Anúncio
ALMA obtém observações da mais alta resolução possível
15 de Novembro de 2023
O Atacama Large Millimeter/submillimeter Array (ALMA), do qual o ESO é um parceiro, atingiu a mais alta resolução de observações desde o início das suas operações. Durante um teste técnico, uma equipa de especialistas do Observatório Conjunto do ALMA (JAO), do Observatório Astronómico Nacional do Japão (NAOJ), do Observatório Nacional de Radioastronomia (NRAO) nos EUA e do ESO, obteve imagens de uma estrela evoluída com uma resolução angular de 5 milissegundos de arco. Isto mostra que o ALMA pode ser usado pelos astrónomos para observar objetos com um detalhe equivalente a conseguirmos ver um autocarro de 10 metros na Lua.
O ALMA é composto por 66 antenas que podem ser colocadas em diferentes posições no planalto do Chajnantor, no Chile. Cada uma está equipada com recetores que lhe permitem observar ondas rádio em diferentes gamas de frequência, ou bandas. A resolução do ALMA aumenta com o aumento da separação máxima entre as antenas e com o aumento da frequência a que se observa. As novas imagens foram obtidas com a configuração mais alargada possível da rede ALMA: uma separação máxima entre as antenas de 16 km. As observações foram realizadas com os recetores de Banda 10, que permitem ao ALMA observar a frequências de 950 GHz, as mais altas possíveis para a rede.
As observações foram bastante difíceis de executar, já que foi necessário utilizar as capacidades mais extremas do ALMA. Embora os recetores de Banda 10 estejam já disponíveis desde 2014, os astrónomos tiveram de esperar pela validação de uma nova técnica de calibração (chamada banda a banda), para poderem realizar as novas observações. Isso ocorreu durante um teste técnico em 2021, quando foi observada uma estrela evoluída da Via Láctea, R Leporis. Foi utilizado como calibrador um núcleo galáctico brilhante, o qual, apesar de distante, aparece-nos no céu perto desta estrela. Os resultados foram publicados hoje na revista da especialidade Astrophysical Journal.
Para se alcançar este resultado o apoio do pessoal do ESO foi crucial, já que esteve envolvido nas observações de teste, nas experiências anteriores que conduziram a este feito técnico final e no desenvolvimento da nova técnica de calibração.
Informações adicionais
Este resultado foi descrito num artigo intitulado “ALMA High-frequency Long Baseline Campaign in 2021: Highest Angular Resolution Submillimeter Wave Images for the Carbon-rich Star R Lep” publicado na revista da especialidade Astrophysical Journal (doi:10.3847/1538-4357/acf619).
A equipa é composta por: Y. Asaki (JAO; NAOJ; SOKENDAI), L. Maud (ESO; Universidade de Leiden), H. Francke (JAO), H. Nagai (NAOJ), D. Petry (ESO), E. B. Fomalont (NRAO), E. Humphreys (JAO; ESO), A. M. S. Richards (University of Manchester), K. T. Wong (IRAM; Universidade de Uppsala), W. Dent (JAO), A. Hirota (JAO; NAOJ), J. M. Fernandez (Lowell Observatory), S. Takahashi (NAOJ) e A. S. Hales (JAO; NRAO).
Um estudo técnico anterior, que levou à Campanha de 2021 pode ser encontrado em: “ALMA High-frequency Long-baseline Campaign in 2019: Band 9 and 10 In-band and Band-to-band Observations Using ALMA's Longest Baselines”, também publicado na revista Astrophysical Journal em Agosto de 2023 (doi: 10.3847/1538-4365/acd6f1).
O ALMA é uma parceria entre: ESO (que representa os seus Estados Membros), NSF (EUA) e NINS (Japão), juntamente com NRC (Canadá), NSTC e ASIAA (Taiwan), e KASI (República da Coreia), em cooperação com a República do Chile. O Observatório Conjunto do ALMA é operado pelo ESO, AUI/NRAO e NAOJ.
Links
Contactos
Luke Maud
ALMA Regional Centre at ESO
Garching bei München, Alemanha
Tel: +49 89 3200 6765
Email: Luke.Maud@eso.org
Bárbara Ferreira
ESO Media Manager
Garching bei München, Alemanha
Tel: +49 89 3200 6670
Email: press@eso.org
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