Engulfed by stars near the Milky Way’s heart: The NASA/ESA Hubble Space Telescope has imaged an area so jam-packed with stars that they almost overwhelm the inky blackness of space. This includes the globular star cluster Djorgovski 1, which was only discovered in 1987 Djorgovski 1 is located close to the centre of our Milky Way Galaxy, within the bulge. If the galaxy is thought of as being like a city, then this bulge is the very busiest district at its centre. Djorgovski 1's proximity to this hub — within just a few degrees — explains why the picture is teeming with stars. Globular clusters like Djorgovski 1 formed early in the Milky Way's history, and as such may hold clues about the inner galaxy’s early evolution. However, with so much material in the way, obtaining accurate data is problematic. To make matters worse, these stars are faint. Even the most luminous stars in Djorgovski 1 are fainter than the brightest giant stars in the bulge. Another quandary is apparent: how do you know which stars belong to Djorgovski 1, and which are from the bulge? To determine this, astronomers have studied the chemical composition of numerous stars in the area. Stars with a similar composition likely belong in the same group, like siblings in a family. This technique has successfully provided the information to distinguish between stars in Djorgovski 1 and the surrounding bulge. These studies also reveal that Djorgovski 1’s stars contain hydrogen and helium, but not much else. In astronomical terms, they are described as “metal-poor”. In fact, it appears that Djorgovski 1 is one of the most metal-poor clusters in the inner galaxy. It is not clear why this is the case, but additional research may shed light on the issue. This picture was created from multiple images taken with the Wide Field Camera of Hubble’s Advanced Camera for Surveys. Exposures through a yellow/orange filter (F606W) are coloured blue and images through a near-infrared filter (F814W) are shown as red. The total exposure times per filter are 340 s and 360 s, respectively, and the field of view is 2.7 by 1.5 arcminutes in extent.

Name: Djorgovski 1
Type: Milky Way : Star : Grouping : Cluster : Globular
Category: Star Clusters
Constellation: Scorpius
Distance: 40000 light years
Release date: 27 June 2011, 10:00
Credit: ESA/Hubble & NASA

Return to the Carina Nebula: Looking like an elegant abstract art piece painted by talented hands, this picture is actually a NASA/ESA Hubble Space Telescope image of a small section of the Carina Nebula. Part of this huge nebula was documented in the well-known Mystic Mountain picture (heic1007a) and this picture takes an even closer look at another piece of this bizarre astronomical landscape (heic0707a). The Carina Nebula itself is a star-forming region about 7500 light-years from Earth in the southern constellation of Carina (The Keel: part of Jason’s ship the Argo). Infant stars blaze with a ferocity so severe that the radiation emitted carves away at the surrounding gas, sculpting it into strange structures. The dust clumps towards the upper right of the image, looking like ink dropped into milk, were formed in this way. It has been suggested that they are cocoons for newly forming stars. The Carina Nebula is mostly made from hydrogen, but there are other elements present, such as oxygen and sulphur. This provides evidence that the nebula is at least partly formed from the remnants of earlier generations of stars where most elements heavier than helium were synthesised. The brightest stars in the image are not actually part of the Carina Nebula. They are much closer to us, essentially being the foreground to the Carina Nebula’s background. This picture was created from images taken with Hubble’s Wide Field Planetary Camera 2. Images through a blue filter (F450W) were coloured blue and images through a yellow/orange filter (F606W) were coloured red. The field of view is 2.4 by 1.3 arcminutes.

Name: Carina Nebula
Type: Milky Way : Nebula
Category: Nebulae
Constellation: Carina
Distance: 7500 light years
Release date: 4 July 2011, 10:00
Credit: ESA/Hubble & NASA

Rare cosmic footprint: The NASA/ESA Hubble Space Telescope has been used to capture a striking image of a rare astronomical phenomenon called a protoplanetary nebula. This particular example, called Minkowski’s Footprint, also known as Minkowski 92, features two vast onion-shaped structures either side of an ageing star, giving it a very distinctive shape. Protoplanetary nebulae like Minkowski’s Footprint have short lives, being a preliminary stage to the more common planetary nebula phase. In the middle of the image is a star, soon to be a white dwarf, puffing out material due to intense surface pulsations. Charged particle streams, called stellar winds, are shaping this gas into the interesting shapes that Hubble allows us to see. Technically speaking Minkowski’s Footprint is currently a reflection nebula as it is only visible due to the light reflected from the central star. In a few thousand years the star will get hotter and its ultraviolet radiation will light up the surrounding gas from within, causing it to glow. At this point it will have become a fully fledged planetary nebula. The processes behind protoplanetary nebulae are not completely understood, making observations such as this even more important. Hubble has already conducted sterling work in this field, and is set to continue. The image was obtained with the Hubble's Wide Field Planetary Camera 2. The picture has been made from many exposures through four different colour filters. Light from ionised oxygen has been coloured blue (F502N), light passing through a green/yellow filter (F547M) is coloured cyan, light from atomic oxygen is coloured yellow (F631N) and light from ionised sulphur is coloured red (F673N). The total exposure times per filter were 2080 s, 960 s, 2080 s and 1980 s respectively and the field of view is only about 36 arcseconds across.

Name: IRAS 19343+2926, Minkowski’s Footprint
Type: Milky Way : Nebula : Type : Planetary
Category: Nebulae
Constellation: Cygnus
Distance: 8000 light years
Release date: 11 July 2011, 10:00
Credit: ESA/Hubble & NASA