Local_Bubble - Wikiparency

# Local Bubble  **Microsim — three.js (Wikitube framework):** *Out to the nearest star (Solar System explorer)* <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/solar/Solar_System.html?view=neighborhood&embed=1" data-title="Out to the nearest star (Solar System explorer)"></div> *The Solar System explorer locked on this article's state (`?view=neighborhood`); every object and population of the [[PORTAL_Solar_System|Solar System portal]] has its own state in the same scene.*  *Try: read the ruler from the heliopause tick at 121 AU outward past the Oort cloud at about 2,000 AU and the Hill sphere at about 200,000 AU to Proxima Centauri at 4.25 light-years; set show to clouds and boundaries so that only the Oort cloud points and the boundary shells remain; press l to hide the labels and drag the scene edge-on, remembering that the Local Bubble is more than a hundred times wider than the ruler's whole length.* The **Local Bubble**, also called the **Local Cavity**, is a region of unusually thin, hot gas in the [[Interstellar_medium|interstellar medium]] of the [[Orion_Arm|Orion Arm]] of the [[Milky_Way|Milky Way]], at least 1,000 light-years across, in which the [[Sun]] lies.[^abt2015][^frisch2006] Its neutral hydrogen density, about 0.05 atoms per cubic centimetre, is about a tenth of the galactic average and a sixth of that in the [[Local_Interstellar_Cloud|Local Interstellar Cloud]], the small warm cloud that surrounds the Solar System inside the bubble.[^jpl-neighborhood] The bubble contains the nearest stars, the Hyades cluster and the Ursa Major moving group. The cavity was blown out by a series of supernovae over the past 10 to 20 million years. Early proposals traced it to a single explosion, and later ones to a subgroup of the Pleiades moving group; current work points to massive stars in subgroups of the Scorpius–Centaurus association, of which about 14 to 20 exploded.[^berghoefer2002][^maiz2001][^fuchs2006][^schulreich2023] The same explosions are thought to have seeded Earth with the radioactive [[Isotope|isotope]] [[Iron|iron]]-60 and to have swept up the gas from which every young star near the Sun formed.[^wallner2021][^zucker2022] The explorer at the top of this page does not reach the bubble. Its neighbourhood view is a logarithmic ruler that stops at Proxima Centauri, 4.25 light-years out, a distance more than a hundred times smaller than the bubble's radius, so the Local Bubble here is context for the scale the explorer does draw. ## Description The Solar System entered the region the bubble now occupies about five million years ago; Zucker and colleagues find that the [[Sun]] now sits, by chance, close to its centre.[^cfa2022] Estimates of when the Sun came in differ, and a radioisotope model places the entry about 4.5 million years ago.[^schulreich2023] Inside the bubble the Sun is currently passing through the [[Local_Interstellar_Cloud|Local Interstellar Cloud]], one of several small, cooler and denser clouds inside the cavity. The collision of the Local Bubble with its neighbour, the Loop I bubble, has been proposed as the origin of a ring of denser gas between them, and the Local Interstellar Cloud may have formed in such an interaction zone.[^egger1995] The cavity is not a sphere. Maps of the dense gas around it show a shape that is narrower in the galactic plane and opens out above and below it, more like an hourglass or a chimney than a ball.[^lallement2003] Its walls are not closed either: it adjoins other low-density bubbles, above all Loop I, which was cleared and is kept hot by supernovae and stellar winds from the Scorpius–Centaurus association about 500 light-years away, and which contains the red supergiant Antares. Narrow passages of low density, such as the Lupus tunnel, connect the two cavities.[^lallement2003][^egger1995] A simple estimate shows how vigorous the early expansion was. A radius of about 150 parsecs (500 light-years) reached in 14 million years corresponds to an average speed of about 10 km/s (derived), while the shell's present speed, about 6 km/s, shows that the expansion has slowed.[^cfa2022][^zucker2022] With so little gas, the bubble holds very little mass for its size: at 0.05 atoms per cubic centimetre, a cubic light-year contains about 7 × 10²⁵ kg of [[Hydrogen|hydrogen]], some 12 [[Earth]] masses or 4 × 10⁻⁵ solar masses (derived).[^jpl-neighborhood] ## Observation The bubble is mapped by what is missing. Starlight that crosses dense interstellar gas carries narrow absorption [[Spectral_line|lines]], and stars inside the cavity show almost none, so charting where absorption appears maps the bubble's walls. Lallement and Bertin had completed the first such mapping of the local cloud in 1992.[^lallement1992] In 2003 Lallement and colleagues used absorption by neutral [[Sodium|sodium]] toward about 1,000 stars to draw the cavity's boundary in three dimensions and found the tunnels that link it to neighbouring cavities.[^lallement2003] Space observatories have studied the hot gas directly. The small satellite CHIPSat, the Cosmic Hot Interstellar Plasma Spectrometer, observed the bubble's diffuse extreme-ultraviolet glow from 2003 to 2008.[^chips] In 2019 Farhang and colleagues produced a three-dimensional map of the hot interior from diffuse interstellar bands, broad absorption features whose carriers are still unidentified.[^farhang2019] In 2020 Pelgrims and colleagues extracted the inner surface of the bubble's dusty shell from three-dimensional maps of dust extinction and used it to model how the shell distorts the galactic magnetic field in the Sun's neighbourhood.[^pelgrims2020] These maps rest on stellar distances from the European Space Agency's Gaia mission. ## Impact on star formation In January 2022 Zucker and colleagues combined three-dimensional dust maps with Gaia positions and motions of young stars and found that every young star and star-forming region within about 500 light-years of the Sun lies on the surface of the Local Bubble.[^zucker2022] Tracing the young stars backward, they reconstructed a sequence that begins about 14 million years ago: roughly 15 supernovae, going off one after another, pushed the surrounding gas outward into a shell, and the shell, compressed and cooled, fragmented into the molecular clouds that are forming stars now.[^zucker2022][^cfa2022] Seven well-known star-forming regions sit on the shell, among them the Taurus molecular cloud, and the young stars there move outward, roughly perpendicular to the shell's surface.[^zucker2022] The result is a direct case of triggered star formation, in which one generation of massive stars, by dying, sets up the birth of the next.[^cfa2022] Zucker's team also argued that the Sun's position near the centre of such a bubble would be very unlikely if bubbles were rare, which suggests that the disc of the [[Milky_Way|Milky Way]] is riddled with them.[^cfa2022] The idea that a young stellar group near the Sun could be linked to the formation of the bubble is older; Berghöfer and Breitschwerdt had proposed a link to the Pleiades moving group in 2002.[^berghoefer2002] ## Connection to radioactive isotopes on Earth A supernova within a few hundred light-years sends debris across the Solar System, and some of it settles on [[Earth]] and the [[Moon]]. The clearest tracer is iron-60, with a [[Half-life|half-life]] of about 2.6 million years: it is made in massive stars and supernovae but not in appreciable amounts on Earth, so any found in young natural deposits must have arrived from space in the last few million years.[^rugel2009] Knie and colleagues first reported it in 1999 in a deep-sea ferromanganese crust, a slowly growing rock of [[Iron|iron]] and [[Manganese|manganese]] oxides whose layers can be dated, for example with [[Beryllium|beryllium]]-10.[^knie1999] It has since been found in Antarctic snow and in lunar soil returned by the Apollo missions.[^koll2019][^fimiani2016] Other isotopes add detail. Manganese-53 appears in the same crust layers, and [[Plutonium|plutonium]]-244, an [[Isotope|isotope]] made by rapid [[Neutron|neutron]] capture, was found in step with the iron-60, which constrains where the heaviest elements are made.[^korschinek2020][^wallner2021] [[Aluminium]]-26, expected in the debris, has not been confirmed.[^feige2018] The deposits show two peaks of iron-60, one about 1.7 to 3.2 million years ago and an older one about 6.5 to 8.7 million years ago. In the model of Schulreich and colleagues, the older peak comes from the Sun's passage through the Orion–Eridanus superbubble and the younger from its entry into the Local Bubble.[^schulreich2023] Individual explosions have been proposed as well: Neuhäuser and colleagues trace the runaway star Zeta Ophiuchi and the pulsar PSR B1706−16 back to a supernova in a binary about 1.78 million years ago, about 107 parsecs away, and Hyde and Pecaut suggest that the older peak came from a supernova in the Tucana–Horologium association.[^neuhauser2020][^hyde2018] ## See also - [[Local_Interstellar_Cloud]] - [[Interstellar_medium]] - [[Orion_Arm]] - [[Milky_Way]] - [[Heliosphere]] - Gould Belt · Superbubble · Orion–Eridanus Superbubble · List of nearby stellar associations and moving groups ## References [^abt2015]: Abt, H. A. (2015). "Hot gaseous stellar disks avoid regions of low interstellar densities". *Publications of the Astronomical Society of the Pacific* 127: 1218–1225. https://doi.org/10.1086/684436 [^frisch2006]: Frisch, P. C. (ed.) (2006). *Solar Journey: The Significance of Our Galactic Environment for the Heliosphere and Earth*. Springer, p. 4. ISBN 978-1-4020-4557-8. [^jpl-neighborhood]: NASA/JPL Interstellar Probe (2000). "Our local galactic neighborhood". http://interstellar.jpl.nasa.gov/interstellar/probe/introduction/neighborhood.html (archived). [^berghoefer2002]: Berghöfer, 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: 299–306. https://doi.org/10.1051/0004-6361:20020627 [^maiz2001]: Maíz-Apellániz, J. (2001). "The origin of the Local Bubble". *The Astrophysical Journal* 560: L83–L86. https://doi.org/10.1086/324016 [^fuchs2006]: Fuchs, B.; Breitschwerdt, D.; de Avillez, M. A.; Dettbarn, C.; Flynn, C. (2006). "The search for the origin of the Local Bubble redivivus". *Monthly Notices of the Royal Astronomical Society* 373: 993–1003. https://doi.org/10.1111/j.1365-2966.2006.11044.x [^schulreich2023]: Schulreich, M. M.; Feige, J.; Breitschwerdt, D. (2023). "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. https://doi.org/10.1051/0004-6361/202347532 [^wallner2021]: Wallner, A.; Froehlich, M. B.; Hotchkis, M. A. C.; et al. (2021). "⁶⁰Fe and ²⁴⁴Pu deposited on Earth constrain the r-process yields of recent nearby supernovae". *Science* 372: 742–745. https://doi.org/10.1126/science.aax3972 [^zucker2022]: Zucker, C.; Goodman, A. A.; Alves, J.; et al. (2022). "Star formation near the Sun is driven by expansion of the Local Bubble". *Nature* 601: 334–337. https://doi.org/10.1038/s41586-021-04286-5 [^cfa2022]: Center for Astrophysics, Harvard & Smithsonian (12 January 2022). "1,000-light-year wide bubble surrounding Earth is source of all nearby, young stars". https://www.cfa.harvard.edu/news/1000-light-year-wide-bubble-surrounding-earth-source-all-nearby-young-stars [^egger1995]: Egger, R. J.; Aschenbach, B. (1995). "Interaction of the Loop I supershell with the Local Hot Bubble". *Astronomy and Astrophysics* 294: L25–L28. Bibcode 1995A&A...294L..25E. [^lallement2003]: 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: 447–464. https://doi.org/10.1051/0004-6361:20031214 [^lallement1992]: Lallement, R.; Bertin, P. (1992). "Northern-hemisphere observations of nearby interstellar gas: possible detection of the local cloud". *Astronomy and Astrophysics* 266: 479–485. Bibcode 1992A&A...266..479L. [^chips]: Space Sciences Laboratory, University of California, Berkeley (2003). "Cosmic Hot Interstellar Plasma Spectrometer (CHIPS)". http://chips.ssl.berkeley.edu/chips.html [^farhang2019]: Farhang, A.; van Loon, J. Th.; Khosroshahi, H. G.; Javadi, A.; Bailey, M. (2019). "A three-dimensional map of the hot Local Bubble using diffuse interstellar bands". *Nature Astronomy* 3: 922–927. https://doi.org/10.1038/s41550-019-0814-z [^pelgrims2020]: Pelgrims, V.; Ferrière, K.; Boulanger, F.; Lallement, R.; Montier, L. (2020). "Modeling the magnetized Local Bubble from dust data". *Astronomy & Astrophysics* 636: A17. https://doi.org/10.1051/0004-6361/201937157 [^rugel2009]: Rugel, G.; Faestermann, T.; Knie, K.; et al. (2009). "New measurement of the ⁶⁰Fe half-life". *Physical Review Letters* 103: 072502. https://doi.org/10.1103/PhysRevLett.103.072502 [^knie1999]: Knie, K.; Korschinek, G.; Faestermann, T.; Wallner, C.; Scholten, J.; Hillebrandt, W. (1999). "Indication for supernova produced ⁶⁰Fe activity on Earth". *Physical Review Letters* 83: 18–21. https://doi.org/10.1103/PhysRevLett.83.18 [^koll2019]: Koll, D.; Korschinek, G.; Faestermann, T.; et al. (2019). "Interstellar ⁶⁰Fe in Antarctica". *Physical Review Letters* 123: 072701. https://doi.org/10.1103/PhysRevLett.123.072701 [^fimiani2016]: Fimiani, L.; Cook, D. L.; Faestermann, T.; et al. (2016). "Interstellar ⁶⁰Fe on the surface of the Moon". *Physical Review Letters* 116: 151104. https://doi.org/10.1103/PhysRevLett.116.151104 [^korschinek2020]: Korschinek, G.; Faestermann, T.; Poutivtsev, M.; et al. (2020). "Supernova-produced ⁵³Mn on Earth". *Physical Review Letters* 125: 031101. https://doi.org/10.1103/PhysRevLett.125.031101 [^feige2018]: Feige, J.; Wallner, A.; Altmeyer, R.; et al. (2018). "Limits on supernova-associated ⁶⁰Fe/²⁶Al nucleosynthesis ratios from accelerator mass spectrometry measurements of deep-sea sediments". *Physical Review Letters* 121: 221103. https://doi.org/10.1103/PhysRevLett.121.221103 [^neuhauser2020]: Neuhäuser, R.; Gießler, F.; Hambaryan, V. V. (2020). "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. https://doi.org/10.1093/mnras/stz2629 [^hyde2018]: Hyde, M.; Pecaut, M. J. (2018). "Supernova ejecta in ocean cores used as time constraints for nearby stellar groups". *Astronomische Nachrichten* 339: 78–86. https://doi.org/10.1002/asna.201713375 ## Further reading - Frisch, P. C.; Redfield, S.; Slavin, J. D. (2011). "The interstellar medium surrounding the Sun". *Annual Review of Astronomy and Astrophysics* 49: 237–279. https://doi.org/10.1146/annurev-astro-081710-102613 - Zucker, C.; et al. (2022). Project site, "Star formation near the Sun is driven by expansion of the Local Bubble". https://sites.google.com/cfa.harvard.edu/local-bubble-star-formation ## External links - Center for Astrophysics, Harvard & Smithsonian, news release on the Local Bubble and nearby star formation (2022): https://www.cfa.harvard.edu/news/1000-light-year-wide-bubble-surrounding-earth-source-all-nearby-young-stars - European Space Agency, Gaia mission: https://www.esa.int/Science_Exploration/Space_Science/Gaia ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Local_Bubble) : [Wikitube](https://en.wikitube.io/wiki/Local_Bubble) · pinned revision [1370782944](https://en.wikipedia.org/w/index.php?oldid=1370782944) · 2026-09-18 ## Previous hub tags Hubs: `Life_Physics`. Portals: [[PORTAL_Solar_System]]. --- *Solar System portal child articles, wave 1 · 2026-09-18 · drafted · row SOL-089 · explorer state `?view=neighborhood`.*