Space Sunday: Webb’s views, booster bang + Rogozin’s roulette

Where they are: the five subjects of the first five science images release by NASA for the James Webb Space Telescope (JWST). 1: the Carina Nebula; 2. the Southern Ring Nebula; 3. Stephan’s Quintet; 4. WASP-96b; 5. SMACS 0723. Credit: NASA/Goddard Space Centre / STScI
The first series of science images from the James Webb Space Telescope (JWST) were released on July 12th, 2022 rightly grabbing the headlines around the world, revealing as they did elements of our universe and our own galaxy in stunning detail and offering a superb launch for the observatory’s science mission.

At the time of their release, NASA also confirmed that, thanks to the extreme accuracy achieved by the European Ariane 5 rocket in delivering the observatory into is transfer orbit which allowed JWST to establish itself in its L2 position halo orbit, 1.6 million km from Earth, sufficient propellants remained aboard the observatory for it to operate for around 20 years – double its original extended mission time.

The mission itself is broken into periods of 12 months apiece, with science institutions, universities, etc., from around the world able to submit papers outlying studies they like to carry out using JWST to the Space Telescope Science Institute (STScI) in Baltimore, USA which form the management and operational centre for both JWST and the Hubble Space Telescope (HST). As such, the initial images selected for release on July 12th represent study targets for JWST accepted for its first year of observational science – but they are not the only targets. Since formally commencing its science programme in June, JWST has already gathered around 40 terabytes of images and data, and following the high-profile release of the initial images, on July 14th, 2022, STScI started issuing raw images of other targets so far examined by the observatory, including images of objects without our own solar system.

Webb is designed to collect light across the entire red to mid-infrared spectrum wavelengths of light that are blocked by Earth’s atmosphere, and while Hubble crosses from visible light into the near-infrared, JWST has a light collection area 5 times greater than that of HST. Taken together, these facts mean that JWST can reveal objects near and far with a lot more detail than we’ve ever been able to see them, and can also see much further out in the cosmos, allowing us to see the light of objects as they appeared close to the birth of the universe. Add this to the fact that the four science instruments on JWST can be combined to operate in a total of 17 different modes, and JWST is genuinely unparalleled in its capabilities.

The following is a brief summary of the images released on July 12th.

Carina Nebula

Lying some 7,600 light-years away and visible in southern hemisphere skies within the constellation Carina, this nebula (NGC 3372) is a familiar sight among astronomical photographs and studies. It is a massive birth-place of stars, with multiple young stellar groupings like Trumpler 14, and Trumpler 16.

The former, measuring just 6 light-years across (or roughly 1.5 times the distance between our Sun and the Alpha Centauri system) is just half a million years old – but it is home to around 2,000 young stars! Slightly older, Trumpler 16 is home to two of the most luminous stars in our galaxy: Eta Carinae and WR 25. These are two of the most luminous objects in our galaxy – while both are invisible to the naked eye on Earth, they are nevertheless several million times brighter than the Sun.

The “cosmic Cliffs” of NGC within the Carina Nebula, showing the blue “bowl” of hot stars that have pushed interstellar dust and gases into to a ring that resembles towering cliffs and mountains, and within which younger, new stars can be seen. Credit: NASA/Goddard Space Centre / STScI

Neither of these stellar groups was the focus in the Carina Nebula image release on July 12th. This honour went to the “Cosmic Cliffs”, part of a nebula-within-a-nebula (NGC 3324). A ring of dust and debris, it has been formed by the young, super-hot, super-active blue-white stars at the centre of NGC3324 (seen at the top of the image above) generating a collective powerful radiative force that has pushed the remaining gases and dust left over from their formation outwards to a point where the pressure of their own radiation is matched by that of the surrounding larger nebula.

Normally invisible to the naked eye, the portion of the “Cosmic Cliffs” have been beautifully rendered using images from both the Near-Infrared Camera (NIRCam) and the Mid-InfraRed Instrument (MIRI) on JWST, which have been processed to produce a remarkable composite image that reveals never-before-seen details. Within this ring of material, compression and gravity are combining to create even younger stars, many revealed in this image for the first time – with some even showing protostellar jets of material shooting outwards from them. Images like this shed enormous light (so to speak!) on the process of star formation.

Southern Ring Nebula

Catalogued as NGC 3132, the Southern Ring Nebula stands in contrast to the Carina Nebula, being the home of a binary star system where one of the stars is in its death-throes.

The pairing sits in a tight mutual orbit, and the elder of the two stars has gone through a series of events where it has thrown off shells of gas and mass, which are being mutually “stirred” by the two stars as they continue to orbit one another, leading to a complex pattern of gases around both.

The Southern Ring Nebula as seen by JWST’s NIRCam (l) and MIRI (r). Credit: NASA/Goddard Space Centre / STScI

JWST imaged the nebula with both NIRCam (seen on the left, above) and MIRI (seen on the right), with the latter showing for the first time that the second star is surrounded by dust, suggesting a more “recent” ejection of mass. The brighter star (visible in both images) is in an earlier stage of its stellar evolution and will probably eject its own planetary nebula in the future.

Studies of phenomena like the Southern Cross Nebula is like watching a slow motion film of a star’s evolution towards the end of its life, each of the shells of gas and dust from outer to inner representing increasingly more recent events in its life, allowing astronomers gain insight in the life and death of stars, whilst studies of the gases released provide insight into how these delicate layers of gas and dust will dissipate into surrounding space.

Stephan’s Quintet

This is a visual grouping of five galaxies, four of which (called the Hickson Compact Group 92) are a genuine grouping of galaxies that are gradually being drawn together by gravity, and will all eventually merge. The fifth member of the quintet is the result of line-of-sight alignment, rather than an actual part of the group. It is possibly best known for its appearance in the classic film It’s a Wonderful Life.

Imaged numerous times in the past, JWST nevertheless reveals the quintet in a new light via a mosaic image that represents Webb’s largest image to date, containing over 150 million pixels and comprising 1,000 individual pictures of the galactic group.

Stephan’s Quintet, comprising a close-knit group of four galaxies, two of which have already merged (centre right) to form NGC 7318. Also visible in the image are clouds of sat-forming dust and material, and the shockwave of the NGC 7318 merging rippling through NGC 7319. Credit: NASA/Goddard Space Centre / STScI

The quartet of galaxies are some 280 million light-years from our own, and of particular note in this composite image is the details of gaseous clouds where star formation is going on; the clear view of the two galaxies in the group which have already collided (UGC 12099 and UGC 12100, now collectively classified as NGC 7318) – the lower right of the “three” close-packed galaxies in the central group – and the white shockwaves of that collision as they sweep towards the top right galaxy, NGC 7319.

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