Starship Asterisk*

Image Credit: ESA/Hubble & NASA, K. Noll

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The interaction of two doomed stars has created this spectacular ring adorned with bright clumps of gas — a diamond necklace of cosmic proportions. Fittingly known as the Necklace Nebula, this planetary nebula is located 15 000 light-years away from Earth in the small, dim constellation of Sagitta (The Arrow).

The Necklace Nebula — which also goes by the less glamorous name of PN G054.2-03.4 — was produced by a pair of tightly orbiting Sun-like stars. Roughly 10 000 years ago, one of the aging stars expanded and engulfed its smaller companion, creating something astronomers call a “common envelope”. The smaller star continued to orbit inside its larger companion, increasing the bloated giant’s rotation rate until large parts of it spun outwards into space. This escaping ring of debris formed the Necklace Nebula, with particularly dense clumps of gas forming the bright “diamonds” around the ring.

The pair of stars which created the Necklace Nebula remain so close together — separated by only a few million kilometres — that they appear as a single bright dot in the centre of this image. Despite their close encounter the stars are still furiously whirling around each other, completing an orbit in just over a day.

The Necklace Nebula was featured in a previously released Hubble image, but now this new image has been created by applying advanced processing techniques, making for a new and improved view of this intriguing object. The composite image includes several exposures from Hubble’s Wide Field Camera 3.

Image Credit: ESO/Dusán Tubín et al.

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Do you ever get the feeling that you're being watched? This friendly-looking object is the result of two galaxies merging into one another, complete with a pair of eyes hiding two growing supermassive black holes and a swirling grin. Such mergers are rare in our galactic neighbourhood; Mrk 739 is close enough (astronomically speaking) to study the event in detail, and thus gain a better understanding of the dramatic processes that take place during these cosmic mergers.

By using the MUSE instrument on ESO’s Very Large Telescope, the team of astronomers, led by master’s student Dusán Tubín at the Pontificia Universidad Católica de Chile, were able to study the effects of both the merger and the radiation emitted by the growing gigantic black holes. Their study answers questions about the motion of the galaxies, the age of their stars, and the elements they are made up of. They have found that one of these galaxies is much older than its companion, and that their merging process is at an early stage.

MUSE is a 3D spectrograph that takes images — known as “datacubes” — of the object being observed over thousands of wavelengths. With MUSE, astronomers are therefore able to map in great detail the properties of the objects they study, because each individual pixel contains an impressive amount of information. Obtaining these exciting insights into galaxy merging and evolution with MUSE is enough to make anyone smile.

• Astrophysical Journal 911(2):100 (2021 Apr 23) DOI: 10.3847/1538-4357/abedba
• arXiv.org > astro-ph > arXiv:2103.12180 > 22 Apr 2021

Image Credit: ESA/Hubble & NASA, J. Maund

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This image shows a close-up portrait of the magnificent spiral galaxy NGC 4603, which lies over 100 million light-years away in the constellation of Centaurus (The Centaur). Bright bands of blue young stars make up the arms of this galaxy, which wind lazily outwards from the luminous core. The intricate red-brown filaments threading through the spiral arms are known as dust lanes, and consist of dense clouds of dust which obscure the diffuse starlight from the galaxy.

This galaxy is a familiar subject for Hubble. In the last years of the twentieth century, NGC 4063 was keenly and closely watched for signs of a peculiar class of stars known as Cepheid variables. These stars have a luminosity closely tied to the period with which they darken and brighten, allowing astronomers to accurately measure how far they are from Earth. Distance measurements from Cepheid variables are key to measuring the furthest distances in the Universe, and were one of the factors used by Georges Lemaître and Edwin Hubble to show that the Universe is expanding.

Image Credit: ESO/Petr Horálek

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This panoramic selfie was taken on 9 April 2016 by ESO Photo Ambassador Petr Horálek. Petr was in the Chilean Atacama Desert as a member of ESO’s Fulldome Expedition team, a select group of photographers who captured an array of stunning, ultra-high-definition visuals for use primarily in the ESO Supernova Planetarium & Visitor Centre.

The landscape looms large around photographer Petr in this image, making him appear small beneath the striking Chilean sky. He can be seen standing just beneath a column of zodiacal light — perfect positioning that makes this image appear even more otherworldly.

The wide, round-topped objects visible here are some of the 12-metre antennas comprising the Atacama Large Millimeter/submillimeter Array (ALMA). ALMA is the largest ground-based astronomical observatory in the world, and is located on the Chajnantor Plateau in Chile at an altitude of 5000 metres. A total of 66 antennas make up the array, and can be connected together in different configurations to act as a single telescope, known as an interferometer. This arrangement enables ALMA to be the most powerful explorer of the Universe in millimetre and submillimetre light, the kind of light that is produced by cool, distant, ancient phenomena throughout the cosmos, allowing us to explore the birth of stars, the formation of exoplanets, and distant galaxies.

Image Credit: ESA/Hubble & NASA, D. Coe

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This extraordinary image from the NASA/ESA Hubble Space Telescope of the galaxy cluster Abell 2813 (also known as ACO 2813) has an almost delicate beauty, which also illustrates the remarkable physics at work within it. The image spectacularly demonstrates the concept of gravitational lensing.

In amongst the tiny dots, spirals and ovals that are the galaxies that belong to the cluster, there are several distinct crescent shapes. These curved arcs of light are strong examples of a phenomenon known as gravitational lensing. The image was compiled using observations taken with the Hubble Space Telescope’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3).

Gravitational lensing occurs when an object’s mass causes light to bend. The curved crescents and s-shapes of light in this image are not curved galaxies, but are light from galaxies that actually lie beyond Abell 2813. The galaxy cluster has so much mass that it acts as a gravitational lens, causing light from more distant galaxies to bend around it. These distortions can appear as many different shapes, such as long lines or arcs.

This very visual evidence that mass causes light to bend has been famously used as a proof of one of the most famous scientific theories: Einstein’s theory of general relativity.

Image Credit: ESO/Petr Horálek

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Great care is taken to ensure that the site for a new telescope will provide the best possible observing conditions.

This picture of the week was captured in 2019 by ESO photo ambassador Petr Horálek from the top of Cerro Armazones, Chile, where the Extremely Large Telescope (ELT) is being constructed. Situated in the heart of the Atacama desert, at an altitude of 3046 metres, this high and dry location will be vital to showcase and utilise the ELT’s incredible observational power.

This extraordinary panorama of the Atacama desert frames a sprawling view of our own Milky Way galaxy, seen with stunning clarity as a result of the minimum light pollution in this remote area. Massive interstellar dust clouds obscure the more distant starlight, leading to the distinctive “mottled” band in the night sky.