Superbubble

{{Short description|Cavity hundreds of light years across created by strong stellar winds in a galaxy}} {{Other uses|Super bubble (disambiguation)}} {{Redirect|supershell||Super shell (disambiguation)}} [[File:Henize N70 Superbubble Nebula.jpg|thumb|220x220px|The superbubble Henize 70, also known as N70 or DEM301, in the Large Magellanic Cloud<ref name=n70/>]] In astronomy a '''superbubble''' or '''supershell''' is a cavity which is hundreds of light years across and is populated with hot (106 K) gas atoms, less dense than the surrounding interstellar medium, blown against that medium and carved out by multiple supernovae and stellar winds. The winds, passage and gravity of newly born stars strip superbubbles of any other dust or gas.<ref>{{Cite news|title=Sublime image reveals superbubbles, star formation, and satellite galaxies|last=Thomson|first=Jason|date=2016-05-18|id = {{ProQuest|1789525419}}}}</ref> The Solar System lies near the center of an old superbubble, known as the Local Bubble, whose boundaries can be traced by a sudden rise in dust extinction of exterior stars at distances greater than a few hundred light years.{{Citation needed|date=August 2021}}

==Formation== The most massive stars, with masses ranging from eight to roughly one hundred solar masses and spectral types of O and early B, are usually found in groups called OB associations. Massive O stars have strong stellar winds, and most of these stars explode as supernovae at the end of their lives.

The strongest stellar winds release kinetic energy of 1051 ergs (1044 J) over the lifetime of a star, which is equivalent to a supernova explosion. These winds can form stellar wind bubbles dozens of light years across.<ref>{{cite journal| bibcode=1975ApJ...200L.107C |last1=Castor|first1=J. |last2=McCray|first2=R. |last3=Weaver|first3=R. |title=Interstellar Bubbles| date=1975| journal=Astrophysical Journal Letters| volume=200| pages=L107–L110| doi=10.1086/181908|doi-access=free}}</ref> Inside OB associations, the stars are close enough that their wind bubbles merge, forming a giant bubble called a superbubble. When stars die, supernova explosions, similarly, drive blast waves that can reach even larger sizes, with expansion velocities up to several hundred km s−1. Stars in OB associations are not gravitationally bound, but they drift apart at small speeds (of around 20 km s−1), and they exhaust their fuel rapidly (after a few millions of years). As a result, most of their supernova explosions occur within the cavity formed by the stellar wind bubbles.<ref>{{cite journal| bibcode=1981Ap&SS..78..273T|last1=Tomisaka |first1= K. |author-link= |last2=Habe |first2=A. |author2-link=|last3=Ikeuchi |first3=S. |author3-link=:ja:池内了 |title=Sequential explosions of supernovae in an OB association and formation of a superbubble |year=1981 |journal=Astrophys. Space Sci. |volume=78 |issue= 2 |pages=273–285 |doi=10.1007/BF00648941|s2cid=119740951 |url=https://ir.soken.ac.jp/?action=repository_action_common_download&item_id=3504&item_no=1&attribute_id=22&file_no=1 }}</ref><ref>{{cite journal| bibcode=1987ApJ...317..190M| last1=McCray| first1=R.|last2=Kafatos |first2=M. | title=Supershells and Propagating Star Formation| date=1987| journal=Astrophysical Journal |volume=317 | pages=190–196 |doi=10.1086/165267 |url=http://digitalcommons.chapman.edu/cgi/viewcontent.cgi?article=1121&context=scs_articles| hdl=2060/19870005634| s2cid=53332141| hdl-access=free}}</ref> These explosions never form a visible supernova remnant, but instead expend their energy in the hot interior as sound waves. Both stellar winds and stellar explosions thus power the expansion of the superbubble in the interstellar medium.

{{Easy CSS image crop |Image = Emission nebulae in Cassiopeia.jpg |crop_left_perc = 26 |crop_right_perc = 36 |crop_top_perc = 5 |crop_bottom_perc = 22 |Description = W4 superbubble/chimney in emission lines, as seen by the Northern Sky Narrowband Survey.}}

The interstellar gas swept up by superbubbles generally cools, forming a dense shell around the cavity. These shells were first observed in line emission at twenty-one centimeters from hydrogen,<ref>{{cite journal| date=1979| bibcode=1979ApJ...229..533H| last= Heiles| first=C. | author-link = Carl E. Heiles | title=H I shells and supershells| journal=Astrophys. J.| volume=229| pages=533–544| doi=10.1086/156986| s2cid=119933793}}</ref> leading to the formulation of the theory of superbubble formation. They are also observed in X-ray emission from their hot interiors, in optical line emission from their ionized shells, and in infrared continuum emission from dust swept up in their shells. X-ray and visible emission are typically observed from younger superbubbles, while older, larger objects seen in twenty-one centimeters may even result from multiple superbubbles combining, and so are sometimes distinguished by calling them ''supershells''. <ref>{{Cite journal |last=Lagrois |first=Dominic |last2=Joncas |first2=Gilles |date=2009-03-01 |title=ON THE DYNAMICAL EVOLUTION OF H II REGIONS: AN INVESTIGATION OF THE IONIZED COMPONENT OF W4, A GALACTIC CHIMNEY CANDIDATE. II. KINEMATICS AND DYNAMICS IN THE LATITUDE RANGE 3°

Large enough superbubbles can blow through the entire galactic disk, releasing their energy into the surrounding galactic halo or even into the intergalactic medium.<ref>{{cite journal| bibcode=1986PASJ...38..697T|last1=Tomisaka |first1= K. |author-link=|last2=Ikeuchi |first2=S. |author2-link=:ja:池内了 |title=Evolution of superbubble driven by sequential supernova explosions in a plane-stratified gas distribution| year=1986| journal=Publ. Astron. Soc. Jpn.| volume=38 |issue=5 |pages=697–715}}</ref><ref>{{cite journal| bibcode=1988ApJ...324..776M | last1=Mac Low| first1=M.-M.|last2=McCray |first2=R. | title=Superbubbles in Disk Galaxies| date=1988| journal=Astrophysical Journal | volume=324| pages=776–785| doi=10.1086/165936| doi-access=free}}</ref> A candidate for such a structure, also referred to as a chimney, is the W4 superbubble (depicted on the right). <ref>{{Cite journal |last=Lagrois |first=Dominic |last2=Joncas |first2=Gilles |date=2009-03-01 |title=ON THE DYNAMICAL EVOLUTION OF H II REGIONS: AN INVESTIGATION OF THE IONIZED COMPONENT OF W4, A GALACTIC CHIMNEY CANDIDATE. II. KINEMATICS AND DYNAMICS IN THE LATITUDE RANGE 3°

==Examples== * LHA 120-N 44 (N44) in the Large Magellanic Cloud.<ref>{{cite news|title=A Cosmic Superbubble|url=http://www.eso.org/public/news/eso1125/|access-date=20 July 2011|newspaper=ESO Photo Release}}</ref><ref>{{Cite APOD |date=6 February 2006 |title=N44 Superbubble |access-date=}}</ref> * Anticenter shell, a supershell once called "Snickers" * Henize 70<ref name=n70>[http://antwrp.gsfc.nasa.gov/apod/ap991130.html Henize 70: A SuperBubble In The LMC], Astronomy Picture of the Day, 1999-11-30</ref> * Ophiuchus Superbubble<ref>{{cite journal|last1=Pidopryhora |first1=Yurii |last2=Lockman |first2=Felix J.  |last3=Shields |first3=Joseph C.  |title=The Ophiuchus Superbubble: A Gigantic Eruption from the Inner Disk of the Milky Way |year=2007 | journal=Astrophysical Journal |volume=652 |issue=2 |pages=928–942 |doi= 10.1086/510521|arxiv=astro-ph/0610894v1|bibcode=2007ApJ...656..928P |s2cid=14594723 }}</ref><ref name='huge superbubble'>{{cite news | title=Huge 'Superbubble' of Gas Blowing Out of Milky Way | date=2006-01-13 | publisher= | url =http://www.physorg.com/news9882.html | work =PhysOrg.com | accessdate = 2008-07-04 }}</ref> * The Scutum Supershell<ref>{{cite journal|bibcode=2001ApJ...547..907S |last1=Savage |first1=Blair D. |last2=Sembach |first2=Kenneth R.  |last3=Howk |first3=J. Christopher  |title=STIS and GHRS Observations of Warm and Hot Gas Overlying the Scutum Supershell (GS 018−04+44) |date=February 2001 |journal=Astrophysical Journal |volume=547 |issue=2 |pages=907–921 |doi=10.1086/318411 |arxiv= |s2cid=15066062 |url=https://iopscience.iop.org/article/10.1086/318411/pdf|url-access=subscription }}</ref><ref>{{cite journal|bibcode=2000ApJ...532..943C |last1=Callaway |first1=Matthew B.  |last2=Savage |first2=Blair D. |last3=Benjamin |first3=Robert A.  |last4=Haffner |first4=L. Matthew  |last5=Tufte |first5=Steve L. |title=Observational Evidence of Supershell Blowout in GS 018-04+44: The Scutum Supershell |date=1 April 2000 |journal=Astrophysical Journal |volume=532|issue=2 |pages=943–969 |doi=10.1086/318411 |arxiv= |s2cid=15066062 |url=https://iopscience.iop.org/article/10.1086/318411/pdf|url-access=subscription }}</ref> * Orion-Eridanus Superbubble * The Perseus-Taurus Shell<ref name="10.3847/2041-8213/ac1f95-report1">{{cite news |title='Superbubble' region of star formation was created by supernovae, study suggests |url=https://physicsworld.com/a/superbubble-region-of-star-formation-was-created-by-supernovae-study-suggests/ |access-date=18 October 2021 |work=Physics World |date=11 October 2021}}</ref><ref name="10.3847/2041-8213/ac1f95">{{cite journal |last1=Bialy |first1=Shmuel |last2=Zucker |first2=Catherine |last3=Goodman |first3=Alyssa |last4=Foley |first4=Michael M. |last5=Alves |first5=João |last6=Semenov |first6=Vadim A. |last7=Benjamin |first7=Robert |last8=Leike |first8=Reimar |last9=Enßlin |first9=Torsten |title=The Per-Tau Shell: A Giant Star-forming Spherical Shell Revealed by 3D Dust Observations |journal=The Astrophysical Journal Letters |date=1 September 2021 |volume=919 |issue=1 |pages=L5 |doi=10.3847/2041-8213/ac1f95|arxiv=2109.09763 |bibcode=2021ApJ...919L...5B |s2cid=237581543 |language=en |issn=2041-8205 |doi-access=free }}</ref> * The Local Bubble

==Image gallery== <gallery mode=packed heights="220px" style="text-align:left"> Image: Superbubble LHA 120-N 44 in the Large Magellanic Cloud.jpg|Very Large Telescope image of superbubble LHA 120-N 44 in the Large Magellanic Cloud. Credit: ESO/Manu Mejias. Image: Side-on 3D view of the Per-Tau Shell, giant structure forming star-forming molecular clouds (with Sun).png|The Per-Tau Shell, a giant star-forming spherical shell with the Perseus and Taurus molecular clouds on its edge.<ref name="10.3847/2041-8213/ac1f95-report1"/><ref name="10.3847/2041-8213/ac1f95"/> Image:Localbubble.png|The Local Bubble, a ~1,000-light-years wide and ~14 Myr old superbubble, is driving nearly all recent star formation near the Sun.<ref>{{cite news |title=1,000-light-year Wide Bubble Surrounding Earth Is Source Of All Nearby, Young Stars - SCIENMAG: Latest Science And Health News |url=https://scienmag.com/1000-light-year-wide-bubble-surrounding-earth-is-source-of-all-nearby-young-stars/ |access-date=12 February 2022 |date=12 January 2022 |archive-date=22 December 2022 |archive-url=https://web.archive.org/web/20221222130830/https://scienmag.com/1000-light-year-wide-bubble-surrounding-earth-is-source-of-all-nearby-young-stars/ |url-status=dead }}</ref><ref>{{cite journal |last1=Zucker |first1=Catherine |last2=Goodman |first2=Alyssa A. |last3=Alves |first3=João |last4=Bialy |first4=Shmuel |last5=Foley |first5=Michael |last6=Speagle |first6=Joshua S. |last7=Großschedl |first7=Josefa |last8=Finkbeiner |first8=Douglas P. |last9=Burkert |first9=Andreas |last10=Khimey |first10=Diana |last11=Swiggum |first11=Cameren |title=Star formation near the Sun is driven by expansion of the Local Bubble |journal=Nature |date=January 2022 |volume=601 |issue=7893 |pages=334–337 |doi=10.1038/s41586-021-04286-5 |pmid=35022612 |arxiv=2201.05124 |bibcode=2022Natur.601..334Z |s2cid=245906333 |language=en |issn=1476-4687}}</ref> Image:Orion–Eridanus Superbubble in H-alpha and continuum.jpg|Orion–Eridanus Superbubble (the nearest superbubble) in emission lines, as seen by the Northern Sky Narrowband Survey. </gallery>

==References== {{Reflist}}

==External links== * Tenorio-Tagle, G., & Bodenheimer, P. "[http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1988ARA%26A..26..145T Large-scale expanding superstructures in galaxies]". 1988, ''Annual Review of Astronomy and Astrophysics'' '''26''', 145–197. General overview.

Category:Superbubbles