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Thread: Nu Ophiuchi's planetary system - sharing data

  1. #1
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    Nu Ophiuchi's planetary system - sharing data

    This thread is for group discussion of discoveries concerning the Nu Ophiuchi planetary system, and what consequences such discoveries may imply. I have not seen any other threads on this topic in CosmoQuest, so... here one is.


    Personal Notes

    Why I personally like the Nu Oph system appears at first to have no connection to astronomy, but bear with me.

    Between 1983 and 2000, I was a magazine/game editor, writer, and creative director with TSR, Inc., and its later incarnations as part of Wizards of the Coast and Hasbro. As such, I was highly aware that TSR was the first publisher of Professor M.A.R. Barker's fantasy game campaign, "Empire of the Petal Throne". The fantasy world of Tékumel was set on a terraformed planet in the Nu Ophiuchi star system. Why that particular star attracted Prof. Barker's attention, I have no idea. I had friends in the 1970s who gamed in that campaign and enjoyed it, though they all said it was challenging as it was so complicated. Prof. Barker was another world-building Tolkien. I've looked over copies of "EPT" and it is a staggering work of imagination.

    Recently it was discovered that Nu Ophiuchi DOES have a planetary system, though nothing like Prof. Barker had imagined. So far two super-Jupiters (brown dwarfs, whatever) are known to be in orbit around their giant K0III parent, with suspicions that smaller worlds also exist. Long an astronomy fan and prone to play with numbers, I spend time figuring out additional details about the planetary system, derived from what is already known, and I wish to share the results with anyone interested. Hope it is fun for you.

    Lastly, my writing style tends toward the conversational but will include math and science and stuff. The tendency for me is to write a message-board post like a magazine article, with technical notes. I will stay on topic as best I can.


    Mathematics & Equations

    Equations are formatted for Microsoft Excel, for practical reasons: they are easier to proofread, and you can copy the equations into Excel and, with modification, use them for other purposes. Using Excel was also the only way I could guarantee a degree of accuracy in the figures shared here. (A calculus professor once told me, "Your work is good but riddled with errors." Ouch.) Corrections are very much welcome.


    Naming of Names

    Nu Ophiuchi has a number of alternate names, but few of these will be used here. I prefer saying "Nu Oph" in reference to the star, capitalizing the Greek letter as an editorial convention for clarity. However, it comes out exactly like "New Oaf". I don't like calling the star HIP 88048, BD–09 4632, HD 163917, or the like. Calling it "Sinistra" makes me think of a vampire with sinus problems. Nu Oph it will have to be.

    The super-Jupiters will be known as Nu Oph B (smaller one nearer to Nu Oph) and Nu Oph C (larger one farther from Nu Oph). This sounds clunky but nothing better comes to mind. (Hope one of the planets is officially named "Tékumel". So fitting. Pluto has a Mordor region, after all.)


    Possible Topics to Cover

    Some topics I've been puzzling on for this thread include the following, in no real order, with calculations and speculations as appropriate. (Non-facts from me will be noted as such).

    * Perihelion & aphelion of b & c
    * Hill Sphere dimensions of b & c, thoughts on satellite systems
    * Effects of very large Hill Spheres on possible planetary positions in Nu Oph system, clearing the orbits
    * Luminosity of Nu Oph as seen from b & c compared to Sol/Earth, implications thereof
    * Visual size (angular) of Nu Oph as seen from b & c compared to Sol/Earth
    * Roche limits (for solid bodies) for Nu Oph, b & c, and tidal effects, tidal locking given age of star system
    * Resonance effects on other potential planets in system likely strong
    * Barycenters with Nu Oph radius, maximum and minimum effects (conjunction/opposition)
    * Possible other planetary signals and periods, resonances, possible planets in life zones around Nu Oph
    * Possibilities for asteroid belts, comets, depleted debris. Probably no quasi satellites for big ones. Kirkwood gaps, Trojans, past periods of Heavy Bombardment, giant planet migration and spacing
    * Magnetic fields, radiation belts, etc. for giant planets, space weather, solar stability, effects on satellites and other worlds
    * Delta vee (per Dr. Jerry Pournelle), and why getting close to b & c might mean being trapped there; use of b & c as "whipping worlds" to maneuver and power spacecraft

    It intrigues me that one of the defining features of the Nu Oph system is the extreme effect of the tremendous gravitational fields therein. Nu Oph itself is about 3 solar masses, and Nu Oph b & c are each over 20 Jupiter masses. Any discussion of Jupiter here always includes the effects its great mass has had on the solar system's past and present. Comets are flung away on hyperbolic orbits. Asteroids never coalesced into a world of their own. A great mini-planetary system was formed around Jupiter. Fields of Trojan asteroids lead and follow the world, and so on. Similar consequences, MUCH magnified, should be expected in the Nu Oph system.


    More to come. Wish I could upload Excel sheets, it would make sharing data a lot easier. I will upload images of Excel sheets, at least.

  2. #2
    I have not done these calculations in a while but first the perihelion and aphelion for b and c, first b.
    b perihelion 2.43*10^{8}km, aphelion 3.16*10^{8 }km, with an angular size at perihelion 2.29 degrees, at aphelion of 1.77 degrees.
    c perihelion 1.08*10^{9 }km, aphelion 1.56*10^{9 }, angular size at perihelion of .51 degrees, at aphelion of 0.35 degrees.
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  3. #3
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    Nu Oph B: Hill Sphere
    =====================

    MATH SOURCE: D.P. Hamilton & J.A. Burns (1992). "Orbital stability zones about asteroids. II - The destabilizing effects of eccentric orbits and of solar radiation". Icarus. 96 (1): 43–64.
    http://www.sciencedirect.com/science...1910359290005R (abstract)

    radius of Hill Sphere ~= a*(1-e)*((m/M/3)^(1/3))
    a = semi-major axis of smaller body
    e = eccentricity of smaller body
    m = mass of smaller body
    M = mass of larger body

    However, due to additional compounding factors, real stability in satellite orbits is achieved only at 0.333 to 0.5 of theoretical Hill Sphere value.

    Basic issues are the ratio of mass for smaller body compared to larger body, and how close the smaller body will ever get to the larger body.

    Using data from: Hou et al., The Probabilities of Orbital-Companion Models for Stellar Radial Velocity Data, 2014:

    1M⊙ = 1,047.56 Jupiter-masses
    Nu Oph has mass 3.04M⊙ = 3,184.582 Jupiter-masses
    Nu Oph B has mass 23.9 ± 0.6 Jupiter-mass, e = 0.1298 ± 0.0045, a = 1.86 ± 0.01
    Nu Oph B/Nu Oph mass ratio = 23.9/3184.582 = 0.007505

    1 AU = 149,597,870.7 km
    radius of Hill Sphere ~= a*(1-e)*((m/M/3)^(1/3)) = 0.219722 AU = 32,869,943 km. Diameter of Hill Sphere is 65,739,886 km.
    Mercury has a semi-major axis of 0.387098 AU, or 57,909,050 km.
    Practical radius of Nu Oph B's Hill Sphere = 10,956,648 to 16,434,972 km

    Depending on how the Nu Oph system evolved and what debris was picked up later, the satellite and ring systems of Nu Oph B could be enormous.

    Search for a debris disk centered on Nu Oph B? Any possibility of transit of Nu Oph by satellites/rings around Nu Oph B?

    However, see information on Nu Oph C's Hill Sphere, below.

    ================================================== ===========

    Nu Oph C: Hill Sphere
    =====================

    Using data from: Hou et al., The Probabilities of Orbital-Companion Models for Stellar Radial Velocity Data, 2014:

    1M⊙ = 1,047.56 Jupiter-masses
    Nu Oph has mass 3.04M⊙ = 3,184.582 Jupiter-masses
    Nu Oph C has mass 26.3 ± 0.7 Jupiter-masses, e = 0.195 ± 0.012, a = 6.17 ± 0.04
    Nu Oph C/Nu Oph mass ratio = 26.3/3184.582 = 0.008259

    1 AU = 149,597,870.7 km
    Radius of Nu Oph B's Hill Sphere ~= a*(1-e)*((m/M/3)^(1/3)) = 0.696105 AU = 104,135,900.21 km. Diameter of Hill Sphere is 208,271,80.43 km.
    Mercury has a semi-major axis of 0.387098 AU, or 57,909,050 km.
    Venus has a semi-major axis of 108,208,000 km from Sol's center.
    Practical radius of Nu Oph C's Hill Sphere = 34,711,967 to 52,067,950 km.

    Even at half its theoretical value, the Hill Sphere of Nu Oph C still encompasses a space about the size of the entire orbit of Mercury.

    The increase in mass of Nu Oph C over Nu Oph B is not as signficant a factor in increasing the former's Hill Sphere as is the greater distance of Nu Oph C from its sun.

    Depending on how the Nu Oph system evolved and what debris was picked up later, the satellite and ring systems of Nu Oph C could be staggering in scope. Search for debris disk around Nu Oph C?


    "There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact."
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    Nu Oph B & C: Perihelion, Aphelion, & Luminosity Received
    ================================================== =======
    (some data taken from Wikipedia pages on planets, forgive me)

    Orbital elements first.

    radius at aphelion = a*(1+e)
    radius at perihelion = a*(1-e)
    a = semi-major axis of orbiting body
    e = eccentricity of orbiting body
    1 AU = 149,597,870.7 km

    =================================================

    Using data from: Hou et al., The Probabilities of Orbital-Companion Models for Stellar Radial Velocity Data, 2014:
    https://arxiv.org/pdf/1401.6128v2.pdf

    Nu Oph B has e = 0.1298 ± 0.0045, a = 1.86 ± 0.01
    aphelion = 2.101428 AU = 314,369,154.23 km
    perihelion = 1.618572 AU = 242,134,924.775 km

    By comparison:
    Mars has a semi-major axis of 1.523679 AU
    Ceres has a semi-major axis of 2.7675 AU

    Nu Oph B's eccentricity of 0.1298 is greater than that for any Solar System true planet except Mercury (0.2056). Mars comes closest (0.0934).

    ====================

    Using data from: Hou et al., The Probabilities of Orbital-Companion Models for Stellar Radial Velocity Data, 2014:
    https://arxiv.org/pdf/1401.6128v2.pdf

    Nu Oph C has e = 0.195 ± 0.012, a = 6.17 ± 0.04
    aphelion = 7.37315 AU = 1,103,007,540.352 km
    perihelion = 4.96685 AU = 743,030,184.0863 km

    By comparison:
    Jupiter has a semi-major axis of 5.20260 AU
    Saturn has a semi-major axis of 9.554909 AU

    Nu Oph C's eccentricity of 0.195 is greater than that for any Solar System true planet except Mercury (0.2056), which is closest in value to it.

    ====================

    At closest possible conjunction, Nu Oph B & C would be separated by = 4.96685 - 2.101428 = 2.865422 AU = 428,661,029.857 km. This is about the semi-major axis of Ceres (2.7675 AU) or a little more than the average distance of Ceres from Jupiter (2.4351 AU).

    Wonder what this says about any planets lying between the two super-Jupiters. I recall constantly reading that asteroids developed in part because of Jupiter's gravitational influence preventing any other world from forming there. Will revisit this later.


    ================================================== ======================================
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    ================================================== ======================================


    Luminosity Received
    ===================

    Using data from: Sato et al., Substellar Companions to Seven Evolved Intermediate-Mass Stars, 2012 (which is where (Hou et al., 2014) got their data):
    https://arxiv.org/pdf/1207.3141v1.pdf

    Luminosity of Nu Oph = 123 L⊙ (Sol). (This is more than I usually see listed for this star, oddly.) Anyway, if Earth were 1 AU from Nu Oph, we would get 123 times Sol's luminosity. Global warming? Global frying.

    This is equivalent to (by inverse-square law) => 123 = 1/(x^2), x = ((1/123)^(1/2)) = 0.090167 AU. This is closer to Sol than any hypothetical vulcanoid.

    In fact, to reduce 123 L⊙ to Earth-normal levels (1 L⊙), we would have to be = (123^(1/2)) = 11.09054 AU from Nu Oph, or farther than Saturn at aphelion (10.086 AU).

    Using the inverse-square law:

    Nu Oph B aphelion = 2.101428 AU => luminosity recv'd = 123/(2.101428^2) = 27.85326 L⊙
    Nu Oph B semi-major axis = 1.86 AU => luminosity recv'd = 123/(1.86^2) = 35.55324 L⊙
    Nu Oph B perihelion = 1.618572 AU => luminosity recv'd = 123/(1.618572^2) = 46.95059 L⊙

    These luminosities are equivalent to being very close to Sol in our Solar System.

    Nu Oph B aphelion = 27.85326 L⊙ => = 1/(x^2), x = ((1/27.85326)^(1/2)) = 0.18948 AU equivalent
    Nu Oph B semi-major axis = 35.55324 L⊙ => = 1/(x^2), x = ((1/35.55324)^(1/2)) = 0.16771 AU equivalent
    Nu Oph B perihelion = 46.95059 L⊙ => = 1/(x^2), x = ((1/46.95059)^(1/2)) = 0.14594 AU equivalent

    Equal to being well inside the orbit of Mercury here. Nu Oph B is being fried like an egg on Icarus. This is not at all how I saw this coming out. When I think of super-Jupiters I usually think of cold ones.

    Does my math look right to you? :/

    Does this count as a sort of "hot super-Jupiter"? Now puzzled as to what Nu Oph B might look like. Could gas from its atmosphere become so superheated as to go into higher orbit around it? Not sure as Nu Oph B mass/gravity would be so great. Will revisit the escape-velocity issue later if my math was close to being right.

    ==========================================

    Trying this for Nu Oph C.

    Using the inverse-square law:

    Nu Oph C aphelion = 7.37315 AU => luminosity recv'd = 123/(7.37315^2) = 2.26255 L⊙
    Nu Oph C semi-major axis = 6.17 AU => luminosity recv'd = 123/(6.17^2) = 3.23098 L⊙
    Nu Oph C perihelion = 4.96685 AU => luminosity recv'd = 123/(4.96685^2) = 4.98589 L⊙

    Kind of takes your breath away. Nu Oph is darn hot. For equivalencies:

    Nu Oph C aphelion = 2.26255 L⊙ => x = ((1/2.26255)^(1/2)) = 0.6648 AU equivalent
    Nu Oph C semi-major axis = 3.23098 L⊙ => x = ((1/3.23098)^(1/2)) = 0.5563 AU equivalent
    Nu Oph C perihelion = 4.98589 L⊙ => x = ((1/4.98589)^(1/2)) = 0.4478 AU equivalent

    Venus at perihelion is 0.71844 AU from Sol.
    Mercury at aphelion is 0.4667 AU from Sol.

    Nu Oph C is not as boiling hot as Nu Oph B, but it is quite warm there.


    ================================================== ======================================
    ================================================== ======================================
    ================================================== ======================================


    Implications
    ============

    No water ice on any solid surface (e.g., satellites) of either Nu Oph B or C. Doubtful any light gases in satellite atmospheres, if any. Heavier gases like CO2 possible.

    Possible high turbulence in atmospheres of both Nu Oph B & C. Could either Nu Oph B or C leave a gaseous torus around Nu Oph, or would the heated gas molecules be bound to their brown dwarfs?

    How would such temperatures and closeness to Nu Oph affect the development and internal composition of these brown dwarfs? It does not seem possible these two are like any other brown dwarfs, given the circumstances, but maybe so. Could heavier elements have been taken in by Nu Oph or terrestrial inner planets (closer in than Nu Oph B), leaving both brown dwarfs with lighter elements?

    Looking doubtful at the possibility of any significant planet lying between Nu Oph B & C. Asteroid belts (small bodies) with Kirkwood gaps?

    Between the high temperatures and high (implied) gravities of the system as we know it, Nu Oph is not looking hospitable. Good for armored robots, maybe. If anything goes there, it stays there.

    Not even going to speculate about life-as-we-don't-know-it in the atmospheres of Nu Oph B & C, or on their moons.

    Still want to name one of these worlds Tékumel.

    More later. Must recover from all this joy of discovery stuff.

  5. #5
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    Here's an image I found online, showing one of these brown dwarfs as seen in Celestia
    http://astrologyking.com/wp-content/...u-ophiuchi.png

    These brown dwarfs seem to be orbiting the central star in planet-like orbits, which is interesting. I don't think they are unusually hot compared to some of the hot jupiter-type planets that have been found, but they might emit a significant amount of heat which they generate themselves, so they are probably hotter than gas giants would be in the same location.

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    Quote Originally Posted by eburacum45 View Post
    Here's an image I found online, showing one of these brown dwarfs as seen in Celestia
    http://astrologyking.com/wp-content/...u-ophiuchi.png

    These brown dwarfs seem to be orbiting the central star in planet-like orbits, which is interesting. I don't think they are unusually hot compared to some of the hot jupiter-type planets that have been found, but they might emit a significant amount of heat which they generate themselves, so they are probably hotter than gas giants would be in the same location.
    Hey, how did I miss that? Love it!

    Nu Oph B would be doubly baked, then, by its sun and from internal heat. Interesting thought as to how that works out.

  7. #7
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    Quote Originally Posted by Roger E. Moore View Post
    Hey, how did I miss that? Love it!

    Nu Oph B would be doubly baked, then, by its sun and from internal heat. Interesting thought as to how that works out.
    According to Jim Kaler this system is about 400 million years old. (I don't know if you have any more up-to-date information about that).
    A brown dwarf starts its life hot and capable of deuterium fusion, but over time this capacity reduces, allowing them to cool down somewhat. Fusion probably stops after about 10 million years, then the object contracts under gravity, emitting more heat.

    I think 400 million years is quite young for such an object, so Nu Oph B and Nu Oph C should be quite hot. Maybe a real astronomer (rather than a hobbyist worldbuilder like me) might be able to calculate exactly how hot.
    Last edited by eburacum45; 2016-Dec-21 at 10:34 PM.

  8. #8
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    I have more stuff to post (tomorrow), but this is growing on me. I want to look up planetary formation and see how far things got in, for example, our solar system at the 400 million year mark. I also don't know nearly as much as I wish about brown dwarfs.

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    SIZES AND APPEARANCES: Nu Oph B & C
    ========================================

    Just about everyone says brown dwarfs (T dwarfs) of any sort are roughly the size of Jupiter. It doesn't get any more exact than that, no matter what you read.

    https://arxiv.org/ftp/astro-ph/papers/0608/0608417.pdf
    Basri & Brown, Planetesimals to Brown Dwarfs: What is a Planet? 2006

    Per Table 2 in this slightly dated paper (2006), the maximum size of cold giant planets (and brown dwarfs) will not normally exceed 11 Earth radii. To paraphrase the paper's authors, planets grow denser and smaller after they reach 2-5 times Jupiter's mass, which is the limit for the largest possible planetary size. A planet at 10 times Jupiter's mass will have a smaller radius than Jupiter; this is also true of brown dwarfs. However, the outer layers must be cool to make this so. For example, “hot Jupiters” seen to transit their suns have greater radii than the largest cold planets. (Various other papers have indicated that accurate radii cannot be gleaned if the suspected planet does not transit its star.) This makes sense as Earth's atmosphere expands during periods of increased solar radiation, causing low-orbiting spacecraft to reenter and be destroyed.

    (from Wikipedia)
    Sun's mass = 1047.56 Jupiter masses
    Sun's equatorial radius: 695,700 km = 9.73116 Jupiter radii
    Jupiter's mean radius: 69,911 ± 6 km
    Jupiter's equatorial radius: 71,492 ± 4 km (11.209 Earths)
    Jupiter's polar radius: 66,854 ± 10 km (10.517 Earths)

    So, brown dwarfs are across the board about 10% the diameter of the Sun, or about the diameter of Jupiter. CAVEATS: The warmer they are, the larger. I would add that the faster they rotate, the larger their equitorial diameters.

    MY THEORIZING: Nu Oph B & C should be larger than normal, given their young age at 400 million years (hence retained warmth) and proximity to a giant star. Nu Oph B in particular might be oversized for a brown dwarf.

    What color are brown dwarfs? I skipped Wikipedia on this (said they were the color of "magenta coal tar dye") and tried to find accurate source material. I discovered multiple sources that said brown dwarfs were magenta, though illustrations of them are nearly always dim and dark magenta with Jovian-like atmospheric banding. They give off most of their radiation as infrared heat, but X-ray bursts are also noted. Methane has been detected in their upper atmospheres.

    Still cannot find who said they were the color of "magenta coal tar dye", which is awfully specific. Dark magenta it is, then.


    Brown dwarf "magenta" color sources:
    ====================================
    https://www.nasa.gov/mission_pages/W.../pia14720.html
    "'Y Dwarf' Chillin' in Space"

    http://w.astro.berkeley.edu/~gmarcy/...iled_stars.pdf
    Burgasser, "Brown dwarfs: Failed stars, super Jupiters", 2008

    https://arxiv.org/pdf/astro-ph/0103383v1.pdf
    Burrows et al., "The Theory of Brown Dwarfs and Extrasolar Giant Planets", 2001

    http://spider.ipac.caltech.edu/staff...omparison.html
    "An Artist's View of Brown Dwarf Types" (art by Dr. Robert Hurt of the Infrared Processing and Analysis Center)


    ================================================== =======================================
    ================================================== =======================================

    Can brown dwarfs have planets (or satellites)?
    ==============================================

    Yes.

    https://arxiv.org/pdf/1609.05053v1.pdf
    He et al., First limits on the occurrence rate of short-period planets orbiting brown dwarfs, 2016

    Brown dwarfs are likely to have their own planets, and searches are underway to find them.

    MY THEORIZING: This dovetails nicely with the information on Hill Sphere radii found for Nu Oph B & C, as mentioned in earlier posts. Nu Oph B & C can have their own planet-sized satellites.

  10. #10
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    For your reading pleasure, find attached two JPG files, each with about half of a large table I created in Excel showing the data available on the Nu Oph system, depending on which science paper you are reading. All of them give data in the same ballpark, just coming from different bases or outfields, if that does not stretch the analogy too far.

    Commentary, as always, appreciated and welcome.

    Do I get a "citizen scientist" badge for this?
    Attached Images Attached Images

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    https://arxiv.org/pdf/1612.02809.pdf

    Just discovered this paper on brown dwarfs, looks very applicable to the Nu Oph B & C issue. Chemical abundances in atmospheres and more.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

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    Smile

    Does Nu Ophiuchi have other planets? Several papers have suggested it does. Here are the results, in Excel format (jpg image).
    Attached Images Attached Images
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  13. #13
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    A table of radius sizes and Jovian comparisons, should better data come out about the radii of Nu Oph B & C.
    Attached Images Attached Images
    Last edited by Roger E. Moore; 2016-Dec-29 at 11:56 PM.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

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    Thumbs up

    And possible Roche limits for rigid bodies of different densities and masses.


    Enough for now. Will wait for more responses before posting more. Keep looking for Nu Oph papers!
    Attached Images Attached Images
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  15. #15
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    Hooray! More about the planetary system made up solely of brown dwarfs!

    https://arxiv.org/abs/1904.03557

    Precise radial velocities of giant stars. XII. Two brown dwarfs in 6:1 mean motion resonance around the K giant star ν Ophiuchi

    Andreas Quirrenbach, et al. (Submitted on 7 Apr 2019)

    We present radial-velocity (RV) measurements for the K giant nu Oph (= HIP88048, HD163917, HR6698), which reveal two brown dwarf companions with a period ratio close to 6:1. For our orbital analysis we use 150 precise RV measurements taken at Lick Observatory between 2000 and 2011, and we combine them with RV data for this star available in the literature. Using a stellar mass of M = 2.7 M_sol for nu Oph and applying a self-consistent N-body model we estimate the minimum dynamical companion masses to be m_1\sin i approx 22.2 M_Jup and m_2\sin i approx 24.7 M_Jup, with orbital periods P_1 approx 530 d and P_2 approx 3185 d. We study a large set of potential orbital configurations for this system, employing a bootstrap analysis and a systematic \chi_{nu}^2 grid-search coupled with our dynamical fitting model, and we examine their long-term stability. We find that the system is indeed locked in a 6:1 mean motion resonance (MMR)... We also test a large set of coplanar inclined configurations, and we find that the system will remain in a stable resonance for most of these configurations. The nu Oph system is important for probing planetary formation and evolution scenarios. It seems very likely that the two brown dwarf companions of nu Oph formed like planets in a circumstellar disk around the star and have been trapped in a MMR by smooth migration capture.
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

  16. #16
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    News article on previous science paper. However, the Heidelberg team did not just discover the two brown dwarfs in 6:1 resonance. They were discovered years ago, per the rest of this topic (see above).

    https://phys.org/news/2019-04-brown-...r-planets.html

    Are brown dwarfs failed stars or super-planets?
    by Heidelberg University
    There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.
    — Mark Twain, Life on the Mississippi (1883)

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