Missing Mass.

[BlameTheEx]

Is the Missing mass necessarily exotic?

Here is evidence that, some, perhaps a large fraction, up to 35%, of the missing mass is white dwarfs.

http://news.bbc.co.uk/1/hi/sci/tech/1236460.stm

or in a bit more detail here:

http://www.sciforums.com/showthread....;threadid=2758

Sadly only nearby white dwarfs can be detected. They just don't give out much light.

Regarding not just white dwarfs, but largish, but dim, stellar objects in general. Up to 50% of the local missing mass may be accounted for:

http://www.llnl.gov/llnl/06news/News...-01-12-02.html

Some of the remainder could be gas, but not much because large clouds of gas block out starlight. We can give reasonably accurate upper limits to the amount of gas in a galaxy. But this doesn't take into account objects larger than single atoms, but smaller than planets. Rocks or even dust don't block much light for their mass when compared to gas. The amount of light blocked is proportional to total mass, but inversely proportional to average diameter. Make them large enough, and we can't detect them by simple dimming of starlight. Make them small enough and we can't detect them by microlensing events*. There is a large range of sizes in between, that would be effectively undetectable, except as meteorites and the like. By direct observation, we are left with the problem of trying to extrapolate the missing mass from the mass of small bodies in our solar system. Not a viable extrapolation, as we need to find their prevalence in interstellar space.

Still, it may be possible to calculate, or at least hazard a guess for such matter. If the mass of up to 35% of the missing mass is in the form of white dwarfs, then where is the matter lost as planetary nebulae? This should be in the form of grains of carbon and silicon, or in the case of more massive stars, iron.

http://www.astronomynotes.com/evolutn/s6.htm

I am contending that the bulk of Dark matter may be in the form of dust or rocks that condensed near the surface of ordinary stars during their Red Giant stage, and then was ejected into space as Planetary Nebulae when they were transformed into white dwarfs.

Does anybody have a method of ruling this possibility out?

*The MACHO group rules out the hypothesis that 20% or more of the halo mass is made of objects with mass less than about 0.03 Msun. (As long as the mass of these objects is at least 0.000001 Msun. http://zebu.uoregon.edu/~soper/Mass/macho.html

[Tormod]

I wrote a hypography about "missing matter" a while back. The first half of the links are dead now but the rest actually work:

http://www.hypography.com/topics/missingmatter.cfm