For our latest planet candidates paper, there were many volunteers who helped identify these potential transits on Talk. To thank all of them for their hard work and effort, their contributions are individually acknowledged here. A few people stood out organizing a  significant follow-up effort on their own working to  sort these potential candidates identified on Talk into a list of potential planet candidates. This included looking for repeat transits and performing checks  to rule out potential  false positives. To acknowledge their effort, the science asked Abe Hoekstra, Tom Jacobs, Kian Jek, Daryll LaCourse, and Hans Martin Schwengeler  to be co-authors on the paper. I’ve asked them each write a bit about this experience and about being part of Planet Hunters.

Abe Hoekstra

I am from the Netherlands and am fifty years of age. In the past I used to be a teacher. Astronomy has always been a hobby of mine, I am what they call an armchair astronomer. I couldn’t pursue a career in astronomy as I am very bad at maths and physics. Early 2011 I got my first laptop and I subscribed to the NASA Newsletter. When I was reading up on exoplanets, I came across Planet Hunters. I am very glad I can make a contribution to astronomy, however small.

When I heard my name was going to be mentioned on the Planet Hunter Planet Candidates paper, I was quite surprised, excited and very honoured. I have been so busy with eclipsing binaries, variable stars, dwarf novae and checking out dozens and dozens of collections of fellow planet hunters, that I almost forgot I made some contributions with respect to finding planetary transits.I had to check the candidates on the list to see where I made those contributions. I found  one candidate that I may have discovered first, shortly after I started here in February 2012, and another where I was among he first to spot a transit.  I also helped in  finding repeats of transit features, by checking out NASA’s Exoplanet Archive  (NEA). I definitely remember two candidates I found in other planet hunters’ collections in November.Finding a transit feature and/or repeat is very exciting. It doesn’t stop there. I am among those planet hunters that regularly check stars on Sky View and the NEA. Other hunters are very experienced in doing contamination checks, determining the length and depths of transits, and also determining the period of a planet.That is what I like about Planet Hunters. There is a great sense of community and cooperation here. I hope a lot of planet hunters get a mention in the paper. A great deal of hard work has gone into finding these planet candidates, and finding your name up there is very rewarding.Let’s hope we can add a few more candidates to the list in 2013!

Tom Jacobs

I am a graduate of the University of Washington with a non science degree in Business Administration and later commissioned as an officer in the U.S. Navy. Currently, I reside in Bellevue, Washington with my family and work as an employment consultant for workers with developmental disabilities going on 17 years. I have always been a treasure hunter and consider Planet Hunters a great way to find planet and other unique star treasures and learn some astrophysics through immersion along the way.

It is a great honor to be part of this planet candidate discovery paper as a Planet Hunters’ citizen scientist. Nothing occurs in a vacuum at Planet Hunters.  If not for all your hard work in classifying light curves and posting your finds on Talk, most likely these planet gems would have slipped away unnoticed. You all deserve as much credit as those mentioned in the  science paper.  It is all about teamwork and diligent pursuit in analyzing the Kepler light curves. We are collectively demonstrating what the incredible pattern recognition of the human mind can accomplish that challenges the high powered state of the art computer algorithms and we are having fun while doing it.

Kian Jek

I have been fascinated by the stars ever since my uncle handed me a copy of a book by H. A. Rey when I was 10 years old. It wasn’t until much later when I had children of my own that I realized that Rey also wrote the Curious George books. I guess I must have been a geek since then because the other things going on that grabbed my attention were the Apollo moon landings and the original Star Trek series.

I used to spend hours with a tiny 2-inch telescope at night looking for the Messier objects, not knowing that it was almost impossible to see them all with an aperture that small – I was hung up on M1 for a long time! It was astronomy got me hooked on science but by the time I went to college I was sidetracked by an interest in DNA and I went on to get a degree in molecular genetics at Cambridge in the UK. One of my biggest thrills while studying there was being able to use a 180-year old 12-in refractor, the Northumberland telescope (http://www.ast.cam.ac.uk/about/northumberland.telescope) during freezing winter mornings. You had to open and rotate the observatory dome using a hand-crank! At last I managed to see the Crab Nebula for the first time. It was, of course, not as impressive as the photographs in the books.

After my studies, I was again sidelined by another passion, I spent the next 20 years or so in a career in computers, ending up as a founder of an Internet service provider during the start of the dot-com craze in 1995. In December 2010 I rekindled my long-lost affair with astronomy by volunteering on Planethunters.org. I am very sure it was in December very near the beginning of the project because I remember working through Christmas Day 2010 writing a javascript planetary calculator.

It’s been two years since the Planet Hunters was initiated and I’m so proud to be a part of its community. We’ve come quite a long way since those early days in December 2010. Back then very few amateur volunteers like ourselves really knew much about exoplanet transit photometry and we were marking every dip in flux as a transit (I guess many people still do!) and we thought that going beyond 5000 classifications was a big deal – there is even a forum topic devoted to this! I won’t mention who he is because he might be embarrassed but he is one of the co-authors and among my most prolific collaborators – he has done over 100,000 classifications!

Since 2010 then we’ve learned much about determining what is and isn’t a planet candidate. We discovered that 99% of transit events weren’t even due to planets. Most of the time they were glitches and even if they were real, they turned out to be false positives, e.g eclipsing binaries (EBs) or contamination due to background blends. I recall being so frustrated by demonstrating that so many of these were EBs that I started a secondary effort to collect what we called unlisted EBs – these were EBs not identified by Kepler’s EB expert Andrej Prsa.

But over the two years we learned how to separate a good PC from a false positive. We learned how to use a periodogram and phase plots, what were pixel centroid shifts, how to analyze TPFs, how to pull down Skyview and UKIRT images and how to model a transit light curve accurately.

Although I was named in the PH-1 discovery paper, and as exciting as that discovery is, I feel that was just happenstance. My more important contribution to the Planet Hunters initiative has been in collecting, compiling and curating the efforts of the community – In the last two years the Planet Hunters have turned up a lot of potential PCs that seemed to me to be real, and by applying all the methods and techniques mentioned above I eliminated all those that failed the tests. We were disappointed a few times when many of these discoveries were overtaken by events. I recall that the list was pared down from over 50 PCs down to 20 when the February 2012 Kepler paper was released (Batalha et al 2012). But I realized that if over 30 of our independent discoveries were real PCs, that fact alone vindicated our efforts. Slowly that list went up to beyond 30 and then reached 40 PCs. In May 2012, another paper by the Princeton team (Huang et al, 2012) took out another chunk of our PCs, but we continued to persevere and by the time the data releases of July and October came around, we had even more PCs to consider. I spent the last quarter of this year rounding these up and characterizing them.

I would not have been able to do this with the help and contribution of the community. I’ve been very privileged to work with some of the smartest and dedicated citizen scientists on this site. I tried my best to follow up on every e-mail and private message you sent me – please keep them coming!

Daryll LaCourse

I’m a Canadian aerospace machinist and amateur astronomer living in the Pacific Northwest. I prefer working with Kepler data to backyard stargazing as heavy clouds and rain can’t interfere with the former.

I am very pleased to see the release of the fifth Planet Hunters discovery paper and the addition of PH2b to the family of confirmed exoplanets. Every volunteer that has participated in the Planet Hunters project thus far has played an important role in the efforts that led to the identification and consolidation of this latest candidate list, which includes a stunning array of potential habitable zone prospects. It is impressively difficult to confirm that a Kepler candidate is a bona fide exoplanet rather than a false positive; thanks to the meticulous follow up work of Ji Wang and the rest of the PH Science team we can say with confidence that these 43 candidates are very likely the real deal.

It has been a privilege to work with so many talented individuals on PH Talk as these discoveries were sifted from the many thousands of highlighted light curves. The tenacity and resourcefulness of the PH volunteers can’t be understated or underestimated, and I look forward to what we will find in 2013 as the extended mission progresses. There are already new targets of interest popping up on the radar for the team to pursue, and the single/double transit candidates (some of which are mentioned in the new paper) hint at a hidden population of long period exoplanets that have yet to fully reveal themselves to us. How will our own solar system eventually fit into this widening hierarchy of possible arrangements and configurations? How common are exoplanets within the habitable zones of Sun-like stars? These questions may not be resolved quickly, but the discovery of every new candidate brings us closer to definitive answers. Experts in the field have speculated that the first true Earth analog candidate may be found this year, which will be a very exciting and historic milestone. I don’t think it is a huge stretch of the imagination to consider that with some sharp eyed luck, it may even be found by one of you!

Hans Martin Schwengeler

I’m a regular user (zoo3hans) on PH, more or less from the beginning two years ago. My name is Hans Martin Schwengeler and I live near Basel in Switzerland. I’m 54 years old, I’m married and we have two children. I’m a mathematician and work as a computer professional. I like to advance Science in general and Astronomy in particular. I did work a few years at the Astronomical Institute of the University of Basel (before it got closed because they decided to save some money…), mainly on Cepheids and the Hubble Constant (together with Prof. G.A. Tammann). Nowadays I’m very interested in exoplanets and spend every free minute on PH.

I’m pleased to hear that I’m going to be mentioned as a co-author of the PH Habitable Zone (HZ) candidates paper. My motivation to participate in the PH project is not really to “name” a planet or such a silly thing, but to advance Science in general and Astronomy in particular. Probably I’m just a curious fellow, although I’ve got named “a cold precise German” on PH Talk by someone (actually I’m Swiss).

I think we have a few very good cases of fine planet candidates collected over the last two years, a few of them even in the HZ of their host stars. Kian Jek (kinjin) has made a good list, many other PH users have also contributed a lot to our collaborative effort. I try to classify as many stars as possible, and also to comment on promising cases, or comment avoiding glitches and other bad features. To examine a promising star, it needs a lot of time. First I just look at the light curve and try to let my brain do the pattern recognition. I actually believe it might indeed be superior to computer algorithms to discriminate between real transits and just glitches or processing artifacts. In my experience it only works down to about 2.0 R_Earth planets, below this border size they cannot be detected anymore just by eye without prior detrending of the light curve. Second I do therefore download the FITS files from MAST and detrend roughly the light curve. Further inspection of the whole Q0-Q13 detrended light curve often reveals already if it might be an interesting case or not. If I suspect a regular signal (i.e. a well defined period) is present in the data, then I try a periodogram to see if the potential transit looks symmetrical, U-shaped and so on. Also important is to check the sky view. We are dealing with stars on the sky after all.A bit frustratingly often it’s just contamination by a nearby background star. Of course I post all findings to the PH Talk pages, so others can profit from the work done so far, and to get their opinion about the case.

Although I have classified over 30000 stars so far, even I select sometimes
a glitch for a transit. It’s not an easy “game”, but rather addictive I think. I also like the teamwork aspect of the PH community. It’s great to get help from the
“specialists” out there who can do contamination vector determination, Keppix series analysis, transit curve fitting and much more. I’d like to thank them all for their great help. I thank also Meg for her great effort to vet more promising exoplanet candidates. PH is a great project!

Yours,
Hans Martin Schwengeler (aka zoo3hans)

Artistic rendition of a sunset view
from the perspective of an imagined Earth-like moon orbiting the giant planet, PH2 b. Image Credit: H. Giguere, M. Giguere/Yale University

We are pleased to announce the discovery and confirmation of our second confirmed planet : PH2 b-a Jupiter-size planet in the habitable zone of a star like the Sun-by the Planet Hunter project. The paper has already been submitted to the Astrophysical Journal and has been made public via arxiv.org.

The estimated surface temperature of 46 degrees Celsius is right for there to be liquid water, but it is extremely unlikely that life exists on PH2 b because it is a gas planet like our Jupiter, and thus there is no solid surface or liquid environment for life to thrive. In order to study this interesting system, we used the HIRES spectrograph and NIRC2 adaptive optics system on the Keck telescopes in Hawaii to obtain both high resolution spectrum and high spatial-resolution images. The observations help us to rule out possible scenarios for false positive detections and give us a measured confidence level of more than 99.9% that PH2 b is a bona-fide planet rather than just an illusion.

In the meantime, we also announce the discoveries of 31 long-period planet candidates with periods more than 100 days, including 15 candidates located in the habitable zones of their host stars. The candidate list is a joint effort between the volunteer Planet Hunters, and the science team. Each individual planet candidate was identified and then discussed on Talk by Planet Hunters. Several dedicated Planet Hunters collected information on candidates and carried out light curve modeling and initial vetting for false positives. The science team then decided the priority of each target on the candidate list and conducted follow-up observations.

Although most of these planets are large, like Neptune or Jupiter in our own Solar System, these discoveries increase the sample size of long-period planet candidates by more than 30% and almost double the number of known gas giant planet candidates in the habitable zone. In the future, we may find moons around these planet candidates (just like Pandora around Polyphemus in the movie Avatar) that allows life to survive and evolve under a habitable temperature.

In addition to the 31 long-period planet candidates, we announce a watch list for 9 further planet candidates which have only 2 transits observed. They do not currently meet the three-transit criteria of being a planet candidate set by the Kepler team. However, the Planet Hunters were able to pull them out and a future third transit would greatly increase the probability of them being real, allowing us to promote them into the full candidate list.

Lots of our candidates appear on a recent list published by the Kepler team (Tenenbaum et al. 2012) of possible transit signals, but it’s good to see they have now passed the additional tests to be planet candidates (not all of the Tenenbaum objects are real planet candidates; there are plenty of false positives). 6 candidates on our list were somehow missing in that list, all of which have periods of more than 240 day. This is an indication that we, the Planet Hunters, are effective in detecting long-period planet candidates. Heading into the future, we have reason to believe that more long-period planets and potentially habitable planets can be discovered by us. Go Planet Hunters, go hunting planets!

Ji Wang

Ji is a post-doctoral associate in the department of Astronomy at the Yale University, and the lead author on the latest Planet Hunters paper. Before assuming his current position, he attended college at the University of Science and Technology of China and obtained his Ph.D. at the University of Florida. The roll of honour for planet hunters who contributed to these discoveries is here.

When I posted with news of our second paper’s submission last week I mentioned that the new paper from the Kepler team included a section on Planet Hunters.

The section (7.4, since you’re asking) is fabulous, mentioning the ‘remarkable enthusiasm’ of Planet Hunters volunteers, who are not only have the ‘opportunity to experience the scientific method but also the possibility of experiencing the gratification of discovery’.

There should be a whole lot of gratification around, because as well as our own candidates the paper included details of several co-discoveries, where nine of Kepler’s planet candidates were independently identified by our volunteers. The following Planet Hunters thus can claim to have officially discovered planet candidates. In each case, the names in bold were the first to identify a transit in a particular light curve – congratulations to all involved.

KIC 5864975

pina1234, Mary Corfield, Frank Barnet, Derrick Martinez, Vince Brytus, Darin Ragozzine (!), Gary Butler, Robert Casey, Krishna Babu, ‘shutterbug’, Hein Min Tun, Juan Albornoz, Gerald R. Green, Robert Spiker, Natalie Van Cleef

KIC 11875734

Robert Gagliano (who was on the list for the recently announced candidates too), Malcolm Lambert, Di Miceli Gaetano, Hitesh Patel, Robert Rozanski, Penn Gwenn, Jari Paakkonen, ‘maya’, John Mackereth, ‘zocker’, Dominick Dennis, Carl-Johan Wikman, ‘chulej’, Oleg Tsybulskyi

KIC 8160953

Frank Barnet, John Robinson, ‘colinjdavis’, Jari Paakkonen, Carl Davidson, Bruno Mauguin, Jan Bernard, Lee Chapman, Hans Martin Schwengeler, ‘Aurelhun’, Pablo Barroso Rodriguez, Julie Donnell, Dani Iannarelli, Peter Kool, Simon Humphreys, Chris Price, Alan Bowler, Jeff Mack, Rafal Konkol

KIC 6504954

Patrick Gruber, Malcolm Wain, Andrew Young, Steve Harris, ‘planet10′, Juha Lindqvist, Navid Baraty, ‘ahora’, Julia Fedyakina, John Harper, Pablo Barroso Rodriguez, Sue Wilson, Mathew Hadfield, John Ord, Bob Chau, Calum Patterson, Matthew Connolly

KIC 7761918

Breeann Phillips, Abe Hoekstra, ‘ozanne’, Daniel Speir, ‘komandantmirko’, Daryll LaCourse, Daniel Getler, Gene Cumberland, Dave Skillman, Tony Hoffman, Joe Johnson, ‘Tem’, Steve Stav, Daniel Meyersohn, Frederico Centeno Selbach, Mark Riggs

KIC 3326377

‘ronalde000′, Bob Leask, ‘oneironautics’, Bartömiej Jaracz, Priscilla Nowajewski, ‘lolodec’, Michael Ware, Larry Melanson, Victor Gabriel Bibeo, ‘AtheistRamblings’, Stuart Lynn (!), Abe Hoekstra, Andrew Rose, ‘dalwhinnie’, Loic Petitpas

KIC 6268648

‘snark’, Fiona Wynn, Ilya Karpeev, Lily Lau, ‘nargatte’, Kristian U. Saetre, Lubomir Stiak, D Le Clercq, Jeremy Garrett, Lee Martin, Verena Resch, Robert Fletcher, Jason Muir, Nick Amsel, Michael Kavanagh, Anthony Goddard, Tom Hartfil-Allgood, Shannon McLaughlin, ‘Natframpton’, Peter Unitt, Steve House, Paul Wightman, Pooja Rathod, Simon Stockwell, Jenny Satelle, Owain Dewi Hughes, Richard Hopkins, Adam Bunce, Simon Gardiner, ‘snorrelo’, Thomas McGauran, ‘tom0366′, ‘Chippywheetoes’, Ben Galley, Kirsty McMonagle, Rich Haines, Adam Derdzikowski, ‘pat’, Mark Halstead

Way back in January I blogged about our announcement of two new candidates, confidently predicting that the paper would be out in the next few days. That didn’t happen for all sorts of reasons, but it’s now submitted to the Astronomical Journal. Rather than wait until we get the referee’s seal of approval (or a lot of criticism!), we’ve made the paper public via the arXiv – you can read it here.

As the picture on the blog post shows, five volunteers are co-authors, many more are thanked in the paper, and there’s a link to the authors page to give credit to all our volunteers for taking part. In the month or so that we’ve had since the conference, we’ve done some more work to pin down the behaviour of these systems. The first exciting new discovery was the length of time between transits was changing slightly for KIC4552729. These transit timing variations, or TTVs, suggest that there’s something else there, another body whose gravity is affecting the orbit of the planet candidate whose transits we do detect. We need more data to work out exactly what’s going on, but the immediate implication is that it’s more likely that our planet candidate is real, as it’s harder to create a three-body system using interference from background eclipsing binaries.

We also – mostly for fun – worked out whether the two planets that Planet Hunters had uncovered could be in the habitable zone of their star, that thin sliver of space where liquid water, and hence life, might be able to survive on the surface of a planet. Now, both of ours are almost certainly too large to be anything but gaseous, and one has to make a planet’s worth of assumptions about things like its albedo (how much light is reflected and how much absorbed by the atmosphere) and its atmosphere. Nonetheless, the encouraging thing is that both of our candidates seem to lie in the habitable zone of their star system, making them interesting targets.

As if that wasn’t enough for one day, also on the arXiv and submitted to the journal is the latest Kepler paper announcing new candidates. They include a section on Planet Hunters, and announce another handful of independent discoveries where we found candidates they’d already uncovered. More on that – including a list of Planet Hunters involved in those discoveries – in the next few days.