[X] My Assistant

[Palomar]

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.

While the findings in Lost Star are controversial, astronomers now agree that most stars are likely part of a binary or multiple star system. Dr. Richard A. Muller, professor of physics at UC Berkeley and research physicist at Lawrence Berkeley National Laboratory, is an early proponent of a companion star to our sun; he prefers a 26 million year orbit period.

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.

[Jeff7]

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?

[RedSky]

Far-out theores - a small black hole without any infalling matter, or a big chunk of dark matter.

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

[Guest_Richard Trigaux_*]

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.

[jamescanvin]

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.