“NGC 1052-DF2”的意思、由来-开放百科全书

NGC 1052-DF2 is an ultra diffuse galaxy in the constellation Cetus, which was identified in a wide-field imaging survey of the NGC 1052 group by the Dragonfly Telephoto Array. It has been proposed that the galaxy contains little or no dark matter, the first such discovery. On March 20, 2019, a follow-up study announcing the discovery of a second UDG lacking dark matter, DF4, was published confirming this.

The distance to the galaxy from Earth, derived by surface brightness fluctuation, is 19

1.7 Mpc. Due to close proximity, it is assumed to be associated with the elliptical galaxy NGC 1052 and to lie at a distance of about {{val|80|u=Kpc}} from NGC 1052.^[4]^[5]^[6]^[7].

The apparent lack of dark matter in NGC 1052-DF2 may help prove that dark matter is real: if what appears to be dark matter is really just a currently unknown effect of the gravity of ordinary matter then this apparent dark matter should also appear in this galaxy. Further study will be needed before this and any other possible implications can be confirmed.^[8]^[9] If confirmed, the absence of dark matter may also have implications for theories of galaxy formation, as dark matter has been thought to be needed for galaxy formation.^[9]

A later study purports to show that the galaxy may contain more dark matter than initially reported. It may have a mass-to-light ratio towards the low end of expected values for a dwarf galaxy. ^[18] However, a follow-up study on March 20, 2018 and a new discovery of a second UDG, NGC 1052-DF4, also apparently lacking dark matter challenge this study's conclusion.^[10]

[https://www.sciencealert.com/a-second-galaxy-has-been-found-without-any-dark-matter-ironically-supporting-its-existence Same as NGC 1052-DF2, Astronomers discovered a second Galaxy with No Dark Matter]. NGC 1052-DF4, is an ultra-diffuse galaxy - quite large, spread-out, and faint to observe. Discovering another galaxy with very little to no dark matter means the chances of finding more of these galaxies are now higher than cosmologists previously thought.

See also

References

1. ^{{cite web|title=Hubble finds first galaxy in the local Universe without dark matter|url=https://www.spacetelescope.org/news/heic1806/|website=www.spacetelescope.org|accessdate=30 March 2018}}
2. ^¹²{{cite simbad|title=LEDA 3097693|accessdate=15 April 2018}}
3. ^https://m.phys.org/news/2019-03-unusual-galaxies-defy-dark-theory.html
4. ^B. Famaey, S. McGaugh, M. Milgrom, "MOND and the dynamics of NGC1052-DF2" https://arxiv.org/abs/1804.04167 Monthly Notices of the Royal Astronomical Society, Volume 480, Issue 1, 11 October 2018, Pages 473–476, https://doi.org/10.1093/mnras/sty1884
5. ^Website of one of the authors of a paper regarding NGC1052-DF2 https://www.pietervandokkum.com/ngc1052-df2 (last reviewed January 21, 2019)
6. ^Evolutionary history of the elliptical galaxy NGC 1052 Michael Pierce Jean P. Brodie Duncan A. Forbes Michael A. Beasley Robert Proctor Jay StraderMonthly Notices of the Royal Astronomical Society, Volume 358, Issue 2, 1 April 2005, Pages 419–431, https://doi.org/10.1111/j.1365-2966.2005.08778.x https://academic.oup.com/mnras/article/358/2/419/998620
7. ^Stacy McGaugh, "The Dwarf Galaxy NGC1052-DF2" (April 4, 2018) https://tritonstation.wordpress.com/2018/04/04/the-dwarf-galaxy-ngc1052-df2/ last reviewed January 21 2019)
8. ^{{cite web|url=https://www.bbc.com/news/science-environment-43543195|title=Ghostly galaxy may be missing dark matter|author=Mary Halton, Science reporter|publisher=BBC News|date=28 March 2018 |access-date=29 March 2018 |quote=For Mack, the most exciting aspect of this galaxy is its potential to prove that dark matter - until now widely theorised but not directly observed - is real. If dark matter were just an unexplained effect of the gravity from regular matter, its effects would be visible in this galaxy. ... More work remains to be done on this and similar objects before dark matter theory needs to be fundamentally altered, however.}}
9. ^¹{{cite web|url=https://www.nasa.gov/feature/goddard/2018/dark-matter-goes-missing-in-oddball-galaxy|title=Dark Matter Goes Missing in Oddball Galaxy|author=|publisher=NASA|date=28 March 2018 |access-date=2 April 2018 |quote="We thought that every galaxy had dark matter and that dark matter is how a galaxy begins," said Pieter van Dokkum of Yale University in New Haven, Connecticut, lead researcher of the Hubble observations. "This invisible, mysterious substance is the most dominant aspect of any galaxy. So finding a galaxy without it is unexpected. It challenges the standard ideas of how we think galaxies work, and it shows that dark matter is real: it has its own separate existence apart from other components of galaxies. This result also suggests that there may be more than one way to form a galaxy."}}
10. ^https://cosmosmagazine.com/physics/galaxies-without-dark-matter-confirmed
11. ^¹{{cite journal|doi=10.3847/2041-8213/aac216|bibcode=2018ApJ...859L...5M|arxiv=1804.04136|title=Current Velocity Data on Dwarf Galaxy NGC 1052-DF2 do not Constrain it to Lack Dark Matter|journal=The Astrophysical Journal|volume=859|issue=1|pages=L5|year=2018|last1=Martin|first1=Nicolas F|last2=Collins|first2=Michelle L. M|last3=Longeard|first3=Nicolas|last4=Tollerud|first4=Erik}}

词条	NGC 1052-DF2
释义	See also References {{short description\|Ultra diffuse galaxy in the constellation Cetus}}{{Infobox galaxy \| name = NGC 1052-DF2 \| image = NGC 1052-DF2 a ghostly galaxy lacking dark matter.jpg \| caption = Hubble Space Telescope image of NGC 1052-DF2 show lack of dark matter^[1] \| epoch = \| pronounce = \| constellation name = Cetus \| ra = {{RA\|02\|41\|46.8}} \| dec = {{DEC\|-08\|24\|12}} \| z = \| h_radial_v = \| gal_v = \| dist_pc = {{convert\|19.0\|+/-\|1.7\|Mpc\|Mly\|abbr=on\|lk=on}} \| group_cluster = \| type = Sp...^[5] \| mass = {{val\|2e8}} \| mass_light_ratio = \| size = \| stars = \| appmag_v = \| appmag_b = \| absmag_v = \| size_v = 1.20′ × 1.12′^[2] \| notes = \| names = {{odlist\|PGC=3097693}}^[2] \| references = }} NGC 1052-DF2 is an ultra diffuse galaxy in the constellation Cetus, which was identified in a wide-field imaging survey of the NGC 1052 group by the Dragonfly Telephoto Array. It has been proposed that the galaxy contains little or no dark matter, the first such discovery. On March 20, 2019, a follow-up study announcing the discovery of a second UDG lacking dark matter, DF4, was published confirming this. ^[3] The distance to the galaxy from Earth, derived by surface brightness fluctuation, is 19 1.7 Mpc. Due to close proximity, it is assumed to be associated with the elliptical galaxy NGC 1052 and to lie at a distance of about {{val\|80\|u=Kpc}} from NGC 1052.^[4]^[5]^[6]^[7]. The apparent lack of dark matter in NGC 1052-DF2 may help prove that dark matter is real: if what appears to be dark matter is really just a currently unknown effect of the gravity of ordinary matter then this apparent dark matter should also appear in this galaxy. Further study will be needed before this and any other possible implications can be confirmed.^[8]^[9] If confirmed, the absence of dark matter may also have implications for theories of galaxy formation, as dark matter has been thought to be needed for galaxy formation.^[9] A later study purports to show that the galaxy may contain more dark matter than initially reported. It may have a mass-to-light ratio towards the low end of expected values for a dwarf galaxy. ^[18] However, a follow-up study on March 20, 2018 and a new discovery of a second UDG, NGC 1052-DF4, also apparently lacking dark matter challenge this study's conclusion.^[10] [https://www.sciencealert.com/a-second-galaxy-has-been-found-without-any-dark-matter-ironically-supporting-its-existence Same as NGC 1052-DF2, Astronomers discovered a second Galaxy with No Dark Matter]. NGC 1052-DF4, is an ultra-diffuse galaxy - quite large, spread-out, and faint to observe. Discovering another galaxy with very little to no dark matter means the chances of finding more of these galaxies are now higher than cosmologists previously thought. See also Abell 520 Bullet cluster Dragonfly 44, a galaxy thought to be almost all dark matter. References 1. ^{{cite web\|title=Hubble finds first galaxy in the local Universe without dark matter\|url=https://www.spacetelescope.org/news/heic1806/\|website=www.spacetelescope.org\|accessdate=30 March 2018}} 2. ^¹²{{cite simbad\|title=LEDA 3097693\|accessdate=15 April 2018}} 3. ^https://m.phys.org/news/2019-03-unusual-galaxies-defy-dark-theory.html 4. ^B. Famaey, S. McGaugh, M. Milgrom, "MOND and the dynamics of NGC1052-DF2" https://arxiv.org/abs/1804.04167 Monthly Notices of the Royal Astronomical Society, Volume 480, Issue 1, 11 October 2018, Pages 473–476, https://doi.org/10.1093/mnras/sty1884 5. ^Website of one of the authors of a paper regarding NGC1052-DF2 https://www.pietervandokkum.com/ngc1052-df2 (last reviewed January 21, 2019) 6. ^Evolutionary history of the elliptical galaxy NGC 1052 Michael Pierce Jean P. Brodie Duncan A. Forbes Michael A. Beasley Robert Proctor Jay StraderMonthly Notices of the Royal Astronomical Society, Volume 358, Issue 2, 1 April 2005, Pages 419–431, https://doi.org/10.1111/j.1365-2966.2005.08778.x https://academic.oup.com/mnras/article/358/2/419/998620 7. ^Stacy McGaugh, "The Dwarf Galaxy NGC1052-DF2" (April 4, 2018) https://tritonstation.wordpress.com/2018/04/04/the-dwarf-galaxy-ngc1052-df2/ last reviewed January 21 2019) 8. ^{{cite web\|url=https://www.bbc.com/news/science-environment-43543195\|title=Ghostly galaxy may be missing dark matter\|author=Mary Halton, Science reporter\|publisher=BBC News\|date=28 March 2018 \|access-date=29 March 2018 \|quote=For Mack, the most exciting aspect of this galaxy is its potential to prove that dark matter - until now widely theorised but not directly observed - is real. If dark matter were just an unexplained effect of the gravity from regular matter, its effects would be visible in this galaxy. ... More work remains to be done on this and similar objects before dark matter theory needs to be fundamentally altered, however.}} 9. ^¹{{cite web\|url=https://www.nasa.gov/feature/goddard/2018/dark-matter-goes-missing-in-oddball-galaxy\|title=Dark Matter Goes Missing in Oddball Galaxy\|author=\|publisher=NASA\|date=28 March 2018 \|access-date=2 April 2018 \|quote="We thought that every galaxy had dark matter and that dark matter is how a galaxy begins," said Pieter van Dokkum of Yale University in New Haven, Connecticut, lead researcher of the Hubble observations. "This invisible, mysterious substance is the most dominant aspect of any galaxy. So finding a galaxy without it is unexpected. It challenges the standard ideas of how we think galaxies work, and it shows that dark matter is real: it has its own separate existence apart from other components of galaxies. This result also suggests that there may be more than one way to form a galaxy."}} 10. ^https://cosmosmagazine.com/physics/galaxies-without-dark-matter-confirmed 11. ^¹{{cite journal\|doi=10.3847/2041-8213/aac216\|bibcode=2018ApJ...859L...5M\|arxiv=1804.04136\|title=Current Velocity Data on Dwarf Galaxy NGC 1052-DF2 do not Constrain it to Lack Dark Matter\|journal=The Astrophysical Journal\|volume=859\|issue=1\|pages=L5\|year=2018\|last1=Martin\|first1=Nicolas F\|last2=Collins\|first2=Michelle L. M\|last3=Longeard\|first3=Nicolas\|last4=Tollerud\|first4=Erik}} ^[11] }}{{galaxy-stub}} 3 : NGC objects\|Cetus (constellation)\|Dwarf galaxies
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