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Comet C/2020F3 (Neowise) with separate dust and ion gas tails and a green glowing coma, by Dietmar Gutermuth, Germany
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Criado para o OAE
Legenda: 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.
Crédito: Dietmar Gutermuth/IAU OAE
Termos do Glossário:
Coma cometária , Cometa , Cauda de cometa
Categorias
Sistema Solar
Licença: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) ícones
Este arquivo no Zenodo ( imagem 683.77 kB)
The Pleiades M45 with Majestic Dust
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Criado para o OAE
Legenda: 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.
Crédito: Mohamed Usama/IAU OAE
Termos do Glossário:
Aglomerado , Objeto Messier , Nuvem de poeira , Nuvem de gás , Meio interestelar , Aglomerado aberto , Plêiades
Categorias
Via Láctea e Meio Interestelar
, Astronomia a Olho Nu
, Estrelas
Licença: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) ícones
Este arquivo no Zenodo ( imagem 5.83 MB)
Nuvens de poeira e nebulosas perto de R Coronae Australis
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Legenda: A imagem mostra uma nuvem escura e empoeirada e algumas nebulosas de reflexão brilhantes perto da estrela binária R Coronae Australis. A nuvem escura se estende por vários anos-luz e está localizada na constelação Corona Australis, perto da constelação de Sagitário, na direção do centro da Via Láctea. A nuvem parece engolir a luz de estrelas distantes atrás dela, pois as partículas de poeira nela contidas dispersam a luz que passa em todas as direções. Isso lhe dá a aparência de um vazio no céu. Esta nebulosa escura faz parte das Nuvens Moleculares de Corona Australis, uma região mais ampla. R Coronae Australis faz parte do Aglomerado Coronet, um conjunto de estrelas jovens que se formou em algum momento nos últimos dois milhões de anos.
Ao redor de R Coronae Australis, no centro da imagem, encontra-se a pequena nebulosa de reflexão NGC 6729, com duas nebulosas de reflexão azuladas NGC 6726 e NGC 6727 situadas no canto superior direito. Nessas nebulosas, a poeira dispersa a luz de estrelas brilhantes próximas, direcionando-a para um observador na Terra, fazendo-a brilhar nesta imagem.
Crédito: ESO
Link do crédito
Termos do Glossário:
Nebulosa Escura , Poeira , Nebulosa , Meio interestelar , Extinção interestelar , Nuvem Molecular
Categorias
Via Láctea e Meio Interestelar
Licença: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) ícones
Arquivo
( imagem
20.18 MB)
Planet formation around the star TW Hydrae
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Legenda: This image shows the disk around the young star TW Hydrae. This star is only about 10 million years old, young enough that planets are still forming in a disk of gas and dust around it. This image was created using an array of submillimetre telescopes, each of which looks like a satellite dish. The signals from these telescopes were combined by a central processing computer to make this image. The lighter and darker patches show areas of the disk where there is more or less dust respectively. The dark rings and bright rings are evidence that the dust in the disk has been shepherded into some orbits and away from others. This is likely because there is one or more planets that are still forming hidden in the disk.
The whole image shows the disk around TW Hydrae out to a distance of about 70 astronomical units frm the central star. The two outer dark rings are separated from the central star by approximately the average distance between the Sun and Uranus and the average distance between the Sun and Pluto. The inner central hole appears to have been carved out by a planet orbiting TW Hydrae at a distance similar to the distance between the Earth and the Sun.
Crédito: S. Andrews (Harvard-Smithsonian CfA); B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO)
Link do crédito
Termos do Glossário:
Formação planetária
Categorias
Exoplanetas e Astrobiologia
Licença: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) ícones
Arquivo
( imagem
210.48 kB)
WISE Survey Capturing the Whole Sky in Infrared Light
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Legenda: This image presents the entire sky mapped in infrared light from space by the WISE satellite. While dust in the plane of the Milky Way blocks visible light, obscuring the heart of our Galaxy, infrared light passes through the dust. The most prominent feature is the broad, bright band running horizontally through the centre — this is the plane of our Milky Way galaxy. Numerous brighter knots and patches appear above and below the band, marking regions of active star formation and nearby galaxies.
Such a dataset is a classic example of an astronomical survey, in which large portions of the sky is scanned to build a comprehensive catalogue of cosmic sources. The WISE satellite operated in space, allowing it to study parts of the infrared spectrum blocked by Earth's atmosphere.
Crédito: NASA/JPL-Caltech
Link do crédito
Termos do Glossário:
Astronomia infravermelha , Levantamento Astronômico
Licença: Domínio Público Domínio Público ícones
Arquivo
( imagem
64.59 MB)
