Annonce

ALMA réussit ses observations à la plus haute résolution

15 novembre 2023

L'Atacama Large Millimeter/submillimeter Array (ALMA), dont l'ESO est partenaire, a atteint la plus haute résolution de ses observations depuis le début de ses opérations. Lors d'un test technique, une équipe d'experts du Joint ALMA Observatory (JAO), du National Astronomical Observatory of Japan (NAOJ), du National Radio Astronomy Observatory (NRAO) aux États-Unis, et l'ESO, ont réalisé une photo d'une vielle étoile avec une résolution de 5 millisecondes d'arc. C'est la preuve qu'ALMA peut servir aux astronomes pour observer des objets avec des détails équivalents à voir un bus de 10 mètres de long sur la Lune.

ALMA se compose de 66 antennes qui peuvent être disposées en différentes positions sur le plateau de haute altitude de Chajnantor, au Chili. Chaque antenne est équipée de détecteurs qui lui permettent d'observer les ondes radio dans différentes gammes de fréquences, ou bandes. La résolution d'ALMA augmente à la fois en fonction de la distance maximale entre les antennes et de la fréquence des observations. Les nouvelles images ont été obtenues dans la configuration la plus étendue possible du réseau ALMA, avec une séparation maximale entre ses antennes de 16 km. Elles ont été réalisées en utilisant les détecteurs de la bande 10, qui permettent à ALMA d'observer à des fréquences aussi élevées que 950 GHz, les plus élevées possibles pour le réseau.

Comme ces observations poussent les capacités de l'ALMA à l'extrême, elles ont été incroyablement difficiles à réaliser. Bien que les récepteurs de la bande 10 soient disponibles sur ALMA depuis 2014, les astronomes ont dû attendre la validation d'une nouvelle technique d'étalonnage, appelée bande à bande, pour pouvoir effectuer ces nouvelles observations. C'est ce qu'ils ont fait lors d'un test technique en 2021 en observant une étoile évoluée de la Voie lactée, R Leporis, en utilisant comme calibreur un noyau galactique brillant qui, bien que distant, apparaît à proximité de R Leporis dans le ciel. Les résultats sont publiés aujourd'hui dans l'Astrophysical Journal.

Plus d'informations

Ce résultat a été obtenu grâce au soutien important du personnel de l'ESO, qui a participé aux observations de test, aux expériences précédentes qui ont conduit à cette réalisation technique finale, et au développement de la nouvelle technique d'étalonnage.

Ce résultat a été présenté dans l'article intitulé “ALMA High-frequency Long Baseline Campaign in 2021: Highest Angular Resolution Submillimeter Wave Images for the Carbon-rich Star R Lep”, à paraître dans la revue Astrophysical Journal (doi:10.3847/1538-4357/acf619).

L'équipe est composée de Y. Asaki (JAO; NAOJ; SOKENDAI), L. Maud (ESO; Leiden University), H. Francke (JAO), H. Nagai (NAOJ), D. Petry (ESO), E. B. Fomalont (NRAO), E. Humphreys (JAO; ESO), A. M. S. Richards (Université de Manchester), K. T. Wong (IRAM; Uppsala University), W. Dent (JAO), A. Hirota (JAO; NAOJ), J. M. Fernandez (Lowell Observatory), S. Takahashi (NAOJ), and A. S. Hales (JAO; NRAO).

Une précédente étude technique, menant à la campagne 2021 est disponible dans l'article “ALMA High-frequency Long-baseline Campaign in 2019: Band 9 and 10 In-band and Band-to-band Observations Using ALMA's Longest Baselines”, publié dans la revue Astrophysical Journal du mois d'août 2023 (doi: 10.3847/1538-4365/acd6f1).

ALMA est un partenariat de l'ESO (représentant ses Etat-membres), le NSF (États-Unis) et le NINS (Japon), ainsi que le NRC (Canada), le NSTC et l'ASIAA (Taïwan), et le KASI (Corée du Sud), en coopération avec la République du Chili. Le Joint ALMA Observatory est géré par l'ESO, le AUI/NRAO et le NAOJ.

Liens

 

 

Contacts

Luke Maud
ALMA Regional Centre at ESO
Garching bei München, Allemagne
Tel: +49 89 3200 6765
Email:
Luke.Maud@eso.org

Bárbara Ferreira
ESO Media Manager
Garching bei München, Allemagne
Tel: +49 89 3200 6670
Email:
press@eso.org

À propos de l'annonce

Identification:ann23019

Images

R Leporis telle qu'observée par ALMA
R Leporis telle qu'observée par ALMA
Méthode de calibrage utilisée pour atteindre la plus haute résolution d'image avec ALMA
Méthode de calibrage utilisée pour atteindre la plus haute résolution d'image avec ALMA

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