Anúncio

O caçador de planetas ESPRESSO prepara-se para rumar ao Chile

22 de Agosto de 2017

O instrumento ESPRESSO — Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations — passou a fase de aceitação preliminar na Europa, o que significa que completou de forma bem sucedida todos os testes preliminares e será agora embalado e enviado para o Chile, para ser instalado no foco coudé combinado do Very Large Telescope (VLT). Espera-se que o ESPRESSO veja a sua primeira luz no final de 2017.

O ESPRESSO, um espectrógrafo echelle, é um dos instrumentos aguardados com mais expectativa pela comunidade astronómica mundial [1]. É o sucessor do instrumento HARPS, o caçador de exoplanetas do ESO montado no telescópio de 3,6 metros em La Silla, e terá cerca de dez vezes mais precisão que o seu predecessor [2]. Como caçador de planetas de próxima geração, o ESPRESSO medirá minúsculas variações na luz emitida pelas estrelas, que ocorrem quando existem planetas em sua órbita — muitos deles mais pequenos que Neptuno. Este método, conhecido por método das velocidades radiais, procura variações minúsculas no movimento de uma estrela, originadas pela influência gravitacional dos planetas — a estrela “oscila” à medida que o planeta gira à sua volta. Quanto mais pequeno for o planeta, mais pequena será esta oscilação, de modo que para detectar exoplanetas pequenos e rochosos, passíveis de albergar vida, precisamos de um instrumento com uma precisão muito elevada. Através deste método, o ESPRESSO será capaz de detectar alguns dos planetas mais pequenos que esperamos encontrar [3].

Tal como o HARPS, o ESPRESSO será também usado para espectroscopia de trânsito de exoplanetas — quando, visto a partir da Terra, um planeta passa em frente da sua estrela progenitora — assim como para espectroscopia de trânsito de candidatos a exoplanetas — para confirmar a sua natureza planetária e determinar a sua massa. Esta técnica observacional permite aos astrónomos determinar elementos constituintes chave da atmosfera de um planeta, tais como o sódio ou o vapor de água.

O ESPRESSO utilizará radiação colectada por qualquer um dos quatro Telescópios Principais (UT) do VLT, mas poderá também combinar a radiação colectada pelos quatro UT do VLT, tirando assim partido de uma área colectora equivalente a um único telescópio de 16 metros de diâmetro e tornando possível a observação de objetos muito ténues. Deste modo, o ESPRESSO poderá investigar também os mais profundos recantos do Universo, observando com elevada precisão o meio intergaláctico que existe entre nós e quasares muito distantes e permitindo investigar se as constantes fundamentais da física variam no tempo ou no espaço.

Notas

[1] O ESPRESSO está a ser concebido e construído por um consórcio constituído por: Observatório Astronómico da Universidade de Genebra e Universidade de Berna, Suíça; INAF-Osservatorio Astronomico di Trieste e INAF-Osservatorio Astronomico di Brera, Itália; Instituto de Astrofísica de Canarias, Espanha; Instituto de Astrofísica e Ciências do Espaço, Universidades do Porto e Lisboa, Portugal; e ESO.

[2] O instrumento HARPS consegue medir o movimento de uma estrela com uma precisão melhor que um metro por segundo, enquanto o ESPRESSO irá ter uma precisão de alguns centímetros por segundo, graças aos avanços na tecnologia e à sua colocação num telescópio muito maior.

[3] O método das velocidades radiais é muito importante se quisermos saber as propriedades físicas de um exoplaneta, como por exemplo a sua massa. Quando combinado com os resultados obtidos por outros métodos, tal como o método dos trânsitos, podemos inferir ainda mais informação, incluindo o tamanho e a densidade do exoplaneta. O telescópio NGTS do ESO (Next-Generation Transit Survey) instalado no Paranal, procura exoplanetas pelo método dos trânsitos.

Links

Contactos

Francesco Pepe
Observatoire de l’Université de Genève
Versoix, Suíça
Tel: 0041 (0)22 379 23 96
Email: Francesco.Pepe@unige.ch

Antonio Manescau
ESO
Garching bei München, Alemanha
Tel: +49 89 3200 6142
Email: amanesca@eso.org

Gaspare Lo Curto
ESO
Santiago de Chile, Chile
Tel: +56 22 463 3092
Email: glocurto@eso.org

Richard Hook
ESO Public Information Officer
Garching bei München, Alemanha
Tel: +49 89 3200 6655
Telm: +49 151 1537 3591
Email: rhook@eso.org

Sobre o anúncio

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Imagens

ESPRESSO takes shape
ESPRESSO takes shape
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