ABSTRACT
We report the detection of proper motions in [Fe ii] 1.644 µm emission among the southeasternmost features in the Herbig-Haro object complex GGD 37. Imaging observations were made over a period of 5 yr, at epochs 1993.67, 1996.71, and 1998.68, that reveal proper-motion velocities of 400+/-200 km s-1 at GGD 37:W2 and 850+/-200 km s-1 at a newly identified object, designated GGD 37:RWPF 1. We believe the proper-motion velocity of GGD 37:RWPF 1 is the highest found to date for a Herbig-Haro object. The direction of GGD 37:RWPF 1's proper motion is almost due west, away from the nearby young stellar object complex in Cep A East. GGD 37:W2's direction of proper motion is north/northwest, which does not lead back to any of the compact objects in Cep A East.
ABSTRACT
The solvation force between two planar surfaces immersed in a model liquid mimicking water is obtained using Monte Carlo computer simulations and free energy functional theory calculations. When the surfaces are hydrophilic, the solvation force is repulsive, as is the net force, provided the solvent-surface interaction is strong, compared with the surface-surface and solvent-solvent interactions. The range of the surface-solvent interaction is shown to have a profound influence on the resulting solvation force, whereas solvent orientational order is only of minor importance. We conclude that a repulsive force would also be found in a less polar solvent, confined between sufficiently solvophilic surfaces. With hydrophobic surfaces, the solvation force is attractive. The net lowering of solvent density between the surfaces increases the attraction beyond the expected van der Waals interaction. This density depression contribution is substantial even at rather large separations and will be present for all fluids confined between solvophobic surfaces. Our calculations suggest that the famous "hydrophobic force" is often dominated by density depression. Copyright 1997 Academic Press. Copyright 1997Academic Press
