Fomalhaut b

Astrônomos americanos anunciaram que o Telescópio Espacial Hubble captou a imagem de um novo exoplaneta, pela primeira vez, com luz natural, distante apenas 25 anos-luz da Terra, a constelação de Piscus Austrinus (Peixe do Sul).

A imagem mostra o sistema planetário em sua totalidade, formado por um cinturão de poeira e fragmentos cósmicos junto ao exoplaneta, chamado Fomalhaut b, cujo movimento de translação em torno de seua estrela dura o equivalente a 872 anos terrestres.

Até hoje, foram detectados cerca de 300 exoplanetas, mas nenhum pela observação de sua luz natural. O exoplaneta deve ter massa semelhante à de Júpiter, e orbita uma estrela chamada Fomalhaut. Poderia ter um sistema de anéis como teve Júpiter, que depois formaram suas luas.

Astrónomos estadounidenses han anunciado hoy que el telescopio espacial Hubble ha captado la primera imagen fotográfica con luz natural de un exoplaneta (que orbita alrededor de otro sol) a sólo 25 años luz de la Tierra, en la constelación de Piscus Austrinus. La imagen muestra el sistema planetario en su totalidad formado por un cinturón de polvo y escombros cósmicos junto al exoplaneta, llamado Fomalhaut b, cuyo movimiento de traslación en torno a la estrella dura 872 años terrestres.

Hasta ahora se había determinado la existencia de unos 300 exoplanetas, pero nunca se había conseguido captar la imagen de uno de ellos con luz natural.

El exoplaneta tiene probablemente la masa de Júpiter y gira en la órbita de una estrella identificada como Fomalhaut. Podría tener un sistema de anillos similares a los que rodearon a Júpiter y que después se condensaron para formar lo que son ahora sus lunas.

NASA's Hubble Space Telescope has taken the first visible-light snapshot of a planet circling another star. The team of astronomers who made the discovery includes researchers at NASA's Jet Propulsion Laboratory, Pasadena, Calif. Estimated to be no more than three times Jupiter's mass, the planet, called Fomalhaut b, orbits the bright southern star Fomalhaut, located 25 light-years away in the constellation Piscis Australis, or the "Southern Fish."

Fomalhaut has been a candidate for planet hunting ever since an excess of dust was discovered around the star in the early 1980s by NASA's Infrared Astronomy Satellite. In 2004, the coronagraph in the High Resolution Camera on Hubble's Advanced Camera for Surveys produced the first-ever resolved visible-light image of the region around Fomalhaut. It clearly showed a ring of protoplanetary debris approximately 21.5 billion miles (34.6 billion kilometers) across and having a sharp inner edge.

This large debris disk is similar to the Kuiper Belt, which encircles our solar system and contains a range of icy bodies from dust grains to objects the size of dwarf planets, such as Pluto. Hubble astronomer Paul Kalas, of the University of California at Berkeley, and team members proposed in 2005 that the ring was being gravitationally modified by a planet lying between the star and the ring's inner edge. Circumstantial evidence came from Hubble's confirmation that the ring is offset from the center of the star.

The sharp inner edge of the ring is also consistent with the presence of a planet that gravitationally "shepherds" ring particles. Independent researchers have subsequently reached similar conclusions. Now, Hubble has actually photographed a point source of light lying 1.8 billion miles (2.9 billion kilometers) inside the ring's inner edge. The results are being reported in the November 14 issue of Science magazine. "Our Hubble observations were incredibly demanding. Fomalhaut b is 1 billion times fainter than the star. We began this program in 2001, and our persistence finally paid off," Kalas said.