Red, but not dead: This NASA/ESA Hubble Space Telescope picture depicts the galaxy NGC 1533 in the southern constellation of Dorado (the Dolphin-fish). Around 62 million light-years from Earth, NGC 1533, which is classed as a lenticular galaxy, is a transitional type that shows characteristics of both spiral and elliptical galaxies. Like elliptical galaxies, NGC 1533 is largely made up of older and redder stars and vast numbers of them create the smooth glow across the whole picture. However, it also has a residual level of star formation and some young blue stars, which are revealed by its weak barred spiral structure that is faintly visible in this image. Astronomers studying star formation in this type of galaxy are able to subtract the bright light of the stars to reveal the details of a subtle spiral structure that cannot be well seen in less heavily processed images such as this one. John Herschel, son of William Herschel, the astronomer who discovered Uranus, found NGC 1533 in 1834 during his survey of the southern skies from the Cape of Good Hope. The image was created from images taken using the Wide Field Channel of Hubble's Advanced Camera for Surveys. It is a composite of images taken through yellow (F606W) and near-infrared (F814W) filters. The total exposure times were 38 minutes and 82 minutes respectively and the field of view is about 2.6 by 1.5 arcminutes across. structure

Name: NGC 1533
Type: Local Universe : Galaxy : Type : Lenticular
Category: Galaxies
Constellation: Dorado
Distance: 60 million light years
Release date: 26 July 2010, 10:00
Credit: ESA/Hubble and NASA

A piercing eye in the sky: This dramatic image from the NASA/ESA Hubble Space Telescope shows the planetary nebula NGC 3918, a brilliant cloud of colourful gas in the constellation of Centaurus, around 4900 light-years from Earth. In the centre of the cloud of gas, and completely dwarfed by the nebula, are the dying remnants of a red giant. During the final convulsive phase in the evolution of these stars, huge clouds of gas are ejected from the surface of the star before it emerges from its cocoon as a white dwarf. The intense ultraviolet radiation from the tiny remnant star then causes the surrounding gas to glow like a fluorescent sign. These extraordinary and colourful planetary nebulae are among the most dramatic sights in the night sky, and often have strange and irregular shapes, which are not yet fully explained. NGC 3918’s distinctive eye-like shape, with a bright inner shell of gas and a more diffuse outer shell that extends far from the nebula looks as if it could be the result of two separate ejections of gas. But this is in fact not the case: studies of the object suggest that they were formed at the same time, but are being blown from the star at different speeds. The powerful jets of gas emerging from the ends of the large structure are estimated to be shooting away from the star at speeds of up to 350 000 kilometres per hour. By the standards of astronomical phenomena, planetary nebulae like NGC 3918 are very short-lived, with a lifespan of just a few tens of thousands of years. The image is a composite of visible and near-infrared snapshots taken with Hubble’s Wide Field Planetary Camera 2. The filters used were F658N, F814W, F555W and F502N, seen in red, orange, green and blue respectively. The image is about 20 arcseconds across.

Name: NGC 3918
Type: Milky Way : Nebula : Type : Planetary
Category: Nebulae
Constellation: Centaurus
Distance: 5000 light years
Release date: 2 August 2010, 10:00
Credit: ESA/Hubble and NASA

Frenzied star birth in Haro 11: Haro 11 appears to shine gently amid clouds of gas and dust, but this placid facade belies the monumental rate of star formation occurring in this “starburst” galaxy. By combining data from the NASA/ESA Hubble Space Telescope and ESO’s Very Large Telescope, astronomers have created a new image of this incredibly bright and distant galaxy. The team of astronomers from Stockholm University, Sweden, and the Geneva Observatory, Switzerland, have identified 200 separate clusters of very young, massive stars. Most of these are less than 10 million years old. Many of the clusters are so bright in infrared light that astronomers suspect that the stars are still emerging from the cloudy cocoons where they were born. The observations have led the astronomers to conclude that Haro 11 is most likely the result of a merger between a galaxy rich in stars and a younger, gas-rich galaxy. Haro 11 is found to produce stars at a frantic rate, converting about 20 solar masses of gas into stars every year. Haro galaxies, first discovered by the noted astronomer Guillermo Haro in 1956, are defined by unusually intense blue and violet light. Usually this high energy radiation comes from the presence of many newborn stars or an active galactic nucleus. Haro 11 is about 300 million light-years away and is the second closest of such starburst galaxies. The paper describing this result (“Super star clusters in Haro 11: Properties of a very young starburst and evidence for a near-infrared flux excess”, by A. Adamo et al.) is available at http://adsabs.harvard.edu/doi/10.1111/j.1365-2966.2010.16983.x

Name: ESO 350-38, Haro 11
Type: Local Universe : Galaxy : Activity : Starburst
Category: Galaxies
Constellation: Sculptor
Distance: 300 million light years
Release date: 9 August 2010, 10:00
Credit: ESA/Hubble/ESO and NASA

A snowstorm of distant galaxies: 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. This apparently placid scene also hides a storm of epic scale. This picture shows a region where three galaxy clusters are merging and releasing enormous amounts of energy in the form of X-rays. These distant objects are around 5.4 billion light-years from Earth, and were imaged during the Massive Cluster Survey, a project to study distant clusters of galaxies using Hubble. 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. Predicted by Einstein in his famous general theory of relativity, gravity’s ability to distort light was first demonstrated in 1919 in a well-known experiment carried out by Sir Arthur Eddington, who led an expedition to the island of Principe, off the coast of Africa, to measure the apparent shift of a star when observed close to the edge of the Sun’s disc during a solar eclipse. This picture was created from images taken through near-infrared (F814W) and yellow (F555W) filters using the Wide Field Channel of Hubble’s Advanced Camera for Surveys. The exposure times were about 67 minutes and 33 minutes respectively and the field of view of the image is about 3 arcminutes across.

Name: MACS J0717.5+3745
Type: Local Universe : Galaxy : Grouping : Cluster
Category: Galaxies
Constellation: Auriga
Distance: z=0.546 (redshift)
Release date: 16 August 2010, 10:00
Credit: ESA/Hubble, NASA and H. Ebeling.