Ian: Is that a result from the binary orbit? Or... and I'm guessing here... some kind of pulsing during the nova?
And what elements are found in the dust? Is it as enriched with heavy elements like a supernova remnant?
Rich: You are nearly right! As I mentioned before, RN enrich the interstellar medium by blowing off surface layers of material. In the past (before 2007) it was thought that the way dust is created by RN is that the blast from the event compresses the immediate environment about the binary causing condensation of dust.
For dust creation, you must have a critical density of material so that three-body collisions can occur - two to stick together and one to carry away excess momentum.
Well, we happened to be commissioning the Keck Interferometer Nuller (KIN) when the nova RS Ophiuchi occurred. The KIN uses the combined light from the two largest optical telescope in the world (each of which is 10m) to form the equivalent of an 85m telescope.
We use the interference of the light from the two telescopes to form a fringe pattern - of dark and bright fringes. We then place one of the dark fringes on the brightest part of the object - in this case, the WD in eruption - and can look at the faint material in the immediate vicinity. . This was completely invisible to science ... until now! So, we accumulated 20 minutes of data from the KIN on the nova and in the data we found that there was silicate dust a mere 17 AU from the central bright source! What this meant to us is that the old theory simply did not hold up in the light of this new data. The old theory told us that that dust should not have been there at all. It should have long since been blown away by the wind from the recurring nova! Ian: Wow, that must have been thrilling to see. Was it a surprise discovery or had the dust been predicted before? Rich: This was a complete surprise to all parties. The silicate dust had been unexpected. To form the dust, as I mentioned, you must have enough density of material and it has to be at the right temperature. Using these observations, we have now formulated a new theory of how silicate dust is created by recurring novae! ! Ian: So is it fair to say that RS Ophiuchi has been key to recurrent novae research? Sounds like a fascinating system! Rich: Yes! What you see in the artwork is an Archemidian dust spiral caused by the massive WD plowing through the massive wind from the RG. Then, every 20 years or so, mass that has accumulated on the WD from the RG explodes and completely clears the beautiful spiral! Ian: Absolutely stunning. Rich: Right now, as we 'speak' the spiral should be reforming. At some point in the near future, we may even be able to see the spiral in reflected light using Hubble or possibly JWST. Ian: Actual optical images? Now that would be a great sight Rich: Yes, very beautiful and exciting. This will drive a stake in the old theory! To answer your previous question, recurring novae do enrich the interstellar medium with lighter elements. When they go supernova, THEN they produce the really massive elements. You need a very strong explosion to do that. . Ian: So am I correct in saying that recurrent novae can be a precursor to an eventual supernova? Could RS Ophiuchi (for example) ever get completely destroyed by a supernova? Or is the white dwarf simply too small? Rich: Yes, you are correct. RS Ophiuchi is likely to go supernova at some point in the future. The reason that it erupts every 20 years or so is because the WD is so very near the Chandrasekhar mass limit. It is really wonderful that we have this great laboratory for the study of very dense matter and nucleosynthesis right in our own back yard! Ian: RS Ophiuchi is possibly the most exciting system I have ever heard of! I hope there isn't any planetary systems around either of the binary stars... or in neighboring star systems for that matter. They would have a very bad day (every 20 years or so). Rich: Yes! It is also a good thing that by 'back yard' I mean astronomically speaking. The system is 1.4 [+0.6, -0.2] Kpc away from us. My colleagues and I wrote an entire ten page paper on just the distance to it. It is surprisingly tricky to figure out the exact distance to novae. Ian: Finally, we're in the clear if that thing decides to blow as a supernova then..? Rich: Oh, yes. No worries. We made sure of that. Ian: Great, I'll let everyone know about that good news... a lot of people were freaking out about WR 104, they don't need to worry about RS Ophiuchi as well. Well, thank you so much for chatting with me! Rich: Great, Ian. Lots of fun!