Galactic wreckage in Stephan's Quintet: A clash among members of a famous galaxy quintet reveals an assortment of stars across a wide colour range, from young, blue stars to aging, red stars. This portrait of Stephan's Quintet, also known as the Hickson Compact Group 92, was taken by the new Wide Field Camera 3 (WFC3) aboard the NASA/ESA Hubble Space Telescope. Stephan's Quintet, as the name implies, is a group of five galaxies. The name, however, is a bit of a misnomer. Studies have shown that group member NGC 7320, at upper left, is actually a foreground galaxy that is about seven times closer to Earth than the rest of the group. Three of the galaxies have distorted shapes, elongated spiral arms, and long, gaseous tidal tails containing myriad star clusters, proof of their close encounters. These interactions have sparked a frenzy of star birth in the central pair of galaxies. This drama is being played out against a rich backdrop of faraway galaxies. The image, taken in visible and near-infrared light, showcases WFC3's broad wavelength range. The colours trace the ages of the stellar populations, showing that star birth occurred at different epochs, stretching over hundreds of millions of years. The camera's infrared vision also peers through curtains of dust to see groupings of stars that cannot be seen in visible light. NGC 7319, at top right, is a barred spiral with distinct spiral arms that follow nearly 180 degrees back to the bar. The blue specks in the spiral arm at the top of NGC 7319 and the red dots just above and to the right of the core are clusters of many thousands of stars. Most of the Quintet is too far away even for Hubble to resolve individual stars. Continuing clockwise, the next galaxy appears to have two cores, but it is actually two galaxies, NGC 7318A and NGC 7318B. Encircling the galaxies are young, bright blue star clusters and pinkish clouds of glowing hydrogen where infant stars are being born. These stars are less than 10 million years old and have not yet blown away their natal cloud. Far away from the galaxies, at right, is a patch of intergalactic space where many star clusters are forming. NGC 7317, at bottom left, is a normal-looking elliptical galaxy that is less affected by the interactions. Sharply contrasting with these galaxies is the dwarf galaxy NGC 7320 at upper left. Bursts of star formation are occurring in the galaxy's disc, as seen by the blue and pink dots. In this galaxy, Hubble can resolve individual stars, evidence that NGC 7320 is closer to Earth. NGC 7320 is 40 million light-years from Earth. The other members of the Quintet reside about 300 million light-years away in the constellation Pegasus. These more distant members are markedly redder than the foreground galaxy, suggesting that older stars reside in their cores. The stars' light also may be further reddened by dust stirred up in the encounters. Spied by Edouard M. Stephan in 1877, Stephan's Quintet is the first compact group ever discovered. WFC3 observed the Quintet in July and August 2009. The composite image was made by using filters that isolate light from the blue, green and infrared portions of the spectrum, as well as emission from ionised hydrogen. These Hubble observations are part of the Hubble Servicing Mission 4 Early Release Observations. NASA astronauts installed the WFC3 camera during a servicing mission in May to upgrade and repair the 19-year-old Hubble telescope.

Name: Hickson Compact Group 92, Stephan's Quintet
Type: Local Universe : Galaxy : Grouping : Cluster
Category: Galaxies
Constellation: Pegasus
Distance: 300 million light years
Release date: 9 September 2009, 17:00
Credit: NASA, ESA and the Hubble SM4 ERO Team

Probing the tattered remains of the supernova remnant N132D: The wispy, glowing, magenta structures in this NASA/ESA Hubble Space Telescope image are the remains of a star 10 to 15 times the mass of the Sun, which we would have seen exploding as a supernova 3000 years ago. The remnant's fast-moving gas is ploughing into the surrounding gas of the galaxy, creating a supersonic shock wave in the surrounding medium and making the material glow. The Hubble visible-light image reveals, deep within the remnant, a crescent-shaped cloud of pink emission from hydrogen gas and soft purple wisps that correspond to regions of glowing oxygen. A dense background of colourful stars is also visible. Probing this tattered gaseous relic, the newly installed Cosmic Origins Spectrograph (COS) aboard the NASA/ESA Hubble Space Telescope detected pristine gas ejected by the doomed star that has not yet mixed with the gas in the interstellar medium. The supernova remnant, called N132D, resides in the Large Magellanic Cloud, a small companion galaxy of the Milky Way located 170 000 light-years away. The resulting spectrum, taken in ultraviolet light, shows glowing oxygen and carbon in the remnant. These results allow astronomers to better understand why some stars form an abundance of certain elements, like oxygen, but not others. Ultraviolet light is blocked by Earth's atmosphere, so the observation of N132D in the ultraviolet requires the use of the space-borne Hubble. The broadest range of spectral signatures of the glowing gas appear in the ultraviolet, allowing astronomers to determine the quantities, or abundances, of key elements such as oxygen, as well as elements whose abundances cannot be traced from visible-light images, including carbon, magnesium and silicon. Previous ultraviolet instruments on Hubble were not sensitive enough to distinguish between the unmixed ejecta, fresh from the supernova, and the "shocked" gas of the surrounding interstellar medium. Supernova remnants provide a rare opportunity to search for the material hidden deep inside a star. This in turn yields information on how stars evolve and how they manufacture chemicals in their interiors. Supernova explosions also enrich the interstellar medium with new chemical elements, which are incorporated into future generations of stars. The COS observations were made on 10 August 2009. COS was installed by NASA astronauts in May 2009, during the Servicing Mission to upgrade and repair the 19-year-old Hubble. The visible-light image was taken on 2 August 2009 with Hubble's new Wide Field Camera 3 (WFC3). A filter that isolates emission from sulphur was combined with archival data from the Advanced Camera for Surveys (ACS). The ACS data include colour filters that sample starlight in the blue, green and red portions of the spectrum, as well as the pink emission from glowing hydrogen gas. These Hubble observations of the N132D are part of the Hubble Servicing Mission 4 Early Release Observations.

Name: CAL 35, LHA 120-N 132D
Type: Local Universe : Nebula : Type : Supernova Remnant
Category: Nebulae
Constellation: Dorado
Distance: 170000 light years
Release date: 9 September 2009, 17:00
Credit: NASA, ESA and the Hubble SM4 ERO Team

Digitized Sky Survey Image of PKS 0405-123 (ground-based image): This image is a colour composite made from exposures from the Digitized Sky Survey 2 (DSS2). The field of view is slightly more than 0.5 x 0.5 degrees.

Name: PKS 0405-123
Type: Early Universe : Galaxy : Activity : AGN : Quasar
Category: Quasars and Black Holes
Constellation: Eridanus
Distance: z=0.574 (redshift)
Release date: 9 September 2009, 17:00
Credit: NASA, ESA, the Hubble SM4 ERO Team and Digitized Sky Survey 2