Did I mention that I have been here a week and not got to the beach yet...
One of the penalties of being an organiser. Of course I slept that one free afternoon, but that was after trying to find the Olympic Airways office for 3 hours - they shut it, apparently people kept bothering them or something - did I mention it has been rather hot here?
Then there are these mystery people who keep sending me lengthy snippets of text they claim to be "thesis chapters" or something. Strange behaviour.
The Macs are nice, but the screen contrast is not good enough to read 20-40 pages of text in the afternoon sun, outside, at the beach. Or even the pool...
Ok, some theory speculations:
dynamicists have been playing with formation models, and there is a hint that we can match the observed systems - prescription is that systems form "crowded" - just pack in as many planets as can fit, then let there be some migration, resonant locking and planet-planet scattering, and what emerges has statistical distributions that are not too far off from what is observed.
Now, we could be missing a class of systems more like the Solar System where there was little gross scattering or migration, but probably some, and we are starting to see those systems now.
Ed Thommes had an interesting talk on extensions of his old models and the "Nice" models of Morbadelli et al.
Looks like the outer solar system, with late heavy bombardment, would have come together nicely if there was another Neptune out there to begin with.
So we let debris drag bring Jupiter and Saturn into resonance with a little bit of orbital migration, scatter Uranus and Neptune out (and use the debris to recircularise) and we get the details more or less right if we let a second Neptune have been there and been ejected, either to infinity or outer Oort cloud. Hard to accommodate a planet X that big in the outer system, but maybe possible.
Some interesting news on debris disks, and possible planets around very young stars.
All very preliminary, but clearly something there that can be pushed on with better data.
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Quote: "Looks like the outer solar system, with late heavy bombardment, would have come together nicely if there was another Neptune out there to begin with."
Now this could really be quite fascinating. I recall reading papers by the likes of Hal Levison where it was argued that the mass of all TNOs, SDOs, and LPCs added added up together cannot be more than a few Mearths at best. A far cry from the predicted 10-30 Mearths postulated to have exited these nether regions in the beginning. Question is what happened to the missing mass (i.e. of these TNos, SDOs, LPCs, etc)? And why are the solar system's outliers like dwarf planet Eris (ex Planet X), Sedna ala 2003 VB12 and CR 105 have such high orbital inclinations of 44.187°, 11.934° and 22.770° respectively?
I have come across a paper by Morbadelli et al., where it was argued that a ~50 MJup rogue BD flyby can account for the perturbed orbits of some of these outer solar system bodies and they even suspect that Sedna could actually be but an extrasolar planetoid captured from this rogue BD. It begets the question i.e. let's assume that they are right, that indeed this BD interloper is the culprit responsible, but what if it wasn't an interloper? What if it was of a lower mass and really but a highly eccentric (0.9 <= eBD <= 0.99), <=20 MJup coeval companion to our Sun or maybe even a captured ultracool VLM substellar companion (given the likely birth of the Sun in an Orion like cluster and the case of B1620-26c, this can't be entirely ruled out right?) with periastron at 100-200 AU instead? The Teff of such an object is likely to be only about ~360° K according to Burrows et al., and if it still around, could be near or at apastron at this moment i.e. almost a light year away. And if this is not enough, if we are still turning up more M Dwarfs from the RECONS project (e.g. http://www.noao.edu/outreach/press/pr06/pr0614.html) and elsewhere in this day and age, how very much more tedious is locating objects with even lower masses and Teffs e.g. BDs with SpTs T and Y?
Gomes et al. (Gomes, R. S., Matese, J. J., Lissauer, J. J., 2006, Icarus, 184, pp. 589-601), likewise have also come to a rather similar conclusion like Levision et. al., albeit one involving even lower masses perturbers and maybe with particular interest and relevance here is that one of the possibilities involves having a Neptune mass planet out at semiminor axis 2000 AU or a Jovian with semiminor axis at 5000 AU could explain the perturbed natured of many of the TNOs.
Refs:
Morbidelli, A., Levison, H. F., 2004, Scenarios for the Origin of the Orbits of the Trans-Neptunian Objects 2000 CR105 and 2003 VB12 (Sedna), AJ, 128, pp. 2564-2576
Burrows, A., Marley, M., Hubbard, W. B., Lunine, J. I., Guillot, T., Saumon, D., Freedman, R.; Sudarsky, D., & Sharp, C., 1997, A Nongray Theory of Extrasolar Giant Planets and Brown Dwarfs, ApJ 491, p.856
Gomes, R. S., Matese, J. J., Lissauer, J. J., 2006, A distant planetary-mass solar companion may have produced distant detached objects, Icarus, 184, pp. 589-601
Links:
http://adsabs.harvard.edu/abs/2004AJ....128.2564M
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WGF-4KGX8CX-…
Steinn:
Wouldn't perturbations caused by a Neptune/Uranus-like planet in the outer system show up, easily?
There are anomalies in all of the hypotheses about formation of the outer planets.
Something has to be postulated that explains the loss of significant planet sizes in the Kuiper Belt. And no one, as far as I know, has provided a reasonable explanation.
Rich Reynolds
Quote: "Looks like the outer solar system, with late heavy bombardment, would have come together nicely if there was another Neptune out there to begin with."
Now this could really be quite fascinating. I recall reading papers by the likes of Hal Levison where it was argued that the mass of all TNOs, SDOs, and LPCs added added up together cannot be more than a few Mearths at best. A far cry from the predicted 10-30 Mearths postulated to have existed in these nether regions i.e. the Edgeworth-Kuiper Belt (EKB), Scattered Disk in the beginning. Question is what happened to the missing mass (i.e. of these TNOs, SDOs, LPCs, etc)? And why do the solar system's outliers like dwarf planet Eris (ex Planet X), Sedna ala 2003 VB12 and CR 105 have such high orbital inclinations (i) of 44.187°, 11.934° and 22.770° respectively? Or why are their orbits so eccentric (e.g. e=0.44177, e=0.855, e=0.798)? Also why the abrupt sharp edge to the Classical EKB at 50 AU? What could have produce it? Could there have been numerous factors at play with regards to these abnormalies? Or could any or all of these abnormalies be the by-products of a stellar flyby, BD or planetary mass (i.e. planemos) interlopers maybe even a Planet X? Why not a distant substellar mass BD common proper motion Solar companion?
I have come across a paper by Morbadelli et al., where it was argued that a ~50 MJup rogue BD flyby can account for the perturbed orbits of some of these outer solar system bodies and they even suspect that Sedna could actually be but an extrasolar planetoid captured from this rogue BD. It begets the question i.e. let's assume that they are right, that indeed this BD interloper is the culprit responsible, but what if it wasn't simply just an interloper? What if it was of a lower mass and really but a highly eccentric (0.9 <= eBD <= 0.99), 13 MJup <= Mbd <=20 MJup coeval substellar mass BD companion to our Sun or maybe even a captured ultracool VLM substellar companion (given the likely birth of the Sun in an Orion like open cluster and the case of B1620-26c, this can't be entirely ruled out right?) with periastron at 100-200 AU instead? The Teff of such an object is likely to be only about ~360° K according to Burrows et al., and if it still around, could be near or at apastron at this moment i.e. almost a light year away. And if this is not enough, if we are still turning up more M Dwarfs from the RECONS project (e.g. http://www.noao.edu/outreach/press/pr06/pr0614.html) and elsewhere in this day and age, how very much more tedious is the task of locating objects with even lower masses and Teffs e.g. BDs with SpTs T and Y?
Gomes et al. (Gomes, R. S., Matese, J. J., Lissauer, J. J., 2006, Icarus, 184, pp. 589-601), likewise have also come to a rather similar conclusion like Levision et. al., albeit one involving even lower masses perturbers and maybe with particular interest and relevance here is that one of the possibilities involves having a Neptune mass planet out at semiminor axis 2000 AU or a Jovian with semiminor axis at 5000 AU could explain the perturbed natured of many of the TNOs.
References:
Morbidelli, A., Levison, H. F., 2004, Scenarios for the Origin of the Orbits of the Trans-Neptunian Objects 2000 CR105 and 2003 VB12 (Sedna), AJ, 128, pp. 2564-2576
Burrows, A., Marley, M., Hubbard, W. B., Lunine, J. I., Guillot, T., Saumon, D., Freedman, R.; Sudarsky, D., & Sharp, C., 1997, A Nongray Theory of Extrasolar Giant Planets and Brown Dwarfs, ApJ 491, p.856
Gomes, R. S., Matese, J. J., Lissauer, J. J., 2006, A distant planetary-mass solar companion may have produced distant detached objects, Icarus, 184, pp. 589-601
Links:
http://en.wikipedia.org/wiki/Eris_(dwarf_planet)
http://en.wikipedia.org/wiki/90377_Sedna
http://en.wikipedia.org/wiki/2000_CR105
http://en.wikipedia.org/wiki/PSR_B1620-26c
http://www.noao.edu/outreach/press/pr06/pr0614.html
The simplest scenario is if any "second Neptune" was ejected to infinity
but there may be room for it out around 10,000+ AU - like the old "Nemesis" models.
Not clear the whole sky has been searched to adequate depth to rule it out.
Current explanations for the dynamical structure of the Kuiper belt are tending to a "stellar flyby" coming within 100 AU of the Sun when it was less than 10 million years old.
Implies the Sun formed in a moderately rich star forming association of maybe few thousand stars. Also broadly consistent with isotope anomalies in meteorite data.
Reynolds and all, you may want to read http://physicsforums.com/showthread.php?t=175508
Thanks, Shaun and Steinn....
(My weekend will be spent reading apparently.)
RR