Citizen Planet Hunters Find a Planet in a Four-Star System

A family portrait of the PH1 planetary system: The newly discovered planet is depicted in this artist’s rendition transiting the larger of the two eclipsing stars it orbits. Off in the distance, well beyond the planet orbit, resides a second pair of stars bound to the planetary system. Image Credit: Haven Giguere/Yale.

A planet has been discovered orbiting in a four-star system — and no, that doesn’t mean the accommodations and conditions are excellent. It literally means four stars, where a planet is orbiting a binary star system that in turn is orbited by a second distant pair of stars. This is the first system like this that has ever been found, and its discovery demonstrates the power of citizen scientists, as it was found by a joint effort of amateurs participating on the Planet Hunters website under the guidance of professional astronomers.

This is might be an extremely rare planetary setup, astronomer Meg Schwamb from Yale says, as only six planets are currently known to orbit two stars, and none of these are orbited by other stellar companions. Astronomers are calling the newly found world a ‘circumbinary’ planet.

“Circumbinary planets are the extremes of planet formation,” said Schwamb, Planet Hunters scientist and lead author of a paper about the system presented Oct. 15 at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society in Reno, Nevada. “The discovery of these systems is forcing us to go back to the drawing board to understand how such planets can assemble and evolve in these dynamically challenging environments.”

The planet is called PH1, for the first confirmed planet identified by the Planet Hunters citizen scientists, but it has the nickname of Tatooine, the planet in Star Wars that orbited two suns.

Planet Hunters uses data from the Kepler spacecraft, specially designed for looking for signs of planets.

The volunteers, Kian Jek of San Francisco and Robert Gagliano of Cottonwood, Arizona, spotted faint dips in light caused by the planet as it passed in front of its parent stars, a common method of finding extrasolar planets. Schwamb, a Yale postdoctoral researcher, led the team of professional astronomers that confirmed the discovery and characterized the planet, following observations from the Keck telescopes on Mauna Kea, Hawaii. PH1 is a gas giant with a radius about 6.2 times that of Earth, making it a bit bigger than Neptune.

“Planet Hunters is a symbiotic project, pairing the discovery power of the people with follow-up by a team of astronomers,” said Debra Fischer, a professor of astronomy at Yale and planet expert who helped launch Planet Hunters in 2010. “This unique system might have been entirely missed if not for the sharp eyes of the public.”

PH1 orbits outside the 20-day orbit of a pair of eclipsing stars that are 1.5 and 0.41 times the mass of the Sun. This planet is dense — it has perhaps about 170 times more mass than Earth — and is about half the diameter of Jupiter. It revolves around its host stars roughly every 138 days. Beyond the planet’s orbit at about 1000 AU (roughly 1000 times the distance between Earth and the Sun) is a second pair of stars orbiting the planetary system.

Gagliano, one of the two citizen scientists involved in the discovery, said he was “absolutely ecstatic to spot a small dip in the eclipsing binary star’s light curve from the Kepler telescope, the signature of a potential new circumbinary planet, ‘Tatooine,’ and it’s a great honor to be a Planet Hunter, citizen scientist, and work hand in hand with professional astronomers, making a real contribution to science.”

Jek expressed wonder at the possibility of the discovery: “It still continues to astonish me how we can detect, let alone glean so much information, about another planet thousands of light years away just by studying the light from its parent star.”

Read the paper here.

Source: Planet Hunters

19 Replies to “Citizen Planet Hunters Find a Planet in a Four-Star System”

  1. “Rare PH1” hasn’t the same clang to it as the luckily demised “Rare Earth”, but it is the envy of many galactic citizens. Think of the real estate value!

    1. The real estate value is nothing compared to the cost of actually getting there, especially as it is about the distance of about 1500 parsecs away. Kepler is measuring far-off systems.

      Note: Also as a comment, this article by UT again misses the essentially points that leads to the reader to wrong conclusions. I read the paper, and yet the author has failed to extract the appropriate information.

      It is also interesting that this particular article paraphrases others really close. I.e. Sciencedaily : “Circumbinary Planet in Quadruple Star System Discovered by Astronomers Aided by Volunteer ‘Planet Hunters.”

      (I should say Nancy is usually pretty spot on with her reportage, though others here are not so careful.)

      1. Do you realise how much cost there would be to reach across 1500 parsec, let alone the investment in time? I.e. +6000 years or more. It would also take most of all the countries combined GDP for many years just to fund it!

        Your point is it is a ridiculous assumption, as we don’t have the technology to get there nor the resources to do so!

      2. There may be better planets. Technology will continue. Once a mission is launched there is no further earthly cost on a private endevor without the burden on groundcontrol. GDP and inflation have no relevency. We can’t is not a valid point.

      3. Rubbish. Clear avoidance and obfuscation. We are talking about one star 1500 pc away and not “There may be better planets.”

        “Real estate” here is what is irrelevant, as it is meaningless unless someone can claim it the buy it!

      4. Real estate value is estimated locally. I don’t see many US citizens bid on the houses around here.

        Similarly I wasn’t suggesting interplanetary travel. The two feasible galactic economies proposed seems to be information barther (so no travel) or migration (so no interest in existing and competitive biospheres).

    2. Not only does Earth appear “rare”, but even its Solar System. A system that contributes to the stability of our World in the Habitable Zone. You, no doubt, have read descriptions, and seen various graph depictions of the alien systems so far unveiled. All kinds of inhospitable variations, it seems. But not so life-friendly differences.

      – From Extreme Solar Systems: Why Aren’t We Finding Other Planetary Systems Like Our Own?

      “The fact that almost all solar systems found so far are so different than our own has astronomers wondering if we are, in fact, the oddballs.” Or, one could say, “rare Earth” in rare Solar System.

      “A study from 2010 concluded that only about 10 – 15 percent of stars in the Universe host systems of planets like our own, with terrestrial planets nearer the star and several gas giant planets in the outer part of the solar system.” ….

      “But the surprising new population of planetary systems discovered in the Kepler data that contain several planets packed in a tiny space around their host stars does give credence to the thinking that our solar system may be somewhat unique.” One could also say, very unique.

      Article also points out an interesting observation, some or all of these strange systems’ architecture
      may at one time have been more favorable for hosting life-planets (inferred). Migration…

      – You can refer to large “rocky” worlds as Super-Earths. But from what I have read, a far
      cry from potential living planets, those heavyweight contenders.

      Me thinks your rejoicing at “rare Earth” demise is premature. When anything remotely resembling
      our “Miracle Planet” is discovered and confirmed, then you can confidentially write a happy obituary
      on one unique Planet of Life’s place in the Universe.

      (I post this assuming one can occasionally dare to disagree with mainstream thinking: the standing

      1. Every planet is unique in certain ways. The Earth though may have close analogues in the universe. I even suspect there may be several hundred or maybe several thousand in this galaxy. The Earth and analogues like it may be one in a hundred million or so. That would make a planet like this rare, but not completely exceptional.

        Based on analysis I did of orbital dynamics and the stability of putative planets at 1AU around known stars I found only one other star system that might be comparable to ours. A planet at 1AU would be comparatively stable, but of course this does not mean there is such a planet. I then worked some statistics and come up with the estimate of about 1000 possible Earth-like planets in this galaxy.


      2. I appreciate your reply. — We can speak of “Earth”-like planets out there among the myriad stars, even it they are few and far between,–or rare,–but what does that really mean? A world approximating the size of Earth, in a habitable zone orbit, yes. But, if we are disusing LIFE-complex-worlds, a whole lot more must be included beyond beyond world composition, planet-system location, and star-type. (I speak as layman.)

        I do not doubt, that in basic frame, there are “Earth”-like worlds in size, and even general orbital location, hidden in the distant starfields. But whether those relatively few planets, in possible Solar System-like configurations, have ALL that is required for life preservation, is something else–requiring a whole lot more.

        After all, would not Venus come close to being classed an “Earth”-like world? – JRC

      3. My analysis involved low F, G, and high K class stars. These stars are comparable to the sun. I then did some chaos theory on possible 1AU orbits around these stars using data on the Jovian planets. The chaotic dynamics, or equivalently the Lyapunov exponent for sensitive dependency on initial conditions, was examined and a distribution of these exponents used as a Bayesian prior. There may only be in the entire galaxy about 1000 planets comparable to Earth. This does not mean all of these are biologically active.

        I think lots of planets may have life. Mars may have life in its subterranean environment where liquid water can exist, Europa and Enceladus may have life in oceans under an ice crust and so forth. I doubt that these types of world give rise to complex life, but microbial life similar to prokaryotes are possible. Some of these planets found in habitable zone around Gliese 581 and other M-class stars might have life as well.

        What has occurred on Earth is that life reached a level of complexity and dominance that it has control of the Earth’s environment. Photosynthetic plants produce oxygen, life controls the chemistry of the oceans and fresh water systems and so forth. Earth is a bio-planet, not just a planet with simple life forms existing in some margins. I think a planet existing in the habitable zone of a G-class star has some probability of becoming Earth-like. The energy, thermal and chemical conditions might be comparable to Earth, or have been comparable to the early Earth, so that biology can not just emerge, but evolve and flourish.

        I don’t think life is so completely exceptional as to either be a one time fluke or that it exists here by supernatural or élan vitale principles. I think biology has some repeatable or Copernican aspect to it, so that if one could sample planets on a vast scale across the universe there would be a more or less uniform density of bio-planet comparable to Earth. That density might though prove to very small and as local observers we will have a tough time finding such a planet.


      4. Carefully read your reply (learning you are an accomplished author and theoretical physicist). From one perspective–the reigning mainstream view,–the emergence of life in some form, at some time, somewhere in space, on condition-favorable world (though many fine balances must still be tuned just right for anything like an Earth-scale biosphere complex), sounds plausible (as much as I could understand, anyway)–to an extent. Even in our own backyard, as described.

        “[B]io-planet”: Earth almost seems alive (BBC series, “The Living Planet”)—literally infused with life. Even in frames of what you and Mr. Larsson say, it still stands a rare, life-reflecting emerald-jewel in Space.

        Good success in future endeavors. JRC (non-scientist)

      5. I think most scientists or physicists and astronomers hold to a sort of Copernican conjecture. This says the laws of physics are not specific to any location or coordinates in the universe, and further specific occurrences found in one region are repeated in some categorical sense elsewhere.

        If life is found on Mars, and even more inside Enceladus (found by a spacecraft bearing an aerogel that flies through these geysers and returns the samples) or Europa, then even if these bodies have niche forms of life the door is open for a vast diversity of life in the universe. I suspect that if life is found on other planets in the solar system that these exist in marginal eco-niches, maybe analogous to life forms found in arctic conditions — without the penguins and polar bears. So if we find life in solar system exploration the door is then clearly open for there to be bioplanets closely analogous to Earth.

        I will also say that if there are such planets, and I suspect even marginal bio-planets that Mars might be, you would probably not want to walk on its surface — certainly not without a spacesuit as was often portrayed in Star Trek. If there is alternative biochemistry in their life forms our immune systems may be unable to adapt to them. We might be a vulnerable to microbes on this planet as a loaf of bread is to mold. HG Wells probably got this right at the end of his novel “War of the Worlds.”


      6. I would like to reply to that “copernican conjecture” idea, but would be at risk of becoming a blip on someone’s radar, and posts could disappear.

        – Interesting, speculation of interior life on airless Enceladus-like worlds: it never occurred to me that traces might shoot out into space with frozen spray of roaring geysers. Makes sense, though (in a given frame). Aerogel capture, also interesting.

        – I can agree with you, IF an organism, or even past trace, however “simple”, is discovered in our Home System, that would open a door to a universe of possibility! The Cosmos is huge, with worlds beyond counting, turning to their own clockwork movements. But do, or did, the few rare ones of finely balanced condition, ever turn to their own global biologies? That is the trillion-dollar question. The billion dollar question, I guess, expanding number of candidates: Just one quivering amoeba?

        – If H.G. Well’s novel reflected his personal beliefs, then his story concept of how the two world bio-systems arose, contrasts with what would now be imagined. Your cautionary point puts a damper on star-field civilizations freely interacting. We know what happened when 15th Century Europe made contact with the Americas: the meeting of two “worlds” of the same “bioplanet”—widespread death. A potential nightmare scenario, on an inter-stellar scale. And as you suggest, H.G. Wells book penned it first (a learned man in history, no doubt).

        No happy, intermingling “Federation of Worlds”, but (in extreme case) self-quarantined planet systems, desperate to maintain isolation—and separation. “Send us an Inter-cosmic U-mail, if you wish. But don’t you dare set biological foot in our star-space!”

        Its been stimulating. JRC

      7. The problem is of course is all observers are local. We can only observe so much. I wrote in this post about the multiverse, where in this perspective we may be at best fortunate to get some weak signatures of this. In particular we may only get signature of the nucleation bubbles or “pocket universes” that interacted with our “pocket universe” in the earliest phase of the big bang. Maybe the CMB holds evidence for this. In addition D-brane interactions may have weak signatures as well. With respect to finding life in the universe we may only be able to observe so far. We may be able to find basic life forms on Mars or emitted from the subsurface of Jovian moons such as Enceladus. Our extra-solar observations might find evidence of planetary chemistry that suggests life. A distant planet with an oxygen atmosphere with traces of methane would be such evidence. We may have to search through millions of planetary systems to find this however. It could of course be the case we never find this.
        I would not worry about direct contamination from outside the solar system. I doubt we humans are going to star travel in the way depicted in science fiction films.

        As for post being lost, this blog article is on the verge of dropping off this page, so these posts are going to soon sail off the horizon.


      8. I did over-inflate your cautionary note.

        It is truly awesome (as I read your piece) to think the CMB may hold faint signature-trace of what was behind—caused—the Cosmic birth. An alternate reality, to be sure. Ah, but what was, or still is, that veiled reality? Something so enormous in significance as this Universe could not have come from nothing. You seem to recognize that.

        Is man alone? Maybe that is the trillion dollar (pound or euro) question.

        With dreams of “Trek”ing the stars, once read an account of what would be involved in star travel (something your no stranger to)—what a deflation of dream. The cliff-face of physics (hardly understood) took on herculean mass! And, the possibility seemed to vanish with a phantom neutrino.

        Without celestial navigation aids and directional compass, to keep a charted course, sailors of old could lose their bearings, and their ship of endeavor, over a vast ocean become lost. Fair wind, as you navigate your theoretical path under the stars of space, and through the physics of time. – JRC

      9. I meant rare as in few like it in a distribution. Every system found is individual, more individual than planetary scientists expected. But the statistics is robust, and they predict many habitable Earth similar planets.

        Testing that we have already found 8 planets (including Earth) within 1 – 0.66 on the Earth Similarity Index scale.

        The “Rare Earth” hypothesis on the other hand took all sorts of habitability and observability measures (such as having a moon situated to learn about planetary roundness from its shadow !) and combined them with bayesian subjectivity measures. That is meaningless of course, one can always choose such measures to get any result between 0 and 1 as one wish. Not so with ESI.

      10. Sorry if I misunderstood you. — About statistics being robust in predicting “many” habitable (a key word) “Earth similar planets”, I would ask, how much assumption is programed into those statistical computations? You are specific in singling out Life-Worlds, as opposed to just “Earth”-like planets.

        The points you mention may not carry much weight, regarding the “rare Earth” idea, but all the real-World, known properties of our animated Home, its life-supporting conditions, do carry substantial weight:

        A quick-scan sampling of the delicate complex of intersecting balances required to preserve and sustain the Biosphere Life-Complex: Volcanically active lithosphere, and molten core generating(?) the Magnetosphere. Star-class Sun (stable star with a steady energy output). Hydrological cycle of the well-circulated Hydrosphere. Does not the Moon play an important–if not vital–role in its tidal stirrings of orbital 29+ day motion (too far, not enough; too close, too much). Whether scientifically established or not, I suspect the Moon has a more important role on this Life-World than we realize (both physically, and otherwise). The Atmospheric composition. Time-factors: 24hr days of axis rotation (Moon’s role on Climate by stabilizing its axial variation). Its degree-tilt in orbital geometry.

        Just a few broad things we take sooo muuuch for granted. But which do have meaning.

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