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The Horsehead Nebula
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Légende : 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.
Crédit : T.A.Rector (NOIRLab/NSF/AURA) and Hubble Heritage Team (STScI/AURA/NASA)
Lien du crédit
Termes du glossaire:
Nébuleuse sombre , Poussière , Nébuleuse , L'espace
Licence : Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Icônes
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23.89 MB)
Equatorial Milky Way
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Créé pour l'OAE
Légende : Honourable mention in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns: Equatorial Milky Way
Taken in Bromo-Tengger-Semeru National Park, Java Island, Indonesia, in March 2016, this image captures regions of the southern Milky Way and, at its left edge, the two planets Mars and Saturn. Mars appears orange and is similar in colour to the star Antares, whose Greek name — anti Ares — references this. Saturn is a little bit fainter than Mars, but clearly visible among the stars of Ophiuchus, above the Pipe Nebula and forming an isosceles triangle with Mars and Antares.
Mars is on the top and Saturn is vertically below. Visible to the naked eye, both planets have significance in many cultures around the world. In Roman mythology Mars is the god of war and fertility, and Saturn the god of sowing and agriculture. Its Greek equivalent, the god Kronos, is also considered the regent of completion. Indigenous Australians, including the Kamilaroi and Wailan people, associate Saturn with “wunygal”, a small bird. Mars is called Iherm-penh (something burnt in flames) by the Anmatyerre people of the Central Desert, while the Kokatha people of the Western Desert associate Mars and the star Anatres with the red-tailed black cockatoo (Kogolongo).
In the middle of this photograph, the most famous southern constellations are clearly recognisable: the Southern Cross (Crux), the pointer stars, Alpha and Beta Centauri, the dark Coalsack Nebula and the red Eta Carina Nebula, which is not visible to the unaided eye but is prominent in modern photographs. In the 19th century, the star eta Carinae had been the second-brightest star in the sky for some time, but since it varies irregularly, it has hardly been recognisable in recent decades, and its future visibility is unpredictable.
Triangulum Australe is visible between the pointer stars and the Scorpion, and in the constellation of Centaurus, the bright globular star cluster Omega Centauri is clearly displayed. It was considered a “nebulous star” since antiquity and, thus, was listed in star catalogues for at least 2000 years. Only within the last century did astronomers discover that globular star clusters are in the halo of our galaxy and that this one consists of roughly 10 million stars.
The dark regions in the Milky Way, which are cool, dense clouds of dust and gas, form the head and body of the Celestial Emu Tchingal. Together with the Southern Cross and the pointer stars, they appear in the Dreamtime stories of many Indigenous Australians. One story associated with the Djab Wurrung and the Jardwadjali people is part of a Dreamtime Story involving Tchingal, the Bram-bram-bult brothers (the pointer stars), their mother Druk (Delta Crux), and Bunya the hunter, who gets transformed into a possum (Gacrux, the red star at the top of the Southern Cross).
Crédit : Giorgia Hofer/IAU OAE
Termes du glossaire:
Poussière , Mars , Voie lactée , Saturne , Scorpius , Croix du Sud , Nuage de poussière , L'extinction interstellaire , Alpha du Centaure
Catégories :
Voie lactée et milieu interstellaire
, Astronomie à l'œil nu
Licence : Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Icônes
Ce fichier est sur Zenodo ( image 1.61 MB)
Planet formation around the star TW Hydrae
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Légende : 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.
Crédit : S. Andrews (Harvard-Smithsonian CfA); B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO)
Lien du crédit
Termes du glossaire:
Formation de planètes
Catégories :
Exoplanètes et astrobiologie
Licence : Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Icônes
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The LDN 483 Dark Nebula
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Légende : This image shows a dark molecular cloud known as LDN 483, captured by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. At first glance, the patch of sky looks like a region where stars are missing, but the effect is due to interstellar extinction — dust and gas within LDN 483 absorb and scatter light from background stars, making them appear faint or invisible to telescopes that observe visible light. Interstellar extinction is the dimming of light from distant objects caused by dust and gas between the object and the observer, a common phenomenon in astronomy that must be accounted for when measuring stellar brightness and color.
Dark nebulae like LDN 483 are dense concentrations of interstellar matter located within our Milky Way Galaxy. This particular cloud lies about 700 light-years from Earth in the constellation Serpens and contains enough material to block most visible light from stars behind it. Because dust grains preferentially scatter shorter (bluer) wavelengths of light, extinction can also make objects appear redder than they truly are — a related effect known as interstellar reddening. Understanding and correcting for extinction is essential for astronomers to reveal the true brightness, distance, and physical properties of celestial objects seen through dusty regions of space.
Crédit : ESO
Lien du crédit
Termes du glossaire:
Nébuleuse sombre , Milieu interstellaire , L'extinction interstellaire
Licence : Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Creative Commons (CC) Attribution 4.0 International (CC BY 4.0) Icônes
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31.01 MB)
WISE Survey Capturing the Whole Sky in Infrared Light
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Légende : 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.
Crédit : NASA/JPL-Caltech
Lien du crédit
Termes du glossaire:
Astronomie infrarouge , Relevé astronomique
Licence : Domaine Public Domaine Public Icônes
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64.59 MB)
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