Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: moonfire on 01/12/2006 14:26:35
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How many types of different Nebulaes? Is it possible to know? (not referring to stars)
Thanks! I know it is fascinating to see in pictures....
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Hi Lo *giggles* ............at present there are 42 different types of nebulae.
This was recorded at the last Nebulae Census when they each had to fill in a form...
Types ranges from, big ones, small ones, medium ones, curly ones and ones that look like duckies and horsies
Glad I could help !!
...Actually...make that 43 as we have to take into consideration the agoraphobic nebulae who failed to post their forms back !! [;)]
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Hi Lo *giggles* ............at present there are 42 different types of nebulae.
This was recorded at the last Nebulae Census when they each had to fill in a form...
Types ranges from, big ones, small ones, medium ones, curly ones and ones that look like duckies and horsies
Glad I could help !!
...Actually...make that 43 as we have to take into consideration the agoraphobic nebulae who failed to post their forms back !! [;)]
You are so terrible...lol But I love ewes anyways...I am just curious about these gases/clouds
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I am sorry I did not answer your questions adequately. [;)].......in the mean time...before a passing nebulae expert passes by and answers, here's wikis link to some nebulae piccys http://en.wikipedia.org/wiki/Category:Nebular_images
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I love those I bought a book with a bunch of thre Hubble shot so beautiful!
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I love those I bought a book with a bunch of thre Hubble shot so beautiful!
I got that book too...well, my one may have been a sequel called Hubble Revisited...it's well nice !!
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yes, there is so many fascinating things in our galaxies...lol
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Joking apart here is a bit of information
There are three normal ways to get diffuse glowing clouds in interstellar space the first is that there is dust about and the light of bright local stars is reflected from it a bit like fog in the headlights of a car these are called "reflection nebulae". you can tell them because the colour (spectrum) is similar to the stars that are close to them.
An example is the nebula around the peliades star cluster in Taurus
Then there are clouds of gas that are exited to emit spectral lines a bit like a neon tube. These are called emission nebulae. An example is the north america nebula in Cygnus.
There is one rare type of radiation called synchrotron radiation where rapidly moving ions are circulating in a magnetic field this occurs near an oldish supernova like the crab nebula in taurus.
All these are currently reasonably well placed for observation from the northern hemisphere at the moment
Now there are several possible reasons why the clouds of dust or gas are caused to shine. The dust requires one or many very bright stars in the vicnity of the dust cloud another posssibility is a recent supernova local to the cloud when ther is a bright pulse of light travelling through the cloud and you see bits of the cloud lit up in turn like sweeping a torch around in a fog.
The way that gaseous clouds can emit spectrum lines includes very bright stars emitting ultra violet light causing flourescence the exposed core of an old star during the time it is shedding its atmosphere to become what is called a planetary nebula (these are often the prettiest). Also an old supernova shock front or magnetic field can also cause the excitation of atoms.
Many nebulae have several different types of light emission.
One thing that doesn't happen at optical wavelengths is that the clouds glow with heat because they are not really dense enough. Warm glowing nebulae emit in the infra red regions of the spectum not visible light.
finally there are the dark nebulae a bit like fog. They can only be seen by the fact that they hide the light of stars behind them. An example of this is the dark nebula that causes a gap in the mily way through Cygnus.