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{{Bedakan|Sagittarius A}}
{{Starbox begin | name = Sagittarius A}}
{{Starbox image | image = [[Berkas:gcleSag A*.jpg|250px]] | caption = SgrFoto Sagittarius A* (tengah) dan duaoleh [[GemaEvent Cahaya|gemaHorizon cahayaTelescope]] daripada ledakantahun baru-baru ini2017 (dilingkaridirilis tahun 2022)}}
{{Starbox observe
| epoch=[[J2000]]
Baris 9 ⟶ 10:
}}
{{Starbox detail
| mass = {{val|8.26|e=36|u=kilogram}} <br>{{val|4.154|0.014|e=6}}<ref name="GRAVITY"/>
| mass = (4.31&nbsp;±&nbsp;0.38)&nbsp;×&nbsp;10<sup>6</sup><ref name="Gillessen">[[#Gillessen|Gillessen ''et al.'' 2009]]</ref> [[Massa matahari|M<sub>☉</sub>]]<br />(4.1&nbsp;±&nbsp;0.6)&nbsp;×&nbsp;10<sup>6</sup><ref name="Ghez08" />
}}
{{Starbox astrometry |
| dist_ly=25,900{{val|26673|42}}<ref ± 1,400name=GRAVITY/>
| dist_pc={{val|8178|13}}<ref name=GRAVITY/>
| dist_pc=7,940 ± 420<ref>[[#Eisenhauer|Eisenhauer ''et al.'' 2003]], § 3.1</ref>
}}
}}{{Kompas Gramedia|Kompas TV=Kompastv}}
{{Starbox reference
{{Kompas Gramedia|Kompas-Gramedia=}}{{Kompas Gramedia|Kompas Gramedia=}}{{Starbox end}}
|Simbad=NAME+Sgr+A*
[[Berkas:Chandra image of Sgr A.jpg|thumb|Gambar Sgr A* dari [[Observatorium sinar-X Chandra]].]]▼
}}
'''Sagittarius A*''' (diucapkan "Sagittarius A-star", biasa disingkat '''Sgr A*''') adalah [[Sumber Radio Astronomi|sumber radio astronomi]] yang sangat cerah di wilayah [[Pusat Galaksi|pusat]] [[Bima Sakti]]. Sgr A* merupakan bagian dari [[Sagittarius A]]. Sgr A* dipercayai menjadi tempat tinggalnya sebuah [[lubang hitam supermasif]].<ref>[[#Reynolds|Reynolds 2008]]</ref> Observasi bintang [[S2 (bintang)|S2]] yang mengorbit Sagittarius A* telah digunakan untuk menunjukkan adanya lubang hitam supermasif di pusat Bima Sakti, dan telah ditarik kesimpulan bahwa Sagittarius A* merupakan situs terbentuknya lubang hitam.<ref name="Henderson" />
{{Starbox end}}
[[Berkas:Gcle.jpg|jmpl|250x250px|Sgr A* (tengah) dan dua [[gema cahaya]] dari ledakan baru-baru ini (dilingkari)]]
▲[[Berkas:Chandra image of Sgr A.jpg|thumbjmpl|Gambar Sgr A* dari [[Observatorium sinar-X Chandra]].]]
'''Sagittarius A*''' (diucapkan "Sagittarius A-star", biasa disingkat '''Sgr A*''') adalah sebuah [[lubang hitam supermasif]]<ref>{{Cite news|date=2018-10-31|title=Scientists find proof a black hole is lurking at the centre of our galaxy|url=https://metro.co.uk/2018/10/31/scientists-find-proof-a-supermassive-black-hole-is-lurking-at-the-centre-of-the-milky-way-8092994/|work=Metro|language=en-GB|archive-url=https://web.archive.org/web/20181031214911/https://metro.co.uk/2018/10/31/scientists-find-proof-a-supermassive-black-hole-is-lurking-at-the-centre-of-the-milky-way-8092994/|archive-date=2018-10-31|access-date=2018-10-31|url-status=live}}</ref><ref>{{Cite news|date=2018-10-31|title=A 'mind-boggling' telescope observation has revealed the point of no return for our galaxy's monster black hole|url=https://www.middletownpress.com/technology/businessinsider/article/Supermassive-black-holes-gorge-themselves-on-a-7971243.php|work=The Middletown Press|archive-url=https://web.archive.org/web/20181031144008/https://www.middletownpress.com/technology/businessinsider/article/Supermassive-black-holes-gorge-themselves-on-a-7971243.php|archive-date=2018-10-31|access-date=2018-10-31|url-status=dead}}</ref><ref name="plait">{{cite web|last1=Plait|first1=Phil|date=2018-11-08|title=Astronomers see material orbiting a black hole *right* at the edge of forever|url=https://www.syfy.com/syfywire/astronomers-see-material-orbiting-a-black-hole-right-at-the-edge-of-forever|publisher=Syfy Wire|language=en|archive-url=https://web.archive.org/web/20181110143143/https://www.syfy.com/syfywire/astronomers-see-material-orbiting-a-black-hole-right-at-the-edge-of-forever|archive-date=10 November 2018|access-date=12 November 2018}}</ref> di [[Pusat Galaksi]] [[Bima Sakti]]. Sgr A* terletak dekat perbatasan rasi bintang [[Sagitarius|Sagittarius]] dan [[Scorpius]], kira-kira 5,6° selatan [[ekliptika]], dan tampak dekat [[Gugus Kupu-kupu]] (M6) dan [[Shaula]].
 
Observasi beberapa bintang yang mengorbit Sagittarius A*, terutama bintang [[S2 (bintang)|S2]], digunakan untuk mementukan massa dan batas maksimum radius objek. Berdasarkan massa dan batas radius yang semakin presisi, para astronom menarik kesimpulan bahwa Sagittarius A* adalah lubang hitam supermasif di pusat Bima Sakti.<ref name="Henderson" /> Nilai massanya saat ini adalah 4,154 (± 0,014) juta [[massa Matahari]].<ref name="GRAVITY">{{cite journal|author=The GRAVITY collaboration|date=April 2019|title=A geometric distance measurement to the Galactic center black hole with 0.3% uncertainty|url=https://www.aanda.org/articles/aa/full_html/2019/05/aa35656-19/aa35656-19.html|journal=Astronomy & Astrophysics|volume=625|pages=L10|arxiv=1904.05721|bibcode=2019A&A...625L..10G|doi=10.1051/0004-6361/201935656|archive-url=https://web.archive.org/web/20191004044634/https://www.aanda.org/articles/aa/full_html/2019/05/aa35656-19/aa35656-19.html|archive-date=2019-10-04|access-date=2019-10-04|s2cid=119190574|url-status=live}}</ref>
 
[[Reinhard Genzel]] dan [[Andrea Ghez]] menerima [[Penghargaan Nobel Fisika]] 2020 untuk menemukan bahwa Sgr A* adalah objek supermasif dan padat, dimana [[lubang hitam]] adalah satu-satunya penjelasan yang masuk akal pada saat itu.<ref>{{cite news|date=6 October 2020|title=The Nobel Prize in Physics 2020|url=https://www.nobelprize.org/prizes/physics/2020/summary/|language=en-us|archive-url=https://web.archive.org/web/20210424115309/https://www.nobelprize.org/prizes/physics/2020/summary/|archive-date=24 April 2021|access-date=7 October 2020|url-status=live}}</ref>
 
Pada 12 Mei 2022, menggunakan [[Event Horizon Telescope|Teleskop Event Horizon]], para astronom merilis foto Sagittarius A* yang menggunakan data dari observasi radio pada April 2017,<ref name="AJ-202205">{{cite journal|last=Bower|first=Geoffrey C.|date=May 2022|title=Focus on First Sgr A* Results from the Event Horizon Telescope|url=https://iopscience.iop.org/journal/2041-8205/page/Focus_on_First_Sgr_A_Results|journal=[[The Astrophysical Journal]]|accessdate=12 May 2022}}</ref> dan memastikan bahwa objek ini adalah lubang hitam. Ini adalah gambar terkonfirmasi lubang hitam kedua, setelah foto lubang hitam supermasif [[Messier 87]] pada tahun 2019.<ref name="ESO22082">{{cite news|date=12 May 2022|title=Astronomers reveal first image of the black hole at the heart of our galaxy|url=https://www.eso.org/public/news/eso2208-eht-mw/|work=eso.org|access-date=12 May 2022}}</ref><ref name="NYT-20220512">{{Cite news|last=Overbye|first=Dennis|date=2022-05-12|title=The Milky Way's Black Hole Comes to Light|url=https://www.nytimes.com/2022/05/12/science/black-hole-photo.html|work=The New York Times|language=en-US|issn=0362-4331|access-date=2022-05-12}}</ref>
 
== Observasi ==
Para astronom telah mampu mengamati Sgr A* dalam [[Spektrum kasat mata|spektrum optik]] karena efek dari 25 besaran [[magnitudo]] antara Sgr A* dan [[Bumi]].<ref name="Osterbrock">[[#Osterbrock|Osterbrock and Ferland 2006]], p. 390</ref> Beberapa tim peneliti telah berusaha untuk menggambarkan Sagittarius A* dalam spektrum radio dengan menggunakan [[Very-long-baseline Interferometry|interferometri dasar yang sangat panjang]] (VLBI). Pengukuran dengan resolusi tertinggi saat ini, telah dibuat dengan panjang gelombang 1.,3 [[Milimeter|mm]], yang mana menunjukkan [[diameter sudut]] untuk sumber dari 37 [[Menit busur|μas]].<ref name="EHS" /> Sagittarius A* berjarak 26.000 [[tahun cahaya]] (~44 juta [[kilometer]]) dari Bumi.
 
== Sejarah ==
'''Sgr A*''' ditemukan pada tanggal 13 dan 15 [[Februari]] 1974 oleh astronom Bruce Ballick dan Robert Brown dengan menggunakan interferometri dasar dari [[National Radio Astronomy Observatory|Observatorium Radio Astronomi Nasional]].<ref>[[#Melia|Melia 2007]], p. 2</ref> Nama Sgr A* diciptakan oleh Brown karena sumber radio itu "menarik", karena keadaan tereksitasi dari atom ditandai dengan tanda bintang.<ref>http://arxiv.org/abs/astro-ph/0305074</ref>
 
Observasi radio Sgr A* dengan VLBI juga bisa disejajarkan terpusat dengan gambar sehingga bintang S2 bisa dilihat mengorbit Sagittarius A*. Dari analisaanalisis bintang S2 terhadap [[Orbit Kepler]], Sagittarius A* bermassa sekitar 2.,6 ± 0.,2 juta massa matahari.<ref>[[#Ghez03|Ghez ''et al.'' 2003]]</ref> Mereka juga menentukan jarak dari [[Bumi]] ke [[pusat galaksi]], yang mana hal yang sangat penting dalam mengkalibrasi skala astronomi, seperti 8.,0 ± 0.,6 × 10<sup>3</sup> [[parsec]].
 
Pada bulan November 2004, sebuah tim astronom melaporkan penemuan [[Lubang Hitam|lubang hitam bermassa menengah]] yang bernama [[GCIRS 13E]], mengorbit Sagittarius A* dengan jarak 3 tahun cahaya. Lubang hitam ini bermassa 1.300 kali massa matahari. Penemuan ini dapat menambahkan gagasan bahwa lubang hitam supermasif tumbuh dengan menyerap lubang hitam kecil disekitarnya.
 
== Pusat lubang hitam ==
Jika posisi Sagittarius A* benar-benar berada di pusat lubang hitam, akan ada kemungkinan ukurannya telah diperbesar dari ukuran aslinya, karena disebabkan oleh [[lensa gravitasi]]. Menurut teori [[relativitas umum]], hal ini akan menghasilkan ukuran minimal setidaknya 5.,2 kali lebih besar daripada [[Radius Schwarzschild|radius lubang hitam Schwarzschild]].<ref name="EHS">[[#Doeleman|Doeleman ''et al.'' 2008]]</ref>
 
Para astronom yakin bahwa pengamatan ini memberikan bukti empiris baik bahwa galaksi [[Bima Sakti]] kita memiliki lubang hitam supermasif di pusatnya yang berjarak 26.000 tahun cahaya dari [[Tata Surya]],<ref name="Henderson">{{cite news|url=http://www.timesonline.co.uk/tol/news/uk/science/article5316001.ece|title=Astronomers confirm black hole at the heart of the Milky Way|last=Henderson|first=Mark|date=December 9, 2008|publisher= Times Online|accessdate=2009-05-17}}</ref> karena:
* Bintang [[S2 (bintang)|S2]] mengikuti orbit elips dengan periode 15.,2 tahun dan ber-[[apsis]] (jarak terdekat) 17 [[Detik Cahaya|jam cahaya]] ({{val|1.8|e=13|u=m}}) dari pusat objek.<ref>{{cite journal |first=R. |last=Schödel |coauthors=et al. |date=17 October 2002 |title=A star in a 15.2-year orbit around the supermassive black hole at the centre of the Milky Way |url=https://archive.org/details/sim_nature-uk_2002-10-17_419_6908/page/694 |journal=Nature |volume=419 |issue= 6908|pages=694–696 | doi= 10.1038/nature01121 |arxiv=astro-ph/0210426 |pmid=12384690|bibcode = 2002Natur.419..694S }}
</ref>
* Dari pergerakan bintang S2, massanya dapat diperkirakan sekitar 4.,1 juta kali massa matahari.<ref name="Ghez08">{{cite journal
| author = Ghez, A. M.
| coauthors = ''et al.''
Baris 47 ⟶ 58:
}}</ref>
* Jari-jari objek sentral harus secara signifikan kurang dari 17 jam cahaya, karena jika tidak, S2 akan bertabrakan dengannya.
* Satu-satunya objek yang bermassa 4.,1 juta kali massa matahari dalam volume yang kecil adalah lubang hitam.
 
{| class="wikitable"
Baris 63 ⟶ 74:
| [[S1 (bintang)|S1]]
| S0-1
| 0.,412±0.,024
|3300±190
|0.,358±0.,036
|94.,1±9.,0
|2002.,6±0.,6
|<ref name="Eisenhauer">{{cite journal|last=Eisenhauer|first=F.|coauthors=et al|title=SINFONI in the Galactic Center: Young Stars and Infrared Flares in the Central Light-Month|journal=The Astrophysical Journal|date=July 20, 2005|issue=628|pages=246–259| url=http://iopscience.iop.org/0004-637X/628/1/246/62163.text.html}}</ref>
|-
|[[S2 (bintang)|S2]]
|S0-2
|0.,1226±0.,0025
|980±20
|0.,8760±0.,0072
|15.,24±0.,36
|2002.,315±0.,012
|<ref name="Eisenhauer"/>
|-
Baris 83 ⟶ 94:
|
|919±23
|0.,8670±0.,0046
|14.,53±0.,65
|2002.,308±0.,013
|<ref name="Ghez05">{{cite journal |last=Ghez |first=A. M. |authorlink=Andrea Ghez |coauthors=Salim, S.; Hornstein, S. D.; Tanner, A.; Lu, J. R.; Morris, M.; Becklin, E. E.; Duchêne, G. |title=Stellar Orbits around the Galactic Center Black Hole |journal=The Astrophysical Journal |volume=620 |issue=2 |pages=744–757 |date=May 2005 |arxiv=astro-ph/0306130 |doi=10.1086/427175|bibcode = 2005ApJ...620..744G }}</ref>
|-
|[[S8 (bintang)|S8]]
|S0-4
|0.,329±0.,018
|2630±140
|0.,927±0.,019
|67.,2±5.,5
|1987.,71±0.,81
|<ref name="Eisenhauer"/>
|-
|[[S12 (bintang)|S12]]
|S0-19
|0.,286±0.,012
|2290±100
|0.,9020±0.,0047
|54.,4±3.,5
|1995.,628±0.,016
|<ref name="Eisenhauer"/>
|-
Baris 110 ⟶ 121:
|
|1720±110
|0.,833±0.,018
|37.,3±3.,8
|1995.,758±0.,050
|<ref name="Ghez05"/>
|-
|[[S13 (bintang)|S13]]
|S0-20
|0.,219±0.,058
|1750±460
|0.,395±0.,032
|36±15
|2006.,1±1.,4
|<ref name="Eisenhauer"/>
|-
|[[S14 (bintang)|S14]]
|S0-16
|0.,225±0.,022
|1800±180
|0.,9389±0.,0078
|38±5.,7
|2000.,156±0.,052
|<ref name="Eisenhauer"/>
|-
Baris 137 ⟶ 148:
|
|1680±510
|0.,974±0.,016
|36±17
|2000.,201±0.,025
|<ref name="Ghez05"/>
|-
Baris 146 ⟶ 157:
|
|
|0.,68±0.,02
|11.,5±0.,3
|2009.,5±0.,3
|<ref>{{cite web|title=The Shortest Known Period Star Orbiting our Galaxy’s Supermassive Black Hole|last=Meyer|first=L.|coauthors=A. M. Ghez, R. Schödel, S. Yelda, A. Boehle, J. R. Lu, T. Do, M. R. Morris, E. E. Becklin, K. Matthews|date=4 October 2012|accessdate=6 October 2012|url=http://arxiv.org/pdf/1210.1294v1.pdf}}</ref>
|}
Baris 156 ⟶ 167:
 
== Referensi ==
* <cite id=Backer>{{cite journal | author = Backer, D. C. and Sramek, R. A. | title = Proper Motion of the Compact, Nonthermal Radio Source in the Galactic Center, Sagittarius A* | url = https://archive.org/details/sim_astrophysical-journal_1999-10-20_524_2/page/805 | journal = [[The Astrophysical Journal]] | volume = 524 | issue = 2 | pages = 805&ndash;815805–815 | date = 20 October 1999 | doi = 10.1086/307857 | bibcode=1999ApJ...524..805B}}</cite>
* <cite id=Doeleman>{{cite journal | author = Doeleman, Sheperd | coauthors = ''et al.'' | title = Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre | url = https://archive.org/details/sim_nature-uk_2008-09-04_455_7209/page/78 | journal = [[Nature (journal)|Nature]] | volume = 455 | pages = 78&ndash;8078–80 | date = 4 September 2008 | doi = 10.1038/nature07245 | pmid = 18769434 | issue = 7209 | bibcode=2008Natur.455...78D}}</cite>
* <cite id=Eckart>{{cite book|author = Eckart, A.; Schödel, R.; Straubmeier, C.|title = The Black Hole at the Center of the Milky Way|publisher = Imperial College Press|location = London|year = 2005}}</cite>
* <cite id=Eisenhauer>{{cite journal | author = Eisenhauer, F. | coauthors = ''et al.'' | title = A Geometric Determination of the Distance to the Galactic Center | date = 23 October 2003 | journal = The Astrophysical Journal | doi = 10.1086/380188 | pages = L121&ndash;L124L121–L124 | issue = 2 | volume = 597 | bibcode=2003ApJ...597L.121E | arxiv=astro-ph/0306220}}</cite>
* <cite id=Ghez03>{{cite journal | author = Ghez, A. M. | coauthors = ''et al.'' | date = 12 March 2003 | title = The First Measurement of Spectral Lines in a Short-Period Star Bound to the Galaxy’s Central Black Hole: A Paradox of Youth | journal = The Astrophysical Journal | volume = 586 | issue = 2 | pages = L127&ndash;L131L127–L131 | doi = 10.1086/374804 | bibcode=2003ApJ...586L.127G}}</cite>
* <cite id=Ghez08>{{cite journal
| author = Ghez, A. M.
Baris 175 ⟶ 186:
| arxiv=0808.2870}}</cite>
* <cite id=Gillessen>{{cite journal |last=Gillessen |first=Stefan |authorlink= |coauthors=''et al.''|date = 23 February 2009 |title=Monitoring stellar orbits around the Massive Black Hole in the Galactic Center |journal=The Astrophysical Journal |volume=692 |issue= 2|pages=1075–1109 |doi = 10.1088/0004-637X/692/2/1075 |bibcode=2009ApJ...692.1075G }}</cite>
* <cite id=Melia>{{cite book|author = Melia, Fulvio|title = The Galactic Supermassive Black Hole|url = https://archive.org/details/galacticsupermas0000meli|publisher = Princeton University Press|year = 2007|isbn = 0-691-13129-5|location = Princeton}}</cite>
* <cite id=ONeill>{{cite news|author = O'Neill, Ian|title = Beyond Any Reasonable Doubt: A Supermassive Black Hole Lives in Centre of Our Galaxy|url = http://www.universetoday.com/2008/12/10/beyond-any-reasonable-doubt-a-supermassive-black-hole-lives-in-centre-of-our-galaxy/|publisher = Universe Today|date = 10 December 2008 }}</cite>
* <cite id=Osterbrock>{{cite book|author = Osterbrock, Donald E. and Ferland, Gary J.|title = Astrophysics of Gaseous Nebulae and Active Galactic Nuclei|url = https://archive.org/details/astrophysicsofga0000oste|edition = 2nd|publisher = University Science Books|year = 2006|isbn = 1-891389-34-3}}</cite>
* <cite id=Reid>{{cite journal | author = Reid, M.J. | coauthors = Brunthaler, A. | year = 2004 | journal = Astrophysical Journal | volume = 616 | pages = 872&ndash;884872–884 | bibcode = 2004ApJ...616..872R| url = http://simbad.u-strasbg.fr/simbad/sim-id?Ident=SGR+A*&NbIdent=1 |title=Sgr A* -- Radio-source }}</cite>
* <cite id=Reynolds>{{cite journal | author = Reynolds, C. | title = Astrophysics: Bringing black holes into focus | url = https://archive.org/details/sim_nature-uk_2008-09-04_455_7209/page/39 | journal = Nature | volume = 455 | pages = 39&ndash;4039–40 | date = 4 September 2008 | doi = 10.1038/455039a | pmid = 18769426 | issue = 7209 | bibcode=2008Natur.455...39R}}</cite>
* <cite id=Schodel>{{cite journal | author = Schödel, R. | coauthors = ''et al.'' | title = A star in a 15.2-year orbit around the supermassive black hole at the centre of the Milky Way | url = https://archive.org/details/sim_nature-uk_2002-10-17_419_6908/page/694 | date = 17 October 2002 | journal = Nature | volume = 419 | pages = 694&ndash;696694–696 | doi = 10.1038/nature01121 | pmid = 12384690 | issue = 6908 | bibcode=2002Natur.419..694S}}</cite>
* <cite id=Schodel2>{{cite journal | last = Schödel | first = R. | last2 = Merritt | first2 = D. | author2-link = David Merritt | last3 = Eckart | first3 = A. | title = The nuclear star cluster of the Milky Way: Proper motions and mass | date = July 2009 | journal = Astronomy and Astrophysics | volume = 502 | issue = 1 | pages = 91&ndash;11191–111 | bibcode = 2009A&A...502...91S | doi = 10.1051/0004-6361/200810922 }}</cite>
* <cite id=Wheeler>{{cite book|title=Cosmic Catastrophes: Exploding Stars, Black Holes, and Mapping the Universe|url=https://archive.org/details/cosmiccatastroph0000whee_f9s6|author=Wheeler, J. Craig|publisher=Cambridge University Press|location=Cambridge, UK|year=2007|edition=2nd|isbn=0-521-85714-7}}</cite>
 
== Pranala luar ==
{{Commons category|Sagittarius A}}
* [http://video.google.com/videoplay?docid=6199067060728714818&q=black+hole UCLA Faculty Research presentation on Sagittarius A*] {{Webarchive|url=https://web.archive.org/web/20070103022621/http://video.google.com/videoplay?docid=6199067060728714818 |date=2007-01-03 }} (Video)
* [http://www.astro.ucla.edu/~ghezgroup/gc/ UCLA Galactic Center Group - latest results] retrieved 8/12/2009
* [http://arxiv.org/abs/0808.2624 Is there a Supermassive Black Hole at the Center of the Milky Way? (arxiv preprint)]
* [http://arxiv.org/abs/astro-ph/0306130 2004 paper deducing mass of central black hole from orbits of 7 stars (arxiv preprint)]
* [http://www.eso.org/public/archives/videos/old_video/eso0226a.mpg ESO video clip of orbiting star] (533 KB MPEG Video)
* [http://www.eso.org/outreach/press-rel/pr-2002/pr-17-02.html Star Orbiting Massive Milky Way Centre Approaches to within 17 Light-Hours] {{Webarchive|url=https://web.archive.org/web/20080517143546/http://www.eso.org/outreach/press-rel/pr-2002/pr-17-02.html |date=2008-05-17 }} [[ESO]] Press Release, October 16, 2002
* [http://www.mpe.mpg.de/ir/GC/index.php Max Planck page on the galactic center, with animation] {{Webarchive|url=https://web.archive.org/web/20040925044354/http://www.mpe.mpg.de/ir/GC/index.php |date=2004-09-25 }}
* [http://arxiv.org/pdf/astro-ph/0408107 The Proper Motion of Sgr A* and the Mass of Sgr A*] (PDF)
* [http://www.nrao.edu/pr/1998/bhole/ NRAO article] regarding VLBI radio imaging of Sgr A*
Diperoleh dari "https://wiki-indonesia.club/wiki/Sagittarius_A*"