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jonfr
2007-Nov-07, 02:03 AM
On the web page solstation there is a article that mentions the possibility of a second sol that is bound to our sun by gravity. Is there any update on that information or something new. The information on the suggestion of sol b can be read here (http://www.solstation.com/stars/oort.htm#sol-b).

Nowhere Man
2007-Nov-07, 03:28 AM
Sounds like the Nemesis hypothesis. So far as I know, there is no direct or even indirect evidence that Sol has a remote star-sized companion.

Fred

tony873004
2007-Nov-07, 04:08 AM
Sounds like the Nemesis hypothesis. So far as I know, there is no direct or even indirect evidence that Sol has a remote star-sized companion.

Fred

Not quite Nemesis. It says:

"The hypothesized object appears to have a mass smaller than one controversial definition for brown dwarfs specifying a minimum mass of at least 13 Jupiters"

So it sounds like they're talking about a planet-mass object.

If a planet-mass object exists in a distant orbit even a 13-Jupiter mass object, it is beyond our current ability to detect.

astromark
2007-Nov-07, 05:29 AM
Are we talking of Proxima Centaurus?
Recently I read of some doubt as to its being part of the Alpha Centaurus pair.
Could this be Sol's companion.?
Why do they think there is one?
Are the orbital mechanics of this solar system so out of balance as to require a object of this mass? No. This is speculative nonsense until the object is discovered.

tony873004
2007-Nov-07, 07:09 AM
Are we talking of Proxima Centaurus?
Recently I read of some doubt as to its being part of the Alpha Centaurus pair.
Could this be Sol's companion.?
Why do they think there is one?
Are the orbital mechanics of this solar system so out of balance as to require a object of this mass? No. This is speculative nonsense until the object is discovered.

Proxima Centauri's velocity relative to the Sun is WAY above solar escape velocity for its velocity. It is not bound to the Sun.

But Proxima Centauri's velocity is right around the cut-off point for escape velocity of the Alpha Centauri AB system. Hence there is debate over whether or not it is bound to AC AB. On one hand, something that orbits from Proxima's distance should have been stripped away from the other pair by now. On the other hand, Proxima is too close to the AB pair for it to simply be a coincidence. This creates a paradox.

Just my guess: perhaps binary systems often capture additional but temporary stars. They are lost as easily as they are captured. So Proxima is bound to the AB pair, but only temporarily. And it was captured recently.

Tim Thompson
2007-Nov-07, 07:42 AM
Are we talking of Proxima Centaurus? Recently I read of some doubt as to its being part of the Alpha Centaurus pair.
Are Proxima and Alpha Centauri Gravitationally Bound? (http://adsabs.harvard.edu/abs/2006AJ....132.1995W) Wertheimer & Laughlin, Astronomical Journal 132(5): 1995-1997, November 2006. Abstract: Using the most recent kinematic and radial velocity data in the literature, we calculate the binding energy of Proxima Centauri relative to the center of mass of the Alpha Centauri system. When we adopt the centroids of the observed data, we find that the three stars constitute a bound system, albeit with a semimajor axis that is of order the same size as Alpha Cen AB's Hill radius in the Galactic potential. We carry out a Monte Carlo simulation under the assumption that the errors in the observed quantities are uncorrelated. In this simulation, 44% of the trial systems are bound, and systems on the 1-3 sigma tail of the radial velocity distribution can have Proxima currently located near the apastron position of its orbit. Our analysis shows that a further, very significant improvement in the characterization of the system can be gained by obtaining a more accurate measurement of the radial velocity of Proxima Cen.


Could this be Sol's companion?
No. Even if it is not bound to Alpha-Centauri A&B it is still much too far from the sun for that. It would have to be no more than about 1/3 of its current distance from the sun to be gravitationally bound.


Why do they think there is one? Are the orbital mechanics of this solar system so out of balance as to require a object of this mass?
Well, just follow the Solstation link (http://www.solstation.com/stars/oort.htm#sol-b) and read: "In 1999, U.K. and U.S. astronomers independently reported finding evidence that one or more large planets or brown dwarfs gravitationally bound to our Sun, Sol may be perturbing the orbits of two different groups of long-period comets at the outer reaches of the Oort Cloud into the inner Solar System with the assistance of galactic tidal forces."

Cometary Evidence of a Massive Body in the Outer Oort Clouds (http://adsabs.harvard.edu/abs/1999Icar..141..354M), Matese, Whitman & Whitmire, Icarus 141: 354-366, October 1999. Abstract: Approximately 25% of the 82 new class I Oort cloud comets have an anomalous distribution of orbital elements that can best be understood if there exists a bound perturber in the outer Oort cloud. Statistically significant correlated anomalies include aphelia directions, energies, perihelion distances, and signatures of the angular momentum change due to the Galaxy. The perturber, acting in concert with the galactic tide, causes these comets to enter the loss cylinder—an interval of Oort cloud comet perihelion distances in the planetary region which is emptied by interactions with Saturn and Jupiter. More concisely, the impulse serves to smear the loss cylinder boundary inward along the track of the perturber. Thus it is easier for the galactic tide to make these comets observable. A smaller number of comets are directly injected by the impulsive mechanism. We estimate that the perturber–comet interactions take place at a mean distance of ~25,000 AU. The putative brown dwarf would have a mass of 3/2 MJupiter and an orbit whose normal direction is within 5° of the galactic midplane. This object would not have been detected in the IRAS database, but will be detectable in the next generation of planet/brown dwarf searches, including SIRTF. It is also possible that its radio emissions would make it distinguishable in sensitive radio telescopes such as the VLA.

Arguments for the presence of a distant large undiscovered Solar system planet (http://adsabs.harvard.edu/abs/1999MNRAS.309...31M), J.B. Murray, Monthly Notices of the Royal Astronomical Society 309(1): 31-34, October 1999. Abstract: Aphelion distances of long-period comets show a slight excess around 30000 to 50000 au from the Sun. Positions of cometary aphelia within these distance limits are aligned along a great circle inclined to both the ecliptic and the Galactic plane. This paper examines one of the possible explanations for this non-random clustering: that it is due to orbital perturbations by an undiscovered object orbiting within the above-mentioned distances. A model consistent with the observations gives a retrograde orbit (inclination 120°) for the object with a longitude of the ascending node at 77°+/-13°, a period of 5.8x106 yr and a radius of 32000 au. The same model gives a present position for the undiscovered object of RA 20h 35m, Dec.+5°, with an error ellipse semimajor axis of 14° and a semiminor axis of 7°. The magnitude is likely to be fainter than 23. Such a distant object would almost certainly not remain bound for the age of the Solar system, and recent capture into the present orbit, although also of low probability, remains the least unlikely origin for this hypothetical planet.

The effect on the Edgeworth-Kuiper Belt of a large distant tenth planet (http://adsabs.harvard.edu/abs/2000MNRAS.318..101C), Collander-Brown, Maran & Williams, Monthly Notices of the Royal Astronomical Society 318(1): 101-108, October 2000. Abstract: We investigate the orbital evolution of both real and hypothetical Edgeworth-Kuiper Objects in order to determine whether any conclusions can be drawn regarding the existence, or otherwise, of the tenth planet postulated by Murray. We find no qualitative difference in the orbital evolution, and so conclude that the hypothetical planet has been placed on an orbit at such a large heliocentric distance that no evidence for the existence, or non-existence, can be found from a study of the known Edgeworth-Kuiper Objects.

It would appear that, for the time being, the observational evidence for an additional massive planetary body in the Solar System is unconvincing.


No. This is speculative nonsense until the object is discovered.
Speculation, yes; but there is nothing at all "nonsensical" about it. The dynamic evidence is quite real, even if its interpretation is strained & unconvincing. One should look at the evidence first, and retain the privilege of declaring "nonsense" only after it is determined that such a declaration is warranted.

jonfr
2007-Nov-07, 03:51 PM
Thanks for the information. :)

astromark
2007-Nov-07, 06:24 PM
'Warning' Accepting as true something as yet unfound is just a little odd. Scientifically the argument for objects or matter might be reasonable. We are looking. As to if we find a single object or just many small ones is the question.?
I am not brushing aside what might be. I am suggesting that until we know of this matter we would be fools to assume it is there as a single object. Calculating the mass of the Ort cloud objects is not as simple as you might think. Most of it is small.

Noclevername
2007-Nov-07, 10:04 PM
Basing your "evidence" on the supposed gravitational effects of a planet or star on a group of bodies of unknown number, of unknown mass and unknown distribution is not very knowledgeable.

astromark
2007-Nov-08, 05:27 AM
That is perfectly true... We can not hope to make this decision until much more information is obtained. Its going to be a while.... collecting clues is a tough business.

neilzero
2007-Nov-08, 06:39 PM
We can assume a tenth planet perhaps 2000 times farther from the sun than Earth, but the annomolies of comet paths support this idea poorly. Does assuming a planet passing about 2000 AU from the sun a million years ago match the anomolies significantly? If the temporary planet, is travelling a million kilometers per year, it has traveled one trillion kilometers = 1/10th light year since it's closest approach, a million years ago. Comets perturbed 2000 AU from the sun take many centuries to reach the inner solar system, but perhaps not as long as a million years? Neil