| 词条 | Dragonfly Telephoto Array |
| 释义 |
The Dragonfly Telephoto Array is a ground-based optical telescope array that uses a combination of telephoto lenses to observe extragalactic objects.[1] Its main purpose is to take images of ultra-low surface brightness galaxies at visible wavelengths of light. It is well suited for this purpose because its lenses have specially-coated optical glass that reduces scattered light. The telescope was commissioned in 2013 with eight lenses. The number of lenses first increased to ten Canon 400 lenses, and was extended to 2 clusters of 24 lenses in 2016.[2][3][4] The Array is designed to accommodate the addition of lenses to increase its effective aperture with each additional lens.[5] With 48 lenses, the instrument has the light gathering power equivalent to a 99 cm diameter refractor, with a focal length of 40 cm. Astronomers used the Dragonfly Telephoto Array to discover Dragonfly 44, a galaxy that is roughly as massive as the Milky Way, with 99.9% of its mass composed of dark matter.[6] At the other end of the scale it was also used to discover NGC 1052-DF2 which measurements with other instruments suggest is a galaxy with very little dark matter.[7] References1. ^{{cite web|title=Dragonfly - Dunlap Institute|url=http://www.dunlap.utoronto.ca/instrumentation/dragonfly/|website=Dunlap Institute for Astronomy and Astrophysics|accessdate=5 March 2018}} 2. ^http://www.dunlap.utoronto.ca/how-do-you-make-a-galaxy-without-dark-matter/ 3. ^{{cite web|last1=Estes|first1=Adam C.|title=Astronomers Invent New Telescope by Tying Telephoto Lenses Together|url=https://gizmodo.com/astronomers-invent-new-telescope-by-tying-telephoto-len-1604666784|website=Gizmodo|accessdate=5 March 2018}} 4. ^{{cite web|title=Dragonfly - Yale University|url=http://www.astro.yale.edu/dragonfly/|accessdate=5 March 2018}} 5. ^{{cite journal|last1=Abraham|first1=Roberto G.|last2=van Dokkum|first2=Pieter|title=Ultra – Low Surface Brightness Imaging with the Dragonfly Telephoto Array|journal=Publications of the Astronomical Society of the Pacific|date=January 2014|volume=126|issue=935|page=55|arxiv=1401.5473|bibcode=2014PASP..126...55A|doi=10.1086/674875}} 6. ^{{cite web|title=Meet Dragonfly 44, the galaxy made of 99.9% dark matter|url=https://www.wired.co.uk/article/dark-matter-galaxy-dragonfly-44|publisher=Wired|accessdate=5 March 2018}} 7. ^{{cite journal|doi=10.1038/nature25767|pmid=29595770|title=A galaxy lacking dark matter|journal=Nature|volume=555|issue=7698|pages=629|year=2018|last1=Van Dokkum|first1=Pieter|last2=Danieli|first2=Shany|last3=Cohen|first3=Yotam|last4=Merritt|first4=Allison|last5=Romanowsky|first5=Aaron J|last6=Abraham|first6=Roberto|last7=Brodie|first7=Jean|last8=Conroy|first8=Charlie|last9=Lokhorst|first9=Deborah|last10=Mowla|first10=Lamiya|last11=o'Sullivan|first11=Ewan|last12=Zhang|first12=Jielai|arxiv=1803.10237|bibcode=2018Natur.555..629V}} 1 : Optical telescopes |
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