The dust ring around the bright star Fomalhaut obtained by ALMA. The underlying blue picture is an earlier view obtained by the Hubble. Credit: ALMA (ESO/NAOJ/NRAO). Visible light image: the NASA/ESA Hubble Space Telescope
One of the most powerful supercomputers in the world has now been fully installed and tested at its remote, high altitude site in the Andes of northern Chile. The Atacama Large Millimeter/ submillimeter Array (ALMA), is the most elaborate ground-based telescope in history. And Scientists say it will be a game changer in studying the origins of our universe.
The completion of the special-purpose ALMA correlator has over 134 million processors and performs up to 17 quadrillion operations per second, a speed comparable to the fastest general-purpose supercomputer in operation today. This marks one of the major remaining milestones. Astronomers using the telescope to studying a newborn star have already caught a detailed glimpse of planets forming around it, revealing a never-before seen stage of planetary evolution. Detailed visions of star and planet formation, hidden from the eyes of modern optics, can now seen by the ground breaking ALMA radio telescope.
How do planets form? Astronomers at ALMA have caught a giant planet in a nearby solar system being born. Artist’s impression Credit: ALMA (ESO/NAOJ/NRAO)/M. Kornmesser (ESO)
The new star, HD 142527, is the 450-light-years away and at just 2 million years old, is considered to be quite young by cosmological standards. The star — about twice that mass of our sun — is still growing. Such stars grow by “feeding” off of the large, surrounding disc of gas and dust that is left over following its initial nucleosynthesis. This image shows the disk of gas and cosmic dust around the young star HD 142527. Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope have seen vast streams of gas flowing across the gap in the disc. These are the first direct observations of these streams.
Large gas giant planets appear to be clearing a gap in the disk of material surrounding the star, and using gravity to channel material across the gap to the interior, helping the star to grow. Theoretical simulations have predicted such bridges between outer and inner portions of disks surrounding stars, but none have been directly observed until now.
These discs of gas and matter are also the source of planetesimals, or ‘baby planets’, that slowly accrue more and more gas and dust and, over long time scales, become more dense and can form the cores of planets. It is this process that is theorized to cause the gaps observed in other star discs. But this earlier stage of planet formation has never before been observed.
An image taken by ALMA during the early testing stage shows the Antennae Galaxies Collision. Credit: ALMA (ESO/NAOJ/NRAO). Visible light image: the NASA/ESA Hubble Space Telescope.
The ALMA correlator’s 134 million processors will continually combine and compare faint celestial “signals” received by as many as 50 dish-shaped antennas in the main ALMA array, enabling the antennas to work together as a single, enormous astronomical telescope. The correlator can additionally accommodate up to 14 of the 16 antennas in the Atacama Compact Array (ACA), a separate part of ALMA provided by the National Astronomical Observatory of Japan (NAOJ), for a total of 64 antennas . In radio telescope arrays, sensitivity and image quality increase with the number of antennas.
Funded by the US National Science Foundation (NSF), and designed, constructed, and installed primarily by the National Radio Astronomy Observatory (NRAO), the ALMA correlator is a critical component in a radio telescope system that astronomers are already using to make new discoveries about how planets, stars, and galaxies form. Unlike optical telescopes, which observe visible light emitted by stars, ALMA explores a region of the spectrum of invisible light, the millimeter and sub-millimeter wavelength realm. It’s the most expensive one too, with construction costs going up to $1.3 billion. ALMA’s been devised and built by the joint efforts of scientists from European, East Asian and North American countries for more than a decade.
When observing, ALMA’s antennas point at the same celestial object in the sky, gathering faint radio waves. Before astronomers can make detailed images or do other analyses, the information collected by dishes separated by as much as 16 kilometers must be extensively computer processed.
The ALMA correlator performs the first critical steps in this data processing. To make the entire system work as a single telescope, the information collected by each antenna must be combined with that from every other antenna. At the correlator’s maximum capacity of 64 antennas, there are 2,016 antenna pair combinations, and as many as 17 quadrillion calculations every second.
View of a Radio telescope antennas of the ALMA ( Atacama Large Millimeter/submillimeter Array) project, in the Chajnantor plateau, Atacama desert, some 1500 km north of Santiago, on March 12,2013 (AFP Photo / Martin Bernetti)