a question regarding nebulae

[star1961]

nebulae are formed of gas and dust particles? why do they appear to stay in the same shape?

[Esseth]

I think they do, it just takes along long time because there is so much. but im no expert

[coldspace]

Good question, I was going to say maybe gravity but that usually keeps things like stars, planets in round shapes.
I think,
That neb gases and dust are on the move and are influenced by gravity but because of the very vast distances like many, many thousands of light years we will never detect the movement in our short lfe times, but over say hundred or thousands of years they would appear to change shape and expand out from our view point here on earth. Its a bit like if you see someone move say 5 mtrs next to you it would appear that way but if you watched them do it from say 1 km it would appear that they only moved a little and if you could see it from say 100kms then it would appear they did not move, someone witha more scientific answer may help.

Matt.

[mill]

It is the same as looking at something from a big distance.
It just looks as if it almost doesn't move.
Nebula's are at such a big distance it looks as if it doesn't move at all but they expand very fast (hundreds of Km per second).

[BerrieK]

I, like Esseth, am no expert but my thoughts on this question are:

If space is a vaccum then the gas, dust or molecules will not move away from each other (I think) unless you have a difference in pressure between 2 areas - then the gas / vapour would dissipate. From our massive distance away this dissipation appears static.

Also, over billions of years a nebula may undergo accretion to form stars, planets and other objects. As far as I understand it matter (from the nebula) is gravitationally attracted towards a larger mass of matter and so a larger body develops rather than the nebula dissipating. I don't know what the catylist for such a process is.

I am no astro-scientist though - I am sure someone far more knowledgeable will enlighten more accurately and thoroughly.

Kerrie :)

[Esseth]

and thats what i love about this forum, we don't have to be because i am sure there is someone one here that knows all about any particular topic :D

[star1961]

wow that is mind boggling
moving so fast and yet hardly moving at all
makes me feel very tiny

[AlexN]

They stay in space so that we can image them! :)

In all honesty, they do dissipate, they spread out until there is nothing left, but as Martin said, because we are SO far away, and they are SO large, their rather fast rate of expansion seems null...

I read somewhere (I think it was hubblesite) that the pillars of M16 actually do not exist anymore, we still see and image them, because the light we are receiving now left M16 1500yrs ago or there abouts... but in its current state, due to the continuous birth or stars in the area, the pillars apparently would have been blown away by stellar winds and the like... In 1500yrs time, we should see a flat, rather bland looking section of very faint red nebulosity where M16 used to be... Well.. We shouldn't... we'd be fairly decayed by then! :D But future generations should be able to...

Alex.

[renormalised]

Actually, Alex, add about 4000ly to that distance (it's around 5500ly away), but other than that the reasoning is right.:D Your 45th G-Grandson will probably image it's present condition:D. Actually, your 2nd or 3rd G-Grandson will probably go there!!!!:D

[AlexN]

Ahh true.. :) Thanks Carl. I've been so obsessed with our currently rising Orion arm of the milky way that I'm assuming everything is between 1300 and 1700ly distant! :D haha Sagittarius arm is a little further out.. :D

Go there? haha... Yea... sure, I dont see humans succeeding in interstellar travel in the next few thousand years... Call me negative... but there you have it! :D

[TrevorW]

Actually Alex the speed of light can be exceeded, when I reckon, in the next 100 years at a guess but then again I won't be around too see it

Don't be so negative

[AlexN]

exceeded? or a work around found such as folding space or perhaps wormhole travel.. I agree interstellar travel is attainable, but with the current state of the futile human race, I dont see it happening soon.

[xelasnave]

The Universe is far from static its just we can only observe in a miniscul time frame that tells us little about the life time evolvement of things...
Think of a movie..we are only ever looking at a single frame of something that runs for hours the single frame is static but the movie when run has movement.. also a start and and end.
alex

[Jules76]

From what I understand, when a star goes Supernova, the shockwaves which are created and sent outwards trigger the gases to collapse under gravity and start the process of forming new stars etc.

[Baddad]

Hi All, :)

Our own Solar System is believed to have been a super nova in the beginning. A dying star, exploding. The gases recombining to form the sun and planets. 4.65 billion years ago.

The nebula if large enough may combine or dissperse. It depends on what the trigger is. I assume there being no trigger, nothing happens.

That is what I understand from some of the DVD documentaries I have watched on the subject.:D

Cheers Marty

[Outbackmanyep]

Theres no wind up there to blow it away!

[kustard]

I have been racking my brain trying to remember the name of the nebula remnant that the solar system is believed to have originated from but do you think I can remember? I am pretty sure I read it somewhere, though I may be wrong.

[DavidU]

This one Simon?
http://curious.astro.cornell.edu/question.php?number=561

[kustard]

Yeah Dave, that pretty much answers my question :)

Good find, my google-fu failed me. hehe.

[Jen]

:screwy::screwy: so does that mean my favourite horsehead nebula wont be that shape forever :sadeyes:
:question::question:

[AlexN]

Jen, Its likely the horse head does not exist even now... Being that it is a birthplace of new stars, it would likely not be a horses head anymore..

[Paul Haese]

I don't as a rule say the sort of thing I am going to say, however one thing is urking me here.

First, the plural form of nebula is not nebula's. It is nebulae. Please use this term. Using the incorrect terminology devalues the science of astronomy.

That said, nebula congregate by virtue of gravity, the mass of the nebula forms its own gravity and it slowly clumps into knots of gas. The gas gradually condenses and forms more stars over millions of years. Only when star forming is at an end will there be little if any gas remaining. Examples of nebula that have been all but used are the Pleiades. Examples of star forming regions are M42, the Lagoon nebula, the Eagle Nebula and Eta Carina.

Rant over with.

[dannat]

nice definition paul,, as for exceeding the speed of light i think you cannot exceed the speed of light in a vacuum which is about 300000 m/s, but in thoery we may be able to surpass the speed of light when it is moving in another medium (jelly)

[barx1963]

Nebulae (note correct spelling!) come in several varieties. Some are star forming (M42, Eta Carina etc). Others are supernova remnents (or is that supernovae?) such as the Veil, the Crab (M1) and then there are the planetary nebulae which are the expanding shells of stars that have exhausted their fuel and shrunk to white dwarfs after going through a re giant stage, which is the ultimate fate of our sun. Of course there can be combinations of these. For example, as mentioned earlier, supernovae can trigger star formation in nebulae while contrubiting some of their mass to the process.
So the nebulae can be expanding or shrinking, or parts can be collapsing while others are expanding and dissapating into space, thats why they are all different!

[Jen]

:eyepop:awww that is so sad :rolleyes:

[star1961]

this is my first question and very new to these subjects
apologies for my ignorance :sadeyes:
but thanks everyone for your answers

[barx1963]

Lisa, never apologise for ignorance, the only way to learn is to ask questions. The people here are always happy to answer questions and provide great info. Look at the discussion your question started, thats what it is all about.

[DavidU]

Hey ! wrong attitude. We are pleased to answer questions.I learned by asking tons of questions.
Remember, there is no such thing as a silly question.:thumbsup: