Starship Asterisk*

Image Credit: ESO/VVVX Survey

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This Picture of the Week shows a new view of NGC 3603 (left) and NGC 3576 (right), two stunning nebulas imaged with ESO’s Visible and Infrared Survey Telescope for Astronomy (VISTA). This infrared image peers through the dust in these nebulas, revealing details hidden in optical images.

NGC 3603 and NGC 3576 are 22,000 and 9,000 lightyears away from us, respectively. Inside these extended clouds of dust and gas, new stars are born, gradually changing the shapes of the nebulas via intense radiation and powerful winds of charged particles. Given their proximity, astronomers have the opportunity to study the intense star formation process that is as common in other galaxies but harder to observe due to the vast distances.

The two nebulas were catalogued by John Frederick William Herschel in 1834 during a trip to South Africa, where he wanted to compile stars, nebulas and other objects in the sky of the southern hemisphere. This catalogue was then expanded by John Louis Emil Dreyer in 1888 into the New General Catalogue, hence the NGC identifier in these and other astronomical objects.

An enormous spiral galaxy fills half of the frame, in the centre. It is oval-shaped, with four blue spiral arms winding around it. The galaxy’s centre shines brightly with pale yellow light. Thin strands of orange dust are spread around the centre, following the paths of the arms. Above and below the galaxy, very many small stars and galaxies are visible on the black background.

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Image Credit: ESA/Hubble & NASA, D. Jones.
Acknowledgement: G. Anand, L. Shatz

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The spiral arms of the galaxy NGC 7038 wind languidly across this image from the NASA/ESA Hubble Space Telescope. NGC 7038 lies around 220 million light-years from Earth in the southern constellation Indus. This image portrays an especially rich and detailed view of a spiral galaxy, and exposes a huge number of distant stars and galaxies around it. That’s because it’s made from a combined 15 hours worth of Hubble time focused on NGC 7038 and collecting light. So much data indicates that this is a valuable target, and indeed, NGC 7038 has been particularly helpful to astronomers measuring distances at vast cosmic scales.

The distances to astronomical objects are determined using an interconnected chain of measurement techniques called the Cosmic Distance Ladder. Each rung in the ladder is calibrated by earlier steps, based on measurements of objects closer to us. This makes the accuracy of distances at the largest scales dependent on how accurately distances to nearby objects can be determined. Hubble inspected NGC 7038 with its Wide Field Camera 3 to calibrate two of the most common distance measurement techniques: type 1A supernovae and Cepheid variables.

One of Hubble's original science goals was to accurately establish distances to night-sky objects, and over its three decades of operation Hubble’s increasingly precise distance measurements have contributed to one of the most intriguing unsolved problems in astronomy. Distance measurements are used to derive a quantity known as the Hubble constant, which captures how fast the Universe is expanding. As astronomer’s measurements of the Hubble constant have become more precise, their value has become increasingly inconsistent with the value of the Hubble Constant derived from observations of the Big Bang’s afterglow. Astronomers have been unable to explain the mismatch between the two values of the Hubble constant, which suggests that a new discovery in cosmology is waiting to be made.

Click to view full size image 1 or image 2

Image Credit: NASA, ESA, STScI, Wenlei Chen (UMN),
Patrick Kelly (UMN), Hubble Frontier Fields

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Five panels are shown. The larger left panel shows the portion of the galaxy cluster
Abell 370 where the multiple images of the supernova appeared, which is shown in
four panels labelled A through D on the right. These panels show the locations of
the multiply imaged host galaxy after a supernova faded and the different colours
of the cooling supernova at three different stages in its evolution.

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Three different moments in a far-off supernova explosion were captured in a single snapshot by the NASA/ESA Hubble Space Telescope. The progenitor star exploded more than 11 billion years ago, when the Universe was less than a fifth of its current age of 13.8 billion years.

This is the first detailed look at a supernova at such an early time in the Universe’s evolution. The data could help scientists learn more about the formation of stars and galaxies in the early Universe.

This observation was possible thanks to the phenomenon called gravitational lensing, as first predicted by Einstein’s general theory of relativity. In this case, the light took three different paths through the cosmic lens of the massive galaxy cluster Abell 370, bending and magnifying the light from the more distant supernova located behind the cluster. The three paths were of three different lengths, so when the light arrived at Hubble (on the same day in December 2010), the supernova appeared at three different stages of evolution.

The Hubble exposure also captured the fading supernova’s rapid change of colour, which indicates its changing temperature. The bluer the colour, the hotter the supernova is. The earliest phase captured appears blue. As the supernova cooled its light turned redder.

This is also the first time astronomers have been able to measure the size of a dying star in the early Universe. They did this by observing the supernova’s brightness and rate of cooling, both of which depend on the size of the progenitor star. Hubble’s observations show that the red supergiant whose supernova explosion the researchers discovered had a radius about 500 times larger than the Sun. ...

• Nature (online 09 Nov 2022) DOI: 10.1038/s41586-022-05252-5 (pdf)

Image Credit: ESO / VLT / FORS2

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For the past 60 years the European Southern Observatory (ESO) has been enabling scientists worldwide to discover the secrets of the Universe. We mark this milestone by bringing you a spectacular new image of a star factory, the Cone Nebula, taken with ESO’s Very Large Telescope (VLT).

On 5 October 1962 five countries signed the convention to create ESO. Now, six decades later and supported by 16 Member States and strategic partners, ESO brings together scientists and engineers from across the globe to develop and operate advanced ground-based observatories in Chile that enable breakthrough astronomical discoveries.​ ...

In this new image, we see centre-stage the seven-light-year-long pillar of the Cone Nebula, which is part of the larger star-forming region NGC 2264 and was discovered in the late 18th century by astronomer William Herschel. In the sky, we find this horn-shaped nebula in the constellation Monoceros (The Unicorn), a surprisingly fitting name. ...

In this image, obtained with the FOcal Reducer and low dispersion Spectrograph 2 (FORS2) on ESO’s VLT in Chile, hydrogen gas is represented in blue and sulphur gas in red. The use of these filters makes the otherwise bright blue stars, that indicate the recent star formation, appear almost golden, contrasting with the dark cone like sparklers. ...

Image Credit: KPNO/NOIRLab/NSF/AURA/Petr Horálek (Institute of Physics in Opava)

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Next to the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory, a Program of NSF’s NOIRLab, a total lunar eclipse crawls across the desert sky in the early morning hours of yesterday in this week’s Image of the Week. The Milky Way, dotted by star-forming regions, arches over the telescope (explore in the zoomable image).

This year, the typical two annual lunar eclipses were both total, something which hasn’t happened since 2018. You can see the other 2022 total lunar eclipse above Cerro Tololo International Observatory, another Program of NSF’s NOIRLab, in the Image of the Week here and in comparison shots here and a compilation of all 2022 lunar and solar eclipses here.

For a total lunar eclipse to occur, the Moon must enter the innermost part of the Earth’s shadow, the umbra. The Moon doesn’t align within the shadow every time it is full, but the orbits of the Earth and Moon are periodic. This means that lunar eclipses are predictable throughout time, in a roughly 18 year cycle known as the Saros series. Characteristics of the eclipse, like the type of lunar eclipse and where it will be visible on Earth, are known decades in advance. The next total lunar eclipse will happen in March 2025 — and it will be a special one for NOIRLab as the eclipse will be visible at every location where NOIRLab operates an observatory: Arizona, Hawai‘i and Chile.

Another close-up view of this total lunar eclipse can be found here, a 360-degree view to explore interactively here, a beautiful close-up timelapse videos of the eclipse here, a view of full duration of the eclipse here showing the "ozone fringe" in blue due to ozone absorption in the upper stratosphere of the Earth, a 20k fulldome view for planetariums here, and an all-sky timelapse video here.

Image Credit: ESO/Juan Carlos Muñoz Mateos

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The four Auxiliary Telescopes at ESO’s Paranal Observatory can be seen gazing up to the night sky in this Picture of the Week. With dark and pristine skies, Paranal is one of the best places on Earth to study the universe from. As seen in this spectacular image, the view is really full to the brim of exciting things to look at.

For instance, take a closer look to the right of the Milky Way band, at the two clouds that look like galactic fireworks. These are the Large and Small Magellanic Clouds, dwarf galaxies that are trapped by the gravity of the Milky Way. In the Mapuche language in south-central Chile they are known as lafken, labken or künchalabken (“the lagoons”), and also rünanko (“the water wells”).

Peering closer to the horizon we see subtle shades of green and red, but what is it? This is called airglow and is faint light emitted atoms and molecules in the atmosphere. This can happen through various mechanisms, like interaction with solar radiation or chemical reactions between molecules. Green airglow comes from oxygen atoms, whereas the red one is due to both oxygen atoms and hydroxyl molecules. Check this ESO cast to learn more about how airglow is created and why Chile is a particularly good place to see it.

The image shows an irregularly-shaped bright orange object composed of dense gas and dust, which appears darker and more compact at the centre. This dense cloud, called CB 130-3, is outlined by thinner gas and dust in light shades of blue. The background shows a multitude of bright stars against a black background.

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Image Credit: ESA/Hubble, NASA & STScI, C. Britt, T. Huard, A. Pagan

A small, dense cloud of gas and dust called CB 130-3 blots out the centre of this image from the NASA/ESA Hubble Space Telescope. CB 130-3 is an object known as a dense core, a compact agglomeration of gas and dust. This particular dense core is in the constellation Serpens, and seems to billow across a field of background stars.

Dense cores like CB 130-3 are the birthplaces of stars, and as such are of particular interest to astronomers. During the collapse of these cores enough mass can accumulate in one place to reach the temperatures and densities required to ignite hydrogen fusion, marking the birth of a new star. While it may not be obvious from this image, a compact object teetering on the brink of becoming a fully fledged star is embedded deep within CB 130-3.

Astronomers used Hubble’s Wide Field Camera 3 to better understand the environment surrounding this fledgling star. As this image shows, the density of CB 130-3 isn’t constant; the outer edges of the cloud consist of only tenuous wisps, whereas at its core CB 130-3 blots out background light entirely. The gas and dust making up CB 130-3 affect not only the brightness but also the colour of background stars, with stars towards the centre the cloud appearing redder than their counterparts at the outskirts of this image. Astronomers used Hubble to measure this reddening effect and chart out the density of CB 130-3, providing insights into the inner structure of this stellar nursery.