The last 12-m (40-ft) antenna has arrived at the Atacama Large Millimeter/submillimeter Array (ALMA), pushing the project closer to its full operational potential. The final antenna was supplied by the European side of the venture, and completes the 66-dish array stretching across the Chajnantor Plateau in Chile's Atacama Desert. The telescope, which was inaugurated in March, has already made a number of significant discoveries despite its incomplete nature.

The ALMA project is one of the largest and most advanced of its kind. The telescope is a US$1.3 billion joint venture between Europe, North America and East Asia, and spans 16 km (10 miles) across the arid plateau. The high altitude and dry conditions of the Atacama Desert make it the perfect location for the array, which comprises 66 dishes designed to work as one telescope, collecting light from wavelengths found between infrared and radio waves.

These wavelengths, known as millimeter and submillimeter light, emanate from particular cold and distant parts of the universe and have received comparatively little attention in the past.

Early Results

By studying these wavelengths, astronomers hope to answer important questions about the origins of the universe. In fact, despite its incomplete nature, ALMA data has already been used to make a number of important discoveries.

In March 2013, shortly after its inauguration and with only 19 active antennas, the telescope made its first significant discovery. Observing the light from distant galaxies, astronomers were able to detect bursts of star birth that took place 12 billion years ago, a billion years earlier than previously thought. The study also marks the most distant observation of water, with the molecules found in one of the ancient galaxies.

ALMA/ESA Hubble Space Telescope composite images showing five distant galaxies, with ALMA observations shown in red (Image: ESO/NASA)

A month on, the telescope was used to map star-forming galaxies in the early Universe. Though the telescope was only at one quarter capacity, the results of the study provided a significantly clearer picture of the early universe than previous projects, paving the way for future studies.

A close up of star-forming galaxies in the early Universe, with ALMA observations visible in orange and red (Image: ESO/NASA)

In July, ALMA pictured the Milky Way's largest known stellar womb residing within the Spitzer Dark Cloud some 11,000 light-years from Earth. The object, which is still growing in size, is around 500 times the size of the Sun and will eventually produce a star with a mass of anything up to 100 times the size of our home star.

A composite image of stellar womb within the Milky Way, combining ALMA and NASA Spitzer Space Telescope imagery (Image: ESO/NASA)

This may seem like an impressive list considering the telescope's youth, but the above isn't even close to an exhaustive account of ALMA's achievements to date. The telescope has been used on a number of other projects including a detailed study of the newborn star Herbig-Haro 46/47 and a project focusing on the effect of star formation on outflow of molecular gas.

Looking Forward

With all of the above studies having been carried out using just a quarter or less of the telescope's full array of 66 dishes, it's likely that this is just a glimpse of the project's bright future. Now that the last antenna has arrived at the project's lofty site, the array is expected to be working as a single telescope by the end of the year. If the early stages of its life are anything to go by, then we can look forward to further game-changing discoveries from ALMA in the near future.

See the video below for a look at the final antenna being moved into position onsite in Chile.

Source: ESO

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