imported>Patrickwooldridge: /* List of void galaxies */ removed redundancy

2025-06-23T17:47:23Z

List of void galaxies: removed redundancy

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{{Short description|Vast void adjacent to the Local Group}}
{{Distinguish|Local Hole}}
{{Use dmy dates|date=February 2023}}{{sky|18|38|0|+|18|0|0}}
{{Infobox astronomical object
|epoch= [[J2000.0]]<ref name=SIMBAD>{{cite simbad |title= NAME Local Void |accessdate= 21 December 2014 }}</ref>
|ra= {{RA|18|38}}<ref name=SIMBAD/>
|dec= {{DEC|+18.0}}<ref name=SIMBAD/>
|size_v= {{convert|60|Mpc|Mly|abbr=on|lk=off}}<ref name=1997ApJS..112..245N>{{cite journal |last1=Nakanishi |first1=Kouichiro |last2=Takata |first2=Tadafumi |last3=Yamada |first3=Toru |last4=Takeuchi |first4=Tsutomu T. |last5=Shiroya |first5=Ryuichi |last6=Miyazawa |first6=Morio |last7=Watanabe |first7=Shigeo |last8=Saitō |first8=Mamoru |display-authors=1 |date=1 October 1997 |title= Search and Redshift Survey for IRAS Galaxies behind the Milky Way and Structure of the Local Void |journal= [[The Astrophysical Journal Supplement Series]] |volume=112 |issue=2 |page= 245 |bibcode= 1997ApJS..112..245N |doi= 10.1086/313039 |doi-access=free}}</ref>|image=The Local Void.gif|caption=Map of voids and superclusters within 500 million light years from Milky Way. The Local Void in the yellow circle.|image_scale=1.67}}

The '''Local Void''' is a vast, [[Void (astronomy)|empty region]] of [[Interstellar medium|space]], lying adjacent to the [[Local Group]].<ref name="NewScientist">{{cite web|title=Dwarf-flinging void is larger than thought|url=https://www.newscientist.com/article/dn11971-dwarfflinging-void-is-larger-than-thought.html|last=Shiga|first=David|date=1 June 2007|work=[[New Scientist]]|url-status=live|archive-url=https://web.archive.org/web/20180826080737/https://www.newscientist.com/article/dn11971-dwarf-flinging-void-is-larger-than-thought/|archive-date=26 August 2018|accessdate=13 October 2008}}</ref><ref name="journal">{{Cite journal|last1=Tully|first1=R. Brent|author-link=R. Brent Tully|last2=Shaya|first2=Edward J.|last3=Karachentsev|first3=Igor D.|last4=Courtois|first4=Hélène M.|author-link4=Hélène Courtois|last5=Kocevski|first5=Dale D.|last6=Rizzi|first6=Luca|last7=Peel|first7=Alan|display-authors=1|date=20 March 2008|title=Our Peculiar Motion Away from the Local Void|journal=[[The Astrophysical Journal]]|volume=676|issue=1|pages=184–205|arxiv=0705.4139|bibcode=2008ApJ...676..184T|doi=10.1086/527428|doi-access=free}}</ref> Discovered by [[R. Brent Tully|Brent Tully]] and [[J. Richard Fisher|Rick Fisher]] in 1987,<ref name="atlas">{{cite book|last1=Tully|first1=R. Brent|url=http://ned.ipac.caltech.edu/level5/March04/Virgo_cluster/frames.html|title=Nearby Galaxy Atlas|last2=Fisher|first2=J. Richard|date=1987|publisher=[[Cambridge University Press]]|bibcode=1987nga..book.....T|author-link=R. Brent Tully}}</ref> the Local Void is now known to be composed of three separate sectors, separated by bridges of "wispy [[Galaxy filament|filament]]s".<ref name="journal" /> The precise extent of the void is unknown, but it is at least 45 [[parsec|Mpc]] (150 million [[light-year]]s) across,<ref name="astronomy">{{cite web|title=Milky Way moving away from void|url=https://astronomy.com/news-observing/news/2007/06/milky%20way%20moving%20away%20from%20void|date=12 June 2007|work=[[Astronomy (magazine)|Astronomy]]|url-status=dead|archive-url=https://web.archive.org/web/20110608071400/http://www.astronomy.com/en/sitecore/content/Home/News-Observing/News/2007/06/Milky%20Way%20moving%20away%20from%20void.aspx|archive-date=8 June 2011|accessdate=13 October 2008}}</ref> and possibly 150 to 300 Mpc.<ref name="whitbourn">{{cite journal|last1=Whitbourn|first1=Joe R.|last2=Shanks|first2=Tom|date=June 2016|title=The galaxy luminosity function and the Local Hole|journal=[[Monthly Notices of the Royal Astronomical Society]]|volume=459|issue=1|pages=496|arxiv=1603.02322|bibcode=2016MNRAS.459..496W|doi=10.1093/mnras/stw555|doi-access=free}}</ref><ref name="kbc">{{Cite journal|last1=Keenan|first1=Ryan C.|last2=Barger|first2=Amy J.|author-link2=Amy Barger|last3=Cowie|first3=Lennox L.|author-link3=Lennox Cowie|date=5 September 2013|title=Evidence for a ~300 Mpc Scale Under-density in the Local Galaxy Distribution|journal=[[The Astrophysical Journal]]|volume=775|issue=1|pages=62|arxiv=1304.2884|bibcode=2013ApJ...775...62K|doi=10.1088/0004-637X/775/1/62|doi-access=free}}</ref> The Local Void appears to have significantly fewer [[Galaxy|galaxies]] than expected from standard [[cosmology]].<ref>{{Cite journal|last1=Peebles|first1=P. J. E.|author-link=Jim Peebles|last2=Nusser|first2=Adi|date=June 2010|title=Nearby galaxies as pointers to a better theory of cosmic evolution|journal=[[Nature (journal)|Nature]]|volume=465|issue=7298|pages=565–569|arxiv=1001.1484|bibcode=2010Natur.465..565P|doi=10.1038/nature09101|pmid=20520705|s2cid=43767061}}</ref>

==Location and dimensions==
Voids are affected by the way [[gravity]] causes [[matter]] in the [[universe]] to "clump together", herding galaxies into [[Galaxy groups and clusters|clusters]] and chains, which are separated by regions mostly devoid of galaxies, yet the exact mechanisms are subject to scientific debate.<ref name="NewScientist"/><ref name="Iwata"/>

[[Astronomer]]s have previously noticed that the [[Milky Way]] sits in a large, flat array of galaxies called the [[Local Sheet]], which bounds the Local Void.<ref name="NewScientist"/> The Local Void extends approximately {{convert|60|Mpc|lk=in}}, beginning at the edge of the [[Local Group]].<ref name="PPT">{{cite web|title=Our CMB Motion: The Local Void influence|url=http://www.astro.rug.nl/~weygaert/tim1publication/knawvoid/voidknaw.tully.ppt|last=Tully|first=Brent|authorlink=R. Brent Tully|publisher=Institute for Astronomy|url-status=live|archive-url=https://web.archive.org/web/20190928024010/http://www.astro.rug.nl/~weygaert/tim1publication/knawvoid/voidknaw.tully.ppt|archive-date=28 September 2019|accessdate=13 October 2008}}</ref> It is believed that the distance from [[Earth]] to the centre of the Local Void must be at least {{convert|23|Mpc}}.<ref name="journal"/>

The size of the Local Void was calculated due to an isolated [[dwarf galaxy]] known as ESO 461-36 located inside it. The bigger and emptier the void, the weaker its gravity, and the faster the dwarf should be fleeing the void towards concentrations of matter, yet discrepancies give room for competing theories.<ref name="journal"/> [[Dark energy]] has been suggested as one alternative explanation for the speedy expulsion of the dwarf galaxy.<ref name="NewScientist"/>

An earlier "[[Hubble Bubble (astronomy)|Hubble Bubble]]" model, based on measured velocities of [[Type 1a supernovae]], proposed a relative void centred on the Milky Way. Recent analysis of that data, however, suggested that interstellar dust had resulted in misleading measurements.<ref name="moss">{{cite journal|last1=Moss|first1=Adam|last2=Zibin|first2=James P.|last3=Scott|first3=Douglas|date=15 May 2011|title=Precision Cosmology Defeats Void Models for Acceleration|journal=[[Physical Review D]]|volume=83|issue=10|pages=103515|arxiv=1007.3725|bibcode=2011PhRvD..83j3515M|doi=10.1103/PhysRevD.83.103515|s2cid=119261120}}</ref>

Several authors have shown that the local universe up to 300 Mpc from the Milky Way is less dense than surrounding areas – by 15–50%. This has been called the Local Void or Local Hole.<ref name=whitbourn/><ref name=kbc/> Some media reports have dubbed it the [[KBC Void]],<ref name="forbes">{{cite web|title=We're Way Below Average! Astronomers Say Milky Way Resides in a Great Cosmic Void|url=https://www.forbes.com/sites/startswithabang/2017/06/07/were-way-below-average-astronomers-say-milky-way-resides-in-a-great-cosmic-void/#|last=Siegel|first=Ethan|authorlink=Ethan Siegel|date=7 June 2017|work=[[Forbes]]|url-status=live|archive-url=https://archive.today/20200513051220/https://www.forbes.com/sites/startswithabang/2017/06/07/were-way-below-average-astronomers-say-milky-way-resides-in-a-great-cosmic-void/%237342c1b86d05|archive-date=13 May 2020|accessdate=9 June 2017}}</ref> although this name has not been taken up in other publications.{{citation needed|date=May 2020}}

==Effect on surroundings==
Scientists believe that the Local Void is growing and that the [[Local Sheet]], which makes up one wall of the void, is rushing away from the void's centre at {{convert|260|km/s|mi/s}}.<ref name="Iwata">{{cite conference|last1=Iwata|first1=Ikuru|last2=Ohta|first2=Kouji|last3=Nakanishi|first3=Kouichiro|last4=Chamaraux|first4=Pierre|last5=Roman|first5=Adel T.|year=2005|title=The Growth of the Local Void and the Origin of the Local Velocity Anomaly|url=http://www.aspbooks.org/publications/329/059.pdf|conference=Nearby Large-Scale Structures and the Zone of Avoidance|series=[[Astronomical Society of the Pacific Conference Series]]|volume=329|pages=59–66|archive-url=https://web.archive.org/web/20200513030738/http://www.aspbooks.org/publications/329/059.pdf|archive-date=13 May 2020|url-status=dead|access-date=13 May 2020}}</ref> Concentrations of matter normally pull together, creating a larger void where matter is rushing away. The Local Void is surrounded uniformly by matter in all directions, except for one sector in which there is nothing, which has the effect of taking more matter away from that sector. The effect on the nearby galaxy is astonishingly large.<ref name="journal"/> The Milky Way's velocity away from the Local Void is {{convert|600000|mph|km/h|disp=flip}}.<ref name="NewScientist"/><ref name="astronomy" />

==List of void galaxies==
{{incomplete list|date=August 2016}}
Several [[void galaxy|void galaxies]] have been found within the Local Void. These include:
{| class=wikitable
|-
! Galaxy
! Image
! Constellation
! Declination
! Distance
! Right ascension
! Notes

|-
| [[Pisces A]]
| [[File:Pisces A hs-2016-29-b-large web.jpg|100px]]
| Rowspan=2|[[Pisces (constellation)|Pisces]]
| +10° 48′ 47.01″
| 18.4 Mly (5.64 Mpc)
| 00h 14m 46.000s
| rowspan=2|The two void [[dwarf galaxy|dwarf galaxies]] located in the Local Void and are in the Pisces constellation. Pisces A is 18.4 million [[light-year]]s (5.64 [[megaparsec]]s) away and Pisces B is 30 million light-years (9.2 megaparsecs) away. The galaxies were discovered with the [[WIYN Observatory]]. About 100 million years ago, they started moving out of the [[Void (astronomy)|void]] and into the local [[filament of galaxies|filament]] zone and denser gaseous environment. This sparked off a doubling of the rate of star formation.<ref name="SciNews-2016-08-15">{{cite news|date=15 August 2016|title=Hubble Sees Two Dwarf Galaxies in Pisces|publisher=Sci-News|url=http://www.sci-news.com/astronomy/hubble-dwarf-galaxies-pisces-04103.html|url-status=live|archive-url=https://web.archive.org/web/20190403133419/http://www.sci-news.com/astronomy/hubble-dwarf-galaxies-pisces-04103.html|archive-date=3 April 2019}}</ref>
|-
| [[Pisces B]]
| [[File:Pisces B hs-2016-29-c-large web.jpg|100px]]
| +11° 07′ 18.22″
| 30 Mly (9.2 Mpc)
| 01h 19m 11.700s
|-
| [[NGC 7077]]
| [[File:SDSS NGC 7077.jpg|100px]]
| [[Aquarius (constellation)|Aquarius]]
| 02° 24′ 51″
| 56 Mly (17.2 Mpc)
| 21h 29m 59.6s
| A [[lenticular galaxy|lenticular]] [[blue compact dwarf galaxy]] located about 56 million light-years away from Earth in the constellation Aquarius. Discovered by astronomer Albert Marth on 11 August 1863, the galaxy lies within the Local Void.<ref>{{Cite web|title=The Local Void|url=http://amiga.iaa.es/FCKeditor/UserFiles/File/cig09/Tully.pdf|last=Tully|first=R. Brent|authorlink=R. Brent Tully|publisher=Institute for Astronomy|url-status=dead|archive-url=https://web.archive.org/web/20180618175255/http://amiga.iaa.es/FCKeditor/UserFiles/File/cig09/Tully.pdf|archive-date=18 June 2018|access-date=1 May 2018}}</ref>
|-
| [[NGC 6503]]
| [[File:NGC 6503 (2015-06-10).jpg|100px]]
| rowspan=2|[[Draco (constellation)|Draco]]
| +70° 08′ 39.587″
| 13.05 ± 0.33 Mly (4.0 ± 0.1 Mpc)
| 17h 49m 26.4207s
| A [[field galaxy|field]]<ref name=1979A&A....74..235M>{{Cite journal |title= The structure of nearby groups of galaxies – Quantitative membership probabilities |last= Materne |first=J. |date= April 1979 |journal= Astronomy and Astrophysics |volume= 74 |number= 2 |pages= 235–243 |bibcode= 1979A&A....74..235M }}</ref> dwarf [[spiral galaxy]] located at the edge of the Local Void. The [[dwarf galaxy]] spans 30,000 light-years and lies approximately 17 million light-years away in the constellation of Draco (the Dragon). This spiral galaxy is especially colorful, with bright red regions of gas scattered through its spiral arms. Bright blue regions contain stars that are forming. Dark brown dust areas are in the galaxy's arms and center. It has one known satellite galaxy, known as KK 242. With a stellar mass of about 3 million [[solar masses]], KK 242 is on the border between a dwarf [[irregular galaxy]] (dIrr) and a [[dwarf spheroidal galaxy]] (dSph).<ref>{{Cite web|title=Lonely Galaxy Lost in Space|url=https://www.nasa.gov/image-feature/goddard/lonely-galaxy-lost-in-space|date=10 June 2015|editor-last=Jenner|editor-first=Lynn|publisher=[[NASA]]|url-status=live|archive-url=https://web.archive.org/web/20190617084831/https://www.nasa.gov/image-feature/goddard/lonely-galaxy-lost-in-space/|archive-date=17 June 2019}}</ref>
|-
| [[NGC 6789]]
| [[File:NGC 6789 hst 09162 R814B606.png|100px]]
| +63° 58′ 23″
| 12 Mly (3.6 Mpc)
| 19h 16m 41s
| An [[irregular galaxy]] in the constellation Draco. It was discovered by [[Lewis Swift]] on 30 August 1883. It is the nearest [[blue compact dwarf]] (BCD) galaxy to the Milky Way. It is chemically homogeneous and relatively metal-poor.<ref name=Lelli>{{cite journal|bibcode=2014MNRAS.445.1694L|doi=10.1093/mnras/stu1804|title=The triggering of starbursts in low-mass galaxies|year=2014|last1=Lelli|first1=Federico|last2=Verheijen|first2=Marc|last3=Fraternali|first3=Filippo|journal=Monthly Notices of the Royal Astronomical Society|volume=445|issue=2|pages=1694–1712|doi-access=free |arxiv=1409.1239 }}</ref>
|}

==See also==
* {{annotated link|Dipole repeller}}
* [[List of voids]]

==References==
{{reflist}}

[[Category:Astrochemistry]]
[[Category:Interstellar media]]
[[Category:Local Sheet]]
[[Category:Voids (astronomy)]]

Local Void - Revision history

imported>Patrickwooldridge: /* List of void galaxies */ removed redundancy