Local Interstellar Cloud

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Interstellar cloud in the Milky Way Galaxy

title: "Local Interstellar Cloud" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["local-interstellar-cloud"] description: "Interstellar cloud in the Milky Way Galaxy" topic_path: "general/local-interstellar-cloud" source: "https://en.wikipedia.org/wiki/Local_Interstellar_Cloud" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Interstellar cloud in the Milky Way Galaxy ::

::data[format=table title="infobox nebula"]

FieldValue
nameLocal Interstellar Cloud
imageGalaxymap.com, map 10 parsecs (2022).png
captionDiagram of surrounding stars and artist's conception of the Local Interstellar Cloud
typeInterstellar cloud
dimensions30 ly
namesLocal Cloud, Local Fluff, LIC
constellationNone, Solar System is inside the nebula
::

|name= Local Interstellar Cloud |image= Galaxymap.com, map 10 parsecs (2022).png |caption= Diagram of surrounding stars and artist's conception of the Local Interstellar Cloud |type= Interstellar cloud |dimensions = 30 ly |names= Local Cloud, Local Fluff, LIC |constellation=None, Solar System is inside the nebula ::figure[src="https://upload.wikimedia.org/wikipedia/commons/7/7c/The_Local_Interstellar_Cloud_and_neighboring_G-cloud_complex.svg" caption="Map showing the [[Sun]] located near the edge of the Local Interstellar Cloud and [[Alpha Centauri]] about 4 [[light-year]]s away in the neighboring [[G-Cloud]] complex"] ::

The Local Interstellar Cloud (LIC), also known as the Local Fluff, is an interstellar cloud roughly 30 ly across, through which the Solar System is moving. This feature overlaps with a region around the Sun referred to as the solar neighborhood. It is unknown whether the Sun is embedded in the Local Interstellar Cloud, or is in the region where the Local Interstellar Cloud is interacting with the neighboring G-Cloud. Like the G-Cloud and others, the LIC is part of the Very Local Interstellar Medium which begins where the heliosphere and interplanetary medium end, the furthest that probes have traveled.

Structure

The Solar System is located within a structure called the Local Bubble, a low-density region of the galactic interstellar medium. Within this region is the Local Interstellar Cloud (LIC), an area of slightly higher hydrogen density. It is estimated that the Solar System entered the LIC within the past 10,000 years. | vauthors = Frisch PC, etal | date = September 2011 | title = The Interstellar Medium Surrounding the Sun | url = https://www.annualreviews.org/doi/10.1146/annurev-astro-081710-102613 | journal = Annual Review of Astronomy and Astrophysics | volume = 49 | issue = 1 | page = 252 | doi = 10.1146/annurev-astro-081710-102613 | bibcode = 2011ARA&A..49..237F | access-date = 2021-12-28 | url-access= subscription It is uncertain whether the Sun is still inside of the LIC or has already entered a transition zone between the LIC and the G cloud. | vauthors = Linsky JL, etal | date = November 18, 2019 | title = The Interface between the Outer Heliosphere and the Inner Local ISM | journal = The Astrophysical Journal | volume = 886 | issue = 1 | page = 41 | doi = 10.3847/1538-4357/ab498a | arxiv = 1910.01243 | bibcode = 2019ApJ...886...41L | s2cid = 203642080 | doi-access= free A recent analysis estimates the Sun will completely exit the LIC in no more than 1,900 years. | vauthors = Linsky JL, etal | date = March 2020 | title = New results concerning the environment of the heliosphere, nearby interstellar clouds, and physical processes in the inter–cloud medium | journal = Journal of Physics: Conference Series | volume = 1620 | issue = 1 | article-number = 012010 | doi = 10.1088/1742-6596/1620/1/012010 | bibcode = 2020JPhCS1620a2010L | s2cid = 225188522 | doi-access= free

The cloud has a temperature of about 7000 K, about the same temperature as the surface of the Sun. However, its specific heat capacity is very low because it is not very dense, with 0.3 /cm3. This is less dense than the average for the interstellar medium in the Milky Way (0.5 /cm3), though six times denser than the gas in the hot, low-density Local Bubble (0.05 /cm3) which surrounds the local cloud. In comparison, Earth's atmosphere at the edge of space (i.e. 100 km above sea level) has around 1.2 molecules per cubic centimeter, dropping to around 50 million (5.0) at 450 km.

The cloud is flowing outwards from the Scorpius–Centaurus association, a stellar association that is a star-forming region, roughly perpendicular to the Sun's own direction.

In 2019, researchers found interstellar iron-60 (60Fe) in Antarctica, which they relate to the Local Interstellar Cloud.

Interaction with solar magnetic field

::figure[src="https://upload.wikimedia.org/wikipedia/commons/1/1f/Interstellar_medium_annotated.jpg" caption="The Solar System within the [[interstellar medium]], with the different regions and their distances on a logarithmic scale (object sizes not to scale)"] ::

In 2009, Voyager 2 data suggested that the magnetic strength of the local interstellar medium was much stronger than expected (370 to 550 picoteslas (pT), against previous estimates of 180 to 250 pT). The fact that the Local Interstellar Cloud is strongly magnetized could explain its continued existence despite the pressures exerted upon it by the winds that blew out the Local Bubble.

The Local Interstellar Cloud's potential effects on Earth are greatly diminished by the solar wind and the Sun's magnetic field. This interaction with the heliosphere is under study by the Interstellar Boundary Explorer (IBEX), a NASA satellite mapping the boundary between the Solar System and interstellar space.

References

References

  1. "NAME LIC".
  2. (2011). "Encyclopedia of Astrobiology".
  3. Gilster, Paul. (September 1, 2010). "Into the Interstellar Void". Centauri Dreams.
  4. Linsky, Jeffrey. (2020-03-23). "What lies immediately outside of the heliosphere in the very local interstellar medium (VLISM): morphology of the Local Interstellar Cloud, its hydrogen hole, Stromgren Shells, and 60Fe accretion". Copernicus GmbH.
  5. (January 6, 2003). "Near-Earth Supernovas". NASA.
  6. (2000). "Our Local Galactic Neighborhood". NASA.
  7. (2000). "Course 7: Dust in the Interstellar Medium".
  8. United States Committee on Extension to the Standard Atmosphere. (October 1976). "U.S. Standard Atmosphere, 1976". [[NOAA]], [[NASA]] and [[U.S. Air Force]].
  9. (February 10, 2002). "The Local Interstellar Cloud".
  10. (February 17, 2002). "The Local Bubble and the Galactic Neighborhood".
  11. (August 2019). "Interstellar 60Fe in Antarctica". Physical Review Letters.
  12. (December 24–31, 2009). "A strong, highly-tilted interstellar magnetic field near the Solar System". [[Nature (journal).

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