- Local Bubble
The Local Bubble is a cavity in the
interstellar medium (ISM) of theOrion Arm of theMilky Way . It is at least 300light years across and has a neutralhydrogen density approximately one tenth of the 0.5atoms per cubic centimetre average for the ISM in theMilky Way . The hot diffuse gas in the Local Bubble emitsX-rays . The very sparse, hot gas of the Local Bubble is the result ofsupernova e that exploded within the past two to four million years. [http://www.solstation.com/x-objects/chimney.htm Local Chimney and Superbubbles] , Solstation.com] The most likely candidate for the remains of this supernova is "Geminga " ("Gemini gamma-ray source"), apulsar in the constellation Gemini.The
Solar System has been travelling through the region currently occupied by the Local Bubble for the last five to ten million years. Its current location lies in theLocal Interstellar Cloud a minor region of denser material within the Bubble. The cloud formed where the Local Bubble and the Loop I Bubble met. The gas within the LIC has a density of approximately 0.1 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.The Local Bubble abuts other bubbles of less dense ISM, including, in particular, the Loop I Bubble. The Loop I Bubble was created by supernovae and
stellar wind s in theScorpius-Centaurus Association , some 500 light years from theSun . Other bubbles abutting the Local Bubble are the Loop II Bubble and the Loop III Bubble.The Loop I Bubble contains star
Antares (also known as Alpha Scorpii) as shown on the diagram above right.ee also
*
Gould Belt
*Orion Arm
*Perseus Arm
*Superbubble
*List of nearest stars Notes
References
* [http://science.nasa.gov/headlines/y2003/06jan_bubble.htm Near-Earth Supernovas] , NASA
* [http://science.nasa.gov/headlines/y2004/17dec_heliumstream.htm A Breeze from the Stars] , NASA
* Anderson, Mark. "Don't stop till you get to the Fluff", "New Scientist " Issue 2585, 6 Jan, 2007, pp. 26-30. doi|10.1016/S0262-4079(07)60043-8
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