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Welcome To Our Honeycomb-Centered Interstellar Cavity
The "void" between the stars is anything but empty. Interstellar space
is filled with the gaseous remains of supernova explosions, wispy tendrils of plasma from stellar winds and star-forming nebulae. Some of this gaseous matter forms magnetized cloud-like structures, the closest of which is known as the "Local Fluff." However, our solar system sits inside a volume of space that contains 10 times less gas than the galactic average. The sun -- and many nearby stars -- is located in a "cavity" (known, unsurprisingly, as the "Local Cavity") that measures approximately 300 light years across. The presence of this region has been known for some time, but an international team of astronomers have now created a 3-dimensional map of this fascinating region of space in our cosmic backyard. *** Interestingly, by analyzing one particular absorption line (caused by doubly ionized calcium -- CaII), it appears that the Local Cavity contains filamentary structures of partially ionized gas, creating a honeycomb-like pattern of smaller interstellar cells. Although the cause of this cell-like structuring is unknown at present, it is thought that the Local Cavity was formed after a series of supernovae detonated nearby, blowing the cool, dense interstellar medium away and replacing it with a very tenuous volume of hot plasma, creating a 'bubble.' *** Welcome To Our Honeycomb-Centered Interstellar Cavity : Discovery News http://news.discovery.com/space/welc...ar-cavity.html |
#2
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Welcome To Our Honeycomb-Centered Interstellar Cavity
Yousuf Khan wrote:
The "void" between the stars is anything but empty. Interstellar space is filled with the gaseous remains of supernova explosions, wispy tendrils of plasma from stellar winds and star-forming nebulae. Some of this gaseous matter forms magnetized cloud-like structures, the closest of which is known as the "Local Fluff." However, our solar system sits inside a volume of space that contains 10 times less gas than the galactic average. The sun -- and many nearby stars -- is located in a "cavity" (known, unsurprisingly, as the "Local Cavity") that measures approximately 300 light years across. The presence of this region has been known for some time, but an international team of astronomers have now created a 3-dimensional map of this fascinating region of space in our cosmic backyard. *** Interestingly, by analyzing one particular absorption line (caused by doubly ionized calcium -- CaII), it appears that the Local Cavity Ca II is singly-ionized...I see the mistake is in the article. Indeed, these lines have been observed since the early days of stellar spectroscopy. They were for a long time called "stationary lines" because if you observed a binary star, the stellar lines would vary in radial velocity but the Ca II H and K lines (3933 and 3968 A) would stay at constant velocity. It took a while to realize they were from the interstellar gas. contains filamentary structures of partially ionized gas, creating a honeycomb-like pattern of smaller interstellar cells. Although the cause of this cell-like structuring is unknown at present, it is thought that the Local Cavity was formed after a series of supernovae detonated nearby, blowing the cool, dense interstellar medium away and replacing it with a very tenuous volume of hot plasma, creating a 'bubble.' *** Welcome To Our Honeycomb-Centered Interstellar Cavity : Discovery News http://news.discovery.com/space/welc...ar-cavity.html -- Mike Dworetsky (Remove pants sp*mbl*ck to reply) |
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Welcome To Our Honeycomb-Centered Interstellar Cavity
Mike Dworetsky wrote:
Yousuf Khan wrote: Interestingly, by analyzing one particular absorption line (caused by doubly ionized calcium -- CaII), it appears that the Local Cavity Ca II is singly-ionized...I see the mistake is in the article. Yes, this other article has the proper description, it's Sodium that is doubly-ionized. A new 3D map of the interstellar gas within 300 parsecs from the Sun "The team, led by Barry Y. Welsh and his colleagues R. Lallement and J.-L. Vergely, presents new, high spectral resolution measurements of the calcium (CaII) K line (at 3933 Ĺ) and the sodium doublet (at 5889 and 5895 Ĺ). These absorption lines have long been used to study the interstellar medium." http://www.physorg.com/news184953624.html Yousuf Khan |
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Welcome To Our Honeycomb-Centered Interstellar Cavity
"Yousuf Khan" wrote in message ... Mike Dworetsky wrote: Yousuf Khan wrote: Interestingly, by analyzing one particular absorption line (caused by doubly ionized calcium -- CaII), it appears that the Local Cavity Ca II is singly-ionized...I see the mistake is in the article. Yes, this other article has the proper description, it's Sodium that is doubly-ionized. A new 3D map of the interstellar gas within 300 parsecs from the Sun "The team, led by Barry Y. Welsh and his colleagues R. Lallement and J.-L. Vergely, presents new, high spectral resolution measurements of the calcium (CaII) K line (at 3933 L) and the sodium doublet (at 5889 and 5895 L). These absorption lines have long been used to study the interstellar medium." http://www.physorg.com/news184953624.html Yousuf Khan A doublet does not mean "doubly ionized". http://hyperphysics.phy-astr.gsu.edu...um/sodzee.html An ionized atom has an electron completely removed or added, that takes far more energy than kicking it up or down a level or two. |
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Welcome To Our Honeycomb-Centered Interstellar Cavity
Androcles wrote:
A doublet does not mean "doubly ionized". http://hyperphysics.phy-astr.gsu.edu...um/sodzee.html An ionized atom has an electron completely removed or added, that takes far more energy than kicking it up or down a level or two. Point taken. Yousuf Khan |
#6
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Welcome To Our Honeycomb-Centered Interstellar Cavity
Yousuf Khan wrote:
Mike Dworetsky wrote: Yousuf Khan wrote: Interestingly, by analyzing one particular absorption line (caused by doubly ionized calcium -- CaII), it appears that the Local Cavity Ca II is singly-ionized...I see the mistake is in the article. Yes, this other article has the proper description, it's Sodium that is doubly-ionized. No, the sodium is actually neutral, designated Na I. The two lines of the doublet mentioned are what cause the yellow colour of low pressure sodium lamps. A new 3D map of the interstellar gas within 300 parsecs from the Sun "The team, led by Barry Y. Welsh and his colleagues R. Lallement and J.-L. Vergely, presents new, high spectral resolution measurements of the calcium (CaII) K line (at 3933 Ĺ) and the sodium doublet (at 5889 and 5895 Ĺ). These absorption lines have long been used to study the interstellar medium." http://www.physorg.com/news184953624.html Yousuf Khan -- Mike Dworetsky (Remove pants sp*mbl*ck to reply) |
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