Astronomy:G-Cloud

From HandWiki
G-Cloud
Interstellar cloud
The G-Cloud complex and neighboring Local Interstellar Cloud
Observation data
DesignationsG Cloud[1]
See also: Lists of nebulae

The Galactic cloud, G cloud,[2] G-Cloud or G-Cloud complex, is an interstellar cloud located next to the Local Interstellar Cloud, within the Local Bubble. It is unknown whether the Solar System is embedded in the Local Interstellar Cloud or in the region where the two clouds are interacting, although the Solar System is currently moving towards the G-Cloud. The G-Cloud contains the stars Alpha Centauri (a triple star system that includes Proxima Centauri), Altair, and possibly others.[3][4][5][6][7]

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.[4] Like the Local Interstellar Cloud and others, the G-Cloud is part of the Very Local Interstellar Medium which begins where the heliosphere and interplanetary medium end.[8]

Formation

The G-Cloud was formed along with the Local Bubble approximately 20 million years ago due to supernova activities. The Local Interstellar Cloud was also formed at the same time.[9]

Structure

The Solar System is located within a structure called the Local Bubble, a low-density region of the galactic interstellar medium.[10] Within this region is the G-Cloud, an area of slightly higher hydrogen density. It is estimated that the Solar System entered the Local Interstellar Cloud within the past 10,000 years.[11] It is uncertain whether the Sun is still inside of the Local Interstellar Cloud or has already entered a transition zone between the LIC and the G cloud.[11][12][4] The cloud covers 20% of the sky.[6]

Estimates for the n(H I) particle density in the direction of Alpha Centauri. were made in 2011 by Crawford[13] as 0.1 cm−3 and in 2014 by Gry[14] as 0.098 cm−3. The temperature of the G-Cloud is 5500 ± 400 K.[2] It has a comparatively lower metal depletion.[6]

The Local Interstellar Cloud and G-Cloud are moving towards each other. They form a mixed interstellar cloud medium (MICM) where they meet.[2]

See also

References

  1. ↑ "NAME G Cloud". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NAME+G+Cloud. 
  2. ↑ 2.0 2.1 2.2 Swaczyna, Paweł; Schwadron, Nathan A.; Möbius, Eberhard; Bzowski, Maciej; Frisch, Priscilla C.; Linsky, Jeffrey L.; McComas, David J.; Rahmanifard, Fatemeh et al. (2022-10-01). "Mixing Interstellar Clouds Surrounding the Sun". The Astrophysical Journal Letters 937 (2): L32. doi:10.3847/2041-8213/ac9120. ISSN 2041-8205. Bibcode: 2022ApJ...937L..32S. 
  3. ↑ "Our Local Galactic Neighborhood". Interstellar.jpl.nasa.gov. http://interstellar.jpl.nasa.gov/interstellar/probe/introduction/neighborhood.html. Retrieved 7 October 2015. 
  4. ↑ 4.0 4.1 4.2 Paul Gilster (1 September 2010). "Into the Interstellar Void". Centauri-dreams.org. http://www.centauri-dreams.org/?p=14203. 
  5. ↑ "The Interstellar Medium". http://jila.colorado.edu/research/astrophysics/interstellar-medium. 
  6. ↑ 6.0 6.1 6.2 Seth Redfield (2009). "Physical Properties of the Local Interstellar Medium". Igpp.ucla.edu. http://www.igpp.ucla.edu/public/mkivelso/refs/PUBLICATIONS/Redfield%20LISM.pdf. 
  7. ↑ Frisch., Priscilla (3 February 2003). "Local Interstellar Matter: The Apex Cloud". The Astrophysical Journal 593 (2): 868–873. doi:10.1086/376684. Bibcode: 2003ApJ...593..868F. 
  8. ↑ 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", Egu General Assembly Conference Abstracts (Copernicus GmbH): 1410, doi:10.5194/egusphere-egu2020-1410, Bibcode: 2020EGUGA..22.1410L 
  9. ↑ "The Local Interstellar Cloud: An Overview". https://www.thoughtco.com/clouds-in-space-3073644. 
  10. ↑ "Our Local Galactic Neighborhood". NASA. 2000. http://interstellar.jpl.nasa.gov/interstellar/probe/introduction/neighborhood.html. 
  11. ↑ 11.0 11.1 "The Interstellar Medium Surrounding the Sun". Annual Review of Astronomy and Astrophysics 49 (1): 252. September 2011. doi:10.1146/annurev-astro-081710-102613. Bibcode: 2011ARA&A..49..237F. https://www.annualreviews.org/doi/10.1146/annurev-astro-081710-102613. Retrieved 2021-12-28. 
  12. ↑ "The Interface between the Outer Heliosphere and the Inner Local ISM". The Astrophysical Journal 886 (1): 41. November 18, 2019. doi:10.3847/1538-4357/ab498a. Bibcode: 2019ApJ...886...41L. 
  13. ↑ Crawford, Ian A. (2011-04-01). "Project Icarus: A review of local interstellar medium properties of relevance for space missions to the nearest stars" (in en). Acta Astronautica 68 (7): 691–699. doi:10.1016/j.actaastro.2010.10.016. ISSN 0094-5765. Bibcode: 2011AcAau..68..691C. https://www.sciencedirect.com/science/article/pii/S0094576510003954. 
  14. ↑ Gry, Cécile; Jenkins, Edward B. (July 2014). "The interstellar cloud surrounding the Sun: a new perspective". Astronomy & Astrophysics 567: A58. doi:10.1051/0004-6361/201323342. ISSN 0004-6361. Bibcode: 2014A&A...567A..58G. http://www.aanda.org/10.1051/0004-6361/201323342. 




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