Stellar flare hits HD 189733b (artist's impression): This artist’s impression shows exoplanet HD 189733b, as it passes in front of its parent star, called HD 189733A. Hubble’s instruments observed the system in 2010, and in 2011 following a large flare from the star (depicted in the image). Following the flare, Hubble observed the planet’s atmosphere evaporating at a rate of over 1000 tonnes per second.In this picture, the surface of the star, which is around 80% the mass of the Sun, is based on observations of the Sun from the Solar Dynamics Observatory.

Name: HD 189733A, HD 189733b
Type: Milky Way : Star : Circumstellar Material : Planetary System
Category: ExoplanetsIllustrations
Distance: 65 light years
Release date: 28 June 2012, 15:00
Credit: NASA, ESA, L. Calçada

Hubble image of Herbig-Haro object HH 110: The NASA/ESA Hubble Space Telescope has captured a new image of Herbig-Haro 110, a geyser of hot gas flowing from a newborn star. HH 110 appears different from most other Herbig-Haro objects: in particular, it appears on its own while they usually come in pairs. Astronomers think it may be a continuation of another object called HH 270, after it has been deflected off a dense cloud of gas.

Name: HH 110
Type: Milky Way : Star : Evolutionary Stage : Young Stellar ObjectMilky Way : Star : Circumstellar Material : Outflow
Category: Stars
Constellation: Orion
Distance: 1500 light years
Release date: 3 July 2012, 15:00
Credit: NASA, ESA and the Hubble Heritage team (STScI/AURA)

Hubble probes ‘ghost’ galaxy: Astronomers used the NASA/ESA Hubble Space Telescope to unmask the dim, star-starved dwarf galaxy Leo IV. This Hubble image demonstrates why astronomers had a tough time spotting this small-fry galaxy: it is practically invisible. The image shows how the handful of stars from the sparse galaxy are virtually indistinguishable from the background. Residing 500 000 light-years from Earth, Leo IV is one of more than a dozen ultra-faint dwarf galaxies found lurking around our Milky Way galaxy. These galaxies are dominated by dark matter, an invisible substance that makes up the bulk of the Universe’s mass.

Name: Leo IV dwarf galaxy
Type: Local Universe : Galaxy : Size : Dwarf
Category: Galaxies
Constellation: Leo
Distance: 500000 light years
Release date: 10 July 2012, 19:00
Credit: NASA, ESA, and T. Brown (STScI)

Hubble probes ‘ghost’ galaxy: Astronomers used the NASA/ESA Hubble Space Telescope to unmask the dim, star-starved dwarf galaxy Leo IV. These Hubble images demonstrate why astronomers had a tough time spotting this small-fry galaxy. The image at left shows part of the galaxy, outlined by the white rectangular box. The box measures 83 light-years wide by 163 light-years long. The few stars in Leo IV are lost amid neighboring stars and distant galaxies. A close-up view of the background galaxies within the box is shown in the middle image. The image at right shows only the stars in Leo IV. The galaxy, which contains several thousand stars, is composed of Sun-like stars, fainter, red dwarf stars, and some red giant stars brighter than the Sun. Astronomers discovered Leo IV in Sloan Digital Sky Survey images by spotting a region where a clump of stars was huddled closer together than stars in areas around it. Residing 500 000 light-years from Earth, Leo IV is one of more than a dozen ultra-faint dwarf galaxies found lurking around our Milky Way galaxy. These galaxies are dominated by dark matter, an invisible substance that makes up the bulk of the Universe’s mass.

Name: Leo IV dwarf galaxy
Type: Local Universe : Galaxy : Size : Dwarf
Category: Galaxies
Distance: 500000 light years
Release date: 10 July 2012, 19:00
Credit: NASA, ESA, and T. Brown (STScI)

Veil lifted on ‘ghost’ galaxy: These images reveal the small and faint star-starved dwarf galaxy, Leo IV, a close neighbour of our Milky Way galaxy. Leo IV is one of more than a dozen ultra-faint dwarf galaxies found lurking around the Milky Way. These galaxies are dominated by dark matter, an invisible substance that makes up the bulk of the universe’s mass. The wide image, taken by the Sloan Digital Sky Survey, is a view of Leo IV and the surrounding neighbourhood. The galaxy resides 500 000 light-years from Earth. The dotted line marks the galaxy’s boundaries, measuring about 1100 light-years wide. The small white box outlines the Hubble Space Telescope’s view. Leo IV has so few stars, roughly several thousand, that astronomers had difficulty identifying it as a galaxy. Astronomers discovered Leo IV in Sloan Digital Sky Survey images by spotting a region where a clump of stars was huddled closer together than stars in areas around it. The dwarf galaxy is composed of Sun-like stars, fainter, red dwarf stars, and some red giant stars brighter than the Sun. Hubble’s close-up view is shown in the inset at right, measuring 483 light-years wide. Astronomers used Hubble to measure the ages of the stars in Leo IV and two other ultra-faint dwarf galaxies. The measurements revealed that the stars in all three galaxies are more than 13 billion years old, almost as old as the 13.7-billion-year-old universe. Because the stars in these galaxies are so ancient and share the same age, astronomers suggest that a global event, such as reionisation, shut down star formation in them. Reionisation is a transitional phase in the early universe when the first stars burned off a fog of cold hydrogen. The Hubble image is a composite of exposures taken in January 2012 by the Advanced Camera for Surveys.

Name: Leo IV dwarf galaxy
Type: Local Universe : Galaxy : Size : Dwarf
Category: Galaxies
Distance: 500000 light years
Release date: 10 July 2012, 19:00
Credit: NASA, ESA, and T. Brown (STScI)

A swarm of dark matter around the Milky Way: These illustrations, taken from computer simulations, show a swarm of dark matter clumps around our Milky Way galaxy. Some of the dark-matter concentrations are massive enough to spark star formation. Dark matter is an invisible substance that accounts for most of the universe’s mass. In the first panel, thousands of clumps of dark matter coexist with our Milky Way galaxy, shown in the center. The green blobs in the second panel are those dark-matter chunks massive enough to obtain gas from the intergalactic medium and trigger ongoing star formation, eventually creating dwarf galaxies. In the third panel, the red blobs are ultra-faint dwarf galaxies that stopped forming stars long ago. New Hubble Space Telescope observations of three of the puny galaxies reveal that star-making in these faint galaxies shut down more than 13 billion years ago. The synchronised shutdown is evidence that a global event, such as reionisation, swept through the early universe. Reionisation is a transitional phase in the early universe when the first stars burned off a fog of cold hydrogen. Popular theory predicts that most of the Milky Way’s satellites contain few, if any, stars and are instead dominated by dark matter. More than a dozen small-fry galaxies have been found so far, all by the Sloan Digital Sky Survey, which scanned just a quarter of the sky.

Type: Milky Way : Galaxy : Component : HaloLocal Universe : Galaxy : Size : DwarfMilky Way
Category: Galaxies
Distance: 500000 light years
Release date: 10 July 2012, 19:00
Credit: J. Tumlinson (STScI)