Sharpless 308: Una Bolla Stellare

Pubblicato 20/12/2016 | Da Barbara Bubbi

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Questa spettacolare bolla cosmica, soffiata da venti veloci emessi da una calda stella massiccia, è davvero enorme. Catalogata come Sharpless 2-308, si trova a circa 5.200 anni luce di distanza in direzione della costellazione del Cane Maggiore e abbraccia una regione in cielo poco piu grande di una Luna piena. Questo corrisponde ad un diametro di 60 anni luce alla sua distanza stimata. Continua a leggere→

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Scintillio di Stelle

Pubblicato 19/12/2016 | Da Barbara Bubbi

Like a 4th of July fireworks display, a young, glittering collection of stars looks like an aerial burst. The cluster is surrounded by clouds of interstellar gas and dust—the raw material for new star formation. The nebula, located 20,000 light-years away in the constellation Carina, contains a central cluster of huge, hot stars, called NGC 3603. This environment is not as peaceful as it looks. Ultraviolet radiation and violent stellar winds have blown out an enormous cavity in the gas and dust enveloping the cluster, providing an unobstructed view of the cluster. Most of the stars in the cluster were born around the same time but differ in size, mass, temperature, and colour. The course of a star's life is determined by its mass, so a cluster of a given age will contain stars in various stages of their lives, giving an opportunity for detailed analyses of stellar life cycles. NGC 3603 also contains some of the most massive stars known. These huge stars live fast and die young, burning through their hydrogen fuel quickly and ultimately ending their lives in supernova explosions. Star clusters like NGC 3603 provide important clues to understanding the origin of massive star formation in the early, distant Universe. Astronomers also use massive clusters to study distant starbursts that occur when galaxies collide, igniting a flurry of star formation. The proximity of NGC 3603 makes it an excellent lab for studying such distant and momentous events. This Hubble Space Telescope image was captured in August 2009 and December 2009 with the Wide Field Camera 3 in both visible and infrared light, which trace the glow of sulfur, hydrogen, and iron.

Una giovane, scintillante collezione di stelle si presenta come uno spettacolo celeste di fuochi d’artificio. L’ammasso è circondato da nubi di gas e polveri interstellari, la materia prima per la formazione di nuove stelle. La nebulosa, che si trova a 20.000 anni luce di distanza nella costellazione della Carena, contiene un ammasso centrale di stelle ardenti e massicce, chiamato NGC 3603. Continua a leggere→

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Una Ghirlanda in Cielo

Pubblicato 19/12/2016 | Da Barbara Bubbi

In keeping with the spirit of the holidays, NASA’s Wide-field Infrared Survey Explorer (WISE) mission presents the “Wreath Nebula”. Though this isn’t the nebula’s official name (it’s actually called Barnard 3 or IRAS Ring G159.6-18.5), it’s easy to picture a wreath in these bright green and red dust clouds -- a ring of evergreens donned with a festive red bow, a jaunty sprig of holly, and silver bells throughout. Interstellar clouds like these are stellar nurseries, places where baby stars are being born. The green ring (evergreen) is made of tiny particles of warm dust whose composition is very similar to smog found here on Earth. The red cloud (bow) in the middle is probably made of dust that is more metallic and cooler than the surrounding regions. The bright star in the middle of the red cloud, called HD 278942, is so luminous that it is likely what is causing most of the surrounding ring to glow. In fact its powerful stellar winds are what cleared out the surrounding warm dust and created the ring-shaped feature in the first place. The bright greenish-yellow region left of center (holly) is similar to the ring, though more dense. The bluish-white stars (silver bells) scattered throughout are stars located both in front of, and behind, the nebula. Regions similar to the "Wreath nebula" are found near the band of the Milky Way in the night sky. The wreath is slightly off of this band, near the boundary between the constellations of Perseus and Taurus, but at a relatively close distance of only about 1,000 light-years, the cloud is a still part of our Milky Way galaxy. The colors used in this image represent specific wavelengths of infrared light. Blue and cyan (blue-green) represent light emitted at wavelengths of 3.4 and 4.6 microns, which is predominantly from stars. Green and red represent light from 12 and 22 microns, respectively, which is mostly emitted by dust.

In perfetto spirito natalizio questa spettacolare nebulosa ripresa dal telescopio WISE della NASA ha l’aspetto allegro ed elegante di una festosa ghirlanda, ornata di un bel nastro rosso, sempreverde e lucine d’argento. Il nome ufficiale è Barnard 3 o IRAS G159.6-18.5, ma è stata soprannominata in modo appropriato, Nebulosa Ghirlanda. Nubi come questa sono nursery stellari, regioni in cui nascono nuove stelle. Continua a leggere→

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Ghiaccio ovunque su Cerere

Pubblicato 18/12/2016 | Da Barbara Bubbi

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Le immagini di Cerere riprese dalla sonda Dawn della NASA hanno rivelato un mondo scuro, coperto di crateri, la cui zona più brillante è formata da sali altamente riflettenti. Ma anche se a prima vista può non sembrare, due nuovi studi dimostrano che il ghiaccio è presente ovunque sul pianeta nano. Continua a leggere→

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I pianeti esterni più comuni sono simili a Nettuno

Pubblicato 18/12/2016 | Da Barbara Bubbi

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Un nuovo studio statistico basato su pianeti individuati grazie alla tecnica del microlensing gravitazionale suggerisce che i mondi con massa simile a Nettuno siano il tipo più comune di pianeti nelle regioni esterne dei sistemi planetari. Lo studio fornisce la prima indicazione del genere di pianeti in attesa di essere scoperti lontano dalla stella ospite, dove gli scienziati ritengono che la formazione planetaria sia più efficiente. Continua a leggere→

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La Galassia Ruota di Carro

Pubblicato 18/12/2016 | Da Barbara Bubbi
An image of the Cartwheel Galaxy taken with the NASA/ESA Hubble Space Telescope has been reprocessed using the latest techniques to mark the closure of the Space Telescope European Coordination Facility (ST-ECF), based near Munich in Germany, and to celebrate its achievements in supporting Hubble science in Europe over the past 26 years. Astronomer Bob Fosbury, who is stepping down as Head of the ST-ECF, was responsible for much of the early research into the Cartwheel Galaxy along with the late Tim Hawarden — including giving the object its very apposite name — and so this image was selected as a fitting tribute. The object was first spotted on wide-field images from the UK Schmidt telescope and then studied in detail using the Anglo-Australian Telescope.Lying about 500 million light-years away in the constellation of Sculptor, the cartwheel shape of this galaxy is the result of a violent galactic collision. A smaller galaxy has passed right through a large disc galaxy and produced shock waves that swept up gas and dust — much like the ripples produced when a stone is dropped into a lake — and sparked regions of intense star formation (appearing blue). The outermost ring of the galaxy, which is 1.5 times the size of our Milky Way, marks the shock wave’s leading edge. This object is one of the most dramatic examples of the small class of ring galaxies.This image was produced after Hubble data was reprocessed using the free open source software FITS Liberator 3, which was developed at the ST-ECF. Careful use of this widely used state-of-the-art tool on the original Hubble observations of the Cartwheel Galaxy has brought out more detail in the image than ever before. Although the ST-ECF is closing, ESA’s mission to bring amazing Hubble discoveries to the public will be unaffected, with Hubblecasts, press and photo releases, and Hubble Pictures of the Week continuing to be regularly posted on spacetelescope.org. Links Space Telescope European Coordination

   

A circa 500 milioni di anni luce di distanza nella costellazione dello Scultore, la forma della Galassia Ruota di Carro (Cartwheel Galaxy) è il risultato di una collisione galattica violenta. Una galassia più piccola è passata attraverso il disco di una grande galassia e ha prodotto onde d’urto che hanno travolto gas e polveri, in modo simile alle increspature prodotte quando un sasso cade in un lago. Lo scontro titanico ha innescato nella regione intensi fenomeni di formazione stellare. Continua a leggere→

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