Sol Has A Binary Partner? |
Sol Has A Binary Partner? |
Guest_Richard Trigaux_* |
Sep 17 2005, 07:02 AM
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#16
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QUOTE (RedSky @ Sep 17 2005, 04:12 AM) I've never yet heard of "dark matter" as a possibility. I didn't think true DM could even make "big chunks" since it effectively doesn't interact via any force except gravity. Without electromagnetism, there are no atoms or chemical bonds, and no chunks. -RedSky We yet do not know what is dark matter. We even not know if it is large objetcs or subatomic particules. Some hints were found recently that there would be numerous MACHOS (massive planet-sized or star-sized objects) so that to explain a fair amount of dark matter. The most common size found was half the mass of the Sun, pointing at (likely) very ancient white dwarves, very weak and thus invisible, but very numerous, maybe the second generation of stars. If this is confirmed, we have an explanation of the dark matter which fits within the known frame of physics, astrophysics and cosmology. But others explanations are not yet ruled out, the dark matter could be WIMPS, subatomic particles with no strong interaction and no electromagnetic interaction. The neutrino is the most familiar candidate, but it seems that they are not enough to account for the total dark mass. Neutrino-like particules would be simply in orbit around the galaxy, in balistic ellipses, implying they have speeds in the 200km/s range. But some could have weaker speeds, and orbit around the solar system, or even form gravitationally linked clouds (although elsewhere in this thread any massive object of this kind near the Sun was ruled out by accurate measurements). Ordinary neutral atoms and dust can form gravitationally linked clouds as light as the Earth mass, so why not neutrinos? Eventually WIMPS could have interactions of their own, an equivalent of electromagnetism, indetectable for us, but allowing them to form massive planet-like bodies, and emitting a photon-like radiation also indetectable for us. But this would ruin the standard model of physics and require larger models such as supersymmetry. |
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Sep 19 2005, 12:48 AM
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#17
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Senior Member Group: Moderator Posts: 2262 Joined: 9-February 04 From: Melbourne - Oz Member No.: 16 |
QUOTE (Richard Trigaux @ Sep 17 2005, 05:02 PM) We yet do not know what is dark matter. We even not know if it is large objetcs or subatomic particules. Some hints were found recently that there would be numerous MACHOS (massive planet-sized or star-sized objects) so that to explain a fair amount of dark matter. The most common size found was half the mass of the Sun, pointing at (likely) very ancient white dwarves, very weak and thus invisible, but very numerous, maybe the second generation of stars. If this is confirmed, we have an explanation of the dark matter which fits within the known frame of physics, astrophysics and cosmology. If you beleve standard cosmology (even only a little!) then it is pretty clear that this cannot account for dark matter, which must be non-bayonic. James. -------------------- |
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Oct 5 2005, 03:04 AM
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#18
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Senior Member Group: Members Posts: 1276 Joined: 25-November 04 Member No.: 114 |
New article.... http://www.binaryresearchinstitute.org/int...on/binary.shtml
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Mar 14 2006, 03:43 PM
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#19
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Astrophysics, abstract
astro-ph/0603219 From: Jorge Melendez [view email] Date: Thu, 9 Mar 2006 03:05:17 GMT (24kb) HD 98618: A Star Closely Resembling our Sun Authors: Jorge Melendez (1,2), Katie Dodds-Eden (1), Jose A. Robles (1) (1) RSAA/Mt Stromlo Observatory (Australia), (2) Caltech (USA), UNMSM (Peru) Comments: ApJ letters, in press Despite the observational effort carried out in the last few decades, no perfect solar twin has been found to date. An important milestone was achieved a decade ago by Porto de Mello & da Silva, who showed that 18 Sco is almost a solar twin. In the present work, we use extremely high resolution (R = 10^5) high S/N Keck HIRES spectra to carry out a differential analysis of sixteen solar twin candidates. We show that HD 98618 is the second closest solar twin, and that the fundamental parameters of both HD 98618 and 18 Sco are very similar (within a few percent) to the host star of our solar system, including the likelihood of hosting a terrestrial planet within their habitable zone. We suggest that these stars should be given top priority in exoplanet and SETI surveys. http://arxiv.org/abs/astro-ph/0603219 -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Apr 25 2006, 06:11 PM
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#20
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Is Sedna giving us clues that Sol is not alone?
- Evidence Mounts For Companion Star To Our Sun http://www.spacedaily.com/reports/Evidence...To_Our_Sun.html Newport Beach CA (SPX) Apr 25, 2006 - The Binary Research Institute (BRI) has found that orbital characteristics of the recently discovered planetoid, "Sedna", demonstrate the possibility that our sun might be part of a binary star system. A binary star system consists of two stars gravitationally bound orbiting a common center of mass. -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Apr 25 2006, 07:50 PM
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#21
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Junior Member Group: Members Posts: 45 Joined: 8-August 05 Member No.: 457 |
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Apr 25 2006, 09:26 PM
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#22
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Hum, the orbit of Sedna surly points to the possibility that our sun is rather unique in being a solitary star... How do you figure that? -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Apr 26 2006, 03:34 PM
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#23
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
This is funny it is the method we use to detect planets orbiting around far stars, and now this method is applied to our own star!! I wrote a paper for the BAA Journal in, (correction) February 1974 called titled 'Is the Sun an Astrometric Binary' in which I suggested searching for a solar companion by looking for curvature in the proper motions of nearby stars resulting from acceleration around the barycentre. I was not aware of any follow-up then and it is only now from reading this thread that I discover that pulsar radial velocities have indeed provided useful constraints on the mass and distance of hypothetical companions. Great stuff - but there's still plenty of room out there for substantial (earth-sized, maybe) planets orbiting in the dark . . . |
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Guest_Myran_* |
Apr 26 2006, 07:30 PM
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#24
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It have been suggested that the planetesimals, or building blocs, that crated the solar system were made up of many objects where some were sent into the Sun by near encounters with the larger planet building areas like proto-Jupiter. And some might have been sent out of the solar system altogether.
But isnt it likely that some only were sent into distant and elliptical orbits? And isnt that the kind of orbit we see for Sedna? So I cant see why anyone would claim that the orbit would be any 'evidence' for anything ususual, but rather that it is one expected result of the original planet formation process. |
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Apr 27 2006, 09:48 AM
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#25
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
But isnt it likely that some only were sent into distant and elliptical orbits? And isnt that the kind of orbit we see for Sedna? So I cant see why anyone would claim that the orbit would be any 'evidence' for anything ususual, but rather that it is one expected result of the original planet formation process. The problem is that Sedna's present perihelion is too great for it to be perturbed by the giant planets. If it was flung out something further out must have perturbed it again to stop it falling back in. |
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Apr 27 2006, 12:37 PM
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#26
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
NGarticleSMALL.doc ( 176K )
Number of downloads: 1016
Here is the article I mentioned a couple of posts ago: |
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Guest_Myran_* |
Apr 27 2006, 02:18 PM
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#27
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QUOTE ngunn said: The problem is that Sedna's present perihelion is too great for it to be perturbed by the giant planets. Im sorry if you misunderstood my post, my suggestion was that Senda had been ejected and given the orbit it have after one or several encounters with other objects during the planetary formation process. Some are flung away, while those remains looses energy so they can collide less violently with other bodies and then cling together insetad of simply shatter - which would happen at greater speeds and more random orbits. So the orbits of the giant planets today, and the overall ordered solar system have quite little to do with the violent past. I think Senda are one example of the former kind one that was ejected from the onner parts, and so remain as s remnant of the wild youth of the solar system. |
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Apr 27 2006, 03:46 PM
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#28
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
You mean there was at least one giant planet reaching 76AU in the early solar system?
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Guest_Myran_* |
Apr 27 2006, 04:34 PM
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#29
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No I mean that Sedna have been closer to the sun earlier.
Theres additional hints that this might be the case. The unusual red colour of Sedna came as a suprise, but on the other hand if it have spent quite some time nearer to the sun that fact is less strange - the sun could then have cooked a lot of chemicals on the surface, especially during the intense T-tauri phase. Second, the fact that Sedna lacks a moon have been viewed as a disappointment to some astronomers. Now if Sedna did go trough a close pass of a bigger body, then a moon are not likely to remain gravitionally bound. |
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Apr 27 2006, 05:13 PM
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#30
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Member Group: Members Posts: 156 Joined: 18-March 05 From: Germany Member No.: 211 |
No I mean that Sedna have been closer to the sun earlier. Yes, but current models and simulations of planet formation and migration of the early solar system cannot explain the current orbit of Sedna. I recently read a number of current papers on that topic as preparation for a talk on TNOs. They all conclude that encounters with planets/planetesimals (gravity assists) are not able to get Sedna into an orbit with such a large perhelion. Simulations of close encounters with other stars (several hundred AU), on the other hand, resulted in some objects with Sedna-like orbits. Though, none of the models of the early solar system is currently able to reproduce all aspects of the distribution of TNOs. So there might be processes that can place objects into Sedna-like orbits which are currently not known. I think one process which has not been included into these models is the drag excerted by the myridas of small particles and its consequences. Michael |
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