사용자:Ta183ta/연습장: 두 판 사이의 차이

[[File:NGC 4993 map.png|thumb|[[바다뱀자리 프시]] 근처의 성도. NGC 4993과 함께 NGC 4968, NGC 4970, NGC 5042, IC 4180, IC 4197이 보인다. ]]

'''NGC 4993''' 또는 '''NGC 4994'''는 지구로부터 [[바다뱀자리]] 방향<ref name=":4">{{cite web|url=http://www.docdb.net/show_object.php?id=ngc_4993|title=NGC 4993|website=Deep Sky Observer's Companion|accessdate=28 August 2017}}</ref>으로 약 1억 4천만 광년 떨어져 있는<ref>{{Cite web|url=http://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=NGC+4993&extend=no&hconst=73&omegam=0.27&omegav=0.73&corr_z=1&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES|title=Your NED Search Results|website=ned.ipac.caltech.edu|access-date=2018-06-05}}</ref> [[렌즈형은하]]<ref name=":2" />이다. [[윌리엄 허셜이허셜]]이<ref name=":4" /><ref name=":5">{{Cite web|url=https://cseligman.com/text/atlas/ngc49a.htm#4993|title=New General Catalog Objects: NGC 4950 - 4999|website=cseligman.com|language=en-US|access-date=2018-06-05}}</ref> 1789년 3월 26일<ref name=":5" /> 발견했으며 NGC 4993 그룹의집단의 구성원이다.<ref name=":3">{{Cite journal|title=The Distance to NGC 4993: The Host Galaxy of the Gravitational-wave Event GW170817|journal=The Astrophysical Journal|last=Hjorth|first=Jens|last2=Levan|first2=Andrew J.|date=2017-10-16|volume=848|issue=2|pages=L31|language=en|arxiv=1710.05856|bibcode=2017ApJ...848L..31H|doi=10.3847/2041-8213/aa9110|last3=Tanvir|first3=Nial R.|last4=Lyman|first4=Joe D.|last5=Wojtak|first5=Radosław|last6=Schrøder|first6=Sophie L.|last7=Mandel|first7=Ilya|last8=Gall|first8=Christa|last9=Bruun|first9=Sofie H.|hdl=2381/41880}}</ref>

NGC 4993은 [[전자기파|전자기]]/[[중력파|중력 복사가복사]]가 모두 감지된 최초의 천문학적 사건이었던사건 GW170817이[[GW170817]]이 일어난 장소이다. 이 사건은 두 중성자별이[[중성자별]]이 충돌하여 발생한 것으로 [[사이언스]] 지는 이 발견에 2017년 ''Breakthrough of the Year'' 상을 수여했다.<ref>{{cite web|title=Breakthrough of the year 2017|url=http://vis.sciencemag.org/breakthrough2017/|website=Science {{!}} AAAS|language=en|date=22 December 2017}}</ref><ref>{{cite journal|doi=10.1126/science.358.6370.1520|pmid=29269456|title=Cosmic convergence|journal=Science|volume=358|issue=6370|pages=1520–1521|year=2017|last1=Cho|first1=Adrian|bibcode=2017Sci...358.1520C}}</ref> GW170817은GW170817에서 [[중력파]] 사건과 함께 [[감마선 폭발이폭발]]이 관측되었기에관측되어 중성자별 쌍성이 충돌하여 짧은 감마선 폭발을 일으킨다는 가설을 직접가설이 입증해직접적으로 주었다검증되었다.<ref>{{Cite news|url=https://www.nytimes.com/2017/10/16/science/ligo-neutron-stars-collision.html|title=LIGO Detects Fierce Collision of Neutron Stars for the First Time|last=Overbye|first=Dennis|date=16 October 2017|work=[[The New York Times]]|access-date=16 October 2017|language=en-US}}</ref>

NGC 4993은 has항성들이 several[[동심원]] concentric모양의 shells껍질 of구조들을 stars형성하고 and있고, large먼지로 dust된 lane거대한 with띠가 diameter은하핵을 of둘러싸고 approximately있는데 a이 few띠는 kiloparsecs's'자 which모양으로 surrounds뻗어 the있으며 nucleus그 and크기는 is대략 stretched수 out into an "s"[[킬로파섹]] shape정도이다. The이 dust먼지 lane띠는 appears to be connected to a small dust ring with a diameter of지름이 ~{{convert|0.1|kpc|ly|abbr=on|lk=on|order=flip}} 정도인 작은 먼지 원반 하나와 연결되어 있는 것으로 보인다.<ref>{{Cite journal|last=Blanchard|first=P. K.|last2=Berger|first2=E.|last3=Fong|first3=W.|last4=Nicholl|first4=M.|last5=Leja|first5=J.|last6=Conroy|first6=C.|last7=Alexander|first7=K. D.|last8=Margutti|first8=R.|last9=Williams|first9=P. K. G.|date=2017-10-16|title=The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VII. Properties of the Host Galaxy and Constraints on the Merger Timescale|journal=The Astrophysical Journal|volume=848|issue=2|pages=L22|doi=10.3847/2041-8213/aa9055|arxiv=1710.05458|bibcode=2017ApJ...848L..22B}}</ref> TheseNGC features4993의 in이 NGC특징들은 4993가스가 may풍부했던 be후기형 the은하와의 result병합(약 4억 년 전 발생) 때문에 생겨난 것으로 보인다.<ref>{{Cite journal|last=Im|first=Myungshin|last2=Yoon|first2=Yongmin|last3=Lee|first3=Seong-Kook J.|last4=Lee|first4=Hyung Mok|last5=Kim|first5=Joonho|last6=Lee|first6=Chung-Uk|last7=Kim|first7=Seung-Lee|last8=Troja|first8=Eleonora|last9=Choi|first9=Changsu|date=2017-10-26|title=Distance and Properties of NGC 4993 as the Host Galaxy of the Gravitational-wave Source GW170817|journal=The Astrophysical Journal|language=en|volume=849|issue=1|pages=L16|doi=10.3847/2041-8213/aa9367|arxiv=1710.05861|bibcode=2017ApJ...849L..16I}}</ref> of a recent merger with a gaseous late-type galaxy that occurred about 400 million years ago.<ref name=":0"/> However,그러나 Palmese et연구진은 al.NGC suggested4993에 that병합된 the은하에 galaxy가스가 involved결핍되어 in the merger was a gas-poor있었다고 galaxy추정했다.<ref>{{Cite journal|last=Palmese|first=A.|last2=Hartley|first2=W.|last3=Tarsitano|first3=F.|last4=Conselice|first4=C.|last5=Lahav|first5=O.|last6=Allam|first6=S.|last7=Annis|first7=J.|last8=Lin|first8=H.|last9=Soares-Santos|first9=M.|date=2017-11-09|title=Evidence for Dynamically Driven Formation of the GW170817 Neutron Star Binary in NGC 4993|journal=The Astrophysical Journal|language=en|volume=849|issue=2|pages=L34|doi=10.3847/2041-8213/aa9660|arxiv=1710.06748|bibcode=2017ApJ...849L..34P}}</ref>

NGC 4993에는 암흑 물질[[암흑물질]] 헤일로가 있으며 예상 질량은 {{Val|1.939|e=12|ul=M_solar}}이다.<ref name=":0">{{Cite journal|last=Ebrová|first=Ivana|last2=Bílek|first2=Michal|title=NGC 4993 the shell galaxy host of GW170817: constraints on the recent galactic merger|journal=Astronomy & Astrophysics|year=2020|volume=634|pages=A73|doi=10.1051/0004-6361/201935219|arxiv=1801.01493}}</ref>

NGC 4993에는 구상 성단이[[구상성단]]이 약 250 개 정도 있는 것으로 추정된다.<ref name=":2">{{Cite journal|last=Abbott|first=B. P.|last2=Abbott|first2=R.|last3=Abbott|first3=T. D.|last4=Acernese|first4=F.|last5=Ackley|first5=K.|last6=Adams|first6=C.|last7=Adams|first7=T.|last8=Addesso|first8=P.|last9=Adhikari|first9=R. X.|date=2017-12-01|title=On the Progenitor of Binary Neutron Star Merger GW170817|journal=The Astrophysical Journal|language=en|volume=850|issue=2|pages=L40|doi=10.3847/2041-8213/aa93fc|arxiv=1710.05838|bibcode=2017ApJ...850L..40A}}</ref>

NGC 4993의 광도를 통해 이 은하를 둘러싼 구상성단 계에는계는 중원소가[[금속함량|중원소]]가 부족한 구상성단들이 대다수를 차지함을 알 수 있다.<ref>{{Cite journal|last=Lee|first=Myung Gyoon|last2=Kang|first2=Jisu|last3=Im|first3=Myungshin|date=20 May 2018|title=A Globular Cluster Luminosity Function Distance to NGC 4993 Hosting a Binary Neutron Star Merger GW170817/GRB 170817A|journal=The Astrophysical Journal Letters|volume=859|issue=1|pages=L6|doi=10.3847/2041-8213/aac2e9|arxiv=1805.01127|bibcode=2018ApJ...859L...6L}}</ref>

NGC 4993에는 [[초대질량 블랙홀이블랙홀]]이 하나 있으며 이 블랙홀의 예상 질량은 태양질량의 약 8000만 ~ 1억 배로 보인다.({{Val|8|e=7|ul=M_solar}})<ref name=":1">{{Cite journal|last=Wu|first=Qingwen|last2=Feng|first2=Jianchao|last3=Fan|first3=Xuliang|date=6 March 2018|title=The Possible Submillimeter Bump and Accretion-jet in the Central Supermassive Black Hole of NGC 4993|journal=The Astrophysical Journal|volume=855|issue=1|pages=46|arxiv=1710.09590|bibcode=2018ApJ...855...46W|doi=10.3847/1538-4357/aaac28}}</ref>

In2017년 August8월 2017,GRB rumors170817A로 circulated명명된 짧은 감마선 폭발의 원인은 [[중성자별]] 두 개가 서로 충돌하여 발생한 것이라는 추측이 떠돌았다.<ref name="NG-20170825">{{cite web |last=Drake |first=Nadia |title=Strange stars caught wrinkling spacetime? Get the facts. |url=http://news.nationalgeographic.com/2017/08/new-gravitational-waves-neutron-stars-ligo-space-science/ |date=25 August 2017 |work=[[National Geographic (magazine)|National Geographic]] |accessdate=27 August 2017}}</ref> regarding a [[Gamma-ray burst#Short gamma-ray bursts|short gamma-ray burst]] designated [[GRB 170817A]], of the type conjectured to be emitted in the [[Neutron star merger|collision]] of two [[neutron star]]s.<ref>{{cite journal |author=Nakar, E. |date=2007 |title=Short-hard gamma-ray bursts |journal=[[Physics Reports]]|author=Nakar, E.|date=2007|volume=442 |issue=1–6 |pages=166–236 |doiarxiv=10.1016astro-ph/j.physrep.2007.02.005 0701748|bibcode=2007PhR...442..166N |arxivdoi=astro-ph10.1016/0701748 j.physrep.2007.02.005|ref=Nakar07 |citeseerx=10.1.1.317.1544}}</ref> On2017년 16&nbsp;October10월 2017, the16일 [[LIGO]]레이저 and간섭계 [[Virgo중력파 interferometer관측소|VirgoLIGO]]와 collaborationsVirgo announced공동연구진은 thatGW170817로 they had detected a명명된 [[gravitational wave중력파]] event,사건을 designated포착했다고 [[GW170817]]발표했다. The이 gravitational중력파 wave신호는 signal감마선 matched폭발이 prediction생기기 for2 the초 merger전에 of중성자별 two2 neutron개가 stars,합쳐졌을 two것이라는 seconds예측과 before the gamma-ray burst부합했다. The gravitational wave signal, which had a duration of about약 100&nbsp;seconds, was초 the동안 first지속된 gravitational이 wave중력파 detection신호는 of중성자별이 the병합되어 merger생겨난 of중력파로서는 two최초의 neutron발견 stars사례였다.<ref name="NASA-20171016a">{{cite news |last1=Chou |first1=Felicia |last2=Washington |first2=Dewayne |last3=Porter |first3=Molly |title=Release 17-083 - NASA Missions Catch First Light from a Gravitational-Wave Event|url=https://www.nasa.gov/press-release/nasa-missions-catch-first-light-from-a-gravitational-wave-event |date=16 October 2017 |work=[[NASA]] |accessdate=21 October 2017 }}</ref><ref name="NASA-20171016b">{{cite news |last1=Landau |first1=Elizabeth |last2=Chou |first2=Felicia |last3=Washington |first3=Dewayne |last4=Porter |first4=Molly |title=NASA Missions Catch First Light from a Gravitational-Wave Event|url=https://www.jpl.nasa.gov/news/news.php?feature=6975 |date=16 October 2017 |work=[[NASA]] |accessdate=16 October 2017 }}</ref><ref name="PRL-171016">{{cite journal |last1=Abbott |first1=B.P. |display-authors=etal |title=GW&nbsp;170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral |journal=Physical Review Letters |date=16 October 2017 |volume=119 |issue=16 |page=161101 |doi=10.1103/PhysRevLett.119.161101 |pmid=29099225 |bibcode=2017PhRvL.119p1101A |arxiv=1710.05832}}</ref><ref name="SM-20171016">{{cite news |last=Cho |first=Adrian |title=Merging neutron stars generate gravitational waves and a celestial light show |url=http://www.sciencemag.org/news/2017/10/merging-neutron-stars-generate-gravitational-waves-and-celestial-light-show |date=16 October 2017 |work=[[Science (magazine)|Science]] |accessdate=16 October 2017 |doi=10.1126/science.aar2149 }}</ref><ref name="MN-20171016">{{cite news |last=Krieger |first=Lisa M. |title=A Bright Light Seen Across The Universe, Proving Einstein Right - Violent collisions source of our gold, silver |url=http://www.mercurynews.com/2017/10/16/a-bright-light-seen-across-the-universe-proving-einstein-right/ |date=16 October 2017 |work=[[The Mercury News]] |accessdate=16 October 2017}}</ref>

An앞의 [[transient중력파와 astronomical감마선 event|optical신호 transient]],사건으로부터 11 시간 후 순간적 천문 사건 {{nowrap|[[AT 2017gfo]]}} (also또는 knownSSS as SSS&nbsp;17a),가 was포착되어 detected병합 in NGC&nbsp;4993 11&nbsp;hours after the gravitational wave and gamma-ray signals, allowing the location of the사건의 merger위치를 to특정할 be수 determined있었다. The이 optical광학상 emission is thought to be due to a방출은 [[kilonova킬로노바]].가 The원인이었던 discovery것 of같다. AT&nbsp;2017gfo2017gfo의 was발견은 the중력파원에 first대한 observation전자기적 (and대응물을 first최초로 localisation)관측한 of것이자 an그 electromagnetic발생 counterpart장소를 to최초로 a알아낸 gravitational사건이었다는 wave점에 source의의가 있다.<ref name="NASA-20171016b"/>{{r|SM-20171016|MN-20171016}}<ref name="NYT-Dennis">{{cite news |last=Overbye |first=Dennis |authorlink=Dennis Overbye |title=LIGO Detects Fierce Collision of Neutron Stars for the First Time |url=https://www.nytimes.com/2017/10/16/science/ligo-neutron-stars-collision.html |date=16 October 2017 |work=[[The New York Times]] |accessdate=16 October 2017 }}</ref><ref name="PhysRev2017">{{cite journal |last1=Abbott |first1=B. P. |display-authors=etal |collaboration=[[LIGO Scientific Collaboration]] & [[Virgo interferometer|Virgo Collaboration]] |title=GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral |journal=Physical Review Letters |date=16 October 2017 |volume=119 |issue=16 |pages=161101 |doi=10.1103/PhysRevLett.119.161101 |pmid=29099225 |doi-access=free |bibcode=2017PhRvL.119p1101A |arxiv=1710.05832}}</ref>

[[GRB 170817A]] was a170817A는 [[gamma-ray미국 burst항공우주국|NASA]] (GRB) detected by페르미와 [[NASA]]'s유럽 [[Fermi Gamma-ray Space Telescope우주국|FermiESA]]의 andINTEGRAL이 [[ESA]]'s2017년 [[INTEGRAL]]8월 on17일에 17&nbsp;August포착한 감마선 2017폭발(GRB)이다.<ref name="NG-20170825"/><ref name="FERMI-20170817">{{cite web |last=von&nbsp;Kienlin |first=Andreas |title=GCN Circular Number&nbsp;21520; GRB&nbsp;170817A: Fermi GBM detection; 2017-08-17 20:00:07&nbsp;GMT |url=https://gcn.gsfc.nasa.gov/gcn3/21520.gcn3 |date=17 August 2017 |work=[[Max Planck Institute for Extraterrestrial Physics]] |accessdate=28 August 2017 }}</ref><ref name="NAT-20170825">{{cite news |last=Castelvecchi |first=Davide |title=Rumours swell over new kind of gravitational-wave sighting |url=https://www.nature.com/news/rumours-swell-over-new-kind-of-gravitational-wave-sighting-1.22482 |date=25 August 2017 |publisher=[[Nature (journal)|Nature News]] |doi=10.1038/nature.2017.22482 |accessdate=27 August 2017 }}</ref><ref name="WIRED-20170825">{{cite journal |last=Sokol |first=Joshua |title=What Happens When Two Neutron Stars Collide? |url=https://www.wired.com/story/what-happens-when-two-neutron-stars-collide-scientific-revolution/ |date=25 August 2017 |journal=[[Wired (magazine)|Wired]] |accessdate=28 August 2017 }}</ref> Although하늘의 only넓은 localized영역에 to대비하면 a매우 large좁은 area곳에서 of온 the신호일 sky,뿐이지만 it중력파 is사건 believed후 to1.7 correspond초만에 to포착되었음을 the고려하면 other다른 two관측 사례 두 observations,개와 관련이 있는 것으로 받아들여진다.{{r|NYT-Dennis}} in part due to its arrival time 1.7&nbsp;seconds after the GW event.

* {{언어링크|en}} {{cite simbad|title=NGC 4993|access-date=28 August 2017}}

* {{언어링크|en}} {{cite web|title=NGC 4993|publisher=DSO Browser|url=http://dso-browser.com/dso/info/NGC/4993|accessdate=28 August 2017}}

* {{언어링크|en}} {{cite web|title=New General Catalog Objects: NGC 4950 – 4999|url=http://cseligman.com/text/atlas/ngc49a.htm#4993|accessdate=28 August 2017|last=Courtney Seligman}}

* {{언어링크|en}} {{cite web|title=Revised NGC Data for NGC 4993|publisher=SEDS|url=http://spider.seds.org/ngc/revngcic.cgi?NGC4993|accessdate=28 August 2017|last=Hartmut Frommert}}

* {{언어링크|en}} [http://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=grb170817a GRB 170817A] – NASA/IPAC Extragalactic Database (NED)

* {{언어링크|en}} [http://www.mpe.mpg.de/~jcg/grb170817A.html GRB 170817A] – Max Planck Institute for Extraterrestrial Physics (MPE)

* {{언어링크|en}} [http://isdc.unige.ch/integral/ibas/cgi-bin/ibas_acs_web.cgi/?trigger=2017-08-17T12-41-06.00-00000-00000-0 GRB 170817A] - INTEGRAL Science Data Center (ISDC)

* {{언어링크|en}} [https://www.eso.org/public/images/eso1733l Starmap]