Quote:
Originally Posted by CraigD
I believe coldcreation is misinterpreting the description of the CMBR as having the spectrum of a black body at about 2.7 K. This characteristic does not imply that the CMBR is currently being emitted by solid, liquid, or gaseous matter with a temperature of 2.7 K. It is simply a convenient way of describing its spectrum with a single numeric value. |
I don't think there is a misunderstanding. We both agree that the CMB is not being emitted by solid, liquid, or gaseous matter with a temperature of 2.7 K. It is a thermal spectrum with black-body form.
Quote:
Originally Posted by CraigD
The description of the temperature of unusual objects such as the “coldest place in the universe” Boomerang Nebula calls for careful consideration of the definition of temperature, the average kinetic energy of the bodies - in the case of a gas like the Boomerang Nebula, atoms - of a system. It’s very low temperature – about 1 K – is calculated by estimating the mass and initial temperature of the outflowing gas that forms it, and dividing by its current, much greater observed volume. It represents the temperature of a small representational volume of space moving at the same velocity as the average of the gas within it – if the entire volume is considered, the temperature is very high – about a million K - due to the great speed of the outflowing gas – about 167000 m/s. (note that, in terms of mass  and velocity  , temperature  is given by  , where  is the Avogadro number,  the gas constant) |
The actual temperature of the cloud itself is speculative in that the velocity of the particles remains unknown. In fact, is speculative that the gas is out-flowing. What is observed it that this reflecting cloud of dust and gas has bipolar quasi-symmetric lobes of material, not that the material is being ejected from a central star. The possibility exists that what is observed is an inflow of gas. In other words, there is no guarantee that a rapid expansion has cooled molecules in the nebular gas.
Generally, out-flowing gas would be quasi-spherical in structure. In this case, an apparently intact spherical star, internally powered by nuclear fusion, appears to be 'ejecting' material along its axis only: something that has no astrophysical explanation. The diffuse bow-tie shape of the Boomerang Nebula makes it very different from other planetary nebulae observed; which normally have gaseous lobes that look more like 'bubbles.' (
Source).
Bipolar outflows are usually seen to occur from both very young stars, protostars, that are in the process of collapsing and forming, as well as from older stars toward the ends of their lives, from bloated red giants. (
Source)
What may actually be occurring is the formation of a star by a cold accreting gas, rather than the formation of a proto-planetary disc through ejection of hot, cooling gaseous material.
The filaments observed in the gas alternatively resemble
Birkeland currents: caused by the movement of a plasma perpendicular to a magnetic field. (See here, for example:
Boomerang Nebula Comes Back—to Plasma. A cold nebula provides evidence of electrical activity at temperatures near absolute zero.).
Quote:
Originally Posted by CraigD
Even if only a small volume of the gas is considered, the temperature may still be higher than given by the first calculation, because individual atoms of the gas in even a small volume may have fairly high relative velocities. A artificially produced BEC requires that nearly all fast-moving atoms in it be slowed or expelled. Though I’ve encountered some discussion of the possibility of unusual low-temperature effects in expanding nebulae such as the Boomerang, such as superconductivity of Bose-Einstein condensation, to the best of my knowledge the idea is very speculative. Although one can make the argument that BECs of very small numbers of atoms may rarely, randomly form in any very low-density gas, I suspect that it’s not a significant effect in objects like protoplanetary nebulae, even very cold ones like the Boomerang. |
I would be interested to find out where you have encountered discussion of the possibility of unusual low-temperature effects in expanding nebulae such as Boomerang, related to superconductivity of Bose-Einstein condensation.
CC
