Galaxy in constellation Coma Berenices
Dragonfly 44 is an ultra diffuse galaxy in the Coma Cluster .[ 1] [ 3] [ 2] [ 4] This galaxy is well-known because observations of the velocity dispersion in 2016 suggested a mass of about one trillion solar masses , about the same as the Milky Way . This mass was consistent with a count of about 90 and 70 globular clusters observed around Dragonfly 44 in two different studies.
Later, spatially resolved kinematics measured a mass of about 160 billion solar masses , six times less than early mass measurements and one order of magnitude less than the Milky Way's mass.[ 5] The most recent work found 20 globular clusters around the galaxy, which is consistent with the current mass measurement.[ 6] [ 7] The lack of X-ray emission from the galaxy and its surroundings also shows that the number of globular clusters cannot be as many as was claimed before.[ 8]
The galaxy emits only 1% of the light emitted by the Milky Way.[ 9] The galaxy was discovered with the Dragonfly Telephoto Array .[ 10]
^ a b c Van Dokkum, Pieter; et al. (7 January 2015). "Forty-Seven Milky Way-sized, Extremely Diffuse Galaxies in the Coma-Cluster". The Astrophysical Journal Letters . 798 (2): L45. arXiv :1410.8141 . Bibcode :2015ApJ...798L..45V . doi :10.1088/2041-8205/798/2/L45 . S2CID 119279968 .
^ a b c Van Dokkum, Pieter; et al. (1 May 2015). "Spectroscopic confirmation of the existence of large, diffuse galaxies in the coma cluster". The Astrophysical Journal Letters . 804 (1): L26. arXiv :1504.03320 . Bibcode :2015ApJ...804L..26V . doi :10.1088/2041-8205/804/1/L26 . S2CID 54664026 .
^ "Scientists discover the fluffiest galaxies" . phys.org . 14 May 2015.
^ "Dragonfly 44: Ultra-Diffuse Galaxy Made Mostly of Dark Matter" . Sci.News. 25 August 2016. Retrieved 21 January 2024 .
^ Van Dokkum, Pieter; Wasserman, Asher; Danieli, Shany; Abraham, Roberto; Brodie, Jean; Conroy, Charlie; Forbes, Duncan A.; Martin, Christopher; Matuszewski, Matt; Romanowsky, Aaron J.; Villaume, Alexa (2019). "Spatially Resolved Stellar Kinematics of the Ultra-diffuse Galaxy Dragonfly 44. I. Observations, Kinematics, and Cold Dark Matter Halo Fits, Peter van Dokkum et al. 2019" . The Astrophysical Journal . 880 (2): 91. arXiv :1904.04838 . doi :10.3847/1538-4357/ab2914 . S2CID 119185644 .
^ Saifollahi, Teymoor; Trujillo, Ignacio; Beasley, Michael A.; Peletier, Reynier F.; Knapen, Johan H. (2020). " "The number of globular clusters around the iconic UDG DF44 is as expected for dwarf galaxies", Saifollahi et al. 2020" . Monthly Notices of the Royal Astronomical Society . 502 (4): 5921–5934. arXiv :2006.14630 . doi :10.1093/mnras/staa3016 . S2CID 220127887 .
^ "The puzzle of the strange galaxy made of 99.99% dark matter is solved" . Instituto de Astrofísica de Canarias . 13 October 2020. Retrieved 21 January 2024 .
^ Bogdan, Akos (2020). " "The American Astronomical Society, find out more The Institute of Physics, find out more The Archetypal Ultra-diffuse Galaxy, Dragonfly 44, Is not a Dark Milky Way", Bogdan 2020" . The Astrophysical Journal Letters . arXiv :2009.07846 . doi :10.3847/2041-8213/abb886 . S2CID 221761669 .
^ Crosswell, Ken (26 July 2016). "The Milky Way's dark twin revealed" . Nature News. Retrieved 30 July 2016 .
^ Rachel Feltman (25 August 2016). "A new class of galaxy has been discovered, one made almost entirely of dark matter" . The Washington Post .