Starship Asterisk*

The smokey black silhouette in this new image is part of a large, sparse cloud of partially ionised hydrogen — an HII region — known as Gum 15. In wide-field images this nebula appears as a striking reddish purple clump dotted with stars and slashed by opaque, weaving dust lanes. This image homes in on one of these dust lanes, showing the central region of the nebula.

These dark chunks of sky have seemingly few stars because lanes of dusty material are obscuring the bright, glowing regions of gas beyond. The occasional stars that do show up in these patches are actually between us and Gum 15, but create the illusion that we are peering through a window out onto the more distant sky.

Gum 15 is shaped by the aggressive winds flowing from the stars within and around it. The cloud is located near to several large associations of stars including the star cluster ESO 313-13. The brightest member of this cluster, named HD 74804, is thought to have ionised Gum 15’s hydrogen cloud. This ionised hydrogen content is the cause of the red hue permeating the frame. ...

This new image from Hubble’s Wide Field Planetary Camera 2 showcases NGC 1501, a complex planetary nebula located in the large but faint constellation of Camelopardalis (The Giraffe).

Discovered by William Herschel in 1787, NGC 1501 is a planetary nebula that is just under 5000 light-years away from us. Astronomers have modelled the three-dimensional structure of the nebula, finding it to be a cloud shaped as an irregular ellipsoid filled with bumpy and bubbly regions. It has a bright central star that can be seen easily in this image, shining brightly from within the nebula’s cloud. This bright pearl embedded within its glowing shell inspired the nebula’s popular nickname: the Oyster Nebula.

While NGC 1501's central star blasted off its outer shell long ago, it still remains very hot and luminous, although it is quite tricky for observers to spot through modest telescopes. This star has actually been the subject of many studies by astronomers due to one very unusual feature: it seems to be pulsating, varying quite significantly in brightness over a typical timescale of just half an hour. While variable stars are not unusual, it is uncommon to find one at the heart of a planetary nebula.

It is important to note that the colours in this image are arbitrary.

A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Marc Canale.

[b][i]Credit: ESA/Hubble & NASA Acknowledgement: Nick Rose[/i][/b]

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This new image from the NASA/ESA Hubble Space Telescope shows the super-rich galaxy cluster Abell 1413. Located between the constellations of Leo (The Lion) and Coma Berenices, the cluster is over 2 billion light-years from Earth. This image is dominated by a large and highly elliptical galaxy called MCG+04-28-097, with a halo of stars extending for more than 6.5 million light-years.

Abell 1413 is part of the Abell catalogue, a collection of over 4000 rich clusters of galaxies fairly close to Earth — at least from a cosmological perspective — their light took less than 3 billion years to reach us. The clusters are called rich due to the huge number of galaxies they play host to. Abell 1413 is observed to contain more than 300 galaxies held together by the immense gravity of the cluster.

The strong interactions between these galaxies cause the material in the cluster to be heated to extremely high temperatures of almost 100 million degrees. Because of this, the cluster emits very strong X-ray radiation.

Visible distortions in the image can be seen in the form of arcs, caused by gravitational lensing. ...

[b][i]Credit: ESA/Hubble, NASA[/i][/b]

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This new Hubble image is a snapshot of NGC 986 — a barred spiral galaxy discovered in 1828 by James Dunlop. This close-up view of the galaxy was captured by Hubble’s Wide Field and Planetary Camera 2 (WFPC2).

NGC 986 is found in the constellation of Fornax (The Furnace), located in the southern sky. NGC 986 is a bright, 11th-magnitude galaxy sitting around 56 million light-years away, and its golden centre and barred swirling arms are clearly visible in this image.

Barred spiral galaxies are spiral galaxies with a central bar-shaped structure composed of stars. NGC 986 has the characteristic S-shaped structure of this type of galactic morphology. Young blue stars can be seen dotted amongst the galaxy’s arms and the core of the galaxy is also aglow with star formation.

To the top right of this image the stars appear a little fuzzy. This is because a gap in the Hubble data was filled in with data from ground-based telescopes. Although the view we see in this filled in patch is accurate, the resolution of the stars is no match for Hubble’s clear depiction of the spiral galaxy.

[b][i]Credit: ESO/G. Lombardi[/i][/b]

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Have you ever wondered what the inside of ESO's Very Large Telescope looks like? Well, wonder no more, as this picture of the week shows the internal structure of one of the VLT's Unit Telescopes (UTs) — specifically UT3, otherwise known as Melipal.

Seen here, lit by moonlight, is the main steel structure of the Unit Telescope's optical assembly. The main mirror, measuring 8.2 metres in diameter and weighing in at more than 23 tonnes, requires a sturdy frame to allow it to rotate within the structure, while maintaining high optical resolution. This movable steel frame itself weighs over 430 tonnes, about the same as a fully loaded jumbo jet!

The structure, optics and electronics are housed within a further steel enclosure, which provides protection from the harsh Atacama environment.

Melipal is named after the Mapuche term for the constellation of the Southern Cross (Crux). All four of the VLT's Unit Telescopes have Mapuche names relating to well-known and prominent astronomical features: Antu, Kueyen, Melipal, and Yepun, or the Sun, Moon, Southern Cross, and Venus respectively. The Mapuche people are indigenous to the Southern Central region of Chile, and have a long history of astronomy.

This picture was taken by ESO Photo Ambassador Gianluca Lombardi, who, when not taking photographs of the Chilean landscape, spends his days as an ESO astronomer working at La Silla and Paranal.