celeste wrote:Solar,
http://www.nature.com/nature/journal/v4 ... e08515.pdf
That is the perfect analogy. Notice that if ring particles slowly migrate in and strike the leading face of Iapetus, other particles will still continue to stream in and hit Iapetus "broadside", just with lower energy. Iapetus runs into the particles ahead ,while other particles just drift into it's side. An observer on Iapetus should see the same distribution of neutrals from the ring, as we see from the IBEX ribbon. Bright "knot" at end, with lower intensity band across sky.
Also note that they know the ring must be repopulated. Collisions as they think? Or recombination from ring currents, with neutrals continually streaming out?
The rings vertical thickness matches the range of verticle motion of Phoebe. I'll ask, does Phoebe "bob" up and down as it orbits Saturn? Or does it spiral around the surface of the ring? Is this last idea at least testable, since we know the ring's thickness, and how long it takes for Phoebe to cross it, we should be able to compute and detect radial velocity changes for Phoebe if it does spiral around the ring?
StefanR wrote:This can be seen in much higher resolution in this article:
Structural details of the Orion Nebula - Detection of a network of stringlike ionized features
Especially at page 6 and 7, but there is some more info in there that seems relevant to the present discussion.
Birkeland currents follow magnetic field lines, drawing ionized gas and dust from their surroundings and then "pinching" it into heated blobs called plasmoids. - TPOD: Solar Siesta
celeste wrote:It's interesting that in the link by StefanR, "Protoplanetary Disks" by Wilner, that they are so sure they are looking at planet forming disks. They don't see any evolutionary trends with stellar age, and there are no transitional objects. In other words, nothing bigger than rocks, and even those don't get bigger as stars get older. It's just that the disks have all the properties to fit their theories of how planets are built, but none are actually seen building those planets.
Now the higher temperatures in the upper disk, and the evacuation of dust from the core, are effects we expect with electric currents. Most interesting is that the disks disappear with age (remember they don't see planets forming,but the disks diminish significantly between 3 and 5 Myr). We know that what the mainstream sees as age is really current flow, and stars can get "younger",(i.e.,as seen in records of Sirius changing from red to blue). They see younger stars with more disk material. We read that as stars with greater current flow have more disk material. Again, this is what we expect, since more current means also more recombination and ejection of neutral dust radially from the current filament.
… in light of this study and that in SMC12, it is likely that the true nature of many or all of these objects has been misunderstood, and that some (or even all) of the previously classified proplyds in Carina, especially those which are significantly larger in size than the Orion proplyds, are really frEGGs. - Are Large, Cometary-Shaped Proplyds really (free-floating) EGGs
Figure 10 shows dust emission 0.85 mm wavelength from the “integral filament” associated with Orion Molecular Cloud 1 (OMC-1; Johnstone & Bally 1999). In this image, a bright elongated hub extends NS for about 0.3 pc and radiates four filaments to the west, three to the north, and an uncertain number to the east and south, including the Orion “bar” in the south. Johnstone & Bally (1999) state that OMC-1 radiates “at least a dozen dusty filaments.” The four most distinct filaments to the west have approximately equal spacing and are nearly parallel where they join the hub. Within 0.5 pc radius, there are approximately 400 YSOs (Hillenbrand & Hartmann 1998) and the peak gas column density is about 1023 cm–2 (Bally et al. 1987). The gas column density and number of associated stars are much greater than in the nearby young stellar groups of Table 1 and Figures 1-9.
a sinuous filament of cosmic dust more than ten light-years long. In it, newborn stars are hidden, and dense clouds of gas are on the verge of collapsing to form yet more stars
The red filaments stretching across this image denote the presence of polycyclic aromatic hydrocarbons. These organic molecules, comprised of carbon and hydrogen, are excited by surrounding interstellar radiation and become luminescent at wavelengths near 8.0 microns. The complex pattern of filaments is caused by an intricate combination of radiation pressure, gravity and magnetic fields. The result is a tapestry in which winds, outflows and turbulence move and shape the interstellar medium. [..]
Perhaps the most fascinating feature in this image is a long and shadowy linear filament extending towards the 10 o'clock position of DR21. This jet of cold and dense gas, nearly 50 light-years in extent, appears in silhouette against a warmer background. This filament is too long and massive to be a stellar jet and may have formed from a pre-existing molecular cloud core sculpted by DR21's strong winds. Regardless of its true nature, this jet and the numerous other arcs and wisps of cool dust signify the interstellar turbulence normally unseen by the human eye.
The image shows how the raw material from which stars form is organised in tangled nests as well as dense, ridge-like filaments. The white flecks that dot the clouds and filaments are the seeds of future stellar generations.
Abstract:
The recent evidence of cloud-anchoring galactic magnetic fields motivates us to study the link between the Galactic fields and the ubiquitous filamentary structures of molecular clouds. The orientation of filamentary molecular clouds in the Gould Belt and their magnetic fields are studied using dust extinction maps and optical stellar polarimetry data. These filaments are a few to tens of parsecs long and many have parallel and/or perpendicular neighbor filaments. This cannot be explained by shocks due to stellar winds or isotropic super-Alfvenic turbulence. More interestingly, we found that the filaments tend to orient either along or perpendicular to the magnetic fields. Most previous studies recognize that strong magnetic fields can guide gravitational contraction and result in filaments perpendicular to the magnetic fields, but few appreciate the fact that fields can also channel sub-Alfvenic turbulence to form filaments aligned with the fields. Dynamically dominant magnetic fields thus can readily explain the two types (parallel and perpendicular) of field-filament configurations we observed. We further analytically show that, assuming virial equilibrium, filaments parallel to fields should have higher star formation efficiency than the other type of filaments à a fact which agrees with observations.
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