Galaksi spiral: Pabidaan ralatan

'''Galaksi spiral''' mambantuk [[klasifikasi morfologi galaksi|kelas matan galaksi]] nang pamulaannya dijalasakan ulih [[Edwin Hubble]] di buku nang ditulisnya pas tahun 1936 nang bajudul ''The Realm of the Nebulae''<ref name="Hubble-1936">{{cite book|url=https://books.google.com/books?id=kgiXdDGLpFUC|title=The realm of the nebulae|last=Hubble|first=E.P.|publisher=[[Yale University Press]]|year=1936|isbn=9780300025002|series=Mrs. Hepsa Ely Silliman memorial lectures, 25|location=New Haven|oclc=611263346|author-link=Edwin Hubble}} [https://archive.org/details/TheRealmOfTheNebulae Alt URL](pp.&nbsp;124–151)</ref> wan maulah bagian matan [[sistim klasifikasi Hubble]]. Kabanyakannya, galaksi spiral bantuknya rata, baputar kaya [[Cakram (galaksi)|cakram]], baisi [[bintang]], [[Awan antar bintang|gas wan dabu]], wan hintinya nang marupakan gabungan bintang-bintang nang banyak nang biasanya dipinandui lawan ngaran [[TonjolanBinculan (astronomy)|Tonjolanbinculan]]. Galaksi nhinj biasanya dikalilingi jua lawan [[Halo galaksi|halo]] nang takadap matan bintang-bintang, kabanyakannya galaksi ngini baandak di [[gugus bola]].

RoughlyKabanyakannya two-thirdsdua ofpertalu allmatan spiralsgalaksi arespiral observednang todiobservasi havebaisi ankumpunen additionaltambahan componentnang instruktur thebantuknya formnang of a bar-likekaya structurebatang,<ref name="mihalas1968">{{Cite book| author=D. Mihalas | date=1968 | title=Galactic Astronomy | publisher=W. H. Freeman | isbn=978-0-7167-0326-6}}</ref> extendingbapanjang frommulai thematan centralbinculan bulgeditangahnya, atdi thehujungnya endstangan of which thegalaksi spiral arms begindimulai. The proportion ofProporsi [[BarredGalaksi spiral galaxybapalang|barredspiral spiralsbapalang]] relativenang totagantung lawan [[UnbarredGalaksi spiral galaxynang kada bapalang|barlessspiral spiralskada bapalang]] haspinanya likelysudah changedbarubah oversapanjang thesajarah history of thematan [[universealam samasta]], with10% onlyhaja aboutspiral 10%nang containingbaisi bars aboutpalang 8&nbsp;billionmiliar yearstahun agobahari, tosampai roughlysakitar a quartersaparapatnya 2.,5&nbsp;billionmiliar yearstahun ago,bahari. untilSampai present,wayah whereini, over twokira-thirdskira ofdua thepertalu [[galaxygalaksi|galaxiesgalaksi-galaksi]] innangbkawa thediitihi visibledi universealam samasta ([[HubbleVolume volumeHubble]]) havebaisi barspalang.<ref>{{cite web |url= https://www.sciencedaily.com/releases/2014/01/140116085103.htm |title= Hubble and Galaxy Zoo Find Bars and Baby Galaxies Don't Mix |date= 16 January 2014 |website= [[Science Daily]] }}</ref>

The [[Milky Way]] is a barred spiral, although the bar itself is difficult to observe from Earth's current position within the galactic disc.<ref>{{cite magazine|url=http://www.sciamdigital.com/index.cfm?fa=Products.ViewIssuePreview&ARTICLEID_CHAR=3BC08F0C-2B35-221B-67A9F2AE04AFC79A|url-status=dead|archive-url=https://web.archive.org/web/20130906193501/http://www.sciamdigital.com/index.cfm?fa=Products.ViewIssuePreview&ARTICLEID_CHAR=3BC08F0C-2B35-221B-67A9F2AE04AFC79A|title=Ripples in a Galactic Pond|magazine=Scientific American|date=October 2005|archive-date=6 September 2013}}</ref> The most convincing evidence for the stars forming a bar in the galactic center comes from several recent surveys, including the [[Spitzer Space Telescope]].<ref>{{cite journal|date=September 2005|title=First GLIMPSE Results on the Stellar Structure of the Galaxy|journal=The Astrophysical Journal Letters|volume=630|issue=2|pages=L149–L152|arxiv=astro-ph/0508325|bibcode=2005ApJ...630L.149B|doi=10.1086/491785|author1=R. A. Benjamin|author2=E. Churchwell|author3=B. L. Babler|author4=R. Indebetouw|author5=M. R. Meade|author6=B. A. Whitney|author7=C. Watson|author8=M. G. Wolfire|author9=M. J. Wolff|author10=R. Ignace|author11=T. M. Bania|author12=S. Bracker|author13=D. P. Clemens|author14=L. Chomiuk|author15=M. Cohen|author16=J. M. Dickey|author17=J. M. Jackson|author18=H. A. Kobulnicky|author19=E. P. Mercer|author20=J. S. Mathis|author21=S. R. Stolovy|author22=B. Uzpen}}</ref>