Recently the scientific community was abuzz with KIC 8462852, a rather unremarkable star in a section of the night sky currently being watched by the Kepler Space Telescope. Kepler’s mission is to watch the stars in certain sections of the sky and wait for the noticeable dimming that reveals the presence of exoplanets. However, when the Planet Hunters, the group that sifts through this mountain of data, relying on human eyes to pick up the light variations, found that KIC 8462852 had an unusual dimming sequence, that lent to the imagination and challenged Tabetha Boyajian, a postdoctoral Fellow at Yale University, and her colleagues to determine just what they were looking at. I was fortunate to grab some of Tabetha’s time recently, and ask her questions about this intriguing find and the group that examines this massive amount of data.
Joseph Giddings: Tabetha, thank you for your time today. Let’s start with asking what exactly do the Planet Hunters do, and how do they conduct their research?
Tabetha Boyajian: The Planet Hunters are a collaborative science network that anyone can sign up to join to examine the data from the Kepler mission. They then look at 30 days of data and attempt to identify transit signals that happen when a planet crosses in front of a star. The system uses complex algorithms to help identify possible targets for the hunters to examine, and helps to identify possible candidates that may have otherwise slipped through the cracks. This is a great way to get the public involved in planet hunting, and anyone of all ages can do, even my kids do it. They may not completely understand it all, but it’s simple enough for a 6 year old. The site also has the Talk interface that allows everyone to talk about their findings and to get collaboration on unusual items.
JG: So what exactly is it about this object, KIC 8462852, now colloquially being called “Tabby’s Star,” that made it stand out to the Planet Hunters?
TB: When you’re online looking at these light curves from objects you’re examining, you’re looking at the same star over multiple time frames, trying to notice the tell-tale dip in light that can happen from either star spots, a eclipsing binary, or even an exoplanet. When they were looking at this object, they started to notice something they had never seen before. So they started asking things like “What is going on with this star? Why is it looking like a transit but the dimming lasts longer than it should?” This situation was confusing for the Planet Hunters, but even more so for the science team. At first it seemed like perhaps a problem with the instruments, but we were able to rule all of those situations out. Having to rule all this out took quite a while before they could say “Well, this is something real. We need to look into it more.
JG: In the paper I saw that first discussed was the possibility that it’s a pulsating star, but since the period on the pulsations was very erratic, you were able to rule that out and move away from it. Interestingly enough, it was found that the star had a very faint companion. What lead you to that conclusion and how did you follow up on that?
TB: The resolution of the Kepler Space Telescope is very poor – a single pixel is equal to about four arcseconds. So what has to be done is to locate data from a ground based survey that has better resolution. In figure six of the paper you can see the higher resolution data we were able to reference. Kepler’s resolution is about a quarter of one of those squares, which would be one pixel, so you can see how the detail could be missed. In the figure you see the star has a slight bulge to the left for the dwarf companion, which lead us to get a higher resolution image with the Keck telescope and see that the companion star was indeed there.
JG: The paper seems to lean toward the direction of a large collection of comets, asteroids, or other planetesimals. Has any other data been collected at this point to support or refute that finding?
TB: We’re working on it! There are a lot of people interested in it now, which is exactly what we wanted. As of now there’s hasn’t been anything to refute the answers that we have here, but we are still in the process of collecting data to help refine our findings. I haven’t seen anything enlightening (laughs) but it’s still so new and there’s a lot of work to be done. We have some promising leads from archival data that was collected from ground instruments that may have captured the brightness of this star and its variations. There is also continued monitoring of this star from all around the world by amateur astronomers. The light curves that we can see can also be observed from a backyard telescope. The American Association of Variable Star Observers put out an alert to monitor this object. Dozens of people have responded by taking data and uploading it to the site, which is refreshed daily. When we see the object start to be active again, that’s when we can seal the deal on what it is by pointing some really big telescopes at it and getting finer detail on the star to get brightness level, composition, etc.
JG: The observational window for this object is running out because this star is located in the constellation Cygnus, which is quickly disappearing beyond the horizon as the year moves on. I’m sure people are racing to get all of the data they can.
TB: Exactly, very poor timing!
JG: When this whole thing came to the public’s attention, and had a comment from Jason Wright about “alien megastructures” attached to it, of course this blew up everyone’s imaginations. SETI was pointed it to see if it could pick up anything and all eyes were on this object as a possible source of “intelligent life.” What are your thoughts on the fervor that grew up quickly around this?
TB: You said it pretty accurately! Years ago you would talk about it and then joke about, it’s just one of those things. I visited Penn State a year ago and I was talking to Jason Wright and this topic (about the light curve of KIC 8462852) came up in an entirely different context. Jason mentioned he was writing a paper about how Kepler could possibly detect an artificial superstructure around a star, and I mentioned that this star could be a target to look at further. So, even though this is one interpretation of the data we had, we kept it separate so we could consider only the natural scenarios. Jason’s paper is an excellent way to explain the phenomena without trying to convince that it is indeed alien life just that it’s a possible item to consider when doing the research. So I contact Jason again later and mentioned it was a good candidate for his research and we should look at it with the Green Bank Telescope. So we put together a proposal and submitted it in August. Then this paper came out in September, and then a meeting at the White House in October and suddenly there was a lot of attention on this object! But as for the reaction, I wasn’t expecting the magnitude of it all. But it kind of makes sense on how the media picked it up and sensationalized it and put their own pieces together, because that’s what they do. I understand that aliens are a more popular topic than comets, but I found comets cooler myself.
JG: Everybody wants aliens!
TB: I know, I know! I want aliens, too! But it was never considered as a topic for this finding, though some other groups are researching it and posting their data online, but please don’t think we are working with them.
JG: Of course not.
TB: I think we all agree there is a lot of work to be done and this is a very interesting object to study.
JG: Several days after I read this story originally I was watching TV and couldn’t help but think that the Ancient Aliens guys would be all over this.
TB: (laughs) Yeah they emailed me and I ignored it.
JG: That’s probably a good idea! So, what is next for you and your team?
TB: Well, there’s a lot of data coming in for this object, so we are looking into all of that. With all of the monitoring that is in place we don’t know when it will dip again, so we will need to be ready for that. So right now were just getting ready for the next big event on this star, trying to be prepared for that happens.
JG: That and trying to hold back the people with the tinfoil hats!
TB: (laughs) Oh yeah, I’ve gotten so many of those emails!
JG: Thank you so much for your time, I know you have been so busy lately and I feel lucky to have caught you in a quiet moment. Good luck with your research and I’ll be in touch.
TB: Thank you.
This interview was conducted via telephone on November 20, 2015.
Links of interest:
Planet Hunters X. KIC 8462852 – Where’s the Flux? – T. Boyajian, et al.