Astronomy:Local Bubble

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Short description: Cavity in the interstellar medium which contains the Local Interstellar Cloud
Local Bubble
Superbubble, map 100 parsecs (2022).png
Map of open star clusters and bright stars in the Local Bubble, viewed from top down
Observation data
Distancely   (0 pc)
Physical characteristics
Radius500 ly
DesignationsLocal Hot Bubble, LHB,[1] Local Bubble, Local Interstellar Bubble[2]
See also: Lists of nebulae

The Local Bubble, or Local Cavity,[3] is a relative cavity in the interstellar medium (ISM) of the Orion Arm in the Milky Way. It contains the closest of celestial neighbours and among others, the Local Interstellar Cloud (which contains the Solar System), the neighbouring G-Cloud, the Ursa Major moving group (the closest stellar moving group) and the Hyades (the nearest open cluster). It is estimated to be at least 1000 light years in size,[clarification needed] and is defined by its neutral-hydrogen density of about 0.05 atoms/cm3, or approximately one tenth of the average for the ISM in the Milky Way (0.5 atoms/cm3), and one sixth that of the Local Interstellar Cloud (0.3 atoms/cm3).[dubious ][4]

The exceptionally sparse gas of the Local Bubble is the result of supernovae that exploded within the past ten to twenty million years. Geminga, a pulsar in the constellation Gemini, was once thought to be the remnant of a single supernova that created the Local Bubble, but now multiple supernovae in subgroup B1 of the Pleiades moving group are thought to have been responsible,[5] becoming a remnant supershell.[6] Other research suggests that the subgroups Lower Centaurus–Crux (LCC) and Upper Centaurus–Lupus (UCL), of the Scorpius–Centaurus association created both the local bubble and the Loop I Bubble. With LCC being responsible for the Local Bubble and UCL being responsible for the Loop I Bubble.[7] It was found that 14 to 20 supernovae originated from LCC and UCL, which could have formed these bubbles.[8]


The Solar System has been traveling through the region currently occupied by the Local Bubble for the last five to ten million years.[9] Its current location lies in the Local Interstellar Cloud (LIC), a minor region of denser material within the Bubble. The LIC formed where the Local Bubble and the Loop I Bubble met. The gas within the LIC has a density of approximately 0.3 atoms per cubic centimeter.

The Local Bubble is not spherical, but seems to be narrower in the galactic plane, becoming somewhat egg-shaped or elliptical, and may widen above and below the galactic plane, becoming shaped like an hourglass. It abuts other bubbles of less dense interstellar medium (ISM), including, in particular, the Loop I Bubble. The Loop I Bubble was cleared, heated and maintained by supernovae and stellar winds in the Scorpius–Centaurus association, some 500 light years from the Sun. The Loop I Bubble contains the star Antares (also known as α Sco, or Alpha Scorpii), as shown on the diagram above right. Several tunnels connect the cavities of the Local Bubble with the Loop I Bubble, called the "Lupus Tunnel".[10] Other bubbles which are adjacent to the Local Bubble are the Loop II Bubble and the Loop III Bubble. In 2019, researchers found interstellar iron in Antarctica which they relate to the Local Interstellar Cloud, which might be related to the formation of the Local Bubble.[11]

Local stars in the galactic plane (click for rotation)


Launched in February 2003 and active until April 2008, a small space observatory called Cosmic Hot Interstellar Plasma Spectrometer (CHIPS or CHIPSat) examined the hot gas within the Local Bubble.[12] The Local Bubble was also the region of interest for the Extreme Ultraviolet Explorer mission (1992–2001), which examined hot EUV sources within the bubble. Sources beyond the edge of the bubble were identified but attenuated by the denser interstellar medium. In 2019, the first 3D map of the Local Bubble has been reported using the observations of diffuse interstellar bands.[13] In 2020, the shape of the dusty envelop surrounding the Local Bubble was retrieved and modeled from 3D maps of the dust density obtained from stellar extinction data.[14]

Impact on star formation

As the bubble expands it sweeps interstellar gas and dust which collapse to form new stars on its surface but not inside. The Sun entered the bubble around five million years ago.[15][16]
Local Bubble and its molecular clouds

In January 2022, a paper in the journal Nature found that observations and modelling had determined that the action of the expanding surface of the bubble had collected gas and debris and was responsible for the formation of all young, nearby stars.[17]

These new stars are typically in molecular clouds like the Taurus molecular cloud and the open star cluster Pleiades.

Connection to radioactive isotopes on earth

On earth several radioactive isotopes were connected to supernovae occurring relative nearby to the solar system. The most common source is found in deep sea ferromanganese crusts. Such nodules are constantly growing and deposits iron, manganese and other elements. Samples are divided into layers which are dated for example with Beryllium-10. Some of these layers have higher concentrations of radioactive isotopes.[18] The isotope most commonly associated with supernovae on earth is Iron-60 from deep sea sediments,[19] Antarctic snow,[20] and lunar soil.[21] Other isotopes are Manganese-53[22] and Plutonium-244[18] from deep sea materials. Supernova originated Aluminium-26, which was expected from cosmic ray studies, was not confirmed.[23] Iron-60 and Manganese-53 have a peak 1.7–3.2 Million years ago and Iron-60 has a second peak 6.5–8.7 Million years ago. The older peak likely originated when the solar system moved through the Orion-Eridanus superbubble and the younger peak was generated when the solar system entered the local bubble 4.5 Million years ago.[24] One of the supernovae creating the younger peak might have created the pulsar PSR B1706-16 and turned Zeta Ophiuchi into a runaway star. Both originated from UCL and were released by a supernova 1.78 ± 0.21 Million years ago.[25] Another explanation for the older peak is that it was produced by one supernova in the Tucana-Horologium association 7-9 Million years ago.[26]

See also


  1. Egger, Roland J.; Aschenbach, Bernd (February 1995). "Interaction of the Loop I supershell with the Local Hot Bubble". Astronomy and Astrophysics 294 (2): L25–L28. Bibcode1995A&A...294L..25E. 
  2. "NAME Local Bubble". SIMBAD. Centre de données astronomiques de Strasbourg. 
  3. Abt, Helmut A. (December 2015). "Hot gaseous stellar disks avoid regions of low interstellar densities". Publications of the Astronomical Society of the Pacific 127 (958): 1218–1225. doi:10.1086/684436. Bibcode2015PASP..127.1218A. 
  4. "Our local galactic neighborhood". National Aeronautics and Space Administration (NASA). 2000-02-08. 
  5. Berghoefer, T.W.; Breitschwerdt, D. (2002). "The origin of the young stellar population in the solar neighborhood – a link to the formation of the Local Bubble?". Astronomy and Astrophysics 390 (1): 299–306. doi:10.1051/0004-6361:20020627. Bibcode2002A&A...390..299B. 
  6. Gabel, J.R.; Bruhweiler, F.C. (8 January 1998). "[51.09 Model of an expanding supershell structure in the LISM"]. American Astronomical Society. 
  7. Maíz-Apellániz, Jesús (2001-10-01). "The Origin of the Local Bubble". The Astrophysical Journal 560: L83–L86. doi:10.1086/324016. ISSN 0004-637X. 
  8. Fuchs, B.; Breitschwerdt, D.; de Avillez, M. A.; Dettbarn, C.; Flynn, C. (2006-12-01). "The search for the origin of the Local Bubble redivivus". Monthly Notices of the Royal Astronomical Society 373: 993–1003. doi:10.1111/j.1365-2966.2006.11044.x. ISSN 0035-8711. 
  9. "Local Chimney and Superbubbles". 
  10. Lallement, R.; Welsh, B.Y.; Vergely, J.L.; Crifo, F.; Sfeir, D. (2003). "3D mapping of the dense interstellar gas around the Local Bubble". Astronomy and Astrophysics 411 (3): 447–464. doi:10.1051/0004-6361:20031214. Bibcode2003A&A...411..447L. 
  11. Koll, D. (2019). "Interstellar 60Fe in Antarctica". Physical Review Letters 123 (7): 072701. doi:10.1103/PhysRevLett.123.072701. PMID 31491090. Bibcode2019PhRvL.123g2701K. 
  12. "Cosmic Hot Interstellar Plasma Spectrometer (CHIPS)". University of California – Berkeley. 2003-01-12. 
  13. Farhang, Amin; van Loon, Jacco Th.; Khosroshahi, Habib G.; Javadi, Atefeh; Bailey, Mandy (8 July 2019). "3D map of the local bubble". Nature Astronomy 3: 922–927. doi:10.1038/s41550-019-0814-z. 
  14. Pelgrims, Vincent; Ferrière, Katia; Boulanger, Francois; Lallement, Rosine; Montier, Ludovic (April 2020). "Modeling the magnetized Local Bubble from dust data". Astronomy & Astrophysics 636: A17. doi:10.1051/0004-6361/201937157. 
  15. Zucker, Catherine; Goodman, Alyssa A.; Alves, João; Bialy, Shmuel; Foley, Michael; Speagle, Joshua S.; Großschedl, Josefa; Finkbeiner, Douglas P. et al. (2022-01-12). "Star formation near the Sun is driven by expansion of the Local Bubble" (in en). Nature 601 (7893): 334–337. doi:10.1038/s41586-021-04286-5. ISSN 1476-4687. PMID 35022612. Bibcode2022Natur.601..334Z. 
  16. "1,000-Light-Year Wide Bubble Surrounding Earth is Source of All Nearby, Young Stars | Center for Astrophysics" (in en). 
  17. "Star Formation near the Sun is driven by expansion of the Local Bubble". 
  18. 18.0 18.1 Wallner, A.; Froehlich, M. B.; Hotchkis, M. A. C.; Kinoshita, N.; Paul, M.; Martschini, M.; Pavetich, S.; Tims, S. G. et al. (2021-05-01). "60Fe and 244Pu deposited on Earth constrain the r-process yields of recent nearby supernovae". Science 372: 742–745. doi:10.1126/science.aax3972. ISSN 0036-8075. 
  19. Knie, K.; Korschinek, G.; Faestermann, T.; Wallner, C.; Scholten, J.; Hillebrandt, W. (1999-07-01). "Indication for Supernova Produced 60Fe Activity on Earth". Physical Review Letters 83: 18–21. doi:10.1103/PhysRevLett.83.18. ISSN 0031-9007. 
  20. Koll, Dominik; Korschinek, Gunther; Faestermann, Thomas; Gómez-Guzmán, J. M.; Kipfstuhl, Sepp; Merchel, Silke; Welch, Jan M. (2019-08-01). "Interstellar 60Fe in Antarctica". Physical Review Letters 123: 072701. doi:10.1103/PhysRevLett.123.072701. ISSN 0031-9007. 
  21. Fimiani, L.; Cook, D. L.; Faestermann, T.; Gómez-Guzmán, J. M.; Hain, K.; Herzog, G.; Knie, K.; Korschinek, G. et al. (2016-04-01). "Interstellar Fe 60 on the Surface of the Moon". Physical Review Letters 116: 151104. doi:10.1103/PhysRevLett.116.151104. ISSN 0031-9007. 
  22. Korschinek, G.; Faestermann, T.; Poutivtsev, M.; Arazi, A.; Knie, K.; Rugel, G.; Wallner, A. (2020-07-01). "Supernova-Produced 53Mn on Earth". Physical Review Letters 125: 031101. doi:10.1103/PhysRevLett.125.031101. ISSN 0031-9007. 
  23. Feige, Jenny; Wallner, Anton; Altmeyer, Randolf; Fifield, L. Keith; Golser, Robin; Merchel, Silke; Rugel, Georg; Steier, Peter et al. (2018-11-01). "Limits on Supernova-Associated Fe 60 /Al 26 Nucleosynthesis Ratios from Accelerator Mass Spectrometry Measurements of Deep-Sea Sediments". Physical Review Letters 121: 221103. doi:10.1103/PhysRevLett.121.221103. ISSN 0031-9007. 
  24. Schulreich, M. M.; Feige, J.; Breitschwerdt, D. (2023-12-01). "Numerical studies on the link between radioisotopic signatures on Earth and the formation of the Local Bubble. II. Advanced modelling of interstellar 26Al, 53Mn, 60Fe, and 244Pu influxes as traces of past supernova activity in the solar neighbourhood". Astronomy and Astrophysics 680: A39. doi:10.1051/0004-6361/202347532. ISSN 0004-6361. 
  25. Neuhäuser, R.; Gießler, F.; Hambaryan, V. V. (2020-10-01). "A nearby recent supernova that ejected the runaway star ζ Oph, the pulsar PSR B1706-16, and 60Fe found on Earth". Monthly Notices of the Royal Astronomical Society 498: 899–917. doi:10.1093/mnras/stz2629. ISSN 0035-8711. 
  26. Hyde, M.; Pecaut, M. J. (2018-01-01). "Supernova ejecta in ocean cores used as time constraints for nearby stellar groups". Astronomische Nachrichten 339: 78–86. doi:10.1002/asna.201713375. ISSN 0004-6337. 

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