Starship Asterisk*

Click to view full size image 1 or image 2

Image 1: A large, face-on spiral galaxy. The core is radiating very brightly. Streaks
of dust glow intensely red, in the centre and across most of the galaxy. This gas is
surrounded by a dark grey halo made of the galaxy’s stars. The halo stretches out
into a tidal tail at the upper-left, and another at the bottom. Small stars and
galaxies surround the spiral galaxy, on a black background.
Credit: ESA/Webb, NASA & CSA, L. Armus, A. Evans

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Image 2: A large, face-on spiral galaxy. The core is radiating very brightly in white
and bluish colours. Thin webs of dark gas cross the centre and most of the galaxy,
following the twist of the galaxy. This gas continues out into a tidal tail at the
upper-left, and another at the bottom. Small stars can be seen around the spiral
galaxy, on a black background. Credit: ESA/Hubble, NASA

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The peculiar galaxy NGC 3256 takes centre stage in these two images. This distorted galaxy is the wreckage of a head-on collision between two spiral galaxies which likely occurred 500 million years ago, and it is studded with clumps of young stars which were formed as gas and dust from the two galaxies collided. This Milky Way-sized galaxy lies about 120 million light-years away in the constellation Vela, and is a denizen of the Hydra-Centaurus Supercluster.

NGC 3256 may seem peaceful, a swirl of tightly entwined spiral arms set in a hazy cloud of light, but this image shows the aftermath of an ancient cosmic clash. This distorted galaxy is the wreckage of a head-on collision between two equally massive spiral galaxies which astronomers estimate to have met around 500 million years ago. The tumultuous past of NGC 3256 is captured in the long tendrils of shining dust and stars which extend outwards from the main body of the galaxy. These luminous tendrils are called tidal tails, and are studded with young stars which were formed as gas and dust from the two galaxies collided. The striking red wisps spread across the galaxy trace out lanes of dust. Excited by radiation from the galaxy's stars, small dust grains emit infrared light that is captured in astonishing detail by Webb's instruments. ...

[Image 1] contains data from the NASA/ESA/CSA James Webb Space Telescope, using both the Near-InfraRed Camera (NIRCam) and the Mid-InfraRed Instrument (MIRI). The collision that produced NGC 3256 spurred an enormous burst of star formation, and these new stars radiate enormously brightly in infrared wavelengths as seen here.

[Image 2] contains data from the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3). Here the visible light lays out in detail the dark threads of dust and molecular gas that spin around the centres of the two merged galaxies. Many of the young, infrared-emitting stars produced by the collision are obscured in visible wavelengths by this dark dust.

Image Credit: ESO

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Have you ever seen so many telescopes all together? This Picture of the Week was taken at sunset at ESO’s La Silla Observatory, suspended over an ocean of mountains and soft, foggy clouds. Nestled in the Chilean Atacama Desert at an altitude of 2400 metres, La Silla is far from sources of light pollution and has one of the darkest skies on Earth, which explains why it's packed full with telescopes!

How many can you spot here? Let’s take a closer look at a few of them. Almost at the centre of the frame, ESO’s 3.6-metre telescope stands out, with the smaller dome of the Coudé Auxiliary Telescope attached to it. The 3.6 m telescope is home to one of the world’s best extrasolar planet hunters, the so-called High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph. The antenna to the left side of the picture is the Swedish-ESO Submillimetre Telescope (SEST). In the crowded right hand side there’s a pill of history: the rightmost dome in the picture is the ESO 1-metre telescope, which was the first telescope installed at the La Silla Observatory in 1966.

As you can see, La Silla Observatory has a long history, and it has been an ESO stronghold for more than fifty years, helping astronomers to unveil the mysteries of the Universe with its many telescopes. Are you up to the challenge of identifying all of them? This map may help!

A spiral galaxy, a fuzzy oval tilted diagonally and partially towards the viewer. The centre glows in warm colours, and has two prominent spiral arms around it, with bright points of star formation. The galaxy is central in a field of small stars and galaxies on a dark background. Credit: ESA/Hubble & NASA, A. Filippenko, J. D. Lyman

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The spiral galaxy UGC 11860 seems to float serenely against a field of background galaxies in this image from the NASA/ESA Hubble Space Telescope. UGC 11860 lies around 184 million light-years away in the constellation Pegasus, and its untroubled appearance can be deceiving; this galaxy recently played host to an almost unimaginably energetic stellar explosion.

A supernova explosion — the catastrophically violent end of a massive star’s life — was detected in UGC 11860 in 2014 (ASASSN-14dq) by a robotic telescope dedicated to scouring the skies for transient astronomical phenomena; astronomical objects which are only visible for a short period of time. Two different teams of astronomers used Hubble’s Wide Field Camera 3 (WFC3) to search through the aftermath and unpick the lingering remnants of this vast cosmic explosion.

One team explored UGC 11860 to understand more about the progenitor star systems that eventually meet their demise in supernovae. The unimaginably energetic environment during supernova explosions is predominantly responsible for forging the elements between silicon and nickel on the periodic table. This means that understanding the influence of progenitor star systems’ masses and compositions is vital to explaining how many of the chemical elements here on Earth originated.

The other group of astronomers used Hubble to follow up supernovae that were detected by robotic telescopes. These automated eyes on the sky function without the intervention of humans, and capture transient events in the night sky. Robotic telescopes allow astronomers to detect everything from unexpected asteroids to rare, unpredictable supernovae, and can identify intriguing objects that can then be investigated in more detail by powerful telescopes such as Hubble.

Credit: Gemini Observatory/Travis Rector, Univ of Alaska Anchorage

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NGC 6946, the “Fireworks Galaxy,” lies between 10 and 20 million light-years away on the border between the constellations of Cepheus and Cygnus, and was discovered by Sir William Herschel (1738-1822) on September 9, 1798. It continues to fascinate astronomers, who estimate that it contains about half as many stars as the Milky Way. They often use it to study and characterize the evolution of massive stars and the properties of interstellar gas. As viewed in the new Gemini optical image, we see only the “tip of the iceberg” of this galaxy. Its optical angular diameter is about 13 arcminutes, but viewed at radio wavelength at the frequency of neutral hydrogen (1420 Mhz or 21-cm line), it extends considerably more than the angular diameter of the Moon. This Gemini North Gemini Multi-Object Spectrograph (GMOS) image of NGC 6946 utilizes a selective filter specifically designed to detect the radiation emanating from the starbirth regions. Additional filters help to distinguish other details in the galaxy, including clusters of massive blue stars, dust lanes, and a yellowish core where older more evolved stars dominate.

Image Credit: CTIO/NOIRLab/NSF/AURA/T. Matsopoulos

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The Víctor M. Blanco 4-meter Telescope has pristine access to wide open skies of the Chilean Andes from its perch at Cerro Tololo Inter-American Observatory (CTIO), a Program of NSF’s NOIRLab. To the upper left of the telescope is the ‘evening star’, actually the planet Venus. Below on the left are the SMARTS 1.5-meter Telescope and SMARTS 0.9-meter Telescope (furthest back).

Housed within the silver dome of the Blanco Telescope is the Dark Energy Camera (DECam), mounted at the prime (first) focus near the top of the white Serrurier truss. The blue U-shaped structure holding the truss is the large bearing that sweeps the telescope around to a designated position for observing. DECam saw first light on 12 September 2012 and in its more than 10 years of operation it has contributed greatly to the field of astronomy. It was designed specifically for the Dark Energy Survey, operated by the Department of Energy and the National Science Foundation between 2013 and 2019. During this time, DECam cataloged nearly 1 billion objects, helping to construct the largest ever map of the night sky. ...

Image Credit: ESO

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This Picture of the Week shows a beautiful flock of sheep, grazing in the Chilean Andes. No, wait, wait, wait. There's no grass to feed on here, and they are at an altitude of around 5000 metres. Ok, no, they are not sheep. Let’s start again. This Picture of the Week shows the beautiful antennas of the Atacama Large Millimeter/submillimeter Array (ALMA), operated by ESO and its international partners in the Chilean Andes. Ok, that’s better!

As you can see, ALMA’s 66 white antennas are not the same size: most of them are 12-metre antennas, and only twelve are 7-metre antennas (see the smaller ones over to the left of the ‘flock’?). They work together as an interferometer, acting like a single big telescope. ALMA observes the light emitted from some of the coldest objects in the Universe, such as the most distant galaxies.

These antennas can be physically moved and arranged in different configurations, allowing ALMA to view the Universe with different levels of detail. The telescope can in fact probe both the broad structure of an astronomical source and its very finest details. The former requires the antennas to be close to each other, like in this image, whereas for the latter they need to be several kilometres apart. Each antenna is almost 15 metres high and weighs over 100 tons, so moving them across the desert and positioning them on concrete docking pads with millimetre precision is anything but simple — much trickier than herding sheep. To this end, two enormous transporters provided by ESO are used: yellow, 20 metres long and with 28 tyres each, they have been named Otto and Lore.

A cluster of elliptical galaxies, visible as a dense crowd of oval shapes, each glowing orange around a bright core. Right of the largest, central galaxy, a background galaxy is stretched into two connected, thin arcs by the cluster’s gravity. Various other galaxies are dotted all around, a few being small spirals. A bright star with four long spikes stands out at the right. Image Credit: ESA/Hubble & NASA, H. Ebeling

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The NASA/ESA Hubble Space Telescope has captured a monster in the making in this observation of the exceptional galaxy cluster eMACS J1353.7+4329, which lies about eight billion light-years from Earth in the constellation Canes Venatici. This disturbed collection of at least two galaxy clusters is in the process of merging together to create a cosmic monster, a single gargantuan cluster acting as a gravitational lens.

Gravitational lensing is a dramatic example of Einstein’s general theory of relativity in action. A celestial body such as a galaxy cluster is sufficiently massive to distort spacetime, which causes the path of light around the object to be visibly bent as if by a vast lens. Gravitational lensing can also magnify distant objects, allowing astronomers to observe objects that would otherwise be too faint and too far away to be detected. It can also distort the images of background galaxies, turning them into streaks of light. The first hints of gravitational lensing are already visible in this image as bright arcs which mingle with the throng of galaxies in eMACS J1353.7+4329.

The data in this image are drawn from an observing proposal called Monsters in the Making, which used two of Hubble’s instruments to observe five exceptional galaxy clusters at multiple wavelengths. These multi-wavelength observations were made possible by Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys. The astronomers behind these observations hope to lay the groundwork for future studies of vast gravitational lenses with next-generation telescopes such as the NASA/ESA/CSA James Webb Space Telescope.