ALMA celebrates ten years of science

Ten years ago today, the Atacama Large Millimetre/submillimetre Array (ALMA), an international observatory in which ESO is a partner, officially opened to astronomers. The occasion was marked with the release of the first image taken with the array — of the colliding Antennae Galaxies — showcasing ALMA’s potential and heralding the start of a successful decade of astronomy.

Located on the Chajnantor plateau in northern Chile at an elevation of 5000 metres, the array was operating with only a third of its 66 movable antennas when it first opened for scientific observations. Nonetheless, ALMA received over 900 observing proposals, with around 100 being selected, showing just how excited the scientific community were to make use of this new facility. Over the past decade, ALMA has continued to be in high demand for astronomers around the world: observing proposals still far outstrip the available time, and many interesting and novel projects are proposed each year.

The ALMA antennas, spread over distances of up to 16 km, work together as a single telescope observing the Universe in light with millimetre and submillimetre wavelengths, roughly one thousand times longer than visible-light wavelengths. These longer wavelengths are emitted by some of the coldest objects in space, such as the dense clouds of cosmic dust and gas from which stars and planets form, as well as very distant objects in the early Universe. By using interferometry, ALMA has a maximum spatial resolution better than that achieved at visible wavelengths by the NASA/ESA Hubble Space Telescope. Even 10 years on, ALMA remains the largest and most powerful telescope operating in the millimetre and submillimetre range.

In its first decade, ALMA has been used by astronomers across the globe to make significant astronomical breakthroughs. ALMA has so far provided data for close to 2500 papers, around half of these using data obtained during the European ALMA observing time. Highlights include observations of the planetary disc around the young star HL Tauri, revolutionising our understanding of how planets form, images of an Einstein ring which provides the sharpest ever view of star formation in the distant Universe, and the detection of complex organic molecules in an infant star system. In addition, ALMA was one of the eight ground-based telescopes used as part of the Event Horizon Telescope collaboration to capture the first image of a black hole, the supermassive object at the heart of the M87 galaxy.

A truly global astronomy facility, ALMA is the result of an international association between Europe (ESO), North America (National Radio Astronomy Observatory [NRAO]) and East Asia (National Astronomical Observatory of Japan [NAOJ]), in collaboration with Chile. ESO has contributed about a third of the project’s construction and operation budget. Together with industrial partners, ESO built 25 antennas, two special transporters that can move antennas across the Chajnantor plateau, as well as three receiver bands, with a further set of receivers currently being built in Europe [1]. ESO is also the home of the European ALMA Regional Centre, which provides the interface between the ALMA project and the European science community.

Note

[1] Each ALMA antenna is currently operating with receivers capturing light in eight wavelength bands, ranging from band 3, starting at wavelengths of 3.6 mm, to band 10, ending at 0.3 mm. Band 1 (covering wavelengths between 6 and 8.5 millimetres) will be fully operational soon, and band 2 (covering 3.3 to 4.5 millimetres) will be added in the future.

More Information

ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.

Courtesy of European Southern Observatory