Today we have a guest post from Jo Echo Syan (echo-lily-mai) , one of our dedicated Talk moderators, who attended ZooCon13 in Oxford, UK last month. Jo has been a member of the Zooniverse since 2009 and is also a Merger Zoo moderator over on the Galaxy Zoo forum. Completing a 1st class degree in fine art is currently exploring how art and science can fuse together with Enjoy Chaos
Chris Lintott one of the founders of the Zooniverse and representative of Planet Hunters at ZooCon13 has kindly offered to fill in the gaps and answer my questions that were left unanswered in a ball of scribbled notes…
Q: Is it correct that PH has achieved 5 peer review papers and how does that compare with the other Zooniverse projects?
A: We’re on four, and a fifth (Wang et al) waiting some observations to deal with a technical point the referee raised. That puts Planet Hunters joint second amongst Zooniverse projects, but I reckon we have lots more papers to come as more people begin to use the data.
Q: Can PH continue without Kepler? I know you go on to talk about this later, so in one word yes or no.
Q: The team had been warned at the beginning, that people don’t look at graphs for fun!! PH groups were wanting to look at results. Does this make Planet Hunters any different to other Zooniverse project users?
A: Now that’s a good question – we don’t really know, although we’re taking a look at how people behave. One thing the planet hunters are is dedicated; they stick at the task more than most other Zooniverse projects – probably because they really want to find a planet!
Q: 1995 first planet discovered, by 2013 there is now believed to be 17 billion earth like planets in the Milky Way.Are these amazing figures correct? What other amazing leaps do you think will be made within a similar time frame?
A: There’s an error-bar – and you can argue about what Earth-like means – but that sounds about right. With results from Kepler and elsewhere we really have learnt that planets are a very common feature of the Milky Way, and it’s possibel that more stars have planets than don’t. This makes exoplanet hunting one of the most exciting things happening anywhere in science right now, and I don’t think the pace is about to let up. As we find more planets, the focus will shift to trying to characterize those planets, maybe even detecting their atmospheres, and for that we need to look for planets around brighter stars than those that Kepler studies.
Q: What is Earth-like eg. Rocky, good temp, and water making it habitable. How many rocky planets are there that are close to parent stars? Do you think looking at the facts and figures that it is common for habitable planets to be found in most/all solar systems?
A: We don’t know yet. It’s likely that the dataset that Kepler left us has enough information to answer this question, and that’s why it’s important that Planet Hunters (and all the other groups looking for worlds of their own) keep sifting through the data.
Q: How did planets form? What are disks around stars and how did they form?
A: When a star forms from a collapsing cloud of gas and dust, leftover material forms a disk around the star, and it’s from this disk that the planets form. Here’s just such a disk around the star Formalhaut, made visible by blocking out the light from its parent star
Image credit: NASA/Spitzer
The point I was trying to make was that one of the things that our amazing stock of planets lets us do is just our understanding of quite how this process works.
Q: Kepler stared at 160,000 stars. It seems to find lots of super earths (we had a joke about it sounding better than slightly bigger than earth planets) Neptune sizes are the most common, but we are getting more earth and super earths being discovered. How will we turn these candidates into confirmed planets? What needs to happen in the future?
A: Most of them probably will never become confirmed planets. Doing follow-up on stars as faint as those in the Kepler field needs a large telescope, and we typically use the Keck which is one of the largest in the world. If we wanted to systematically confirm all the Kepler candidates we’d have to kick every other astronomer off the telescope, and even then it would take years. Luckily, we don’t have to do that – if all we’re interested in is the statistics of the planet population, we just need to observe enough to understand what the error rate is, and then we can do our science that way. If you know that 95% of your Earth-sized candidates are real, for many purposes (not including space travel) it actually doesn’t matter which ones they are.
Q: There was a two star system found, the Keck telescope was used to check it really was a planet and not just a candidate and it turned out to be a four star system!! PH1 b Is that correct? Why did it need to Keck to see that it was a four star system, why could it not be seen in the light curves?
A: We picked up the signal of the third and fourth stars by using Keck to make what are called radial velocity measurements, looking at the wobble of the stars back and forth as they orbit each other and the planet orbits them. We saw extra movements which we traced to the extra stars – I don’t think those two stars eclipse the others from our perspective in Earth and so they wouldn’t have been picked up by transits.
Q: There is an instability region where planets can simply not exist but all the planets found live on the edge of this region. Does our planetary system exist on an edge of an instability region?
A: This was actually a comment about planets around binary stars, like PH1. It’s intriguing to me at least that wherever we’ve found these worlds, we’ve found them almost as close to their parent stars as they can be without being on an unstable orbit. That must be telling us something about their formation.
Q: 42 planet candidates missed by Kepler etc. found in habitable zone were found by Planet Hunters at the Zooniverse!!! Probably ~37 or so will turn out to be real. We are waiting for PH2B. Why did Kepler miss these candidates?
A: Because it’s hard to get everything! An automatic system doesn’t catch everything we do, although as with previous Planet Hunters discoveries I expect that the automatic routines will learn from their mistakes now we’ve pointed them out and get steadily better and finding these things.
Q: And there was a brief discussion for future developments in the naming of planets.Do you think planets will eventually take more familiar names in the future as people become more aware of other planetary systems?
A: A decision was made a few years ago not to give official names to exoplanets – and it’s not a decision I agree with. I also think it’s pretty clear that the system is broken (it seems weird to me I can call a planet Planet Hunters 1b or Kepler 22 but not Arcardia or Lintott or other such names). The International Astronomical Union, who make decisions about such things, look like they might be moving position so I’m hopeful that we’ll get to name planets properly one day.
Q: Kepler is not well. What is wrong with Kepler?
A: It’s having trouble pointing in the right direction due to problems with its reaction wheels – there are still a few things left to try, but it looks like its main mission is over.
Q: It’s still looking for a planet with a one-year approx. orbit earth sized planet.Has a planet with a one-year approx. orbit not been discovered yet?
A: Several – including lots of the Planet Hunters candidates. We’re still looking for the really small ones, though – and they’re probably hidden in the data.
Q: PH site is still active and has data to look through I guess enough said!! What else is in the data? Stars they are all different to our sun. Why are there not more stars that are the same?
A: It seems that stellar variability is important – as people will know from the Planet Hunters light curves, stars brighten and fade all the time, and Kepler has helped us understand how different each and every star is. There’s loads of work here just on stellar astrophysics alone.
Q: Why are heartbeat binaries so interesting?
A: They’re just unexpected and cool. But also the rapid changes in brightness might allow us to work out what’s going on inside the stars, just as geologists use seismograph data to model the inside of the Earth.
Why is there a gap on the bottom right of this image?Why are PH collaborators so good at filling in the gap?
A: Small planets are harder to find and it takes longer to transit if you’re further away from the star. This gap may be real, but first we need to work out what could be lurking there that we haven’t found yet.
Q. 2 stars going round each other can causing tides, oscillations like in the heartbeat stars, and with asteroseismology we can study the interior of stars. Has the Zooniverse got any future projects planned to study this?
A: Watch this space!
Q: PHer’s have a lot more to do. The TCE review had a catalogue full of candidates. These are folded light curves, which I believe this survey is now complete!?
A: Yep, and Meg’s working on the results!
Q: Do we know how accurate the Kepler algorithm is?
A: We can test it – Schwamb et al. was the first attempt to use Planet Hunters to see how they’re doing. The answer, it seems, is ‘pretty well, but not perfectly’.
Q: The TESS telescope will look at brighter stars. Live data and take us beyond the end of the decade. Will working with TESS data appear the same as the light curves that we are already used to classifying?
A: TESS will target brighter stars so we might see a lot more detail on the light curve, we haven’t really had a chance to think about it yet.
Q: Are tools being built for all different Zooniverse projects?
A: I’m sitting in the Adler in Chicago about to have a meeting about this – we can’t promise tools for all projects, but Planet Hunters will definitely be included. Advanced tools are currently being built and we should watch out for them at the end of September. We should thank people on the PH Talk site who have patiently spent their time trying to help others and explaining by writing’how to’ pages. The Zooniverse team wants to help all people use these types of tools and have easy access to them.