Starship Asterisk*

bystander wrote: ↑Mon Nov 26, 2018 3:03 pm Tangled — Cosmic Edition
ESA Hubble Picture of the Week | 2018 Nov 26

Credit: ESA/Hubble & NASA

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This dark, tangled web is an object named SNR 0454-67.2. It formed in a very violent fashion — it is a supernova remnant, created after a massive star ended its life in a cataclysmic explosion and threw its constituent material out into surrounding space. This created the messy formation we see in this NASA/ESA Hubble Space Telescope image, with threads of red snaking amidst dark, turbulent clouds.

SNR 0454-67.2 is situated in the Large Magellanic Cloud, a dwarf spiral galaxy that lies close to the Milky Way. The remnant is likely the result of a Type Ia supernova explosion; this category of supernovae is formed from the death of a white dwarf star, which grows and grows by siphoning material from a stellar companion until it reaches a critical mass and then explodes.

As they always form via a specific mechanism — when the white dwarf hits a particular mass — these explosions always have a well-known luminosity, and are thus used as markers (standard candles) for scientists to obtain and measure distances throughout the Universe.

Credit: ESA/Hubble & NASA

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This dark, tangled web is an object named SNR 0454-67.2. It formed in a very violent fashion — it is a supernova remnant, created after a massive star ended its life in a cataclysmic explosion and threw its constituent material out into surrounding space. This created the messy formation we see in this NASA/ESA Hubble Space Telescope image, with threads of red snaking amidst dark, turbulent clouds.

SNR 0454-67.2 is situated in the Large Magellanic Cloud, a dwarf spiral galaxy that lies close to the Milky Way. The remnant is likely the result of a Type Ia supernova explosion; this category of supernovae is formed from the death of a white dwarf star, which grows and grows by siphoning material from a stellar companion until it reaches a critical mass and then explodes.

As they always form via a specific mechanism — when the white dwarf hits a particular mass — these explosions always have a well-known luminosity, and are thus used as markers (standard candles) for scientists to obtain and measure distances throughout the Universe.

starsurfer wrote: ↑Wed Nov 21, 2018 11:11 am Sh2-115 and Abell 71
https://www.flickr.com/photos/cfaobam/38421280442/
Copyright: Carsten Frenzl
38421280442_6c85aab014.jpg
Sh2-115 is the emission nebula in the centre and Abell 71 is the planetary nebula near the bottom right corner.

Credit: ESA/Hubble & NASA

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Star clusters are common structures throughout the Universe, each made up of hundreds of thousands of stars all bound together by gravity. This star-filled image, taken with the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3), shows one of them: NGC 1866.

NGC 1866 is found at the very edges of the Large Magellanic Cloud, a small galaxy located near to the Milky Way. The cluster was discovered in 1826 by Scottish astronomer James Dunlop, who catalogued thousands of stars and deep-sky objects during his career.

However, NGC 1866 is no ordinary cluster. It is a surprisingly young globular cluster situated close enough to us that its stars can be studied individually — no mean feat given the mammoth distances involved in studying the cosmos! There is still debate over how globular clusters form, but observations such as this have revealed that most of their stars are old and have a low metallicity. In astronomy, ‘metals’ are any elements other than hydrogen and helium; since stars form heavier elements within their core as they carry out nuclear fusion throughout their lifetimes, a low metallicity indicates that a star is very old, as the material from which it formed was not enriched with many heavy elements. It’s possible that the stars within globular clusters are so old that they were actually some of the very first to form after the Big Bang.

In the case of NGC 1866, though, not all stars are the same. Different populations, or generations, of stars are thought to coexist within the cluster. Once the first generation of stars formed, the cluster may have encountered a giant gas cloud that sparked a new wave of star formation and gave rise to a second, younger, generation of stars — explaining why it seems surprisingly youthful.

Credit: ESO/VLT/FORS 2

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This colourful image shows a part of the Rosette Nebula in the constellation of Monoceros (The Unicorn). It is an emission nebula, composed of clouds of gas that are made to glow by the radiation emanating from stars within. The Rosette Nebula is a fairly typical example of an emission nebula — but typical does not mean boring! Nebulae are some of the most beautiful celestial objects out there, and they frequently show up spectacularly in images taken by astronomical telescopes, as seen here.

In nebulae such as this, gas and dust are combining to produce a new generation of stars. Initially these newly-formed stars are shrouded in the dusty clouds that gave them birth, and cannot be seen in visible light. But after a while they blow away the denser material and their powerful radiation pours out to ionise the surrounding gas, causing it to glow brightly. These elements are all present in this image — the mixture of glowing gas and dark dust has been sculpted into complex patterns on the sky by the stellar radiation, like smoke around a fire.

This particular image was obtained with the FORS 2 instrument on ESO’s Very Large Telescope (VLT), sited in the harsh environment of Chile’s Atacama Desert. FORS 2 is an extremely versatile instrument that can produce very high-quality images (like this one!). It is also a spectrograph that can split the light it collects into a rainbow of colours, giving astronomers information about the chemical composition of objects across the Universe.

This image was created as part of the ESO Cosmic Gems programme, an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.

Ann wrote: ↑Wed Nov 14, 2018 4:34 pm NGC 3293 and NGC 3324
Copyright: Gerald Rhemann
http://www.astrostudio.at/1_Deep%20Sky% ... 8e8a914e40

Click to view full size image

This picture shows the splendid cluster NGC 3293, and the Gabriela Mistral Nebula, NGC 3324.

I have posted it in honor of starsurfer's three thousand two hundred and ninety-third post here at Starship Asterisk*!

Ann