I wanted to give a brief update on the short period planets paper that just recently got accepted to Astrophysical Journal. Once you’ve gone through the referee process and the paper gets accepted. You go through the editorial stage of the paper where the journal formats your paper into the nice two column format of the journal and puts your figures into the text so that everything looks seamless and coherent. On top of that, a copy editor reads your paper searching and correcting for typos, grammatical errors, and formatting errors. Once this has been done, you receive the proofs of your paper, what it will look like in the final print version in the general. One version, the ‘redline’ copy, highlights the corrections and changes from the copy editor and the other shows how the paper will look in journal format including where all the figures will be positioned. So I just got the proofs for my paper a few days, and I’ve gone through and checked the copy editor’s modifications. For the ones I disagree with, I can submit a response explaining my reasoning and those edits may be modified. Now that the proofs are in and reviewed, the next step is publication (expected to be formally in August). The paper is online in pre-print format so everyone can read the results early, but the publishing in the journal is considered the official stamp of approval that the publication is scientifically valid and that the results have been peer-reviewed.
So what’s next? We’ll right now I’m working on some observing follow-up of our highest priority planet candidates. We’ve been getting follow-up observations to help study and confirm if these are real planet transits. I was helping to observe on the Keck telescopes Monday and Tuesday nights (Hawaiian time). I didn’t get to be go out Hawaii or Mauna Kea. I was observing remotely from the comforts of home (well, the Yale Keck remote observing run across from my office in New Haven). So Tuesday and Wednesday morning on the East coast I was helping to drive the Keck I around and take high resolution spectra including observations of a Planet Hunters candidate or two. Additionally, we’re looking for new planet candidates and we could use your help. I’ve run an adapted version of my transit selection pipeline from Q1 data and I’ve applied it to all the classifications from Q2-Q5 that we have complete. We have a large list of potential unknown planet candidates. We need help sorting through identifying those light curves from our top list have actual planet transits similar to what we did for the short period planet analysis. If you’d like to help with the sorting, we could use all the help we can get. Go to http://www.review.planethunters.org now.
Today’s blog post come’s from guest blogger Justin Crepp, co-author on our first Planet Hunters paper. Justin is an expert in adaptive optics and fellow planet hunter. He’s going to tell you more about the observations he carried out to help follow up our planet candidates.
Dear Planet Hunters,
Thank you for your diligent work identifying new Kepler planet candidates!
I am a postdoc at Caltech and my job (normally) entails searching for exoplanets using high-contrast imaging, a technique that involves trying to “take a picture” of faint companions in orbit around bright stars. As you can imagine, this is a challenging task: it requires adaptive optics to correct for the blurring effects of Earth’s turbulent atmosphere (as well as other hardware and some advanced data processing). Ironically, the same technology that I use to detect planets directly can also help to find transiting planets. By eliminating false-positives with imaging observations, we can dramatically reduce the likelihood that a nearby object, such as an eclipsing binary star, is mimicking the periodic signal of a transiting planet. In other words, I am often very anxious to see faint points of light next to bright stars, but, in the case of Kepler targets, it is best not to find any sources in the immediate vicinity of the star.
I recently had the pleasure of working with Debra Fischer, Meg Schwamb, and the rest of the Planet Hunters team, to observe the stars that you found to have intriguing light-curves. Armed with the Keck adaptive optics system and the NIRC2 camera, Tim Morton (Caltech grad student) and I were able to record deep images of each target on your list. After some careful analysis, we found that two of the stars you identified were free of contaminants, and therefore almost certainly (>95% confidence) transiting planet hosts.
I am proud to have contributed to such an exciting project, and would like to thank you once again for your dedication examining Kepler’s exquisite data. These are the lowest mass planets for which I have been a co-discoverer; in fact, one of them may be only several times the mass of Earth. I hope we get a chance to work together again sometime soon.
The images of the two final planet candidate stars (KIC 10905746 and KIC 6185331) and one of our candidates (KIC 8242434) that appears to be a background eclipsing binary system are shown below (regular 2MASS image left, Keck AO Justin took right):
Today’s blog post is brought to you by zookeeper extraordinaire Chris Lintott.
Last week Meg visited me in Chicago for two days of number crunching and data discussion and analysis. We got a lot done (and crushed Zooniverse developer Michael Parrish at shuffleboard) and I’ll write more about that soon, but a lot of our talk centered on a very unusual system unearthed by a few persistent Planet Hunters.
Once the team had – prompted by posts at Talk – taken a closer look at the system in question (we’re keeping the name under wraps for now) we were pretty excited, but also slightly worried. The system in question seems to have multiple transits, but they imply that there would be two large planets relatively close to each other. So close, in fact, that a back of the envelope calculation suggests that they would be expected to disrupt each other’s orbits. So unless our rough working is wrong (certainly possible) or we’ve caught the system in an unusual time during its evolution (surely unlikely) then there’s something mysterious here.
That, of course, is the perfect excuse for an observing run. We’re lucky enough to have access to the Keck telescopes on Mauna Kea in Hawai’i (probably my favourite place in the whole world). Observing at Keck is a little different from the telescopes that I’m used to – rather than trekking to the summit where a lack of oxygen can make observing difficult, Keck astronomers observe remotely, either from sea level in Hawai’i or from their home institutions.
The initial goal of our observations wasn’t to confirm the existence of the planets – the star in question is too faint to make that easy – but to rule out obvious problems. In particular, the team were worried that we weren’t looking at a single star, but receiving light from a combination of a nearby star and a background eclipsing binary which would then be responsible for some or all of the transits. If that’s the case then we should be able to see relatively large wobbles revealed by the stellar spectrum as the binary stars move back and forth. These will be larger than the faint wobble induced by the planets (if they exist) and checking whether they exist or not will take no more than a couple of observations, each lasting less than an hour.
I’ll report back on the Keck observations. Fingers crossed!
Hello PlanetHunters! The Kepler field is finally visible and tonight, grad student John Brewer and I began observing a few of the candidates that you identified. We are operating the Keck telescope in Hawaii remotely from New Haven, CT. The weather in New Haven may not be great tonight, but it’s perfect in Hawaii – we have clear skies!
There were several steps involved in selecting the best candidates to observe tonight.
- You all did the hard first step, classifying data from Q1 to identify prospective transits.
- Stuart extracted 3500 prospective transits from the database.
- We examined all of your selections by eye – about 100 planet candidates survived (many transits per candidates).
- Yale grad student, Matt Giguere, wrote computer programs to model the light curves and to search for evidence of blended background binary stars. Visiting grad student, Thibault Sartori, has been using this code for the past several weeks to model all of the planet candidates – about half of the 100 planet candidates survived that analysis.
- John and I will analyze the spectra we collect tonight to derive stellar parameters (temperature, surface gravity and chemical composition) – this will help to better constrain the planet radius.
- Jason Rowe and Natalie Batalha from the Kepler team kindly agreed to analyze our top candidates with the Kepler data verification pipeline to help eliminate additional false positives.
It will be tough to go to the next level and confirm any of these as planets because the stars are faint. It is sure easy to understand why the Kepler team has more than 1200 planet candidates, but currently only 11 confirmed planet-hosting stars. It is a long road from planet candidate to a bonafide planet!