How fast do nebulae change?

[Alastair Rae]

We name various nebula for their shapes - such as the Horsehead - but how fast do these structures change? Have we been observing DSOs long enough to detect changes of shape?

[Stu]

Pretty sure Hubble has recorded changes over the years it has been up there, mainly in planetary nebulae expanding I believe.

[acey]

Nebuale are very big, so visible changes generally take a long time to happen (hundreds or thousands of years), and there are very few examples where change has been seen by eye. Where it has happened, it has been because of variation in light of an illuminating star: the famous cases are Hind's Variable Nebula and Hubble's Variable Nebula. Hind's has faded since the 19th century when it was discovered, and now needs a very large scope. Hubble's Variable Nebula (actually discovered by Herschel) is an easy target in a small scope from a dark site, and has an interesting comet-like shape.

[Stu]

This is the one I am talking about.

http://hubblesite.org/gallery/album/pr2005002g/

Acey is correct though, most nebulae, although they can be changing pretty fast, are so far away and so large that the changes are imperceptible to us.

Cheers

Stu

[lukebl]

Some of them, like M1, have shown measurable changes. Here's an old pair of images from 1942 and 1976 showing how much it had spread. I think there's a more modern version of this somewhere, with more recent Hubble images showing the spread even further.

[Shibby]

I think there's a more modern version of this somewhere, with more recent Hubble images showing the spread even further.

There's also a time-lapse of the pulsar at its heart, captured by Chandra:

And here is the evolution of a supernove captured by Hubble:

File:SN1987a debris evolution animation.gif - Wikipedia, the free encyclopedia

[Shibby]

Oh, and there was this amazing animation of some supersonic jets recently:

http://www.physorg.com/news/2011-08-hubble-movies-unprecedented-view-supersonic.

[Stu]

Hi Lukebl

Can you re post the 1976 M1 image? It doesn't seem to be there and am interested to see it

Cheers

Stu

[lukebl]

Hi Lukebl

Can you re post the 1976 M1 image? It doesn't seem to be there and am interested to see it

Cheers

Stu

Oh. It's a link to an animated gif which seems to work on mine. Here it is again as an attachment. Hope this works.

[Stu]

Ahh, that makes sense. Am viewing on Tapatalk so just need to save it somewhere to view it.

Thanks

Stu

[Stu]

That worked

Very interesting, and a clear change in a comparatively short space of time

Stu

[JulianO]

Nice illustration of proper motion too in some of the stars, particularly one in the top right corner.

[callump]

And of course there are the variable nebulae - not that these are changing due to the expansion of the nebula, but they change due to lighting effects from companion stars.

There are five well known VN's: Hubble's, Hind's, Gyulbudaghian's, NGC 6729 and McNeil's.

Whilst they may not appear to change much night-to-night they do certainly change over months or years.

The BAA Deep Sky Section has a programme for monitoring these, and quite a lot of work has been done on Gyulbudaghian's Nebula in particular.

You can find out a bit more:

Variable Nebulae

Callum