A Newly Confirmed Planet and 42 Additional Planet Candidates


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 seo services 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.


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39 responses to “A Newly Confirmed Planet and 42 Additional Planet Candidates”

  1. fezman92 says :

    So who are the lucky people who found the confirmed planet and candidates?

    • Andreas says :

      yes, and are they marked within the system?

    • Leslie Martel says :

      Yes, we would like to know who got it right.

    • rcreek says :

      Yes, I would like to know too. I spent a couple hours one night with this project. Many of the gas giants had such noisy signals that finding transitions was pretty difficult. I marked one that clearly had transitions, but when I submitted it, it told me that other people had already noticed them 😦

      • Stephen W. Anderle says :

        don’t be sad. at least if other people see the same thing then you know you are probably looking at the right stuff, congrats. Steve A.

    • Martin says :

      It isn’t a person as such, the planet hunters data is checked over by thousands of people and possible planets are then checked by the boffins, so ten thousand people could have flagged it as a planet ,still pretty cool if you flagged it as a planet thogh, well i think it is

    • Phil Andy Graves says :

      Thank you, Dr. Wang (and team). I love the Kepler system including Planet Hunters dot com and all the other Zooniverse tools because unlike the @Home tools, I feel like I’m actually doing more (despite probably doing less).

      fezman9, they cite who first noticed the planets and candidates on the Planet Hunters website. You can go directly there http://www.planethunters.org/candidates

    • daveen says :

      Click on “here”. The last word in the last paragraph to view who has contributed.

    • Eric H. says :

      I helped find the planet on planethunters.org

    • MJHadley says :

      I have been included in 13 Hunters that have been credited in the latest paper for one of the discoveries of a planet candidate, in this case a gas giant in the habitable zone.
      I responded to Oxford Uni’s request to confirm my details for the submission of a paper to a science jurnal and agreed they could use my details in publicity. I’ve now been contacted by the press and had a live interview on local radio. This was a result of the UK tv series Stargazers and Dr Lintott passing on my details. Amazing!
      PS keep at it. I’m looking for more!

  2. matt haines says :

    Now I can show my wife that I’m not wasting my time with this project. Well actually I’m not sure this would even convince her, but it’s a step! Yay Planet Hunters!

  3. Enrique Ferreyra says :

    Thanks to the team, while im a bit inactive these days i really feel a member of the project, this team and we the hunters have made a top class science project, gratz to all.

  4. Robert Bolt says :

    I agree, revealing the names of those who helped to find this are important both a reward plus it encourages others to continue helping in this massive task.

  5. chrislintott says :

    Hi all

    As several people pointed out, you can see the names of the credited Planet Hunters here : http://www.planethunters.org/LongPeriodCandidates

    If you’re on that list, you should have had an email from us giving details. We’ll also update the page so everyone can see who did what once the paper is through the refereeing process.



  6. fezman92 says :

    Darn. I’m not on there. It is really upsetting since I have been doing this since day one and we thought I found a good choice. 😦

  7. Stephen W. Anderle says :

    -:) YaY!!

  8. Stephen W. Anderle says :

    would you call that a “moon”-rise or a “planet”-rise?!! OOps , sounds like a song, ” Big planet Risin!”

  9. Stephen W. Anderle says :

    Which star is this? I woulkd like to see the transits to see what they look like.

  10. EYO EDET says :

    Any life form in the discovered planets?

  11. Eric H. says :

    I helped find the planet at planethunters.org

  12. Jim says :

    It would be really helpful if links to the stars’ data were provided. This would allow people to see what verified transits look like – advancing their skills at detecting them.

  13. Peter Flodin says :

    I would not be surprised at all if life could develop in a gas giant planet. Especially as the clouds of Earth has been shown to contain active bacteria.


  14. Some Nutcase says :

    I think it would be really cool if the first person who identified it might be a planet gets to name it.

  15. George Kountouris says :

    The above artistic rendition means a satellite world to the gas giant planet similar to the respective in film Ävatar”?

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