The Red Rectangle

The Red Rectangle, courtesy of NASA/JPL-Caltech and ESA.

It was great to spend a little time at the summit last week on my own science project. Actually, it's not my own, it's a collaboration with researchers at The University of Nottingham in the UK where I spent a couple of years as a post-doc., but still, it felt as though I had a little bit of telescope time for myself.

We observed an object called the Red Rectangle, one of the most unusual objects in our Galaxy. We've been observing it for a number of years now and it's certainly become a bit of a pet project, but it's such a fascinating thing.

It's called the Red Rectangle because that's what it looked like on photographic film when it was first discovered decades ago. Technology improves all the time and the above image is one of the latest images of this protoplanetary nebula - this one is from the Hubble Space Telescope.

Planetary nebulae are quite common. The name is a little bit misleading as these nebulae have little to do with planets, the name is a historical accident. They're formed by stars similar to our own sun reaching the end of their lives, and due to complicated processes which I won't go into here, blow off their outer layers to form nebulae - some of them are particularly beautiful. The Red Rectangle, however, is a protoplanetary nebula, that is its central star (actually, there are two of them orbiting each other) has just entered old age and is blasting off its outer atmospheric layers in an old age-induced grumpy temper fit. That's one of the theories behind the ladder effect in the image above, each step resulted from nuclear fusion driven eruptive episodes deep within the star over the last few hundred thousand years.

Why is it such a unique object? Well, although its current protoplanetary phase has being going on for so long, you need to relate that to the total lifetime of the star which is billions of years, therefore the protoplanetary stage is a tiny fraction of the star's total lifetime. Even though we can see millions of stars, it's statistically unlikely we'll be able to observe a star in this stage of its life, especially one as easy to see as the Red Rectangle. We know of a few, but there aren't that many we can easily observe or as beautiful as the Red Rectangle.

It's also unique because of the geometry. The old age pensioner central star has a thick dust disk surrounding it that is edge-on to us and constrains the outflow into an X-shape. There's some pretty complicated physics occurring there as well as chemistry, and it's the latter that interests our small group (actually, I like the physics stuff even more but my research has taken me into the dark and scary world of chemistry in recent years).

The Red Rectangle produces some large molecules and is in effect a chemistry laboratory in space. It creates polycyclic aromatic hydrocarbons (PAHs) which are essentially large molecules made of hydrogen and carbon, as you might guess from the name. You and I create them all the time when we drive our cars or burn a sausage on the grill. They're also important molecules in the formation of life, so are quite important to understand!

So now I'm boring myself. I could probably write a book about the Red Rectangle and don't want to do that here. Suffice to say, we've published a few papers on it over the last decade or so and hopefully there are a few more to come. We've been using an "integral field unit" (IFU) to take spectra of the object at several wavelengths over quite a large part of the nebula looking for molecules and how they're distributed throughout the region. We've already published some nice results and I hope we have more to come. The analysis is difficult though, the picture below shows some raw IFU data from the run last week:

14 spectra and and we have seven different positions where we took data. If the data are treated correctly we'll have hundreds of individual spectra, lots of spectral images and a good idea of the distribution of certain molecules throughout the nebula. Enough for someone's PhD I hope.

You see, I actually do a little astronomical work from time to time and don't just go to the summit to take pictures of the snow and sunsets!