equipotential surfaces

Equipotential surfaces of close binary starclick for a larger image
Equipotential surfaces of close binary star

equipotential surfaces

(ee-kwă-pŏ-ten -shăl, ek-wă-) Imaginary surfaces surrounding a celestial body or system over which the gravitational field is constant. For a single star the surfaces are spherical and may be considered as the contours of the potential well of the star. In a close binary star the equipotential surfaces of the components interact to become hourglass-shaped (see illustration). The surfaces ‘meet’ at the inner Lagrangian point, L1, where the net gravitational force of each star on a small body vanishes; the contour line through this point defines the two Roche lobes. When both components are contained well within their Roche lobes they form a detached binary system. If one star has expanded so as to fill its Roche lobe it can only continue to expand by the escape of matter through the inner Lagrangian point. This stream of gas will then enter an orbit about or collide with the smaller component. The system is then a semidetached binary: dwarf novae, W Serpentis stars, and some Algol variables are examples. When both components fill their Roche lobes, as with W Ursae Majoris stars, they form a contact binary sharing an outer layer of gas. Matter can then eventually spill into space through the outer Lagrangian point, L2 .

References in periodicals archive ?
Etching from drawing by James Clerk Maxwell, Diagram of the Lines of Force and Equipotential Surfaces, plate from A Treatise on Electricity and Magnetism, vol.
James Clerk Maxwell, Plate II, "Lines of Force and Equipotential Surfaces," in A Treatise on Electricity and Magnetism, vol.
Accordingly, the equipotential surfaces of the Earth are curved (Fig.
Where the gravity field is stronger, the distance between the equipotential surfaces is shorter (for example in point A compared to point B on Fig.
Long range interaction of electrostatic potential do not allow equipotential surfaces formation.
Two equipotential surfaces of equal and opposite potentials are thus generated defines the profile of the biconical antenna.
Geopotential numbers are determined in GRS 80 normal field, applying the new European gravity system and evaluating non-linearity of GRS 80 normal field equipotential surfaces (Moritz 1988).
To determine normal height differences of points, it is necessary to evaluate non-paralellity of normal field equipotential surfaces as well as real and normal field non-coincidence.
Normal height difference in LKS 94 (the Lithuanian Coordinate System of 1994) was determined in the GRS 80 normal field, applying the new European gravity system and evaluating the non-linearity of GRS 80 normal field equipotential surfaces (Moritz 1988).