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The Atacama Large Millimeter/submillimeter Array (ALMA) is an astronomical interferometer of radio telescopes in the Atacama desert of northern Chile. Since a high and dry site is crucial to millimeter wavelength operations, the array has been constructed on the Chajnantor plateau at 5,000 meters altitude, near Llano de Chajnantor Observatory and Atacama Pathfinder Experiment. Consisting of 66 12-meter (39 ft), and 7-meter (23 ft) diameter radio telescopes observing at millimeter and submillimeter wavelengths, ALMA is expected to provide insight on star birth during the early universe and detailed imaging of local star and planet formation. ALMA is an international partnership among Europe, the United States, Canada, East Asia and the Republic of Chile. Costing about US$1.4 billion, it is the most expensive ground-based telescope in operation. ALMA began scientific observations in the second half of 2011 and the first images were released to the press on 3 October 2011. The array has been fully operational since March 2013.〔(【引用サイトリンク】url=http://www.bbc.co.uk/news/science-environment-21774448 )〕 ==Overview== The initial ALMA array will be composed of 66 high-precision antennas, and operate at wavelengths of 0.3 to 9.6 mm. The array will have much higher sensitivity and higher resolution than existing submillimeter telescopes such as the single-dish James Clerk Maxwell Telescope or existing interferometer networks such as the Submillimeter Array or the ''Institut de Radio Astronomie Millimétrique'' (IRAM) Plateau de Bure facility. The antennas can be moved across the desert plateau over distances from 150 m to 16 km, which will give ALMA a powerful variable "zoom", similar in its concept to that employed at the Very Large Array (VLA) site in New Mexico, United States. The high sensitivity is mainly achieved through the large numbers of telescopes that will make up the array. The telescopes are provided by the European, North American and East Asian partners of ALMA. The American and European partners have each placed orders for twenty-five 12-meter diameter antennas, that will compose the main array. East Asia is contributing 16 antennas (four 12-meter diameter and twelve 7-meter diameter antennas) in the form of the Atacama Compact Array (ACA), which is also part of the enhanced ALMA. By using smaller antennas than the main ALMA array, larger fields of view can be imaged at a given frequency using ACA. Moving the antennas closer together will enable the imaging of sources of larger angular extent. The ACA will work together with the main array in order to enhance the latter's wide-field imaging capability. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Atacama Large Millimeter Array」の詳細全文を読む スポンサード リンク
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