Astronomy:Dragonfly Telephoto Array
The Dragonfly Telephoto Array is a ground-based optical telescope array developed at the Dunlap Institute for Astronomy & Astrophysics of the University of Toronto in Canada. The array 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.
Design
The telescope was designed by Roberto Abraham of the University of Toronto and Pieter van Dokkum of Yale University.[2] It was commissioned in 2013[1] and initially had eight commercially available Canon EF 400mm f/2.8L IS II USM camera lenses.[3] This was first increased to ten lenses, and was extended to two clusters of 24 lenses each in 2016.[4][5][6] The array is designed to accommodate the addition of lenses to increase its effective aperture with each additional lens.[3]
With 48 lenses, the instrument has a light gathering power equivalent to a 400 mm f/0.4 lens, or a refracting telescope with an objective lens diameter of 990 mm (39 in). In March 2021 plans were announced to add 120 more lenses.[7]
By using a lens based refactor design rather than a mirror based reflector design the telescope suffers less from issues introduced by diffraction and light scattering.[8] Reflector designs have more light scattering due to interactions with dust and any slight roughness on the mirror.[8] Issues with diffraction occur due to the need to place obstructions in the optical path of reflecting telescopes.[8]
Research
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.[9] At the other end of the scale it was also used to discover NGC 1052-DF2, which measurements with other instruments initially suggested was a galaxy with very little dark matter.[10] Further work indicated that NGC 1052-DF2 was closer to the earth than previous thought.[11] If this is the case then the galaxy appears to contain a typical amount of dark matter.[11]
References
- ↑ 1.0 1.1 "Dragonfly - Dunlap Institute". http://www.dunlap.utoronto.ca/instrumentation/dragonfly/.
- ↑ "A New Kind of Telescope" (in en-US). https://magazine.utoronto.ca/research-ideas/technology/a-new-kind-of-telescope-dragonfly-telephoto-array/.
- ↑ 3.0 3.1 Abraham, Roberto G.; van Dokkum, Pieter (January 2014). "Ultra – Low Surface Brightness Imaging with the Dragonfly Telephoto Array". Publications of the Astronomical Society of the Pacific 126 (935): 55. doi:10.1086/674875. Bibcode: 2014PASP..126...55A.
- ↑ "How Do You Make A Galaxy Without Dark Matter?". http://www.dunlap.utoronto.ca/how-do-you-make-a-galaxy-without-dark-matter/.
- ↑ Estes, Adam C.. "Astronomers Invent New Telescope by Tying Telephoto Lenses Together". https://gizmodo.com/astronomers-invent-new-telescope-by-tying-telephoto-len-1604666784.
- ↑ "Dragonfly - Yale University". http://www.astro.yale.edu/dragonfly/.
- ↑ Lens array captures dim objects missed by giant telescopes, Science, Vol 371 p1301 26 March 2021
- ↑ 8.0 8.1 8.2 Jielai Zhang (2018). The Development and Scientific Application of the Dragonfly Telephoto Array (PDF) (PhD). University of Toronto. p. 10.
- ↑ "Meet Dragonfly 44, the galaxy made of 99.9% dark matter". Wired. https://www.wired.co.uk/article/dark-matter-galaxy-dragonfly-44.
- ↑ Van Dokkum, Pieter; Danieli, Shany; Cohen, Yotam; Merritt, Allison; Romanowsky, Aaron J; Abraham, Roberto; Brodie, Jean; Conroy, Charlie et al. (2018). "A galaxy lacking dark matter". Nature 555 (7698): 629–632. doi:10.1038/nature25767. PMID 29595770. Bibcode: 2018Natur.555..629V.
- ↑ 11.0 11.1 Trujillo, Ignacio (14 March 2019). "A distance of 13 Mpc resolves the claimed anomalies of the galaxy lacking dark matter". Monthly Notices of the Royal Astronomical Society 486 (1): 1192–1219. doi:10.1093/mnras/stz771. Bibcode: 2019MNRAS.486.1192T. https://academic.oup.com/mnras/article-abstract/486/1/1192/5380810?redirectedFrom=fulltext. Retrieved 5 June 2019.
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