Dark Galaxy

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 About Dark galaxy-

• A dark galaxy is a hypothesized galaxy with no, or very few, stars. 
• They received their name because they have no visible stars, but may be detectable if they contain significant amounts of gas. 
• The team revealed that it is compact, and containing large quantities of interstellar dust, it is a young galaxy, forming stars at about 1000 times the rate of the Milky Way.
• Astronomers have long theorized the existence of dark galaxies, but there are no confirmed examples to date. 
• Dark galaxies are distinct from intergalactic gas clouds caused by galactic tidal interactions, since these gas clouds do not contain dark matter, so they do not technically qualify as galaxies. 
• Distinguishing between intergalactic gas clouds and galaxies is difficult; most candidate dark galaxies turn out to be tidal gas clouds

What is Atacama Large Millimetre/Submillimeter Array(ALMA)?

• ALMA is an astronomical interferometer of 66 radio telescopes in the Atacama Desert of northern Chile, which observe electromagnetic radiation at millimeter and submillimeter wavelengths. 
• The array has been constructed on the 5,000 m (16,000 ft) elevation Chajnantor plateau – near the Llano de Chajnantor Observatory and the Atacama Pathfinder Experiment. 
• This location was chosen for its high elevation and low humidity, factors which are crucial to reduce noise and decrease signal attenuation due to Earth’s atmosphere. 
• ALMA provides insight on star birth during the early Stelliferous era and detailed imaging of local star and planet formation.

• ALMA is an international partnership amongst Europe, the United States, Canada, Japan, South Korea, Taiwan, and 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.

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