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Thread: Extrasolar Neptune-Pluto Analogue Discovered

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    Extrasolar Neptune-Pluto Analogue Discovered

    "A newfound pair of extrasolar planets may boost the planetary prospects of beleaguered Pluto. The pair has the same orbital resonance as Neptune and Pluto, and the "inner" planet may sometimes lie beyond the "outer" planet--the same situation that prevails for Neptune and Pluto."

    Link here

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    Welcome to BAUT, plutocrat!

    I'm not going to consider advocacy of Pluto's planetary status as against the mainstream. At least, not yet.

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    The comparison to Pluto is quite a stretch.

    1) The secondary exoplanet is 2.2x that mass of Saturn.
    2) It's close proximity to the host star suggests it is not a comet-like or asteroid-like object.
    3) It may have cleared-out its orbit.
    4) It is not the color of Pluto, undoubetdly.
    4b) Speaking of color, at 5435K, I doubt the host star is even orange.
    We know time flies, we just can't see its wings.

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    It's no stretch at all.

    Neither extrasolar planet has cleared its orbital zone of the other; the two planets' orbits can touch and may also overlap. So neither planet is a planet--according to the IAU.

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    I suspect 100% clearage of an orbit was never a requirement. Further, I don't recall a requirement for limiting eccentricity; some overlap may be fine.

    ...the two planets' orbits can touch and may also overlap. So neither planet is a planet--according to the IAU.
    Keep in mind that Neptune was not demoted.
    We know time flies, we just can't see its wings.

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    Neptune was not demoted because there's nothing bigger in its path.

    But in the case of HD 45364 b, there is something bigger in its path--something more than three times its own mass. So this planet is not a planet--according to the IAU--even though it's more massive than Neptune.

    Reductio ad absurdum!

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    Quote Originally Posted by Plutocrat View Post
    Neptune was not demoted because there's nothing bigger in its path.
    I don't think bigger is a requirement either. Even if there are many KBOs at [crossing] Neptune's aphelion, do you think Neptune would be demoted. I don't because the general pathway has been cleared. There will always be objects in the pathway for all our planets, but when their mass is miniscule compared to the planetary size, they do not prevent planethood.

    But in the case of HD 45364 b, there is something bigger in its path--something more than three times its own mass. So this planet is not a planet--according to the IAU--even though it's more massive than Neptune.
    I would [not] bet much on this view. Frankly, I'm more bothered with the orange star error.
    We know time flies, we just can't see its wings.

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    Not that the IAU definition is beyond reproach in wording, but as passed, it's irrelevant to other planetary systems: it says

    The IAU therefore resolves that planets and other bodies in our Solar System, except satellites, be defined into three distinct categories..
    This is at least sensible, since we need a good bit more data to know how to classify things in a population about which we know so little and for which our observations remain biased in important ways. (Had the IAU lost its collective senses and put me in charge for the matter, I would have pushed to leave the matter in abeyance for 5-10 years since efforts in progress will help refine both solar system and extrasolar populations on that time scale. Leaving the committee for naming 2003 UB313 open that long might be a small price in retrospect).

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    Quote Originally Posted by Plutocrat View Post
    "A newfound pair of extrasolar planets may boost the planetary prospects of beleaguered Pluto. The pair has the same orbital resonance as Neptune and Pluto, and the "inner" planet may sometimes lie beyond the "outer" planet--the same situation that prevails for Neptune and Pluto."

    Link here
    Already posted. You should do a search before posting a new thread.

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    The link I posted is dated today and contains substantial new information. The old link merely mentions the 3:2 resonance. But two planets can have a 3:2 resonance without their orbits overlapping, as is the case with the two outermost planets of PSR B1257+12.

    The link I posted is the first to call attention to the failure of either "planet" to "clear its zone." It also notes two other extrasolar planetary systems where the "planets" have overlapping orbits, as Neptune and Pluto do.

    Indeed, this link has just been picked up by Laurel Kornfeld, who writes:

    "Here is one of the most compelling arguments yet. A newfound pair of exoplanets has been discovered, which has the same 3:2 orbital resonance as Neptune and Pluto....According to the IAU definition, neither of these objects would be considered planets, as they do not "clear their orbits" of one another. According to Dr. Neil deGrasse Tyson, crossing another planet's orbit is "no way for a planet to behave." What, then, are these giant objects? Are they really not planets, or more likely, did some astronomers hastily adopt a planet definition based on arbitrary constrictions?"

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    Quote Originally Posted by ngc3314 View Post
    (Had the IAU lost its collective senses and put me in charge for the matter, I would have pushed to leave the matter in abeyance for 5-10 years since efforts in progress will help refine both solar system and extrasolar populations on that time scale. Leaving the committee for naming 2003 UB313 open that long might be a small price in retrospect).
    That would be the best diplomatic approach, but could Tyson and Brown have survived all those 3rd graders for that extended period?

    You might as well tell me... the host star ain't orange either, is it?
    We know time flies, we just can't see its wings.

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    Quote Originally Posted by Plutocrat View Post
    The link I posted is dated today and contains substantial new information. The old link merely mentions the 3:2 resonance. But two planets can have a 3:2 resonance without their orbits overlapping, as is the case with the two outermost planets of PSR B1257+12.

    The link I posted is the first to call attention to the failure of either "planet" to "clear its zone." It also notes two other extrasolar planetary systems where the "planets" have overlapping orbits, as Neptune and Pluto do.

    Indeed, this link has just been picked up by Laurel Kornfeld, who writes:

    "Here is one of the most compelling arguments yet. A newfound pair of exoplanets has been discovered, which has the same 3:2 orbital resonance as Neptune and Pluto....According to the IAU definition, neither of these objects would be considered planets, as they do not "clear their orbits" of one another. According to Dr. Neil deGrasse Tyson, crossing another planet's orbit is "no way for a planet to behave." What, then, are these giant objects? Are they really not planets, or more likely, did some astronomers hastily adopt a planet definition based on arbitrary constrictions?"
    As others have pointed out solar planets and exoplanets have separate definitions, so formally there's no conflict. While the current definition of solar planets will have to be tweaked to conform to some general definition of planets at some point, and such tweaking will take account of resonant orbits, discussions of the Pluto's status are boring so I shall step out of this thread.

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    I really don't get what's so hard about this. Pluto is a tiny object in a belt of comparably sized objects - therefore it's not a true planet (no more than Ceres is). Neptune is a small gas giant that isn't part of a belt of similarly-sized objects. Therefore it's a proper planet.

    Both of the extrasolar objects referred to are clearly massive planets. Being in a 3:2 resonance is not even remotely the same as not "clearing their orbits".

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    Of course, the Pluto debate can be found in a number of threads, including some long ones.

    It is interesing and fun to kick around as it doesn't require much physics and we all have some feelings about Pluto, one way or another. There are some fairly good arguments from both sides, though I agree with the direction Tyson took, which came from a panel recommending and agreeing with his view to group the planets at the Hayden in accordance with their type, not by planetary name.
    We know time flies, we just can't see its wings.

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    Quote Originally Posted by EDG_ View Post
    Both of the extrasolar objects referred to are clearly massive planets. Being in a 3:2 resonance is not even remotely the same as not "clearing their orbits".
    How about their orbits crossing? According to the link in the OP, that may be the case with these two.

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    Crossing orbits shouldn't make a difference. The general point of that "clearing the orbit" thing is that the other objects in the vicinity aren't (a) similarly sized and (b) present in sufficient quantity to be called a "belt".

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    Quote Originally Posted by ngc3314 View Post
    Not that the IAU definition is beyond reproach in wording, but as passed, it's irrelevant to other planetary systems: it says



    This is at least sensible, since we need a good bit more data to know how to classify things in a population about which we know so little and for which our observations remain biased in important ways. (Had the IAU lost its collective senses and put me in charge for the matter, I would have pushed to leave the matter in abeyance for 5-10 years since efforts in progress will help refine both solar system and extrasolar populations on that time scale. Leaving the committee for naming 2003 UB313 open that long might be a small price in retrospect).
    Using one planet definition for our solar system and another for other solar systems is ridiculous. It goes back to the old idea that Earth is special and everything centers on us. Leaving the issue in abeyance for 10 years would be the best option. Brown could still have been given the naming rights for 2003 UB313; Tyson is still dealing with angry letters from third graders anyway, so that would not have changed. What is more likely now is that based on new discoveries, the definition of planet will change every few years.

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    Quote Originally Posted by EDG_ View Post
    I really don't get what's so hard about this. Pluto is a tiny object in a belt of comparably sized objects - therefore it's not a true planet (no more than Ceres is). Neptune is a small gas giant that isn't part of a belt of similarly-sized objects. Therefore it's a proper planet.

    Both of the extrasolar objects referred to are clearly massive planets. Being in a 3:2 resonance is not even remotely the same as not "clearing their orbits".
    What is a "true" or "proper" planet versus an untrue or improper one? This entire concept is absurd. Pluto and Ceres are much larger than almost all the objects in their neighborhoods. They are not of comparable size to those objects. Pluto is the tenth largest body circling our sun. And the concept of "clearing its orbit" is vague in and of itself. Gravitational dominance would be far better wording; while dwarf planets are not gravitationally dominant, that does not make them non-planets or not "proper" planets. It just makes them small planets--similar to the larger ones in their geophysical makeup, only smaller.

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    Wow, a new "what is a planet" thread... it's been so long since the previous one... all of the arguments here we have heard many so times before.

    Come on people... the issue of planetary classification is fundamentally aesthetic, not scientific. Because of this, everyone can be right and so we get these perpetual debates. If we want to have a classification as scientific as possible, we perhaps should ditch the term "planet" altogether and classify objects by their physical and orbital properties separately.

    The decision by the IAU should be seen as a bureaucratic decision, a definition was needed in order to get Eris and other dwarf planets from the limbo and to make possible their numbering and naming.

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    It is almost certain that exoplanet discoveries in the near future will yield new objects in new combinations that we have never seen before. In light of this, it make sense to hold off on anything but a tentative planet definition.

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    Neptune is a gas giant, Pluto is a kuiper belt object. Whether or not one cares to call them wanderers (the meaning of planet) is not nearly as scientifically relevant as the fact they belong to the two groups I note they are in.

    I just went to a Neil deGrasse Tyson lecture on this very subject so I'm full of knowledge.

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    Pluto is not just another member of the Edgeworth-Kuiper belt.

    Pluto is larger than more than 99.9 percent of the other members of the Edgeworth-Kuiper belt. There's only one EKO larger than Pluto--and that's Eris, discovered in 2005.

    Pluto is the tenth largest object that goes around the Sun.

    The typical member of the Edgeworth-Kuiper belt is to Pluto what a ping pong ball is to a basketball.

    More facts about Pluto are here (PDF file).

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    Quote Originally Posted by Plutocrat View Post
    Pluto is larger than more than 99.9 percent of the other members of the Edgeworth-Kuiper belt. There's only one EKO larger than Pluto--and that's Eris, discovered in 2005.
    It's also likely 99.9% the same constitution as the other KBOs, unlike the established planets. Also, no one knows what larger objects lurk in the belt.

    Pluto is the tenth largest object that goes around the Sun.
    Moons go around the sun and they can't be ignored. Thus, Pluto is the 17th largest known object in the Solar system, and it could be stepping down even lower if more larger objects are found.

    The typical member of the Edgeworth-Kuiper belt is to Pluto what a ping pong ball is to a basketball.
    And Pluto is a ping pong ball in size compared to a basketball-sized Earth. Let's compromise and call Pluto and Ping Pong Planet.
    We know time flies, we just can't see its wings.

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    Might I interest you in commenting on deGrasse Tyson's view on this subject, Plutocrat?

    Here's the thread:
    OK, now I know why Pluto is not a planet.

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    Quote Originally Posted by George View Post
    It's also likely 99.9% the same constitution as the other KBOs, unlike the established planets.
    What's the scientific notation for "likely"?
    "I'm planning to live forever. So far, that's working perfectly." Steven Wright

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    It was a compartive percentage to the 99.9% size comparison given for Pluto with the other KBOs. The final count is no where near close to being in. The ability to see any Pluto-sized objects anywhere within the inner, and certainly the outer, region of the Oort Cloud is beyond even the HST. If Pluto were moved to the inner edge of about 2000 AU, though this edge may be further out, it would be a little dimmer than magnitude 32.

    However, I suspect (I think, I'm pretty sure, a reasonable likelihood, SWAG) that there will be consistency found in compositions for KBOs (and Oort objects), though we might want to throw a rogue in there for good measure.
    We know time flies, we just can't see its wings.

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