgment: Bo Reipurth (University of Hawaii)

PEERING INTO THE HEART OF THE CRAB NEBULA

In the year 1054 A.D., Chinese astronomers were startled by the appearance of a new star, so bright that it was visible in broad daylight for several weeks. Today, the Crab Nebula is visible at the site of this violent stellar explosion. In this new image, An amazing shot of the Crab Nebula by the Hubble Space Telescope

An amazing shot of the Crab Nebula by the Hubble Space Telescope

NASA's Hubble Space Telescope has zoomed in on the center of the Crab to reveal its structure with unprecedented detail.
Located about 6,500 light-years from Earth in the direction of the constellation Taurus, the Crab Nebula is the remnant of a star that began its life with about 10 times the mass of our own Sun. Such a massive star consumes its nuclear fuel so rapidly that it lives only some 50 million years before exploding as a supernova. For the Crab star, the end came on July 4, 1054. The explosion was witnessed as a naked-eye "Guest Star" by Chinese astronomers, and is also depicted in rock paintings of Native Americans in the southwestern United States.
The Crab Nebula image was obtained by Hubble's Wide Field and Planetary Camera 2 in 1995. Images taken with five different color filters have been combined to construct this false-color picture. Resembling an abstract painting by Jackson Pollack, the image shows ragged shreds of gas that are expanding away from the explosion site at over 3 million miles per hour.
The core of the star has survived the explosion as a "pulsar," visible in the Hubble image as the lower of the two moderately bright stars to the upper left of center. The pulsar has about 1.4 times the mass of the Sun, but jammed into an object only about 10 miles in diameter. This incredible object, a "neutron star," is even more remarkable because it spins on its axis 30 times a second.
The spinning pulsar heats its surroundings, creating the ghostly diffuse bluish-green glowing gas cloud in its vicinity, including a blue arc just to the right of the neutron star.
The colorful network of filaments is the material from the outer layers of the star that was expelled during the explosion and is now expanding outward at high speed. The picture is somewhat deceptive in that the filaments appear to be close to the pulsar. In reality, the yellowish green filaments toward the bottom of the image are closer to us, and approaching at some 300 miles per second. The orange and pink filaments toward the top of the picture include material behind the pulsar, rushing away from us at similar speeds.
The various colors in the picture arise from different chemical elements in the expanding gas, including hydrogen (orange), nitrogen (red), sulfur (pink), and oxygen (green). The shades of color represent variations in the temperature and density of the gas, as well as changes in the elemental composition.
These chemical elements, some of them newly created during the evolution and explosion of the star and now blasted back into space, will eventually be incorporated into new stars and planets. Astronomers believe that the chemical elements in the Earth and even in our own bodies, such as carbon, oxygen, and iron, were made in other exploding stars billions of years ago.
K. Davidson (U. Minn.) led the research team of W. P. Blair (JHU), R. A. Fesen (Dartmouth), A. Uomoto (JHU), G. M. MacAlpine (U. Mich.), and R. B. C. Henry (U. Okla.) in the collection of the HST data. The Hubble Heritage Team created the color image from black and white data processed by Dr. Blair.
Image Credit: NASA and The Hubble Heritage Team (STScI/AURA) Acknowledgments: William P. Blair (JHU)