Sol has a binary partner???

That'd be fabulous, if so. And I'd want confirmation ASAP. Discusses precession of the equinox in relation to this theory.



Hmmmmm.

Sol is a variable star (little factoid dropped into this post).

Haven't we all naturally considered Sol as sol-itary? Interesting to think it might actually be a double star.

Hmmh is right - I can see how Sol could be part of a multiple star localised group of stars that are in some sort of locked interaction with each other but looking at the stars we know about makes it seem unlikely. Given that Sol "orbits" the Milky way core every 200-250m years or so a small group with some sort of internal periodic behavior on the scale of 26m years is plausible however a back of the envelope calculation gives me a distance of around 1.75LY as the distance between two Sol masses orbiting each other with a period of 26MY. The problem with that is there isn't anything that big that close - but smaller objects would have that period at a distance of around 1.4LY. Small (<<1 Sol mass) at that range pretty much rules out having any effect on the obects in the Solar System that we are aware of.

Looking at the nearest significant masses - the Rigel Kentaurus system has an aggregate mass of around 2xSol @ 4.3LY so it's too far out to be orbitally linked to Sol.

The book in question though talks about a 24000 year orbital period for this mystery companion which would imply a distance of ~ 1000 AU, or 20-30 times further than Pluto. There could be something out there that's pretty big (but still << 1 Sol mass) that we haven't seen but I don't see how that would have any effect on Earth (at least any effect more significant than the other bodies we already know about) and it seems all a bit "Well so what"? to me.

The proposed link to the precession of the equinoxes and his "Long Year" seemed like a woohoo'ism to me which led me to Amazon which yielded these "Editorial Reviews"


Ah nuff said.

The idea that the Sun might have one small companion star have popped in and out of pop-science fashion a number of times over the last decades.
In almost every version it have been used to reverse engineer various astronomical findings such as the orbits of Uranus and Neptune or for sending comets from the Oort cloud.
Someone scraped off the serial number dusted the old theory off even giving the star a name 'Nemesis' added a doomsday scenario probably to sell a lot of books some years back.
So I am afraid I have to be as pessemistic as helvick, too me it seems once again to be more obout a book the author wants to sell.

But not to be a party crasher: The scenario with a very faint red dwarf or brown dwarf at 1 lightyear or more in one orbit that takes millions of years cant be ruled out.
Yet with all the infrared searches brown dwarfs in the Orion nebula etc, so one object that much closer would be bright as a beacon in comparision with those more distant ones, so the chanse that any such have managed to hide might be quite remote IMHO.

Maybe not entirely, but it has very bad knees.

The original Nemesis hypothesis was that, once every 26 million years, a brown-dwarf companion to the Sun brushes the Oort Cloud, leading to periodic comet showers that are claimed to match periodic extinctions on Earth.

This periodicity requires Nemesis to have an elliptical orbit with a semimajor axis of about one and a half light-years. Since the orbit has to be elliptical (otherwise the comet showers wouldn't be periodic) Nemesis' greatest distance from Sol would have to be greater than that, though.

The problem with this idea is that Alpha Centauri is only about 4 light-years away and we can expect that, from time to time, other stars will get closer. This means that Nemesis' orbit would suffer constant perturbations and, in all likelihood, it would ultimately get ejected from solar orbit.

The other idea of a companion star with a ~25K year orbit is pretty ludicrous as, even if it were a brown dwarf, surely its infrared emissions would have been picked up by now. Besides that, the precession of the Earth's equinoxes has already been adequately explained. The only reason to postulate this type of theory is to sell books to people who line up to believe anything "revolutionary" or "unorthodox".

Yes like Myram says this topics regularly pops in and out of fashion, perhaps because it is also in orbit, with a period of say 10-20 years.

Such a close periodic interacion would explain a strange thing: that orbital variations could create climate changes is known, but it was recently discovered a corelation between the famous 25,000 years climatic cycle and a similar 25,000 cycle of... volcanic activity.


However what could have so much gravitationnal effects on Earth would also seriously disturb our nice arrangement of eight planets with neat circular orbits.

Also it is difficult to believe that a companion star so far than 1 light-year would have remained linked to the Sun for 5 Billion years: there was certainy many much closer star encounters during this time, to break such a link. Unless such a star interaction could place a stable companion in orbit...

At last appears the nature of that companion. Everything star-like would have be found from long (like the white dwarf orbiting Sirius). A brown dwarf or planet is much less heavy, and could disturb the solar system only once at the periastron. But it would disturb it in a very visible way. A black hole or neutron star could significantly interact with the solar system without the need to enter in it, but so close it would be detectable in a way or another, and especially have a strong paralax.

The only thing which could be obscure, transparent and still with a heavy mass would be a gas or dust cloud. (This was discussed here

I would not be so abrupt, but...

It had been suggested that a faraway dwarf star, named "Nemesis", was orbiting the sun, or an unknown "Planet X" somewhere far out beyond the solar system that's disturbing the comets in the distant region called the Oort Cloud and might be possible causes for the 62-million-year extinction cycles that were found in geological formations.

However, it has been shown long ago, that the solar barycentre is not being dragged around with respect to the rest of the cosmos by Planet X.

By means of high-precision pulsar timings, astronomers using the Australia Telescope National Facility pulsar database found no evidence for non-zero acceleration.

The sensitivity achieved by their method is comparable to the acceleration due to a Jupiter-mass planet at 200 AU.
The acceleration method rules out the presence of a distant companion (closer than 300-400 AU).

I wasn't being abrupt, Richard. I was being harsh!

And on second thought, it _was_ uncalled for. I had Hoaglandites in mind when I wrote that, but it wouldn't take a Hoaglandite mentality to get suckered into believing that theory, really.

Far-out theores - a small black hole without any infalling matter, or a big chunk of dark matter.
I do recall that they said that a nearby supernova may have induced the nebula to contract and eventually become our solar system. Black hole predecessor perhaps?

I thought that analysis of the Voyager and Pioneer trajectories has excluded the possibility of any reasonable sized anything out there

Hence my "far-out theory" disclaimer.
I do think astronomers would have found something substantial by now, but then, I've not read a whole lot on this subject.

This topic does seem to reappear every now and then. I originally remember it as being an unnoticed "nearby" white dwarf. Except that anything that close (< 2 ly) would have long ago (in the 1940's or 50's) been identified on sky surveys by its high proper motion or parallax. Then it was a brown dwarf. But now with IR obs, that would shine like a beacon at that distance. Then a naked (no disk) black hole. Depending on where it is in its highly elliptical orbit, it might not be noticed or have a noticable effect on things (like Pioneer or Voyagers, ... or maybe it does... the Pioneer Anomaly? ). Since the periaster only has to barely approach the outer Oort cloud to disturb things there.... that's still quite a distance away.

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

My understanding is that since these are heading out of the solar system in 4 different directions and are now almost 200AU apart that anything like this would by now have been noticed. I believe that the measured Pioneer anomoly is an unexplained acceleration towards the Sun which can not be the result of a dense body in the outer solar system. I dont know how far out a body would need to be or the mass limit that would have made its presence known by now, but 200,000 AU is the outer limit at which anything couild be considered to be gravtitationaly bound to our sun.

I had no bad though! The idea of a dark companion is not exactly a hoaglandite, but some may take it in a hoagland mentality. There is enough matter into this mere forum topic to dismiss the idea of a dark companion.



By the way I learned that Hoagland does not exist it is a CIA plot to raise interest into space funding.

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!!

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.

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.

New article.... http://www.binaryresearchinstitute.org/int...on/binary.shtml

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

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.

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?

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 . . .

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.

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.

Click to view attachmentHere is the article I mentioned a couple of posts ago:

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.

You mean there was at least one giant planet reaching 76AU in the early solar system?

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.

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

[quote name='Myran' date='Apr 27 2006, 05:34 PM' post='52043']
No I mean that Sedna have been closer to the sun earlier.

Whatever event left Sedna in its current orbit must have happened somewhere along that current orbit. That could either be its formation or a perturbation - in either case at least 76AU out.

If theres anything I feel more confident about, then it is that Sedna havnt formed on the orbit if has today.

Today it would be quite odd for one natural object to get into the orbit Sedna have, but theres many things that were different in the early solar system. Then there was a strong solar wind, especially in during the T-tari phase I mentioned. Some astronomers have speculated that there was a magnetic field in the planetary nebula, it should also have contained some gas, then we have a large number of planetesimals with their gravitational force. All could have contributed with drag, fields and gravitation to apply a breaking force on Sedna that else would have become a runaway from the solar system.

So I do in fact agree with you that something did contribute to give Sedna the orbit we see, but I dont want to get into speculation on which force cause it or was the main contributor - I simply dont know.

Finally, the orbit of Sedna are unusual, but not completely unique, asteroid Pallas are one other oddball which have a highly inclined orbit. But a majority of the larger asteroids do have orbits in the ecliptic and only moderately eccentric ones. This are likely caused by the planets and the gravitational pushing and pulling which have put the asteroids in more well behaved orbits.
So to me the odd orbit of Sedna are rather one strong indication that there are no larger objects in that remote part of the solar system.