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Dust Clouds and Nebulae near R Coronae Australis
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Caption: The image shows a dark and dusty cloud and some bright reflection nebulae near the binary star R Coronae Australis. The dark cloud spans several light-years and is located in the constellation Corona Australis near the constellation Sagittarius, in the direction of the Milky Way's center. The cloud appears to swallow the light of distant stars behind it as the dust particles in it scatter light passing through in all directions. This gives it the appearance of a void in the sky. This dark nebula is part of the broader Corona Australis Molecular Clouds. R Coronae Australis forms part of the Coronet Cluster, a collection of young stars which formed at some point in the last two million years.
Around R Coronae Australis in the center of the image is the small reflection nebula NGC 6729 with two blueish reflection nebulae NGC 6726 and NGC 6727 lying to the upper right of it. In these nebulae the dust scatters light from bright stars near the nebula towards an observer on Earth, making it glow in this image.
Credit: ESO
Credit Link
Glossary Terms:
Dark Nebula , Dust , Nebula , Interstellar Medium , Interstellar Extinction , Molecular Cloud
Categories:
Milky Way and Interstellar Medium
License: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) icons
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The Pleiades M45 with Majestic Dust
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Created for the OAE
Caption: Honourable mention in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.
Taken in Dar Eid in Saint Catherine/Sinai, Egypt, in October 2021, this image shows the Pleiades, an open cluster also known as The Seven Sisters.
The Pleiades are located in the north-western part of the constellation Taurus, the Bull. This constellation originates from ancient Babylonian or even Sumerian belief, where it was designated the Bull of Heaven, a mighty creature owned by the sky god. In Late Babylonian times, the Pleiades were called The Bristle at the hunchback of The Bull. In China, the asterism is also called The Hair, but this does not necessarily imply any relationship between the East Asian and West Asian names of this asterism, although exchange is hypothesised with the establishment of the Silk Road.
In ancient Babylonian texts the term The Hair does not appear. Instead, the Pleiades are only called The Star Cluster in Sumerian, and the Sumerian term was used in later languages as a loanword. The Sumerian and early Babylonian religion associated all constellations with specific deities, including gods, demons, messengers of gods. The Star Cluster was associated with a deity of the Netherworld that was called The Seven and was considered an ensemble of seven speaking weapons or strongly armed gods. The later Greek name of the Seven Sisters might possibly have sprung from an intercultural misunderstanding of this older religious association, since, in fact, seven stars are not seen in this cluster.
The star cluster of the Pleiades is really prominent in the sky, and thus was used for several cultural purposes, such as determining the calendar and the spring equinox. However, its significance is frequently overstated in cultural astronomy. As the tradition of representing it with seven dots originates from an ancient Sumerian belief, we should be careful about interpreting any group of seven dots on cave walls and archaeological sites across Europe, Asia and America from the Stone Age onwards as a representation of the Pleiades.
Modern astrophysics has found that the star cluster of the Pleiades is extraordinarily young, so there was certainly not an additional star in ancient times. Furthermore, we know that the bright stars are only the core region of an open star cluster that consists of hundreds of stars scattered over an area of the sky which exceeds the bright core by one or two of its diameters in any direction. The photograph does not even show the whole cluster. The group is thought to be about 400 light-years away from Earth, which is relatively close in astronomical terms.
Credit: Mohamed Usama/IAU OAE
Glossary Terms:
Cluster , Messier Object , Dust Cloud , Gas Cloud , Interstellar Medium , Open Cluster , Pleiades
Categories:
Milky Way and Interstellar Medium
, Naked Eye Astronomy
, Stars
License: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) icons
This file on Zenodo ( image 5.83 MB)
Comet C/2020F3 (Neowise) with separate dust and ion gas tails and a green glowing coma, by Dietmar Gutermuth, Germany
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Created for the OAE
Caption: Second place in the 2021 IAU OAE Astrophotography Contest, category Comets.
Comets have a very interesting structure comprising of four main parts: the nucleus, composed of rock, dust and frozen gases, typically spanning a few kilometres, although bigger ones have been observed; a small atmosphere of gas surrounding the nucleus (only present when the comet approaches its closest point to the Sun), called coma; and the two distinctive cometary tails (there is at times third tail). The green colour of the coma is due to carbon and nitrogen present in the coma reacting with the Sun’s ultraviolet radiation. The tail that we are mostly used to observing – dust tail and is composed of micron sized dust particles, the second tail composed of charged particles – ion or gas tail. The tails are released only when the comet approaches the Sun at a distance where the heat and radiation emanating from our star is intense enough to vaporize the frozen gases. The dust tail is curved, while the gas tail is straight and always points away from the Sun as this is carried by the solar wind - flow of charged particles emitted by the Sun. As comets are formed by leftover material, they carry with them important information about the early stages of the Solar System’s formation. This beautiful image shows the comet C/2020 F3 (Neowise), as seen from Germany in July 2020, with three of the four structures clearly visible – coma, gas, and dust tail.
Credit: Dietmar Gutermuth/IAU OAE
Glossary Terms:
Cometary Coma , Comet , Cometary Tail
Categories:
Solar System
License: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) icons
This file on Zenodo ( image 683.77 kB)
The Horsehead Nebula
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Caption: This image shows the Horsehead Nebula, located at a distance of about 1,300 light-years from Earth in the Orion constellation, one of the most iconic examples of a dark nebula. A dark nebula is a dense cloud of interstellar dust and cold gas that absorbs and scatters visible light, preventing background stars and glowing gas from reaching our eyes. This false-color image combines data captured through multiple narrowband filters, each isolating light from different elements in the nebula. The dark, horse-shaped silhouette appears sharply outlined against the luminous nebula behind it, where energetic radiation from nearby young stars causes the gas to glow. The uneven distribution of visible stars in this image is not random: regions rich in dust in the lower part of this image appear almost empty, while clearer areas reveal many background stars. The dust acts like a cosmic curtain, hiding stars that lie behind it while allowing stars in front of the cloud to remain visible. Studying such regions helps astronomers understand how nebulae serve as environments where new stars can form.
Credit: T.A.Rector (NOIRLab/NSF/AURA) and Hubble Heritage Team (STScI/AURA/NASA)
Credit Link
Glossary Terms:
Dark Nebula , Dust , Nebula , Space
License: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) icons
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The Pillars of Creation in comparison
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Caption: The 'Pillars of Creation' are a renowned astronomical feature situated within the Eagle Nebula in the Serpens constellation. The illustration provides a direct comparison between images captured by the Hubble Space Telescope (HST) and the James Webb Space Telescope (JWST), showcasing the pillars, which span several light years in diameter, in both visible light (also known as optical light) and infrared light. On the left are the pillars as seen by Hubble in visual light, taken in 2014. It displays dark pillars against an opaque background, with only a handful of visible stars. Conversely, the counterpart on the right is Webb’s near-infrared view published in 2022, penetrating the dust and revealing numerous stars of varying sizes.
Their distance from Earth is approximately 6,500 to 7,000 light years. Within these pillars, new stars are constantly forming, making them a subject of extensive study by astronomers. Composed mostly of cool molecular hydrogen and small amounts of interstellar dust, they are subject to erosion by the intense ultraviolet radiation emitted by nearby massive and newborn stars, a process known as photoevaporation.
Credit: NASA, ESA, CSA, STScI
Credit Link
Glossary Terms:
Infrared Astronomy , Infrared Telescope , Optical Astronomy , Star Formation , Visible Spectrum , Dust Cloud
Categories:
Milky Way and Interstellar Medium
, Stars
License: Creative Commons Attribution 2.0 Generic Creative Commons Attribution 2.0 Generic icons
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