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Dive into the research topics where Roman Ulrich Sexl is active.

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Featured researches published by Roman Ulrich Sexl.


Earth Moon and Planets | 1971

The directional characteristics of lunar infrared radiation

Roman Ulrich Sexl; Hannelore Sexl; Hanns Stremnitzer; Donald G. Burkhard

A theory of the directional characteristics of the lunar infrared radiation measured by Saari and Shorthill has been derived. This theory is in excellent agreement with experiment at all angles of observation and at all phase angles. The radiation law used to describe the angular dependence of the infrared radiation emitted by a flat element of the lunar surface is 0.85 cosθ + 0.22 cos2θ, where θ is the angle between the surface normal and the direction of observation. This radiation law is subsequently modified by taking into account lunar surface roughness. We assume a surface covered in part with spherical craters of various depth to diameter ratios as a model for the lunar soil. Re-radiation within the craters has been accounted for. Extensive use is made of group theoretical and invariant tensor methods which enable us to show that most of the details of the radiation pattern do not depend on the detailed nature of the surface features assumed, but only on the average surface slope. A best fit to the Saari-Shorthill data has been obtained by assuming 50% of the lunar surface to be covered with craters with a depth to diameter ratio of 1:3, while the remainder of the surface is essentially flat. The mean deviation between theory and experiment is 4K.


Thermal Design Principles of Spacecraft and Entry Bodies | 1969

An exact solution for thermal conduction through a two-dimensional eccentric constriction.

Roman Ulrich Sexl; Donald G. Burkhard

Received October 7, 1968 (not preprinted). Work supported by NASA Contract NAS8-20746, Marshall Space Flight Center, Huntsville, Ala., through PEC Associates, Inc., Louisville, Colo.


Archive | 1979

White dwarfs - black holes : an introduction to relativistic astrophysics

Roman Ulrich Sexl; Hannelore Sexl


Archive | 1975

Weisse Zwerge - schwarze Löcher : Einführung in die relativistische Astrophysik

Roman Ulrich Sexl; Hannelore Sexl


Space Science Reviews | 1981

Book Review - White Dwarfs - Black Holes an Introduction to Relativistic Astrophysics

Roman Ulrich Sexl; Hannelore Sexl; Franco Pacini


Archive | 1981

Nane bianche, buchi neri : l'astrofisica relativistica

Roman Ulrich Sexl; Hannelore Sexl


American Journal of Physics | 1981

The State of the Universe: Wolfson College Lectures 1979 and White Dwarfs–Black Holes: An Introduction to Relativistic Astrophysics

Roman Ulrich Sexl; Hannelore Sexl; Alan Spero


Archive | 1980

Curved Space-Time Near a Neutron Star

Roman Ulrich Sexl; Hannelore Sexl


Archive | 1980

Book-Review - White Dwarfs - Black Holes

Roman Ulrich Sexl; Hannelore Sexl; R. N. Henriksen


Nature | 1980

Book-Review - White Dwarfs - Black Holes - an Introduction to Relativistic Astrophysics

Roman Ulrich Sexl; Hannelore Sexl; John D. Barrow

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