Starship Asterisk*

Image Credit: Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA; Processing: Travis Rector (Univ of Alaska Anchorage/NOIRLab), Jen Miller (Gemini Observatory/NOIRLab), Mahdi Zamani & Davide de Martin (NOIRLab)

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The constellation Coma Berenices hosts the galaxy NGC 4495 among myriad other astronomical objects. This galaxy has a tumultuous history: several supernovae have been recorded over the years, including the three named 1994S, 2010lo, and 2011ca. This last burst of energy from a dying star can be triggered by a number of different processes. 1994S, for example, was triggered by interactions between a white dwarf and another star, which reignited the core of the stellar remnant — a Type Ia supernova. 2011ca on the other hand is a Type Ic supernova, triggered by the core collapse of a single massive star.

This image was captured by the DOE-built Dark Energy Camera (DECam) on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO) as part of the DESI Legacy Imaging Surveys. The DESI Legacy Imaging Surveys were conducted to identify targets for the Dark Energy Spectroscopic Instrument (DESI) operations. These surveys comprise a unique blend of three projects that have observed a third of the night sky. DESI is an international science collaboration managed by the US Department of Energy's (DOE) Lawrence Berkeley National Laboratory with primary funding for construction and operations from DOE’s Office of Science.

Image Credit: Zdeněk Bardon/ESO

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With advanced instruments designed to catch the light from extrasolar worlds and the universe’s most distant stars and galaxies, crystal clear images are a must. To achieve this, the Unit Telescope 4 Yepun of ESO’s Very Large Telescope (VLT) in Chile has an adaptive optics facility equipped with four sodium lasers, aimed towards the sky. When the laser beams reach about 90 kilometers into the atmosphere, they excite sodium atoms that start to glow, creating artificial stars in the sky.

By monitoring how these artificial stars twinkle, the deformable secondary mirror of the telescope reshapes at milli-second speeds, correcting atmospheric turbulence. But the Milky Way already has several billions of stars, so why would we need some more and how will that help to create clearer images, you might wonder? Adaptive optics requires having a relatively bright reference star close in the sky to the object you want to observe, but that’s not always the case, hence the need for artificial laser stars.

PS. Did you know that sodium is the element usually found in older street lamps? It is the two resonance lines of sodium that creates the recognisable intense orange colour as seen in the above image from the VLT.

ESA/Hubble & NASA, B. Reipurth, B. Nisini

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Two wispy, gaseous clouds occupy the corners of this image, HH 1 in the upper right,
and HH 2 in the lower left. Both are light blue and surrounded by dimmer multi-
coloured clouds, while the background is dark black due to dense gas. A very bright
orange star lies just to the lower left of HH 1, and beyond that star is a narrow jet,
emerging from the dark centre of the field.

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The lives of newborn stars are tempestuous, as this image of the Herbig–Haro objects HH 1 and HH 2 from the NASA/ESA Hubble Space Telescope depicts. Both objects are in the constellation Orion and lie around 1250 light-years from Earth. HH 1 is the luminous cloud above the bright star in the upper right of this image, and HH 2 is the cloud in the bottom left. While both Herbig–Haro objects are visible, the young star system responsible for their creation is lurking out of sight, swaddled in the thick clouds of dust at the centre of this image. However, an outflow of gas from one of these stars can be seen streaming out from the central dark cloud as a bright jet. Meanwhile, the bright star between that jet and the HH 1 cloud was once thought to be the source of these jets, but it is now known to be an unrelated double star that formed nearby.

Herbig–Haro objects are glowing clumps found around some newborn stars, and are created when jets of gas thrown outwards from these young stars collide with surrounding gas and dust at incredibly high speeds. In 2002 Hubble observations revealed that parts of HH 1 are moving at more than 400 kilometres per second!

This scene from a turbulent stellar nursery was captured with Hubble’s Wide Field Camera 3 (WFC3) using 11 different filters at infrared, visible, and ultraviolet wavelengths. Each of these filters is sensitive to just a small slice of the electromagnetic spectrum, and they allow astronomers to pinpoint interesting processes that emit light at specific wavelengths. ...

Image Credit: ESO/PHANGS

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In this picture of the week we can see the well-defined arms of the spiral galaxy NGC 4254, also known as the Coma Pinwheel or Messier 99. It’s called a grand design spiral galaxy because of its distinctive pinwheel shape with prominent arms. Since Charles Messier first observed it in the 18th century, modern technology has allowed us to observe galaxies like this in significantly greater detail.

This image is a composite of data taken with ESO’s Very Large Telescope (VLT) and the Atacama Large Millimeter/submillimeter Array (ALMA), co-owned by ESO. The VLT data, shown in blue and purple tones, was captured with the Multi-Unit Spectroscopic Explorer (MUSE) instrument, mapping the distribution of stars. The ALMA data –– shown here by the red and orange regions –– originates from cold clouds of gas which can eventually collapse into stars. Comparing these two datasets allows for a better understanding of how stars form.

This image was taken as part of the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) survey, which produces high-resolution images of nearby galaxies across all wavelengths of light. This will allow astronomers to learn more about the diverse range of galactic environments found in our Universe.

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

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This peculiar portrait from the NASA/ESA Hubble Space Telescope showcases NGC 1999, a reflection nebula in the constellation Orion. NGC 1999 is around 1350 light-years from Earth and lies near to the Orion Nebula, the closest region of massive star formation to Earth. NGC 1999 itself is a relic of recent star formation — it is composed of detritus left over from the formation of a newborn star.

Just like fog curling around a street lamp, reflection nebulae like NGC 1999 only shine because of the light from an embedded source. In the case of NGC 1999, this source is the aforementioned newborn star V380 Orionis which is visible at the centre of this image. The most notable aspect of NGC 1999’s appearance, however, is the conspicuous hole in its centre, which resembles an inky-black keyhole of cosmic proportions.

This image was created from archival Wide Field Planetary Camera 2 (WFPC2) observations that date from shortly after Servicing Mission 3A (SM3A) in 1999. At the time, astronomers believed that the dark patch in NGC 1999 was something called a Bok globule — a dense, cold cloud of gas, molecules, and cosmic dust that blots out background light. However, follow-up observations using a collection of telescopes including ESA’s Herschel Space Observatory revealed that the dark patch is actually an empty region of space. The origin of this unexplained rift in the heart of NGC 1999 remains unknown.

Click to view full size image 1 or image 2

Credit: ESA/Webb, NASA & CSA, L. Armus & A. Evans; Acknowledgement: R. Colombari
Credit: ESA/Hubble & NASA, R. Chandar

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This image from the NASA/ESA/CSA James Webb Space Telescope depicts IC 1623, an entwined pair of interacting galaxies which lies around 270 million light-years from Earth in the constellation Cetus. The two galaxies in IC 1623 are plunging headlong into one another in a process known as a galaxy merger. Their collision has ignited a frenzied spate of star formation known as a starburst, creating new stars at a rate more than twenty times that of the Milky Way galaxy.

This interacting galaxy system is particularly bright at infrared wavelengths, making it a perfect proving ground for Webb’s ability to study luminous galaxies. A team of astronomers captured IC 1623 across the infrared portions of the electromagnetic spectrum using a trio of Webb’s cutting-edge scientific instruments: MIRI, NIRSpec, and NIRCam. In so doing, they provided an abundance of data that will allow the astronomical community at large to fully explore how Webb’s unprecedented capabilities will help to unravel the complex interactions in galactic ecosystems. These observations are also accompanied by data from other observatories, including the NASA/ESA Hubble Space Telescope, and will help set the stage for future observations of galactic systems with Webb.

The merger of these two galaxies has long been of interest to astronomers, and has previously been imaged by Hubble and by other space telescopes. The ongoing, extreme starburst causes intense infrared emission, and the merging galaxies may well be in the process of forming a supermassive black hole. A thick band of dust has blocked these valuable insights from the view of telescopes like Hubble. However, Webb’s infrared sensitivity and its impressive resolution at those wavelengths allows it to see past the dust and has resulted in the spectacular image above, a combination of MIRI and NIRCam imagery.

The luminous core of the galaxy merger turns out to be both very bright and highly compact, so much so that Webb’s diffraction spikes appear atop the galaxy in this image. The 8-pronged, snowflake-like diffraction spikes are created by the interaction of starlight with the physical structure of the telescope. The spiky quality of Webb’s observations is particularly noticeable in images containing bright stars, such as Webb’s first deep field image.

Hubble celebrates the spooky season with Abell 611 — a cobweb of galaxies held together by a dark secret

Image Credit: ESA/Hubble, NASA, P. Kelly, M. Postman, J. Richard, S. Allen

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Nowadays, all galaxies and galaxy clusters are thought to be dominated by dark matter — an elusive quantity whose nature astronomers are still working to determine. Abell 611, the glowing galaxy cluster shown in this Hubble image, is no exception. In fact, Abell 611 is a popular target for investigating dark matter, in part because of the numerous examples of strong gravitational lensing visible amongst the cluster’s intricate web of galaxies.

In celebration of Halloween, Hubble brings you this inky image of the galaxy cluster Abell 611, located over 1000 megaparsecs, or roughly 3.2 billion light years, from Earth. Like all galaxy clusters, the continued existence of Abell 611 poses a mystery to astronomers. Specifically, there does not appear to be enough mass contained within its web of rapidly rotating constituent galaxies to prevent the cluster from flying apart. This is a well-established issue in astronomy with very massive structures, such as galaxies and galaxy clusters — they just do not seem to contain enough combined mass to remain whole. Interestingly, this problem does not present itself on smaller cosmic scales. For example, the passage of the planets of the Solar System around the Sun can be calculated relatively easily using the masses and locations of the planets and the Sun. No extra mass is needed to explain the integrity of the Solar System, or other star-planet systems. So why does this intuitive rule break down at larger scales? ...

Image Credit: Zdeněk Bardon/ESO

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Ever wondered what the inside of the Very Large Telescope (VLT) looks like? Wonder no more! In this Picture of the Week we invite you into the dome of the Unit Telescope 3 (Melipal) to take a closer look.

With this fisheye view of the internal structure of Melipal, the whole telescope and its dome is caught on camera. The main mirror, measuring an impressive 8.2 metres in diameter, weighs in at more than 23 tonnes. To support the mirror and other components and make sure they’re kept steady during observations, a sturdy steel frame is required.

The whole movable structure of the telescope weighs about 430 tonnes, like a ​​a fully loaded jumbo jet! Yet, it can be smoothly moved by hand because it’s perfectly balanced and rests on oil-film bearings. The dome containing the telescope is a sturdy steel enclosure; it not only provides protection from the harsh Chilean Atacama Desert, but also controls the temperature and air flow to minimise turbulence inside the dome that could degrade the images.

Two spiral galaxies are viewed almost face-on; they are a mix of pale blue and yellow in colour, crossed by strands of dark red dust. They lie in the upper-left and lower-right corners. A long, faint streak of pale blue joins them, extending from an arm of one galaxy and crossing the field diagonally. A small spiral galaxy, orange in colour, is visible edge-on, left of the lower galaxy.

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Image Credit: ESA/Hubble & NASA, Dark Energy Survey/
DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA, J. Dalcanton

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This image from the NASA/ESA Hubble Space Telescope shows two of the galaxies in the galactic triplet Arp 248 — also known as Wild's Triplet — which lies around 200 million light-years from Earth in the constellation Virgo. The two large spiral galaxies visible in this image — which flank a smaller, unrelated background spiral galaxy — seem to be connected by a luminous bridge. This elongated stream of stars and interstellar dust is known as a tidal tail, and it was formed by the mutual gravitational attraction of the two foreground galaxies.

This observation comes from a project which delves into two rogues’ galleries of weird and wonderful galaxies: A Catalogue of Southern Peculiar Galaxies and Associations, compiled by astronomers Halton Arp and Barry Madore, and the Atlas of Peculiar Galaxies, compiled by Halton Arp. Each collection contains a menagerie of spectacularly peculiar galaxies, including interacting galaxies such as Arp 248, as well as one- or three-armed spiral galaxies, galaxies with shell-like structures, and a variety of other space oddities.

Hubble used its Advanced Camera for Surveys (ACS) to scour this menagerie of eccentric galaxies in search of promising candidates for future observations with the NASA/ESA/CSA James Webb Space Telescope (Webb), the Atacama Large Millimeter/submillimeter Array (ALMA), and Hubble itself. With such a wealth of astronomical objects to study in the night sky, projects such as this, which guide future observations, are a valuable investment of observing time. As well as the scientific merits of observing these weird and wonderful galaxies, they were also — very unusually — selected as Hubble targets because of their visual appeal to the general public!

Image Credit: ESO/VPHAS+ team.
Acknowledgement: Cambridge Astronomical Survey Unit

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This image shows a spectacular view of the orange and pink clouds that make up what remains after the explosive death of a massive star — the Vela supernova remnant. This detailed image consists of 554 million pixels, and is a combined mosaic image of observations taken with the 268-million-pixel OmegaCAM camera at the VLT Survey Telescope (VST), hosted at ESO’s Paranal Observatory.

OmegaCAM can take images through several filters that each let the telescope see the light emitted in a distinct colour. To capture this image, four filters have been used, represented here by a combination of magenta, blue, green and red. The result is an extremely detailed and stunning view of both the gaseous filaments in the remnant and the foreground bright blue stars that add sparkle to the image.