A little evening's diversion. A few weeks ago there was this ALMA press release (which I came across again today) about observations of the gas around the star LL Pegasi (). It was already fairly famous from Hubble observations thanks to its remarkably neat spiral pattern. The ALMA observations add velocity information and I wanted to see what this would look like in 3D. Actually I've been wondering about this for a while since there was a similar-ish press release about another sort-of similar object some time ago.
For those who aren't familiar with these types of observations, have a look at the gif in the press release first. There you see the data in a slightly more usual format, as a series of images. Each one shows the gas at some particular velocity along our line of sight. What I've done here is use each image as the slice of a 3D cube - it's fun to look at (maybe even useful) but it doesn't show you the true 3D structure of the object.
The last time something similar like this was doing the rounds I couldn't find the original FITS data I needed to display it. This time I didn't bother. I took the gif, converted it into a sequence of png images, then wrote a Python script to convert the image sequence into a FITS cube and then ran it through FRELLED (what else ? http://www.rhysy.net/frelled-1.html). Oh, and I interpolated extra velocity channels because there weren't very many in the gif (there might be more in the original data, I don't know). So there's a fair amount of extra processing for this one, but probably nothing that would result in any serious differences from the raw data.
What does it all mean ? Haven't got a clue, I just thought it would be nice to look at.
The Space Cigar o' Doom. Or Sausage. (Would make a good "warp field" visualization for some SF show.)
ReplyDeleteFirst I thought your great model was about 51Peg binary stars and found the shape could represents the system's synergy. Then realised my mistake while reading the whole article about LL nebula... still the pattern holds :-) The stretch aberration revealed by your exhaustive presentation recalls a cocoon core which is surely a fact to consider in the fundamental cosmic portrait. Your intriguing rich gif made me lurn a lot. :-) Very interesting.
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