Prediction using Titus-Bode Relation

Posted: April 15, 2015 by tchannon in Astrophysics

Ian Wilson suggests this paper ought to be aired.

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Exoplanet Predictions Based on the Generalised Titius-Bode Relation
Timothy Bovaird, Charles H. Lineweaver

ABSTRACT
We evaluate the extent to which newly detected exoplanetary systems containing at least four planets adhere to a generalized Titius-Bode (TB) relation. We find that the majority of exoplanet systems in our sample adhere to the TB relation to a greater extent than the Solar System does, particularly those detected by the Kepler mission. We use a generalized TB relation to make a list of predictions for the existence of 141 additional exoplanets in 68 multiple-exoplanet systems: 73 candidates from interpolation, 68 candidates from extrapolation. We predict the existence of a low-radius (R < 2.5R ? ) exoplanet within the habitable zone of KOI-812 and that the average number of planets in the habitable zone of a star is 1-2. The usefulness of the TB relation and its validation as a tool for predicting planets will be partially tested by upcoming Kepler data releases.
http://arxiv.org/abs/1304.3341
— Open access PDF from there

Over to you folks since this subject is out of my zone.

Post by Tim

Comments
  1. oldbrew says:

    T-B law lacks any logic for me. It doesn’t work at all for Neptune which is a bit of a clue IMO.

  2. Geoff Sharp says:

    Thanks Ian and Tim, I have been looking for solar systems like ours for some time now and the data in this paper makes it a lot easier. One thing that is becoming clear from the over 1000 solar systems discovered so far is that none are quite like our own. Most have massive hot Jupiters with very fast close orbits, these hot Jupiters look to be wrecking balls of solar systems as they migrate in.

    Its my opinion that so far we probably have the only star that is capable of a solar grand minimum.

  3. oldbrew says:

    With current detection methods e.g. transit timing variation there’s a bias towards finding planets close to their star, because it’s much easier to do so on short time scales of searching.

    Synodic periods don’t seem to get any attention for exoplanets?

  4. Ian Wilson says:

    One of the biggest problems with the ground based detection techniques is that they use the Doppler-shift of the parent star. This method specifically excludes [even mildly] magnetically active stars – as the high short-term variability of magnetically active stars mimics the underlying planetary Doppler signal e.g. you most likely could not use the Doppler on our solar system because the 11 year sunspot cycle would probably masked the Doppler effects of Jupiter.

    Thankfully, the Kepler [space] observatory uses the occultation method which gets around the magnetic activity problem. The problem is that many of the planetary systems found in the Kepler survey are too far away to easily measure their levels of magnetic activity.

    The above two facts are unfortunate because it is possible that the level of magnetic activity may in fact be related to how close to resonance the planets in a given solar-system are. It would be interesting to see if stars with planets exhibiting a Titius-Bode resonance are more magnetically active [for a fixed age and spectral type] than stars with planets in disordered orbits.

  5. Ian Wilson says:

    Olbrew,

    Neptune is not close to its expected position because Uranus [and Neptune itself] moved outwards with time. Only Uranus has reached its expected TB distance at this time. The forces driving Neptune out are much weaker and so did not fully succeed in placing it at its expected distance.

    Uranus 19.6 A,U ____Expected from BD law – actual distance 19.2 (18.3 to 20.1) A.U
    Neptune 38.8 A.U___Expected from BD law – actual distance 30.1 (29.8 to 30.3) A.U

  6. oldbrew says:

    IW: From 30.1 AU to 38.8 is nearly nine times the distance from the Earth to the Sun. A lot of forces would be needed to push a massive planet that far (8.7 AU), considering the nearest large planet to Neptune is already even further away than that.

    A check on the data for KOI-812 aka Kepler-235 came up with these synodic ratios for planets b,c, and e:
    b-c : b-e = 1.6186142 : 1
    c-e : b-c = 1.6165164 : 1
    b-e : e-c = 2.6165166 : 1

    Phi = 1.6180339~, Phi² = 2.6180339~

    Data: http://exoplanet.eu/catalog/?f=%27Kepler-235%27+in+name

  7. tchannon says:

    How far are we from the technology able to have direct observation of these planets?

  8. oldbrew says:

    We can only just see Pluto without sending a space probe there.

    ‘The best picture we have of Pluto is a blurry, pixelated blob, but that is about to change when a NASA spacecraft makes the first-ever flyby of the dwarf planet.’

    http://phys.org/news/2015-04-pluto-blurry-nasa-flyby.html

  9. tchannon says:

    So this is still a solar system wide telescope, not just yet.

  10. oldbrew says:

    First colour shot of Pluto and Charon – still blurry.

    http://www.sciencedaily.com/releases/2015/04/150415131946.htm

    Meanwhile: ‘NASA’s Spitzer Space Telescope has teamed up with a telescope on the ground to find a remote gas planet about 13,000 light-years away, making it one of the most distant planets known.’

    http://www.sciencedaily.com/releases/2015/04/150414160722.htm

  11. Ian Wilson says:

    olbrew said:

    IW: From 30.1 AU to 38.8 is nearly nine times the distance from the Earth to the Sun. A lot of forces would be needed to push a massive planet that far (8.7 AU), considering the nearest large planet to Neptune is already even further away than that.

    That is my point.

  12. oldbrew says:

    So perhaps the reason they claim to find this…
    ‘We find that the majority of exoplanet systems in our sample adhere to the TB relation to a greater extent than the Solar System does, particularly those detected by the Kepler mission’

    …is that Kepler mostly detects planets close in to their star.