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Hot Friends of Hot Jupiters: The WASP-47 system

Ever since a mechanical failure caused the end of the original Kepler mission in 2013, the Kepler spacecraft has been conducting a survey of new stars, searching for planets across the ecliptic plane in its new K2 mission (https://blog.planethunters.org/2014/12/12/more-about-the-k2-campaign-0/). The K2 dataset is a goldmine of fascinating science results. One such result is the recent discovery of two new planets in the WASP-47 system.

Until a few months ago, everyone knew that hot Jupiter planets don’t have “friends”, or nearby small planets in close orbits to the host star. These other planets had been searched for extensively, through radial velocity measurements, analysis of the transit times of the hot Jupiters, and even through transits by Kepler during its original mission. All of these searches turned up nothing.

This all changed one day last July, when Hans Martin Schwengeler, a Planet Hunter who enjoys poring over Kepler and K2 data searching for new transiting planets by eye, came across the telltale signatures of two extra transiting planets in the hot Jupiter system WASP-47. WASP 47b was, by all indications, a perfectly normal hot Jupiter — in the discovery paper, Coel Hellier wrote “With an orbital period of 4.16 days, a mass of 1.14 Jupiter masses, and a radius of 1.15 Jupiter radii, WASP-47b is an entirely typical hot Jupiter”. The discovery of additional transiting planets dramatically changed the narrative.

When Hans came across the planets, he posted them to the Planet Hunters forum, where he and other citizen scientists discuss their findings. Andrew Vanderburg came across the post suggesting that a known hot Jupiter had planetary companions. Using his K2 data reduction pipeline (https://blog.planethunters.org/2015/01/08/a-recipe-for-making-a-k2-light-curve/), he analyzed the light curve and confirmed Hans’s discovery – there were additional planets in the system, a super-Earth at a 0.8 day period and a Neptune at a 9 day period!

Andrew emailed me, and at first I hardly believed that the lightcurve was real. How could a hot Jupiter have close-in planetary companions? I knew people had been looking for this type of companion for years via both photometry and transit timing variations, but the lack of discoveries indicated that they might not exist. I performed some numerical stability simulations (because it seemed at first like this system could not be dynamically stable!) and sure enough, the N-body simulations showed that the system was likely stable on timescales of 10 million years.

At that point, we formed a team with Hans, Andrew, MIT Professor Saul Rappaport, University of Michigan Professor Fred Adams (my advisor!), and me. Once this team was formed, we devoted ourselves to understanding as much about the systems as we could. Some work by Saul and Andrew confirmed that the planets were all orbiting the same star, Andrew fit the lightcurve to get the planet properties, and I ran more stability simulations. Soon enough, Fred suggested that I look at what transit timing variations (or TTVs, which happen when transits come late or early because of the gravity of other planets in the system) we would theoretically expect to see from the system – and I found that for the outer two planets, the TTVs should be observable.

I then measured the TTVs from the lightcurve, and sure enough – there was something there. After some discussion, we realized we could measure the masses of the planets from those TTVs! Though I had never done dynamical fits before, I wrote the code to utilize Kat Deck’s TTVFAST code in a Markov Chain Monte Carlo fit. With some advice from Kat and help from Fred, I eventually got the fits working and we were able to measure or put limits on the masses of each planet.

In a little less than two weeks, we had put together a paper deriving planet properties from the lightcurve, mass limits from the TTVs, and showing that you CAN detect companions to hot Jupiters using TTVs!

This result is exciting because it is the very first time a hot Jupiter has been found to have such close-in other planets. Before this discovery, it was unclear if hot Jupiter could have nearby friends, as they might destabilize the friends’ orbits during migration. This discovery opens up new questions about how these systems form – it is possible that there is more than one migration mechanism for hot Jupiters.

The paper on WASP-47 and its new companions, which was published earlier this week in ApJ Letters and is available at http://arxiv.org/abs/1508.02411, was a collaboration between myself (Juliette Becker, a graduate student at the University of Michigan), graduate student Andrew Vanderburg (Harvard CfA), Professor Fred Adams (the University of Michigan), Professor Saul Rappaport (MIT), and Hans Schwengeler (a citizen scientist).

 

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Comets or Aliens?

Let’s deal with the big question first. Has Planet Hunters discovered aliens?

The answer is no. But that doesn’t mean that all of the press who have written about us in the last 48 hours, sending a flood of volunteers to the site, are completely misguided. Let me backtrack…

A few weeks ago we submitted the ninth planet hunters paper to the journal, and that paper is now available on the arXiv service. Led by Tabetha Boyajian at Yale, it describes a rather unusual system (what the Atlantic called the most interesting star in the Galaxy), which was identified by Planet Hunters, four of whom (Daryll, Kian, Abe, Sam) are named on the paper*. They spotted a series of transits – which is normally what signifies the presence of a planet – but these were unusual.

The star’s light dimmed for a long period of time, loosing a fifth of its brightness for days or even months at a time. More mysteriously, the duration of the dips was not always the same, so this couldn’t possibly be a planet. This behaviour is unique amongst the more than a hundred thousand stars studied by Kepler – we have a bone fide mystery on our hands.I think the team’s immediate thoughts were that it must be the star itself that’s misbehaving, but stars aren’t known to behave like this and some careful follow up reveals it to be nothing more than a normal F-type star, slightly hotter and more massive than the Sun. So it’s not the star, and we’re sure too that it’s not Kepler itself misbehaving; something is really blocking the light from this star.One option is a disk of dust around the star. It’s from such disks that planets form (see DiskDetectives.org for more on this!) and so that wouldn’t be too surprising. Yet enough dust to cause the deep eclipses we see would glow brightly in the infrared, and there’s no sign of a strong infrared source around this star.

You can read the paper to find out what else we considered, but we think the best explanation is that there is a group of exocomets in orbit around the star. Comets are an appealing scenario to invoke because they would be faint in the infrared, and because they move on elliptical orbits, accounting for the random timing of the transits and their different lengths. Such a group of comets could have come from the breakup of a larger object, leaving a cloud of smaller remnants in similar orbits behind.

Much detailed work is needed to flesh out the details of this (pleasingly outlandish!) scenario. One possibility is that the recent passage of a nearby star triggered the cometary bombardment whose effects we’re seeing. The paper is currently in the peer review process and there is – of course – the possibility that there is a perfectly sensible solution we haven’t yet considered. However, so  far over 100 professional scientists have had a look at the lightcurves and not managed to come up with a working solution.

One other proposed theory is that this pattern of behaviour is due to a fleet of alien spaceships in orbit around a star, a possibility considered by Jason Wright and collaborators here. Jason and co were tipped off about our discovery by the team, and it’s included in their paper as an object with ‘a bizarre light curve consistent with a “swarm” of megastructures’, much to the excitement of much of the internet. ‘Consistent with’ isn’t the same as ‘definitely is’, of course – and personally, my money is very firmly on the comet theory with a side bet on weird stellar behaviour – but until those models are properly investigated alien spaceships remain a possibility. The Wright paper points out this star is now a supremely interesting target for SETI (the search for extraterrestrial intelligence), and we agree – I hope radio astronomers will go and listen for signals. We need more observations of transits in action, too, and will be trying to follow-up to try and work out what’s actually going on.In the meantime, who knows what else is lurking in the Kepler data? Planet Hunters is about finding planets, but this ability to identify the weird and unusual is one of the project’s great advantages. Get clicking at www.planethunters.org, and let us know through Talk if you find anything a little odd.

Chris

* – This isn’t the final version of the paper, and we have more names to mention too before we’re done.

A New Paper and New Planet Discoveries

Today we have a  post from Joey Schmitt, a graduate student in the Astronomy department at Yale University, where he is  working with the exoplanet group led by Debra Fischer, and in particular he has been working on the follow-up of Planet Hunters planet candidates.

We’re happy to announce the discovery of a new planet discovered by Planet Hunters volunteers, which is now published in The Astrophysical Journal. You can read the article for free on the arXiv here.

The star (PH3/Kepler-289/KOI-1353/KIC 7303287) is young and Sun-like. Two planets in the system, with periods of 35 and 126 days, had been previously validated statistically, the outer planet being a gas giant. However, Planet Hunters volunteers discovered a third transit signal between these two planets at a period of 66 days (PH3 c).

A quirk in the system allowed us to actually measure the mass of all the planets using only the exact times that each planet transited. The outer two planets, PH3 c and d, do not have a constant period like most planets do. Instead, it oscillates around an average value in a regular manner, which meant that it had been missed by computer algorithms but was easy to find for human eyes. In particular, the period of PH3 c changes by 10.5 hours in just 10 orbits due to the gravitational influence of the outer gas giant tugging on the middle planet. If Earth experienced such large changes, then if 2014 were 365 days long, 2024 would be 367.4 days long, almost two and a half days longer than 2014.

The new planet is about 2.7 times the radius of Earth and 4 times as massive. Its low density means that, despite its low mass, a large chunk of the planet must be composed of hydrogen and helium: 2% by mass and 50% by radius. The outer planet, on the other hand, is like a warm version of our Saturn, while the inner planet’s mass is poorly known. It could be mostly rocky, watery, or gassy.

We would like to thank all of the people involved in the project and all of the Planet Hunters volunteers for making this possible. We hope to find more gems like this in the future.

Latest Science Paper Accepted for Publication: The First Kepler Seven Planet Candidate System and 13 Other Planet Candidates from the Kepler Archival Data

Today we have a  post from Joey Schmitt, a graduate student in the Astronomy department at Yale University, where he is  working with the exoplanet group led by Debra Fischer, and in particular he has been working on the follow-up of Planet Hunters planet candidates.

We at Planet Hunters are happy to announce the acceptance of the PHVI paper to the Astronomical Journal, in which 14 new planet candidates were discovered. All of these new planet candidates are located far from their host stars. In fact, seven of them lie in their host star’s habitable zone. Unfortunately, all of these planets are too large to be Earth-like.

Two of the new planet candidates are in multiple candidate systems. One of them, the new candidate orbiting KOI-351, is the seventh planet candidate orbiting its host star. Planet Hunters actually detected three new candidates around this star when KOI-351 was only known to have three candidates, showing how great the Planet Hunters can be in discovering multiple planet systems. The planets in KOI-351 also show strong gravitational interactions between the planets, which helps to confirm them as true planets. The gravity from some planets in the system causes other planets to transit before or after what we would otherwise expect, called transit timing variations. In fact, the second-to-last planet transited a full day after we expected it would. Others in the exoplanet field have been working for over a year to determine the masses of these planets.

The new candidate in KOI-351 makes it the only star with seven known transiting planets. After our submission in October, two other teams claimed confirmation of the seven signals to various levels of certainty. Look forward to the brand new stars in the K2 campaign, changes to the Planet Hunters strategy, and new papers of the latest planets and candidates discovered by Planet Hunters.

You can read the revised accepted version of the paper here. The Planet Hunters volunteers who participated in identifying and analyzing the candidates presented in this paper are acknowledged  at http://www.planethunters.org/PH6, and the contributions of the entire Planet Hunters community are individually acknowledged at http://www.planethunters.org/authors.

PH2 b Paper Accepted

Today’s post is from Ji Wang. Ji is a post-doctoral associate working with Planet Hunters at Yale University. He obtained his PhD at the University of Florida in 2012. He is interested in exoplanet detection and characterization, statistics of exoplanets and its link to planet formation and evolution.

We are delighted to announce that the discovery paper of PH2 b is officially accepted and published on Astrophysical Journal. The link to the paper can be found here. PH 2b has been assigned with a Kepler number: Kepler-86b. PH2 b is a Jupiter-sized planet in the habitable zone of a solar-like star. Its radius is ten times of the Earth radii and it finishes one round trip around its host star every 282.5 days. PH2 b has the forth longest orbital period among Kepler detected planets, and it has the largest radius among all confirmed Kepler planets with periods longer than 100 days.

Over the past nine months, we have been working on the follow-up observations for PH2 b. From June 3rd 2013 to June 25th 2013, we obtained 4 data points of high-precision radial velocities using the Keck HIRES spectrograph. These observations allow us to rule out the possibility of false positives such as an eclipsing binary and a brown dwarf at a confidence of 96% and 80%, respectively. More radial velocity measurements in the future will allow us to precisely determine the mass of PH2 b.

Along with PH2 b, we have also announced 42 plant candidates identified by Planet Hunters. Most of them have orbital periods longer than 100 days and 20 of them are potentially located in the habitable zone. Our discoveries nearly double the number of previously known planets in the habitable zone and provide a sample of planet candidates for the study of planet formation and evolution at the habitable zone distances. Most of the planet candidates are larger than the radius of Neptune, they may not be habitable by themselves because of a lack of a rocky surface for life to form and evolve. However, satellites around them, analogs of moons around Saturn and Jupiter, may harbor life in a similar way as depicted in the movie of
Avatar. Our discoveries are therefore suitable for the search for exo-moons, which is a frontier in the exoplanet research. As we are writing this blog, we already know that other groups are using the planet candidates in our paper to study the interior structure of gas giant planets and to conduct follow-up observations to confirm their planet nature. The race is on, but we are so glad that the Planet Hunters’ work has drawn so much attention across the community.

A mysterious object no more

This post is by Tabby Boyajian, one of the Planet Hunters science team at Yale

As you all know, planethunter volunteers use archive data taken with the Kepler space telescope to classify lightcurves and identify transiting planets. Since the launch of the Planethunters citizen science program, we have contributed five scientific publications reporting on the discovery of dozens of candidate and confirmed exoplanetary systems – otherwise undiscovered by the Kepler team.

The design of the project is expanding with the opportunity for Planethunter volunteers to support astronomers interested in using Kepler data for scientific research unrelated to the main exoplanet goals of the Kepler mission. We have dubbed this as our own ‘Guest Scientist’ program. The idea is that guest scientists participate in Planethunters Talk forum and make requests for the public to collect particular light curves, such as signatures of moons or rings, pulsators, variable stars, flare stars, cataclysmic variables, or microlensing events.

This schematic, by Planet Hunter Daryll LaCourse, shows off our new discovery.

This schematic, by Planet Hunter Daryll LaCourse, shows off our new discovery. (Click to make larger)

We are delighted to announce that the first paper presenting results associated with the Planethunters Guest Scientist program has been accepted for publication in the Astrophysical Journal! In this paper, the lead scientists Doug Gies and Zhao Guo from Georgia State University and Steve Howell and Martin Still from NASA AMES follow up on a mysterious object in the Kepler field identified by Planethunters, later confirming it to be an unusual type of cataclysmic variable. They perform an in-depth analysis on the Kepler lightcurve as well as observations made at the Kitt Peak National Observatory 4-m Mayall telescope and RC spectrograph. The result is a newly published paper, so take a momtent to read ‘KIC 9406652: An Unusual Cataclysmic Variable in the Kepler Field of View’ or to check out the planethunters talk thread where the object was first discovered and discussed:

Thanks you all for your enthusiasm and contributions to the scientific community. We have several other projects underway so keep an eye out for updates in the future!

PH1 Paper Offically Accepted for Publication

Last October we announced the discovery of PH1 – a four star planetary system hosting a circumbinary planet (PH1b). The transits were spotted by volunteers Robert Gagliano and Kian Jek  on Talk. I’m thrilled to announce that our paper “Planet Hunters: A Transiting Circumbinary Planet in a Quadruple Star System” has been officially accepted to Astrophysical Journal. Congratulations to all involved.

Now that the paper has been accepted and is in press, you can find the accepted manuscript online and added to the Zooniverse publications page (which has a total of 4 Planet Hunters in press/published papers based on your clicks). The official journal version will be published sometime in May.

PH1b is our first confirmed exoplanet discovery, a milestone for Planet Hunters. The 6.18 Earth radii planet orbits outside the 20-day orbit of an eclipsing binary consisting of an F dwarf ( 1.734 x the Radius of the Sun) and M dwarf ( 0.378 x the Radius of the Sun). For the planet, we find an upper mass limit of 169 Earth masses (0.531 Jupiter masses) at the 99.7% confidence level. With a radius and mass less than that of Jupiter, PH1b is a bona fide planet. Not all planet candidates can be confirmed as we could with PH1b. Since PH1b is orbiting an eclipsing binary, we could use the fact that there are no changes in the timing of the stellar eclipses due to the planet to constrain PH1b’s mass.

With the acceptance of the paper, we have asked that PH1b be added to the NASA Exoplanet Archive (NExSci)’s  list of confirmed exoplanets . NExSci has taken on the role of being the keeper of the list of confirmed exoplanet discoveries. In addition, PH1b has bestowed the Kepler # that was saved for us in October. PH1b has been given officially a Kepler designation of Kepler-64b and added to the list of planets in the Kepler field. You can find out more about what the criteria for obtaining a Kepler # is here.

In the list of confirmed planets, the planet is referred to as PH1b (you might notice an extra space – that should be revised in an update to the NASA Exoplanet Archive). I like to think of the Kepler # as icing on the cake. We’ll still refer to the planet as PH1b. Kepler-64b will be an alternate designation and used in the catalog of planets in the Kepler field (PH1b will be listed as an alternative designation). The full data page for PH1b on the NASA Exoplanet Archive can be found here

For those who are wondering what the NASA Exoplanet Archive  is, Rachel Akeson, Deputy Director of NexSci and Project Scientist for the NASA Exoplanet Archive, explains below:

The NASA Exoplanet Archive is an online astronomical exoplanet and stellar catalog and data service provided to the astronomical community to assist in the search for and characterization of exoplanets and their host stars.

Current data content and tools include:

  • Interactive tables of confirmed planets, Kepler Objects of Interest (which includes the planet candidates), Kepler Threshold Crossing Events, stellar parameters for all Kepler targets in Q1-12 and a list of Kepler confirmed planet names and aliases.
  • Overview pages with all available data for each confirmed planet and Kepler Object of Interest
  • Tools to view, normalize, phase and calculate periodograms for light curves, particularly those from Kepler and CoRoT
  • Transit predictions for all known transiting planets and Kepler Objects of Interest
  • URL-based access to all table data

The archive is available at http://exoplanetarchive.ipac.caltech.edu/index.html and includes links to documentation for all these services.

PH1 Paper Resubmitted

Just a quick note to say that I’ve resubmitted the PH1 paper back to the Astrophysical Journal last week. Many thanks to my co-authors for their help on the revised manuscript. The paper has been received by the Journal and sent to the referee (another scientist in the field whose identify usually remains anonymous to the authors) for a second review as part of the peer review process. The changes we’ve made I think make it a stronger paper. In about a month, we should get a response from the referee. Hopefully (fingers crossed) we have sufficiently addressed the referee’s concerns and questions, and the paper will be accepted at that point. When we hear back from the Journal editor and referee, we’ll let you know.

More about the Discovery of PH2-b

The project’s second confirmed planet, PH2-b (a Jupiter-sized gas giant planet orbiting a Sun-like star), was discovered by several members of the PH community who classified the light curve and then posted the candidate on Talk. A volunteer-organized effort took this from a possible repeat of transits to a likely candidate that was then passed to the Science Team and subsequently validated as a real bona fided planet. Volunteer rafcioo28 who was the first person to mark a transit in Q4. Mike  Chopin was the second and the one to first  post on the Talk page about the transit in February of last year. Hans Martin Schwengeler went to look at the rest of the publicly released Kepler data months later spotting the other transits. Together rafcioo28, Mike, and Hans with the help of Abe Hoekstra, Tom Jacobs, Kian Jek, Daryll LaCourse  have discovered Planet Hunters’ 2nd confirmed planet PH2-b.  I’ve asked Mike and Hans (rafcioo28 we haven’t been able to contact thus far) write a bit about their thoughts on the discovery.

PH2_moon

Artistic rendition is a hybrid photo-illustration, showing a sunset view
from the perspective of an imagined Earthlike moon orbiting the giant planet, PH2 b. Image Credit: H. Giguere, M. Giguere/Yale University

Mike Chopin

At school, at the age of fourteen, I did a project on atomic (particle) physics which gained me a grade 1 CSE. The following year I studied and passed my Physics exam which was interesting for my school since that was a subject not on the school curriculum. After leaving school, I studied OND Engineering at Kingston Polytechnic although I only completed my first year since I longed to go travelling. My wanderlust got the better of me and I joined a shipping line as a Navigating Cadet Officer. I suppose it’s easy to see why astronomy has fascinated me since knowing about stars was part of my navigation syllabus.

My childhood hero was, and still is, Captain James Cook a man I consider to be the greatest explorer of all time. I consider myself fortunate to have visited many places this great navigator charted. In 2012 his observation of the transit of Venus in 1769 was commemorated at Venus Point in Tahiti. Although I wasn’t there for 2012, I did get to Venus Point a couple of years earlier. Like Cook, I spent some time in the Navy and have a passion for boats especially under sail. I have two complete circumnavigations under my belt; the first by sea (unfortunately via the Panama Canal and not Cape Horn) the second was by air, island hopping my way across the Pacific. I have now visited ninety six countries and hope that it won’t be too long before I join the Travellers’ Century Club.

Latterly, I was employed by Lloyds TSB (Registrars) as a project officer with my principal role as the sole technical writer writing context sensitive help for software, on-line documentation, trouble-shooting guides for the IT department and interactive eLearning modules. Following redundancy, I went freelance as a writer and have had a couple of small contracts both as a writer and as a data manager.

I am delighted to have been involved with the discovery of an exoplanet, a planet orbiting a distant sun. From the outset, I enjoyed the thrill of analysing the light signals recorded and posted on the planethunters.org website. This website invites ordinary people to take part in analysis of vast amounts of data. Often called ‘Citizen Science’ this excellent website provides clear tutorials to enable the amateur to partake in this worthwhile research project.

In its simplest form, when an exoplanet passes between our line of sight and its sun, there is a reduction in the amount of light that we receive. This effect can be seen if we plot the light output from this star against time. While trying to analyse the data, I would try to imagine the planet transiting its sun, if it was a large planet and close to its sun would it cut more light than if it had been a small planet and a giant sun? Does it have a high reflectivity (albedo) and is it inclined to its ecliptic and if so, would it add or reduce the amount of light recorded. If distant suns had multiple planets with systems similar to our own solar system, then would it be possible to identify additional planets. It was with all these ideas in mind that I began my quest for the exoplanets.

Sometimes, the pattern appeared to be too random to be able to distinguish a planet and at others, beautiful patterns could be seen as if generated by an oscilloscope, these it would seem were possible candidates for a binary star and so these were recorded also. Now and again, a pattern would emerge which would make you sit up and take notice. Using the sliders on the screen, I would drag out the ‘x’ scale to magnify a section of the screen where I was certain a transit was occurring and then I would check to see whether there was a second transit which may indicate its periodicity. It was during such an event that I found, what is recently been called, PH2-b. With, what at time was simply a planetary candidate; I posted a note to see if any of my fellow planet hunters had seen what I had seen.

Carl Sagan spoke of the ‘Pale Blue Dot’, the Earth as seen from Voyager 1 in the distant reaches of space, how exciting would it be if spectral analysis revealed this planet to have water and an atmosphere, another ‘Pale Blue dot’, now that would be truly remarkable.

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’ve always been interested in stars, planets and the universe in general. So when I studied Mathematics at the ETH in Zurich it was natural to choose Astronomy as a second discipline. After working a few years on a Statistics research program (based on the Kalman Filter) I managed to get a job at the Astronomical Institute of the University of Basel (Switzerland) as a system manager. There I could work part time on research programs, mainly on Cepheids to determine the Hubble Constant (together with G.A.Tammann and Allan Sandage). I did this with the image processing software ESO-MIDAS, where we analyzed images taken by the ESO New Technology Telescope (NTT) or the Hubble Space Telescope (HST). I also used a program (written in Fortran-77) called superperiod to find the periods of the variable stars found in the galaxy images and see if they could be cepheids with periods between 2 and 100 days. With the Cepheid period-luminosity relationship we were then able to determine the distance of the Cepheid and the host-galaxy.

As soon as Michel Mayor and Didier Queloz detected the planet around 51 Pegasi, I was drawn in into exoplanets. I followed every single announcement of the detection of a new exoplanet on Exoplanet.eu and arXiv.org and elsewhere. So when I first took notice of the Planet Hunters project, I joined immediately. In the meantime the Astronomical Institute has been closed down (on monetary reasons) and I was working as a systems engineer at the Federal Office for Information Technologies and Telecommunications in Bern. I did not have anymore the tools needed to analyze light curves and so on. I also had to realize that to detect a planet transit in a Kepler light curve is not so easy as I first thought (except for the very big Jupiter-like ones). The learning curve was rather steep. Fortunately some fellow hunters had already gathered some very good insight and also some useful tools. So after some months I think I accumulated enough experience to do some real work here on PH.

So when I got the light curve for KID 12735740 I thought it looks very nice and might be a real planetary transit. Kian Jek had already commented on it favorably. The transit shape is more like an “U” instead of a “V”, the transit depth and duration is compatible with a 1.1 R_Jupiter planet with a period around 282.6 days. We can check this with Kian’s very good Planetary Calculator. The first thing I then usually do, is to have a look at the sky view  and then post this image to the PH Talk pages for others to have a look too My second step is then to download the FITS files from MAST (using the very good tools from http://www.kianjin.com/kepler/detrend.tar.gz ), detrend the curve roughly and view it by eye first (often using the program ggobi for this purpose). I upload the light curve also to PH if it looks interesting. Thirdly I may do a periodogram to find the period if a good period seems to be present (and upload it as well of course).

In the case of KID 12735740 I think all looks very good for a real planet candidate. Not much would be possible without the help of others, especially Kian Jek (aka kianjin) is invaluable here at PH. He compiles very good lists of “good candidates” or EB lists. I also find the other lists of “good Q2 candidates (non Kepler favorites)” (or Q3, Q4, etc. lists) very helpful in finding candidates and discuss them in more detail. It’s otherwise rather difficult to keep track of all the interesting cases on PH Talk. Kian does also the best detrending jobs, contamination vector determination, fitting of transit parameters, and more. nighthawk_black does perfect Keppix analysis, troyw has his amazing AKO service, capella, JKD, ajebson, gccgg, Tom128 and many other are very helpful too.So very often we work together here at PH as a good team.

In order to discriminate between real transits and instrumental or processing artifacts, I add comments to the “consolidated list of glitches” in the Science section on the PH Talk site. I collected a few bright and quiet and constant stars over the last few months / years exactly for this purpose. When I see a dip on one light curve and the same feature is also present on the other light curves, then it’s very likely a glitch.

I think the PH project is a great contribution to Science. I’d like to thank all fellow PH hunters for their help and also to Meg.

Kind regards,
Hans Martin Schwengeler (aka zoo3hans)

In addition to Mike, Hans, and rafcioo28, several others get a tip of the hat for marking transits in the discovery light curve for PH2: Sean Flanagan, Anand, and Jaroslav Pešek. Congratulations to you as well.

Revising the PH1 Paper

I just wanted to give you all a quick update on the PH1 paper.  We submitted the paper in October to a scientific journal, Astrophysical Journal. We got a few months ago feedback from the referee (another scientist in the field who reads the paper, gives to the editor his/her opinion on if the paper is worthy of publication, and many times raise issues or concerns he/she would like to see addressed before publication will be recommended).  Recently, I’ve been working on finishing the response to the referee’s report. I have been making changes and edits to the text to address the specific  concerns and questions raised by the referee. I think the changes make it a stronger paper. I sent the revised manuscript to the rest of the coauthors last night. I’m waiting for their comments and feedback. Hopefully in the next few weeks, we’ll have the paper resubmitted to the journal and referee. With any luck, hopefully the paper will be accepted soon after that. I’ll keep you updated on our progress.