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Monday, June 10, 2013

Supernova Remnant NGC 6960: Witch's Broom Nebula

Supernova Remnant NGC 6960: Witch's Broom Nebula
Click on the image for full resolution (1.5 MB)

Ten thousand years ago, before the dawn of recorded human history, a new light would have suddenly have appeared in the night sky and faded after a few weeks. Today we know this light was from a supernova, or exploding star, and record the expanding debris cloud as the Veil Nebula, a supernova remnant. This sharp telescopic view is centered on a western segment of the Veil Nebula cataloged as NGC 6960 but less formally known as the Witch's Broom Nebula. Blasted out in the cataclysmic explosion, the interstellar shock wave plows through space sweeping up and exciting interstellar material. Imaged with narrow band filters, the glowing filaments are like long ripples in a sheet seen almost edge on, remarkably well separated into atomic hydrogen (red) and oxygen (blue-green) gas. The complete supernova remnant lies about 1400 light-years away towards the constellation Cygnus. This Witch's Broom actually spans about 35 light-years. The bright star in the frame is 52 Cygni, visible with the unaided eye from a dark location but unrelated to the ancient supernova remnant.
The full resolution image weighs 1.5 MB, so please be (a little) patient when downloading!
Image Credit: Martin Pugh
Image enhancement: Jean-Baptiste Faure

Wednesday, May 29, 2013

The Large Magellanic Cloud

The Large Magellanic Cloud
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The 16th century Portuguese navigator Ferdinand Magellan and his crew had plenty of time to study the southern sky during the first circumnavigation of planet Earth. As a result, two fuzzy cloud-like objects easily visible to southern hemisphere skygazers are known as the Clouds of Magellan, now understood to be satellite galaxies of our much larger, spiral Milky Way galaxy. About 160,000 light-years distant in the constellation Dorado, the Large Magellanic Cloud (LMC) is seen here in a remarkably deep and colorful composite image. Spanning about 15,000 light-years or so, it is the most massive of the Milky Way's satellite galaxies and is the home of the closest supernova in modern times, SN 1987A. The prominent patch just left of center is 30 Doradus, also known as the magnificent Tarantula Nebula, is a giant star-forming region about 1,000 light-years across.
Image Credit: L. Comolli, L. Fontana, G. Ghioldi & E. Sordini

Monday, May 27, 2013

Open Cluster and Emission Nebula IC 2944

Open Cluster and Emission Nebula IC 2944
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This intriguing new view of a spectacular stellar nursery IC 2944 is being released to celebrate a milestone: fifteen years of ESO's Very Large Telescope. This image also shows a group of thick clouds of dust known as the Thackeray globules silhouetted against the pale pink glowing gas of the nebula. These globules are under fierce bombardment from the ultraviolet radiation from nearby hot young stars. They are both being eroded away and also fragmenting, rather like lumps of butter dropped onto a hot frying pan. It is likely that Thackeray's globules will be destroyed before they can collapse and form new stars. This new picture celebrates an important anniversary for the Very Large Telescope – it is fifteen years since the first light on the first of its four Unit Telescopes, on 25 May 1998. Since then the four original giant telescopes have been joined by the four small Auxiliary Telescopes that form part of the VLT Interferometer (VLTI). The VLT is one of the most powerful and productive ground-based astronomical facilities in existence. In 2012 more than 600 refereed scientific papers based on data from the VLT and VLTI were published. Interstellar clouds of dust and gas are the nurseries where new stars are born and grow. The new picture shows one of them, IC 2944, which appears as the softly glowing pink background. This image is the sharpest view of the object ever taken from the ground. The cloud lies about 6500 light-years away in the southern constellation of Centaurus (The Centaur). This part of the sky is home to many other similar nebulae that are scrutinised by astronomers to study the mechanisms of star formation. Emission nebulae like IC 2944 are composed mostly of hydrogen gas that glows in a distinctive shade of red, due to the intense radiation from the many brilliant newborn stars. Clearly revealed against this bright backdrop are mysterious dark clots of opaque dust, cold clouds known as Bok globules. They are named after the Dutch-American astronomer Bart Bok, who first drew attention to them in the 1940s as possible sites of star formation. This particular set is nicknamed the Thackeray Globules. Larger Bok globules in quieter locations often collapse to form new stars but the ones in this picture are under fierce bombardment from the ultraviolet radiation from nearby hot young stars. They are both being eroded away and also fragmenting, rather like lumps of butter dropped into a hot frying pan. It is likely that Thackeray's Globules will be destroyed before they can collapse and form stars. Bok globules are not easy to study. As they are opaque to visible light it is difficult for astronomers to observe their inner workings, and so other tools are needed to unveil their secrets — observations in the infrared or in the submillimetre parts of the spectrum, for example, where the dust clouds, only a few degrees over absolute zero, appear bright. Such studies of the Thackeray globules have confirmed that there is no current star formation within them. This region of sky has also been imaged in the past by the Hubble Space Telescope. This new view from the FORS instrument on ESO's Very Large Telescope at the Paranal Observatory in northern Chile covers a wider patch of sky than Hubble and shows a broader landscape of star formation.
The full resolution image weighs 3.7 MB, so please be patient when downloading!
Image Credit: ESO
Image enhancement: Jean-Baptiste Faure

Planetary Nebula M57, the Ring Nebula

Planetary Nebula M57, the Ring Nebula
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This new Hubble image shows the dramatic shape and color of the Ring Nebula, otherwise known as Messier 57 or M57 for short. From Earth's perspective, the nebula looks like a simple elliptical shape with a shaggy boundary. However, new observations combining existing ground-based data with new Hubble Space Telescope data show that the nebula is shaped like a distorted doughnut. This doughnut has a rugby-ball-shaped region of lower-density material slotted into in its central "gap", stretching towards and away from us. Formed by a star throwing off its outer layers as it runs out of fuel, the Ring Nebula is an archetypal planetary nebula. It is both relatively close to Earth and fairly bright, and so was first recorded in the late 18th century. As is common with astronomical objects, its precise distance is not known, but it is thought to lie just over 2000 light-years from Earth. From Earth's perspective, the nebula looks roughly elliptical. However, astronomers have combined ground-based data with new observations using the Hubble Space Telescope to observe the nebula again, hunting for clues about its structure, evolution, physical conditions and motion. It turns out that the nebula is shaped like a distorted doughnut. We are gazing almost directly down one of the poles of this structure, with a brightly coloured barrel of material stretching away from us. Although the centre of this doughnut may look empty, it is actually full of lower density material that stretches both towards and away from us, creating a shape similar to a rugby ball slotted into the doughnut's central gap. The brightest part of this nebula is what we see as the colourful main ring. This is composed of gas thrown off by a dying star at the centre of the nebula. This star is on its way to becoming a white dwarf - a very small, dense, and hot body that is the final evolutionary stage for a star like the Sun. The Ring Nebula is one of the most notable objects in our skies. It was discovered in 1779 by astronomer Antoine Darquier de Pellepoix, and also observed later that same month by Charles Messier, and added to the Messier Catalogue. Both astronomers stumbled upon the nebula when trying to follow the path of a comet through the constellation of Lyra, passing very close to the Ring Nebula.
The full resolution image weighs 3.1 MB, so please be patient when downloading!
Image Credit: NASA, ESA, and C. Robert O'Dell (Vanderbilt University)
Image enhancement: Jean-Baptiste Faure

Wednesday, May 15, 2013

Galaxy Cluster Abell S1077

Galaxy Cluster Abell S1077
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This Hubble image shows the galaxy cluster Abell S1077. Galaxy clusters are large groupings of galaxies, each of them including millions of stars. They are the largest existing structures in the Universe to be held together by their gravity. The amount of matter condensed in such groupings is so high that their gravity is enough to warp the fabric of spacetime, distorting the path that light takes when it travels through the cluster. In some cases, this phenomenon produces an effect somewhat like a magnifying lens, allowing us to see objects that are aligned behind the cluster and which would otherwise be undetectable from Earth. In this image, you see stretched stripes that look like scratches on a lens but are, in fact, galaxies whose light is heavily distorted by the gravitational field of the cluster. Astronomers use tools like the Hubble Space Telescope and the effects of gravitational lensing to peer far back in time and space to see the furthest objects located in the early Universe. One of the record holders is MACS0647-JD, a galaxy seen by Hubble and the Spitzer Space Telescope with the help of a gravitational lens much like this one in the galaxy cluster MACS J0647.7+7015. Its light has taken 13.3 billion years to reach us. This image is based in part on data spotted by Nick Rose in the Hubble's Hidden Treasures image processing competition.
The full resolution image weighs 3.1 MB, so please be patient when downloading!
Image Credit: ESA/Hubble and NASA
Acknowledgement: N. Rose
Image enhancement: Jean-Baptiste Faure

Sunday, May 5, 2013

Globular Cluster M13

Globular Cluster M13
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M13 (Messier 13) is a globular cluster containing roughly one million stars in the halo of the Milky Way. It lies in the constellation Hercules, 25,000 light years from the Sun. The SDSS obtains images in five filters, allowing these stunning multi-color images to be made. In particular, the range of colors of stars, from red giants to so-called blue straggler stars, is apparent in this image.
The full resolution image weighs 3.2 MB, so please be patient when downloading!
Image Credit: Robert Lupton, The Sloan Digital Sky Survey
Image enhancement: Jean-Baptiste Faure

Monday, April 29, 2013

Supernova Remnant SNR B0519-69.0

Supernova Remnant SNR B0519-69.0
Click on the image for full resolution (6.1 MB)

These delicate wisps of gas make up an object known as SNR B0519-69.0, or SNR 0519 for short. The thin, blood-red shells are actually the remnants from when an unstable progenitor star exploded violently as a supernova around 600 years ago. There are several types of supernova, but for SNR 0519 the star that exploded is known to have been a white dwarf star - a Sun-like star in the final stages of its life. SNR 0519 is located over 150 000 light-years from Earth in the southern constellation of Dorado (The Dolphinfish), a constellation that also contains most of our neighbouring galaxy the Large Magellanic Cloud (LMC). Because of this, this region of the sky is full of intriguing and beautiful deep sky objects. The LMC orbits the Milky Way galaxy as a satellite and is the fourth largest in our group of galaxies, the Local Group. SNR 0519 is not alone in the LMC; the Hubble Space Telescope also came across a similar bauble a few years ago in SNR B0509-67.5, a supernova of the same type as SNR 0519 with a strikingly similar appearance. A version of this image was submitted to the Hubble’s Hidden Treasures Image Processing Competition by Claude Cornen, and won sixth prize.
The full resolution image weighs 6.1 MB, so please be patient when downloading!
Image Credit: ESA/Hubble and NASA
Acknowledgement: Claude Cornen
Image enhancement: Jean-Baptiste Faure