Date: December 17, 2011
Title: Planet Hunters: One Year Later
Podcaster: Meg Schwamb
Organization: Planet Hunters
Links: (http://www.planethunters.org/) &
Zooniverse (https://www.zooniverse.org/)
Description: With NASA’s space-based Kepler mission, we have entered into a new era in the study of extrasolar planets (exoplanets). Planet Hunters is a Zooniverse citizen science project employing human pattern recognition to identify the signatures of transiting exoplanets in the Kepler public data. Chris and Meg celebrate Planet Hunters’ first anniversary by discussing the latest results from the project.
Bios: Chris and Meg are astronomers.
Chris North s a researcher at Cardiff University where he works on Planck’s High Frequency Instrument (HFI). He is also coordinates UK-wide outreach activities for the Herschel Space Observatory.
Meg Schwamb is National Science Foundation (NSF) Astronomy & Astrophysics Postdoctoral Fellow at Yale University’s Center for Astronomy and Astrophysics (YCAA). As part of the La Silla-QUEST KBO Survey she is searching the southern skies for the largest and brightest members of the Kuiper belt and beyond, and studying the orbital and physical characteristics of these new discoveries. Meg is co-founder and project scientist for Planet Hunters, using the results from Planet Hunters classifications to study planet formation and evolution.
Sponsors: This episode of 365 Days of Astronomy is sponsored by Edgardo Molina.
Additional sponsorship for this episode of “365 Days of Astronomy” is provided by the Astronomical Society of the Pacific, a recognized leader in astronomy education. Get Go StarGaze, the iPhone app developed by the Astronomical Society of the Pacific for the NASA Night Sky Network. Find an astronomy event or a club in your area with Go StarGaze or at the Night Sky Network website.
Transcript:
CN: Hello I’m Chris North from Cardiff, and I’m joined by Meg Schwamb from Yale University. Hi Meg.
MS: Hi, how are you?
CN: I’m very well thanks. We’re celebrating today a birthday of Planethunters.org, which is something, you are involved in. So to get us started, what’s Planethunters.org?
MS: Well PlanetHunters.org is a website where you can log-in and you can look for the signatures of extrasolar planets moving in front of their parent star. So, with Planet Hunters we’re using this bet that human beings are better at finding transits than maybe some automated routines. So we’re using the Kepler public data. The Kepler spacecraft is staring at the same field of stars, 150,000 stars and takes a measurement everything 30 minutes. In so we show this brightness over time measurements, and if there is a planet moving in front of its star you see a drop in starlight as the planet crosses the face of its parent star. So, we are asking people to go look at these light curves, these measurements of brightness over time and mark where the think these dips due to these planets. We’ve had over 73,000 people since the launch of the project last year join us looking for these signatures of potential extrasolar planets.
CN: Right, so there are lots of doing it. It’s using data from Kepler. Tell us a little bit about Kepler. It’s a few years old now, right?
MS: Well, it launched in March of 2009 and has about a 115 square degree field of view. It is measuring the brightness of about 150,000 stars. It stares almost continuously at these stars observing their brightness over time so we can see whether or not there is a potential planet moving in front of its star and blocking out this light in what we call a transit. And so the Kepler team has been really successful using these automated routines to look for these transits, but we’re using human beings and human pattern recognition, so these skills that we’ve had since hunting and gathering to look for transits. And human beings are really good at pattern recognition, and so we have been really successful at finding and saving some planet candidates that were missed by these automated routines and vetting processes that the Kepler team has used.
CN: And so, what is the current status of the Planet Hunters discoveries?
MS: Well, we had our first paper come out a month ago. We detected two planet candidates. Two planet candidates that we think are 95% likely to be bonafied planets. These are planets that slipped through the fingers of these automated routines and were saved by our citizen scientists. And, so one of them is a 2.65 earth radii planet with about a 10 day period. The other one has about a 50 day period and is about the size of Saturn. And so looking through the first Quarter of data, the first 30 days of the Kepler mission, we did a preliminary search looking at every light curve that our users had marked, at least half of them had marked a transit in these light curves. And we found these two candidates sitting in the list of several others that we with the help of the Kepler team were able to vet and identify that these two are likely to be planets.
CN: So we these two new planets that you are fairly sure out of how many candidates are there in total?
MS: So the Kepler team has now about 2,000 planet candidates again we use the Kepler public data. They get a lot more data they get to see right now, but we did a quick search through the next 90 days of the Kepler data we’re analyzing and we have about above 35 current planet candidates right now and we’re looking at those, and two of them seem to be promising as well as others we are continuing to check. As more of the Kepler data gets released to the public, we will be able to see if we see repeat transits. A lot of the ones we have right now are single dips, so we need to see if there is another transit or two to confirm that maybe it might be a real signal. And also we’ll try to get follow-up observations to rule out other possibilities like an eclipsing binary where you have a star going around another star that may cause a signature that looks like a transit from a planet but it’s not.
CN: OK. And if people want to go to planethunters.org and start doing this, what do they do on the website? How does someone find a planet on planethunters.org?
MS: So you simply click on our front page, and it takes you to a tutorial star and you look and can see our example and then you get to look at all the data right away. We show 30 day segments of these light curves, so the measurement of brightness over time, and we ask you to mark with boxes with boxes where you think there might be a transit. So this is all you need to do is look with eye and see where you think there might be a dip due to a planet and mark that with box, and you may be one to find that there is a planet orbiting around another star outside our solar system, and be the first to identify that.
CN: That would be amazing for someone to do, I guess. Maybe in the future be able to name them? That’s for the future I suppose.
MS: Um, I hope so. Maybe we can nickname our two planet candidate? Maybe we should ask our discoverers that? So all of our Planet Hunters users who help identify the transits do get recognized. We do have a candidates page, and if you do help us identify a planet or a potential planet candidate you get your name as a co-author on our paper. So for our first paper we have 9 or 8 authors that are citizen scientists who helped us identify these eight stars that we were vetting which led to our two planet candidates. Right now planet candidates or even planets don’t get interesting names. They get these monikers or license planet numbers. They get the name of the star and a letter. So HD4905b. Maybe we will eventually be able to name them, but at least we can nickname them.
CN: Sure. So Planet Hunters, you’ve got the two you found and you’ve got 35 possibles in the next round of data. Do you think in the end, you’ll have looked at all the Kepler data? Is that the aim?
MS: I definitely think that’s the aim and aim to understand what is the frequency of planets. One thing I’m working really hard on right now and trying to finish a paper on is looking at how efficient are Planet Hunters at finding different types of planets. If we know how many of different types of planets we might loose or how likely we are to find them we can understand how many there are once we look at our full list of planet candidates. And, so what I’ve been doing with the first quarter of Kepler data which is about 30 days we injected simulated transits into the light curves and this allows us to understand what things we find and don’t find. With that information we can back out what is the true number of planets with short period orbits, less than 15 days in the Kepler data. So that’s what I’m working on now, and that makes us a novel and complementary technique to the way that the Kepler team’s way of finding planets. So it is really important because if we can compare our results to the Kepler team’s, that allows us to disentangle some of the biases in both these techniques and really back out the true abundance of extrasolar planets. I think that’s really exciting about Planet Hunters and the way that we are looking for planets with human pattern recognition and citizen science.
CN: This is certainly something exciting I look forward to speaking with you in another’s year time, the second birthday of planethunters.org. In the meantime people of course just have to go to planethunters.org to do their own planet finding.
MS: Absolutely, and there is so much data coming our way. Right now we’re looking at about 180 days worth of Kepler observations and there’s another 180 days of data coming our way in January as well as in July of next year. There’s lots more data and lots more planets lurking in the dataset. So come on by to planethunters.org and try your luck.
CN: Brilliant. Meg, thanks very much.
End of podcast:
365 Days of Astronomy
=====================
The 365 Days of Astronomy Podcast is produced by the Astrosphere New Media Association. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow…goodbye.