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Monoceros Ring

January 01, 1970

The Monoceros Ring (monoceros: Greek for 'unicorn') is a long, complex, ring of stars that wraps around the Milky Way three times. This is proposed to consist of a stellar stream torn from the Canis Major Dwarf Galaxy by tidal forces as part of the process of merging with the Milky Way over a period of billions of years, although this view has long been disputed.[1] The ring contains 100 million solar masses and is 200,000 light years long.[2]

The Milky Way galaxy.

The stream of stars was first reported in 2002 by astronomers conducting the Sloan Digital Sky Survey. In the course of investigating this ring of stars, and a closely spaced group of globular clusters similar to those associated with the Sagittarius Dwarf Elliptical Galaxy, they discovered the Canis Major Dwarf Galaxy.[3]

Dispute edit

In 2006, a study using 2MASS data cast doubts on the nature of the "Ring", arguing that the data suggests that the ring is actually part of the warped galactic disc of the Milky Way.[1] However, observations using the Anglo-Australian Telescope published in 2007 suggest that a warped disc cannot create the observed structure, which must therefore be formed either by a flare of the galactic disc or have an extra-galactic origin.[4]

Several members of the scientific community restated their position in 2012, affirming the Monoceros structure is nothing more than an over-density produced by the flared and warped thick disk of the Milky Way.[5]

In 2015, building on the 2002 studies which revealed the Monoceros Ring, M.L. Martialay and colleagues sorted through galactic data from the Sloan Digital Sky Survey suggested that the Milky Way is actually 50 percent larger than previously thought,[6] showing that disk of the Milky Way is not just a disk of stars in a flat plane, but is instead corrugated. As it radiates outward from the Sun, there appear to be at least four ripples in the disk of the Milky Way. Scientists assume that this pattern is going to be found throughout the disk.[7] However, a more recent 2018 paper later somewhat ruled out this hypothesis, and supported a conclusion that the Monoceros Ring, A13 and TriAnd Ring were stellar overdensities rather kicked out from the main stellar disk, with the velocity dispersion of their constituent RR Lyrae variable stars found to be higher and consistent with halo membership.[8]

Using the distance of the Monoceros Ring, the diameter of the Milky Way has been claimed to extend as much as 150,000 to 180,000 light years across. In this revised paradigm, the Solar System lies about halfway between the core and the edge.[9] However, it is more common in the astronomical literature to define the sizes of galaxies using other methods, notably by the D25 isophote and variations of the half-light radius. An earlier study in 1998 using the D25 isophote gave a diameter for the Milky Way at 26.8 ± 1.1 kiloparsecs (87,400 ± 3,590 ly).[10][11][12]

N-body simulations have been used to investigate the possible location of the progenitor of this structure and these calculations show that, if the Ring has a dwarf galaxy progenitor, it might be found in the background of one out of eight specific areas in the sky.[13] A subsequent analysis, that used Gaia DR2 data, found a bimodal Gaussian distribution towards Galactic coordinates (271, +2) degrees in Vela, which is one of the locations of the progenitor proposed in the previous study.[14] This finding may signal the presence of the progenitor of the Monoceros Ring, but the authors indicate that it might also be compatible with the existence of an unrelated kinematically coherent structure.

See also edit

References edit

  1. ^ a b Y. Momany; et al. (2006). (PDF). Astronomy and Astrophysics. 451 (2): 515–38. arXiv:astro-ph/0603385. Bibcode:2006A&A...451..515M. doi:10.1051/0004-6361:20054081. S2CID 18547813. Archived from the original (PDF) on 2016-03-04. Retrieved 2013-12-21.
  2. ^ Ibata, Rodrigo; Gibson, Brad (April 2007). "The Ghosts of Galaxies Past". Scientific American. 296 (4): 40–45. Bibcode:2007SciAm.296d..40I. doi:10.1038/scientificamerican0407-40. PMID 17479629.
  3. ^ Newberg; et al. (1 April 2002). "The Ghost of Sagittarius and Lumps in the Halo of the Milky Way". The Astrophysical Journal. 569 (1): 245–274. arXiv:astro-ph/0111095. Bibcode:2002ApJ...569..245N. doi:10.1086/338983. S2CID 16909562.
  4. ^ Conn, Blair C.; Lane, Richard R.; Lewis, Geraint F.; Gil-Merino, Rodrigo; Irwin, Mike J.; Ibata, Rodrigo A.; Martin, Nicolas F.; Bellazzini, Michele; Sharp, Robert; Tuntsov, Artem V.; Ferguson, Annette M. N. (April 1, 2007). "The AAT/WFI survey of the Monoceros Ring and Canis Major dwarf galaxy". Monthly Notices of the Royal Astronomical Society. 376 (3): 939–959. arXiv:astro-ph/0701664. Bibcode:2007MNRAS.376..939C. doi:10.1111/j.1365-2966.2007.11503.x. S2CID 17927154.
  5. ^ M. Lopez-Corredoira, A; et al. (July 2012). "Comments on the "Monoceros" affair". arXiv:1207.2749. Bibcode:2012arXiv1207.2749L. {{cite journal}}: Cite journal requires |journal= (help)
  6. ^ Mary L. Martialay (March 11, 2015). (Press release). Rensselaer Polytechnic Institute. Archived from the original on March 13, 2015.
  7. ^ Scott Sutherland (March 16, 2015). . The Weather Network. Archived from the original on March 19, 2015.
  8. ^ Sheffield, Allyson A.; Price-Whelan, Adrian M.; Tzanidakis, Anastasios; Johnston, Kathryn V.; Laporte, Chervin F. P.; Sesar, Branimir (2018). "A Disk Origin for the Monoceros Ring and A13 Stellar Overdensities". The Astrophysical Journal. 854 (1): 47. arXiv:1801.01171. Bibcode:2018ApJ...854...47S. doi:10.3847/1538-4357/aaa4b6. S2CID 118932403.
  9. ^ Yan Xu; et al. (March 1, 2015). "Rings and Radial Waves in the Disk of the Milky Way". The Astrophysical Journal. 801 (2): 105. arXiv:1503.00257. Bibcode:2015ApJ...801..105X. doi:10.1088/0004-637X/801/2/105. S2CID 119124338.
  10. ^ Goodwin, S. P.; Gribbin, J.; Hendry, M. A. (22 April 1997). "The Milky Way is just an average spiral". arXiv:astro-ph/9704216.
  11. ^ Goodwin, S. P.; Gribbin, J.; Hendry, M. A. (August 1998). "The relative size of the Milky Way". The Observatory. 118: 201–208. Bibcode:1998Obs...118..201G.
  12. ^ Castro-Rodríguez, N.; López-Corredoira, M.; Sánchez-Saavedra, M. L.; Battaner, E. (2002). "Warps and correlations with intrinsic parameters of galaxies in the visible and radio". Astronomy & Astrophysics. 391 (2): 519–530. arXiv:astro-ph/0205553. Bibcode:2002A&A...391..519C. doi:10.1051/0004-6361:20020895. S2CID 17813024.
  13. ^ Magda Guglielmo; et al. (March 11, 2018). "On the origin of the Monoceros Ring - I. Kinematics, proper motions, and the nature of the progenitor". Monthly Notices of the Royal Astronomical Society. 474 (4): 4584–4593. arXiv:1711.06682. Bibcode:2018MNRAS.474.4584G. doi:10.1093/mnras/stx3048.
  14. ^ de la Fuente Marcos, Raúl; de la Fuente Marcos, Carlos (21 November 2018). "Searching for the lost Unicorn: a prominent feature in the radial velocity distribution of stars in Vela from Gaia DR2 data". Monthly Notices of the Royal Astronomical Society Letters. 481 (1): L64–L68. arXiv:1808.09921. Bibcode:2018MNRAS.481L..64D. doi:10.1093/mnrasl/sly163.

January 01, 1970
monoceros, ring, monoceros, greek, unicorn, long, complex, ring, stars, that, wraps, around, milky, three, times, this, proposed, consist, stellar, stream, torn, from, canis, major, dwarf, galaxy, tidal, forces, part, process, merging, with, milky, over, perio. The Monoceros Ring monoceros Greek for unicorn is a long complex ring of stars that wraps around the Milky Way three times This is proposed to consist of a stellar stream torn from the Canis Major Dwarf Galaxy by tidal forces as part of the process of merging with the Milky Way over a period of billions of years although this view has long been disputed 1 The ring contains 100 million solar masses and is 200 000 light years long 2 The Milky Way galaxy The stream of stars was first reported in 2002 by astronomers conducting the Sloan Digital Sky Survey In the course of investigating this ring of stars and a closely spaced group of globular clusters similar to those associated with the Sagittarius Dwarf Elliptical Galaxy they discovered the Canis Major Dwarf Galaxy 3 Dispute editIn 2006 a study using 2MASS data cast doubts on the nature of the Ring arguing that the data suggests that the ring is actually part of the warped galactic disc of the Milky Way 1 However observations using the Anglo Australian Telescope published in 2007 suggest that a warped disc cannot create the observed structure which must therefore be formed either by a flare of the galactic disc or have an extra galactic origin 4 Several members of the scientific community restated their position in 2012 affirming the Monoceros structure is nothing more than an over density produced by the flared and warped thick disk of the Milky Way 5 In 2015 building on the 2002 studies which revealed the Monoceros Ring M L Martialay and colleagues sorted through galactic data from the Sloan Digital Sky Survey suggested that the Milky Way is actually 50 percent larger than previously thought 6 showing that disk of the Milky Way is not just a disk of stars in a flat plane but is instead corrugated As it radiates outward from the Sun there appear to be at least four ripples in the disk of the Milky Way Scientists assume that this pattern is going to be found throughout the disk 7 However a more recent 2018 paper later somewhat ruled out this hypothesis and supported a conclusion that the Monoceros Ring A13 and TriAnd Ring were stellar overdensities rather kicked out from the main stellar disk with the velocity dispersion of their constituent RR Lyrae variable stars found to be higher and consistent with halo membership 8 Using the distance of the Monoceros Ring the diameter of the Milky Way has been claimed to extend as much as 150 000 to 180 000 light years across In this revised paradigm the Solar System lies about halfway between the core and the edge 9 However it is more common in the astronomical literature to define the sizes of galaxies using other methods notably by the D25 isophote and variations of the half light radius An earlier study in 1998 using the D25 isophote gave a diameter for the Milky Way at 26 8 1 1 kiloparsecs 87 400 3 590 ly 10 11 12 N body simulations have been used to investigate the possible location of the progenitor of this structure and these calculations show that if the Ring has a dwarf galaxy progenitor it might be found in the background of one out of eight specific areas in the sky 13 A subsequent analysis that used Gaia DR2 data found a bimodal Gaussian distribution towards Galactic coordinates 271 2 degrees in Vela which is one of the locations of the progenitor proposed in the previous study 14 This finding may signal the presence of the progenitor of the Monoceros Ring but the authors indicate that it might also be compatible with the existence of an unrelated kinematically coherent structure See also editList of stellar streamsReferences edit a b Y Momany et al 2006 Outer structure of the Galactic warp and flare explaining the Canis Major over density PDF Astronomy and Astrophysics 451 2 515 38 arXiv astro ph 0603385 Bibcode 2006A amp A 451 515M doi 10 1051 0004 6361 20054081 S2CID 18547813 Archived from the original PDF on 2016 03 04 Retrieved 2013 12 21 Ibata Rodrigo Gibson Brad April 2007 The Ghosts of Galaxies Past Scientific American 296 4 40 45 Bibcode 2007SciAm 296d 40I doi 10 1038 scientificamerican0407 40 PMID 17479629 Newberg et al 1 April 2002 The Ghost of Sagittarius and Lumps in the Halo of the Milky Way The Astrophysical Journal 569 1 245 274 arXiv astro ph 0111095 Bibcode 2002ApJ 569 245N doi 10 1086 338983 S2CID 16909562 Conn Blair C Lane Richard R Lewis Geraint F Gil Merino Rodrigo Irwin Mike J Ibata Rodrigo A Martin Nicolas F Bellazzini Michele Sharp Robert Tuntsov Artem V Ferguson Annette M N April 1 2007 The AAT WFI survey of the Monoceros Ring and Canis Major dwarf galaxy Monthly Notices of the Royal Astronomical Society 376 3 939 959 arXiv astro ph 0701664 Bibcode 2007MNRAS 376 939C doi 10 1111 j 1365 2966 2007 11503 x S2CID 17927154 M Lopez Corredoira A et al July 2012 Comments on the Monoceros affair arXiv 1207 2749 Bibcode 2012arXiv1207 2749L a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Mary L Martialay March 11 2015 The Corrugated Galaxy Milky Way May Be Much Larger Than Previously Estimated Press release Rensselaer Polytechnic Institute Archived from the original on March 13 2015 Scott Sutherland March 16 2015 This corrugated view of the Milky Way just made our home galaxy a LOT bigger The Weather Network Archived from the original on March 19 2015 Sheffield Allyson A Price Whelan Adrian M Tzanidakis Anastasios Johnston Kathryn V Laporte Chervin F P Sesar Branimir 2018 A Disk Origin for the Monoceros Ring and A13 Stellar Overdensities The Astrophysical Journal 854 1 47 arXiv 1801 01171 Bibcode 2018ApJ 854 47S doi 10 3847 1538 4357 aaa4b6 S2CID 118932403 Yan Xu et al March 1 2015 Rings and Radial Waves in the Disk of the Milky Way The Astrophysical Journal 801 2 105 arXiv 1503 00257 Bibcode 2015ApJ 801 105X doi 10 1088 0004 637X 801 2 105 S2CID 119124338 Goodwin S P Gribbin J Hendry M A 22 April 1997 The Milky Way is just an average spiral arXiv astro ph 9704216 Goodwin S P Gribbin J Hendry M A August 1998 The relative size of the Milky Way The Observatory 118 201 208 Bibcode 1998Obs 118 201G Castro Rodriguez N Lopez Corredoira M Sanchez Saavedra M L Battaner E 2002 Warps and correlations with intrinsic parameters of galaxies in the visible and radio Astronomy amp Astrophysics 391 2 519 530 arXiv astro ph 0205553 Bibcode 2002A amp A 391 519C doi 10 1051 0004 6361 20020895 S2CID 17813024 Magda Guglielmo et al March 11 2018 On the origin of the Monoceros Ring I Kinematics proper motions and the nature of the progenitor Monthly Notices of the Royal Astronomical Society 474 4 4584 4593 arXiv 1711 06682 Bibcode 2018MNRAS 474 4584G doi 10 1093 mnras stx3048 de la Fuente Marcos Raul de la Fuente Marcos Carlos 21 November 2018 Searching for the lost Unicorn a prominent feature in the radial velocity distribution of stars in Vela from Gaia DR2 data Monthly Notices of the Royal Astronomical Society Letters 481 1 L64 L68 arXiv 1808 09921 Bibcode 2018MNRAS 481L 64D doi 10 1093 mnrasl sly163 Retrieved from https en wikipedia org w index php title Monoceros Ring amp oldid 1188166191, wikipedia, wiki, book, books, library,

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