Author name code: vandehulst ADS astronomy entries on 2022-09-14 author:"Van de Hulst, Hendrik C." ------------------------------------------------------------------------ Title: Radio Astronomy Authors: van de Hulst, H. C. Bibcode: 2016raas.book.....V Altcode: Part I. Spectral Line Investigations; Part II. Point Sources; Part III. Galactic Structure and Statistical Studies of Point Sources; Part IV. The Quiet Sun; Part V. The Active Sun; Part VI. Meteors and Planets. Title: Reciprocity relations in radiative transfer by spherical clouds. Authors: van de Hulst, H. C. Bibcode: 2000JQSRT..64..151V Altcode: Time reversal i.e., the replacement of sources by detectors and conversely, leads in any configuration of light scattering particles to mutually reciprocal problems, which have essentially the same solution. This principle is applied to a set of problems with spherically symmetric radiation fields in a homogeneous spherical cloud. Internal or external sources and detectors are permitted. The individual scatterers may have arbitrary albedo α and an arbitrary phase function. The optical depth R along the radius of the cloud is also arbitrary. Each function belonging to a particular source-detector combination is defined as a quantity measurable in a fictitious experiment. The principle of detailed balancing then is used to establish their reciprocity relations. Additional inter-relations are based on the conservation of energy and on volume integration. The relations permit surprising checks on analytical, numerical, or graphical results cited from papers treating very diverse problems. A set of examples for isotropic scattering is examined in detail and shows excellent agreement throughout. Among the possible extensions is a theorem on a homogeneous cloud of arbitrary shape with arbitrary phase function; this theorem relates the radiation field arising from uniform external illumination to the radiation field arising from uniformly embedded sources. Title: Roaming Through Astrophysics Authors: van de Hulst, H. C. Bibcode: 1998ARA&A..36....1V Altcode: When looking over my past career, it strikes me that so little of it was planned. Surely, the plans for the next weeks and months usually went smoothly ahead. But on a five-year perspective, I see a radically different pattern. Invariably some major turn has taken place, which seemed utterly unpredictable. The reasons are many. Accidental circumstances, new formal tasks or challenges, and often the well-timed advice of a good friend have been instrumental in bringing these changes about. Both sudden and gradual shifts occurred. In the following lines, I try to relate some of these events, which helped shape my professional life. Title: COSPAR's First Years: A Personal View Authors: van de Hulst, H. C. Bibcode: 1998fyc..conf....5V Altcode: No abstract at ADS Title: Molecules in astrophysics half a century ago. Authors: van de Hulst, H. C. Bibcode: 1997IAUS..178...13V Altcode: 1996IAUS..178...13V No abstract at ADS Title: Scaling Laws in Multiple Light Scattering under very Small Angles. (Karl Schwarzschild Lecture 1995) Authors: van de Hulst, H. Bibcode: 1996RvMA....9....1V Altcode: No abstract at ADS Title: Herinneringen aan Chandrasekhar. Authors: van de Hulst, H. C. Bibcode: 1995Zenit..22..518V Altcode: No abstract at ADS Title: Multiple scattering metamorphosis of a non-Gaussian single-scatter phase function Authors: Joelson, Brad D.; Kattawar, George W.; van de Hulst, Hendrik C. Bibcode: 1994SPIE.2258..234J Altcode: Pulse broadening due to multiple scattering has long been of fundamental importance in the study of laser pulse transmission through the ocean as well as other diverse areas of science such as astrophysics, meteorology, and medical physics. We have used a Monte Carlo simulation to investigate the spatial and temporal spreading of a pulse (`pulse stretching') as it propagates through a medium due to small angle multiple scattering as described by van de Hulst and Kattawar. We show the transformation of single scatter distributions into those predicted by the central limit theorem. We also derive the scattering property of the medium finding a simple relation between the phase function and the scattering parameter which connects the single scatter mean square scattering angle, <(Theta) 2>, and the multiple scatter expectation value, <(Theta) 2>, along with well defined limits of validity of the present theory in terms of the basic scattering parameters of the medium. Title: Jan Hendrik Oort (1900 - 1992). Authors: van de Hulst, H. C. Bibcode: 1994QJRAS..35..237V Altcode: 1994QJRAS..35..237. No abstract at ADS Title: Cosmical Aerodynamics - Why was it so Difficult? Authors: van de Hulst, H. C. Bibcode: 1994Ap&SS.216....1V Altcode: An historical perspective of research in the area of cosmic gas dynamics is presented. Topics covered include the following: magnetohydrodynamic waves; shocks and other fronts; numerical solutions; and turbulence. Title: Space Science Beyond the Solar System Authors: van de Hulst, H. C. Bibcode: 1993SSRv...65..201V Altcode: No abstract at ADS Title: Two great astrophysicists: some personal reflections. Authors: van de Hulst, H. C. Bibcode: 1992atc..book....1V Altcode: The author presents some personal reflections on Pikel'ner and Shklovsky. Title: Accurate eigenvalues and exact extrapolation lengths in radiative transfer. Authors: van de Hulst, H. C.; Stark, R. Bibcode: 1990A&A...235..511V Altcode: This paper points out a close connection between two separate problems of radiative transfer with isotropic scattering. First, the eigenvalues ηm(b) of the Milne operator in a plane-parallel slab or a spherical cloud with optical thickness b are transformed in a manner permitting extremely accurate graphical interpolation. Secondly, the extrapolation length z(a) in a semi-infinite atmosphere is discussed for generative media (a > 1) and for absorbing media (a < 1) with the conservative case (a = 1) as their common limit. It is shown that the limiting curve for m → ∞ in the first problem follows from the rigorous solution of the second problem. The properties of z(a) are established in several ways: analytically by classical theory dating back to Davison (1946), numerically, and by expansion in powers of (1-a). Definite integrals representing the values for fixed a and the first three expansion coefficients are derived and computed. The values found for a > 1 from the slab eigenvalues, and for a < 1 via the H-functions, join together in a smooth curve. Suggestions for a generalization of the presented theory to anisotropic scattering are made. Title: The DIM Past of Dusty Space Authors: van de Hulst, H. C. Bibcode: 1989eidr.proc....1V Altcode: No abstract at ADS Title: Diffuse Reflection from a Spherical Interstellar Dust Cloud Authors: van de Hulst, H. C. Bibcode: 1989eidr.proc..275V Altcode: No abstract at ADS Title: Radiative transfer in a spherical dust cloud. II - Asymptotic form of the reflection function for isotropic scattering Authors: van de Hulst, H. C. Bibcode: 1988A&A...207..182V Altcode: The preparatory part of this paper deals with radiative transfer in a homogeneous spherical cloud with isotropic scattering and an arbitrary optical depth r along the radius. The main part derives the terms proportional to r-1 which form the asymptotic corrections to the reflection against and diffusion into a semi-infinite medium. The asymptotic form of the input-output function is expressed by means of a linear differential operator L with respect to μ, the cosine of the angle of incidence or emergence. Title: Radiative transfer in a spherical dust cloud. I - Exact results for isotropic scattering Authors: van de Hulst, H. C. Bibcode: 1987A&A...173..115V Altcode: Expressions are derived for the penetration of diffuse starlight into a spherical interstellar dust cloud and the diffuse reflection from the same cloud - assuming isotropic scattering - based on exact radiative transfer equations. An old mapping theorem is used, stating that the Milne equation for a homogeneous slab of isotropic scatterers with albedo 'a' and its equivalent for a homogeneous spherical cloud have such forms that any symmetric solution in a sphere of optical radius r can be rigorously mapped on an antisymmetric solution in a slab of optical thickness b equals 2r. Procedures are outlined for computing by means of the mapping theorem the full radiation density in the sphere and the spherical reflection function and its moments, using available analytical and numerical results for slabs. A surprising result is that the biomoments of the reflection function of the sphere, including the Bond albedo, are expressed exactly in terms of the well-studied moments of the X- and Y-functions for the slab. Title: Interrelations for the elements of a general scattering matrix. Authors: Hovenier, J. W.; van de Hulst, H. C.; van der Mee, C. V. M. Bibcode: 1986NAC....41...42H Altcode: No abstract at ADS Title: Conditions for the elements of the scattering matrix Authors: Hovenier, J. W.; van de Hulst, H. C.; van der Mee, C. V. M. Bibcode: 1986A&A...157..301H Altcode: A study is made of general conditions for the 16 elements of the scattering matrix that transforms the Stokes parameters of the incident wave into those of the scattered wave. A number of relations is derived for scattering by one particle of arbitrary size, shape and composition. In this case a complete set of nine independent equations is found. Several methods are described to obtain inequalities for the elements of the scattering matrix for an assembly of particles. A selection of these inequalities is explicitly derived and discussed. Title: Grains - What do we know? Authors: van de Hulst, H. C. Bibcode: 1986ASSL..124..161V Altcode: 1986lodm.conf..161V The evolution of various models and observational techniques for detecting the physical characteristics of interstellar grains are summarized. A critical examination is given to phrases such as 'dust', the 'interstellar medium', the H II region, etc., that are routinely applied in descriptions of grains. Possible interpretations of extinction data for grains are discussed, noting the inaccuracies that are introduced by using light from a background star whose distance and spectra cannot be well characterized. The albedo of the grain wisps must be treated as an unknown, and the bases for all models must reside on the size and composition of typical grains of a given cloud. Observational targets which would permit derivation of the critical parameters for modeling the grains are briefly considered. Title: Op het spoor van de 21 cm lijn. Authors: van de Hulst, H. Bibcode: 1986Zenit..13..254V Altcode: No abstract at ADS Title: Book-Review - Multiple Light Scattering Tables Formulas and Applications Authors: van de Hulst, H. C.; Roberge, W. G. Bibcode: 1985SSRv...41R.204V Altcode: No abstract at ADS Title: Interrelations for the Elements of the Scattering Matrix Authors: Hovenier, J. W.; van de Hulst, H. C.; van der Mee, C. V. M. Bibcode: 1985LPICo.569...12H Altcode: Light scattered by molecules and particulate matter in planetary atmospheres was analyzed. The 4x4 scattering matrix that transforms the Stokes parameters of the incident beam into those of the scattered beam is discussed. Elementary methods are described to obtain interrelations for the 16 elements of the scattering matrix, when light is scattered by a particle of arbitrary size, shape and composition or by a collection of such particles. The implications of the results for the interpretation of polarimetric data of planets with an atmosphere are outlined. Title: Book-Review - the Early Years of Radio Astronomy - Reflections Fifty Years after Jansky's Discovery Authors: Sullivan, W. T., III; van de Hulst, H. C. Bibcode: 1984SSRv...39..218S Altcode: No abstract at ADS Title: Book-Review - Guidance and Control 1983 Authors: Brinkman, A. C.; Hovenier, J. W.; Wittenberg, H.; Friedjung, Michael; 't Hooft, G.; Dworetsky, M. M.; Danziger, I. J.; van de Hulst, H. C.; Zimmerman, J. T. F.; Fárník, František; Doom, Cl.; Schuurmans, C. J. E.; Valníček, B.; van Ingen, J. L.; van Konijnenburg, R.; Schuiling, R. D.; Millman, Peter M.; Nordlund, Åke; Maeder, André; Habing, H. J.; Dachs, J.; Kleczek, J.; Wakker, K. F. Bibcode: 1984SSRv...39..215B Altcode: No abstract at ADS Title: Nederland in de ruimte. Authors: van de Hulst, H. C. Bibcode: 1984Zenit..11..292V Altcode: No abstract at ADS Title: Europa bouwde supercamera voor Space Telescope. Authors: van de Hulst, H. C.; Kamperman, T. M. Bibcode: 1984Zenit..11..452V Altcode: No abstract at ADS Title: Nanohertz astronomy Authors: van de Hulst, H. C. Bibcode: 1984eyra.book..385V Altcode: The paper is an attempt at what with a sophistication understandable to radio astronomers might be termed nanohertz astronomy: the art of registering the coming and going of astronomical convictions in periods of the order of 109 seconds = 30 years. Title: Book-Review - Oort and the Universe Authors: van Woerden, H.; Brouw, W. N.; van de Hulst, H. C.; Paul, E. R. Bibcode: 1982JHA....13..141V Altcode: No abstract at ADS Title: Book-Review - Oort and the Universe Authors: van Woerden, H.; Brouw, W. N.; van de Hulst, H.; Davies, R. D. Bibcode: 1982JBAA...92..150V Altcode: No abstract at ADS Title: 1945, The Origin of Radio Waves from Space Authors: van de Hulst, H. C. Bibcode: 1982cra..book..302V Altcode: No abstract at ADS Title: Book-Review - Oort and the Universe Authors: van Woerden, H.; Brouw, W. N.; van de Hulst, H. C.; Abhyankar, K. D. Bibcode: 1981BASI....9..333V Altcode: No abstract at ADS Title: Book-Review - Oort and the Universe Authors: van Woerden, H.; Brouw, W. N.; van de Hulst, H. C.; Tayler, R. J. Bibcode: 1981Obs...101...88V Altcode: No abstract at ADS Title: Book-Review - Oort and the Universe Authors: van Woerden, H.; Brouw, N.; van de Hulst, H. C. Bibcode: 1981JBAA...91..302V Altcode: No abstract at ADS Title: Light scattering by small particles Authors: van de Hulst, H. C. Bibcode: 1981lssp.book.....V Altcode: The measurement of light scattering of independent, homogeneous particles has many useful applications in physical chemistry, meteorology and astronomy. There is, however, a sizeable gap between the abstract formulae related to electromagnetic-wave-scattering phenomena, and the computation of reliable figures and curves. Dr. van de Hulst's book enables researchers to bridge that gap. The product of twelve years of work, it is an exhaustive study of light-scattering properties of small, individual particles, and includes a survey of all the relevant literature. Beginning with a broad overview of basic scattering theory, Dr. van de Hulst covers the conservation of energy and momentum; wave propagation in vacuum and in a medium containing scatterers; and polarized light and symmetry relations. The heart of the book is devoted to the rigorous scattering theory for spheres of arbitrary size (Mie theory) and to various modes of approximation such as the Rayleigh-Gaas approximation, the perfect reflection approximation, the geometrical-optics approximation, and others. Methods of computation are given with respect to different kinds of particles, bodies and phenomena: particles small or very large compared to the wavelength, absorbing and nonabsorbing spheres, water drops, circular cylinders, edge phenomena and surface waves, and many others. In the last part, the author covers the use of scattering and extinction experiments as a practical tool, including applications in chemistry, meteorology and astronomy. This book's comprehensive, lucid coverage of the field makes it a valuable source for all those interested in light-scattering theory. It is absolutely essential for researchers needing to employ light-scattering measurements, and its republication will be welcomed especially by those who have found this necessary source difficult to obtain. Over 400 references. 46 tables. 59 graphs. Subject and name indexes. 44 illustrations. Title: Book-Review - Oort and the Universe Authors: van Woerden, H.; Brouw, W. N.; van de Hulst, H. C.; Perek, L. Bibcode: 1981BAICz..32..318V Altcode: No abstract at ADS Title: Book-Review - Oort and the Universe Authors: van Woerden, H.; Brouw, W. N.; van de Hulst, H. C. Bibcode: 1981JHA....12...73V Altcode: No abstract at ADS Title: Book-Review - Multiple Light Scattering - VOL.1 Authors: van de Hulst, H. C. Bibcode: 1981Sci...211.1458V Altcode: No abstract at ADS Title: Book-Review - Oort and the Universe Authors: van Woerden, H.; Brouw, W. N.; van de Hulst, H. C. Bibcode: 1981S&T....61..440V Altcode: No abstract at ADS Title: Book-Review - Multiple Light Scattering / VOLS.1&2 Authors: van de Hulst, H. C. Bibcode: 1981S&T....62...61V Altcode: No abstract at ADS Title: Oort and the Universe: A Sketch of Oort's Research and Person Authors: van Woerden, H.; Brouw, W. N.; van de Hulst, H. C.; Arp, Halton Bibcode: 1981PhT....34g..62V Altcode: No abstract at ADS Title: Book Review - Oort and the Universe Authors: van Woerden, H.; Brouw, W. N.; van de Hulst, H. C.; Wallenquist, A. Bibcode: 1981SSRv...28..117V Altcode: No abstract at ADS Title: Book-Review - Oort and the Universe Authors: van Woerden, H.; Brouw, W. N.; van de Hulst, H. C.; Richter, G. A. Bibcode: 1981AN....302..256V Altcode: No abstract at ADS Title: Book-Review - Multiple Light Scattering Authors: van de Hulst, H. C.; Mukai, S. Bibcode: 1981SSRv...28..451V Altcode: No abstract at ADS Title: Book-Review - Oort and the Universe Authors: van Woerden, H.; Brouw, W. N.; van de Hulst, H. C.; Whitney, C. A. Bibcode: 1981S&T....62..149V Altcode: No abstract at ADS Title: Multiple light scattering. Tables, formulas and applications Authors: van de Hulst, H. C. Bibcode: 1980mlst.book.....V Altcode: No abstract at ADS Title: The faint object camera for the space telescope Authors: Macchetto, F.; van de Hulst, H. C.; di Serego Alighieri, S. Bibcode: 1980ESASP1029.....M Altcode: 1980STIN...8114937M; 1980focs.book.....M No abstract at ADS Title: Multiple light scattering. Vols._1_and_2. Authors: van de Hulst, H. C. Bibcode: 1980mlsv.book.....V Altcode: No abstract at ADS Title: Models for interpreting the diffuse galactic light. Authors: Bastiaansen, P. A.; van de Hulst, H. C. Bibcode: 1977A&A....61....1B Altcode: The stars which act as primary light sources have a wider distribution perpendicularly to the galactic plane than the dust which causes the diffuse galactic light. This situation is approximated by a model in which a fraction F of the starlight is distributed in proportion to the dust and a fraction 1-F illuminates the dust layer from outside. Computations of the midlayer distribution of diffuse light with latitude are made for various combinations of the single-scattering albedo a and the asymmetry factor g. Curves with different F can in practice be matched if a or g are adjusted. Earlier analyses of observed data based on a model with F = 1 may have led to an underestimate of a and/or g. Title: Book Review: Light scattering in planetary atmospheres. V.V. Sobolev. Pergamon Press, Elmsford, N.Y., 1975.256 pp. $25.00. Authors: van de Hulst, H. C. Bibcode: 1977Icar...32..130V Altcode: No abstract at ADS Title: Hybrid Methods are Helpful Authors: van de Hulst, H. C. Bibcode: 1977NASCP...4....1V Altcode: 1977NASCP.004....1V No abstract at ADS Title: The spherical albedo of a planet covered with a homogeneous cloud layer. Authors: van de Hulst, H. C. Bibcode: 1974A&A....35..209V Altcode: The similarity rules valid for reflection against planetary cloud layers make it possible to transform the set of parameters a (albedo for single scattering), g (asymmetry factor for single scattering), and b (optical thickness) in such a manner that the numerical results remain about the same. Three forms of such rules, which coincide for nearly-conservative scattering, are explained and a preference is expressed for one of them, in which the parameter s is kept invariant. The numerical test on the spherical albedo A* of a homogeneous semiinfinite atmosphere with Henyey-Greenstein scattering confirms that A* may be expressed as a simple function of s alone, with deviations reaching at most 0.002 for any set of parameters (a, g). Such a close similarity cannot be found for the plane albedo. Title: Where is the Interstellar Medium? Authors: van de Hulst, H. C. Bibcode: 1974ASIC....6....1V Altcode: 1974inme.conf....1V No abstract at ADS Title: A Quick Review of Interstellar Grains Authors: van de Hulst, H. C. Bibcode: 1973IAUS...52..569V Altcode: No abstract at ADS Title: Interstellar dust and related topics. Symposium no. 52, held at the State University of New York at Albany, Albany, N.Y., U.S.A. Authors: Greenberg, Jerome Mayo; van de Hulst, Hendrik Christoffel Bibcode: 1973IAUS...52.....G Altcode: 1973QB791.I57...... No abstract at ADS Title: Cosmic-ray Electrons Authors: van de Hulst, H. C. Bibcode: 1972QJRAS..13...10V Altcode: No abstract at ADS Title: Some Problems of Anisotropic Scattering in Planetary Atmospheres Authors: van de Hulst, H. C. Bibcode: 1971IAUS...40..177V Altcode: No abstract at ADS Title: Spectral Analysis of Gamma Rays with the Cos-B Satellite. The Caravane Collaboration Authors: van de Hulst, H. C.; Scheepmaker, A.; Swanenburg, B. N.; Pfeffermann, H. A.; Mayer-Hasselwander, H. A.; Pinkau, K.; Rothermel, H.; Schneider, H.; Voges, W.; Labeyrie, J.; Keirle, P.; Paul, J.; Bellomo, G.; Bignami, G.; Boella, G.; Scarsi, L.; Pearce, G. W.; Hutchinson, A. J.; Ramsden, D.; Wills, R. D.; Wright, P. J. Bibcode: 1971IAUS...41...37V Altcode: No abstract at ADS Title: Multiple scattering in planetary atmospheres. Authors: van de Hulst, H. C. Bibcode: 1971JQSRT..11..785V Altcode: No abstract at ADS Title: The Spectrum of the Anisotropic Transfer Equation Authors: van de Hulst, H. C. Bibcode: 1970A&A.....9..366V Altcode: The discrete values of , for which the equation of transfer in a homogeneous medium with an arbitrary phase function has a solution proportional to exp ( ), where T is optical depth, are studied. Various forms of the characteristic equation, from which ib can be solved, are given. The simple relation g ( 1) 0 for n Co, where g (x) are the Ku er polynomia, is recommended for practical computation. The relation by which the albedo for simple scattering, w0 = a, depends on IC when the form of the scattering pattern is given, is derived both for linearly anisotropic scattering (N = 1) and for the Henyey-Greenstein scattering functions. Knowledge of the multiple values of IC for one a, which may be read from the graphs presented, is helpful in estimating the domain of practical validity of the diffusion approximation. Title: High-order Scattering in Diffuse Reflection from a Semi-infinite Atmosphere Authors: van de Hulst, H. C. Bibcode: 1970A&A.....9..374V Altcode: An asymptotic formula representing the terms with a relative error 0 (n- 8) is found for the radiation intensity reflected from a semi-infinite atmosphere after n successive scatterings. The method, valid for an arbitrary phase function, is to transform a power series in Ic, the diffusion exponent, into one in t = (1 - a)118 and then into one in a, the albedo for single scattering. Four examples, including isotropic and highly anisotropic scattering, show the method to be accurate and convenient. If exact values for the orders n = 1 to 6 are known, values for all higher orders can be estimated to within a percent by this method. Title: Reduction to H-functions in Radiative Transfer with a General Anisotropic Phase Function Authors: van de Hulst, H. C. Bibcode: 1970A&A.....9..359V Altcode: The solution of the diffusion problem in an unbounded homogeneous medium, containing the KuAcer polynomials, and the solution of the reflection function against a semi-infinite atmosphere, containing the Busbridge polynomials and the H4unction, are reviewed. It is shown that the solution of the Milne problem for non-conservative scattering is expressible in the same polynomials, the characteristic root and the H-function The derivation is simple with the help of a new integral containing a combination of these polynomials and the H-function. Some additional constants and the transition to conservative scattering are discussed. In spite of the simplification reached in this paper, the reduction to H-functions is not recommended as a practical method if the phase function contains Legendre polynomials of large order. Title: Search for Galactic γ-RAYS with Energies Greater than 500 MeV on Board OGO-5 Authors: Bleeker, J. A. M.; Burger, J. J.; Deerenberg, A. J. M.; van de Hulst, H. C.; Scheepmaker, A.; Swanenburg, B. N.; Tanaka, Y. Bibcode: 1970IAUS...37..297B Altcode: No abstract at ADS Title: Review of Cosmical Gas Dynamics Authors: van de Hulst, H. C. Bibcode: 1970IAUS...39....3V Altcode: No abstract at ADS Title: Interstellar Grains Authors: van de Hulst, H. C. Bibcode: 1970saac.book..321V Altcode: No abstract at ADS Title: Time variations in the cosmic ray electron spectrum above 500 MeV Authors: Bleeker, J. A. M.; Burger, J. J.; Deerenberg, A. J. M.; van de Hulst, H. C.; Scheepmaker, A.; Swanenburg, B. N.; Tanaka, Y. Bibcode: 1970ICRC....1..209B Altcode: 1970ICRC...11a.209B No abstract at ADS Title: Interstellar Extinction (introductory Lecture) Authors: van de Hulst, H. C. Bibcode: 1970IAUS...36...23V Altcode: No abstract at ADS Title: The cosmic ray electron spectrum between 0. 5 and 10 GeV observed on board OGO-5 Authors: Bleeker, J. A. M.; Burger, J. J.; Deerenberg, A. J. M.; van de Hulst, H. C.; Scheepmaker, A.; Swanenburg, B. N.; Tanaka, Y. Bibcode: 1970ICRC....1..217B Altcode: 1970ICRC...11a.217B No abstract at ADS Title: The interpretation of the diffuse galactic radiation Authors: van de Hulst, H. C.; de Jong, T. Bibcode: 1969Phy....41..151V Altcode: Witt's observations of the diffuse galactic radiation are reinterpreted by solving the same transfer problem exactly, instead of using Eddington's approximation. A range of combinations of a (albedo) and g (anisotropy factor) of the single scattering diagram fits the data. This result does not depart greatly from the conclusion reached by Henyey and Greenstein in 1941. Platt particles and graphite flakes seem to be ruled out. Title: Interstellar Matter Authors: van de Hulst, H. C. Bibcode: 1969crsr.conf..122V Altcode: No abstract at ADS Title: Radiative transfer in thick atmospheres with an arbitrary scattering function Authors: van de Hulst, H. C. Bibcode: 1968BAN....20...77V Altcode: No abstract at ADS Title: Observing the interstellar magnetic field Authors: van de Hulst, H. C. Bibcode: 1968BAAA...11...26V Altcode: Before coming to a more detailed discussion, let us see what ways exist to establish the presence of a magnetic field In the galaxy at all. (Table 1). We shall briefly review these methods one by one. Title: Multiple Light Scattering in Planetary Atmospheres Authors: van de Hulst, H. C.; Grossman, K. Bibcode: 1968avm..book...35V Altcode: No abstract at ADS Title: Observing the galactic magnetic field (Introductory Report). Discussion. Authors: van de Hulst, H. C. Bibcode: 1967IAUS...31..375V Altcode: No abstract at ADS Title: Introduction to Astrophysics Authors: van de Hulst, H. C. Bibcode: 1967ASSL....9....1V Altcode: 1967ers..conf....1V No abstract at ADS Title: Observing the Galactic Magnetic Field Authors: van de Hulst, H. C. Bibcode: 1967ARA&A...5..167V Altcode: No abstract at ADS Title: Book reviews Authors: Fokker, A. D.; van den Heuvel, E. P. J.; van de Hulst, H. C. Bibcode: 1966SSRv....6..415F Altcode: No abstract at ADS Title: The Future of Space Research Authors: van de Hulst, Hendrik C. Bibcode: 1966NASSP..82...34V Altcode: No abstract at ADS Title: The escape of radiation from a semi-infinite non-conservative atmosphere Authors: van de Hulst, H. C.; Terhoeve, F. G. Bibcode: 1966BAN....18..377V Altcode: No abstract at ADS Title: Formation of molecular hydrogen in interstellar space Authors: Knaap, H. F. P.; van den Meijdenberg, C. J. N.; Beenakker, J. J. M.; van de Hulst, H. C. Bibcode: 1966BAN....18..256K Altcode: No abstract at ADS Title: Radio astronomy at Leiden University Authors: van de Hulst, H. C. Bibcode: 1965BAAA...10...55V Altcode: The radiotelescope of 25-meter diameter at Dwingeloo is now 10 years in almost continuous operation. The Observatories of Leiden and Groningen share the observing time. A doctor's thesis is often based on several thousand hours of observation, not all taken by the man himself. A good part of the registration and reduction is automatic. In the following a selection of some recent results is presented. Title: Multiple scattering in plane atmosphere Authors: van de Hulst, H. C. Bibcode: 1965BAAA...10...56V Altcode: Studies on multiple scattering and radiative transfer began early in this century by the work of Schwarzschild, Miln e, and Eddington. In the 1950's the important books of Chandrasekhar, Kourganoff and Sobolev on this subject appeared. In spite of the fact that almost all important questions in this very classical problem have now been solved, it often takes long to obtain the numerical answer to a simple question. For that reason I stated some years ago to prepare a book which should contain many tables and graphs together with a condensed text. In the course of this work it was found useful to deviate from normal usage in some respects, which I shall briefly review. Title: Kirchhoff's law for arbitrarily polarized light Authors: van de Hulst, H. C. Bibcode: 1965BAN....18....1V Altcode: No abstract at ADS Title: Diffuse Reflection and Transmission by a Very Thick Plane-Parallel Atmosphere with Isotropic Scattering Authors: van de Hulst, H. C. Bibcode: 1964Icar....3..336V Altcode: Radiation from arbitrary directions incident on a thick, homogeneous, conservative atmosphere with isotropic scattering is mostly diffusely reflected. A smaller part diffuses through the atmosphere and emerges at the other side. Sobolev's equations, which give the asymptotic forms of the reflection and transmission functions for large thickness, b, in terms of the function H(μ) known from the theory of semi-infinite atmospheres, are newly derived. It is shown by two examples that knowledge of these asymptotic forms makes it possible accurately to interpolate any quantity dependent on bbetweenb = 1 and b = ∞. Title: The point-direction gain in a plane-parallel scattering atmosphere Authors: van de Hulst, H. C. Bibcode: 1964BAN....17..495V Altcode: No abstract at ADS Title: Middel EN doel in de sterrekunde Authors: van de Hulst, Hendrik Christoffel Bibcode: 1963medd.book.....V Altcode: 1963QB51.H87....... No abstract at ADS Title: International agreement as a vital factor in radio astronomy and space research Authors: van de Hulst, H. C. Bibcode: 1963crsp.conf..412V Altcode: No abstract at ADS Title: The interstellar gas and the galactic halo Authors: van de Hulst, H. C. Bibcode: 1963crsp.conf..220V Altcode: No abstract at ADS Title: General Report on Radiation Transfer in Planets Scattering in Model Planetary Atmospheres Authors: van de Hulst, H. C.; Irvine, W. M. Bibcode: 1963LIACo..11...78V Altcode: No abstract at ADS Title: The third integral of motion for low-velocity stars Authors: van de Hulst, H. C. Bibcode: 1962BAN....16..235V Altcode: No abstract at ADS Title: The Astronomical Objectives of Space Research Authors: van de Hulst, H. C. Bibcode: 1962saa..conf....3V Altcode: No abstract at ADS Title: A multiple scattering problem with an anisotropic phase function. Authors: Davis, M. M.; van de Hulst, H. C. Bibcode: 1961PRNAA..64..220D Altcode: 1961RNAAS..64..220D No abstract at ADS Title: A multiple scattering problem with an anisotropic phase function. Authors: van de Hulst, H. C.; Davis, M. M. Bibcode: 1961PRNAA..64..220V Altcode: 1961RNAAS..64..220V No abstract at ADS Title: Space Research II Authors: van de Hulst, H. C.; de Jager, C.; Moore, A. F. Bibcode: 1961spre.conf.....V Altcode: No abstract at ADS Title: Methods for computing the original orbits of comets Authors: Bilo, E. H.; van de Hulst, H. C. Bibcode: 1960BAN....15..119B Altcode: No abstract at ADS Title: Review of Publications- Light Scattering by Small Particles Authors: van de Hulst, H. C. Bibcode: 1960JRASC..54...89V Altcode: No abstract at ADS Title: Neutral hydrogen in extra-galactic systems Authors: Volders, Louise; van de Hulst, H. C. Bibcode: 1959IAUS....9..423V Altcode: No abstract at ADS Title: Concluding lecture Authors: van de Hulst, H. C. Bibcode: 1959IAUS....9..398V Altcode: No abstract at ADS Title: Part VIII: Summaries and Conclusions Authors: Burgers, J. M.; Liepmann, H.; van de Hulst, H. C.; Kahn, F. D.; Seaton, M. J.; Pecker, J. C.; Schatzman, E.; Spitzer, L., Jr. Bibcode: 1958RvMP...30.1095B Altcode: 1958IAUS....8.1095B No abstract at ADS Title: Density and Velocity Distribution of the Interstellar Gas Authors: van de Hulst, H. C. Bibcode: 1958RvMP...30..913V Altcode: 1958IAUS....8..913V No abstract at ADS Title: The distribution of atomic hydrogen in the Galaxy Authors: van de Hulst, H. C. Bibcode: 1958IAUS....5...16V Altcode: No abstract at ADS Title: Buchbesprechungen über: Light scattering by small particles. (Ref. W. Franz) Authors: van de Hulst, H. C. Bibcode: 1958ZA.....45..149V Altcode: No abstract at ADS Title: Buchbesprechung über: Radiostronomy (Ref. W. Priester) Authors: van de Hulst, H. C. Bibcode: 1958ZA.....46..282V Altcode: No abstract at ADS Title: The Interstellar Médium Authors: Van de Hulst, H. C. Bibcode: 1958ICRC....4..497V Altcode: 1958cora.conf..497V No abstract at ADS Title: Magnetic Fields in Astrophysics Authors: van de Hulst, H. C. Bibcode: 1958IAUS....6....5V Altcode: No abstract at ADS Title: Rotation and density distribution of the Andromeda nebula derived from observations of the 21-cm line Authors: van de Hulst, H. C.; Raimond, E.; van Woerden, H. Bibcode: 1957BAN....14....1V Altcode: No abstract at ADS Title: Corrections of 21-cm line profiles Authors: Ollongren, A.; van de Hulst, H. C. Bibcode: 1957BAN....13..196O Altcode: No abstract at ADS Title: Light Scattering by Small Particles Authors: van de Hulst, H. C. Bibcode: 1957lssp.book.....V Altcode: No abstract at ADS Title: Radio astronomy. Authors: van de Hulst, Hendrik Christoffel Bibcode: 1957raas.book.....V Altcode: 1957QB475.H8....... No abstract at ADS Title: Radio astronomy, proceedings from 4th IAU Symposium. Authors: van de Hulst, Hendrik Christoffel Bibcode: 1957IAUS....4.....V Altcode: No abstract at ADS Title: Studies of the 21-cm. line and their interpretation (Introductory Lecture) Authors: van de Hulst, H. C. Bibcode: 1957IAUS....4....3V Altcode: No abstract at ADS Title: The flux densities of some radio sources at 400 Mc/s Authors: Seeger, Ch. L.; Westerhout, G.; van de Hulst, H. C. Bibcode: 1956BAN....13...89S Altcode: No abstract at ADS Title: The zodiacal light Authors: van de Hulst, H. C. Bibcode: 1956VA......2..998V Altcode: No abstract at ADS Title: Cosmic Ray Conference in Mexico Authors: van de Hulst, H. C. Bibcode: 1955S&T....15...63V Altcode: No abstract at ADS Title: Solid Particles in Interstellar Space: introductory report Authors: Van de Hulst, H. C. Bibcode: 1955LIACo...6..393V Altcode: No abstract at ADS Title: A Survey of Problems and Suggested Solutions Authors: van de Hulst, H. C. Bibcode: 1955IAUS....2...42V Altcode: No abstract at ADS Title: On the Polarization of the Zodiacal Light Authors: van de Hulst, H. C. Bibcode: 1955LIACo...6...89V Altcode: No abstract at ADS Title: The spiral structure of the outer part of the Galactic System derived from the hydrogen emission at 21 cm wavelength Authors: van de Hulst, H. C.; Muller, C. A.; Oort, J. H. Bibcode: 1954BAN....12..117V Altcode: No abstract at ADS Title: The Galaxy explored by radio waves Authors: van de Hulst, H. C. Bibcode: 1953Obs....73..129V Altcode: No abstract at ADS Title: The Chromosphere and the Corona Authors: van de Hulst, H. C. Bibcode: 1953sun..book..207V Altcode: 1953sun..book..207H No abstract at ADS Title: The Planetary Nebulae as Ionized Hydrogen Regions. Authors: van de Hulst, H. C. Bibcode: 1952ApJ...115..331V Altcode: No abstract at ADS Title: Observations of the interstellar hydrogen line of wave length 21 cm made at Kootwijk, Netherlands. Authors: van de Hulst, H. C. Bibcode: 1951AJ.....56..144V Altcode: The change of energy effected in the ground state of a hydrogen atom by reversing the electron spin relative to the proton spin corresponds to a frequency of 1420.4 Mc/sec, or a wave length of 21 cm. This line may be emitted by magnetic 4ipole radiation. The computed life time of the upper level, i.e. the inverse transition probability, is I I million years. The discovery of this line as an emission line from interstellar space was made by Ewen on March 25, 1951, about seven years after its prediction. It was confirmed on May I I by Mr. C. A. Muller of the Radio Astronomy Research Group in the Netherlands. A later confirmation was obtained early in July by Christiansen and Hindman of the Australian group. The Dutch measurements were made with a movable mirror of 7 meter diameter and 2?8 beam width. Scans were made across the Milky Way at many longitudes with continuous switching from a frequency in the line to a frequency outside it. The intensity on the galactic equator in Cygnus is somewhat larger than in the direction towards the galactic center. Half the maximum intensity is reached at latitudes +40 to 80, depending on longitude. The large width in latitude suggests that the emission comes from relatively nearby clouds, which is confirmed by a computation of opacity depth based on assumed values of the transition probability, temperature and density. The shape of the line toward the center (1 = 3250) is symmetrical and yields an average cloud velocity of 5 km/sec in one Co- ordinate. At 1 = 3550 the line is broadened by galactic rotation. A scan across the Milky Way at that longitude and at a frequency 250 kc/sec below normal, i.e. in the wing of the line, gave a much sharper drop of intensity with latitude, showing that more distant parts of the galaxy are observed. The importance of this discovery for investigations of galactic structure is very great. The Doppler displacement will reveal for the first time the rotation of the inner parts of our galaxy, which are hidden from sight by obscuring clouds. And the vast regions of interstellar space where hydrogen is neutral become for the first time accessible to observation. A full survey will require three-dimensional scanning, in longitude, latitude and frequency. The equipment at Kootwijk is now disassembled for improvements. More details of these results are described in a letter to Nature. Leiden Observatory, Leiden, Netherlands Title: Interstellar polarization by absorbing particles. Authors: Smith, Elske V. P.; van de Hulst, H. C. Bibcode: 1951AJ.....56R.141S Altcode: absorbing cylinders is applied to test the hypothesis that such particles are responsible for the observed polarization. Among the requirements imposed by the observations on any theory of the interstellar polarization are the facts that the amount of the polarization is independent of the wave length and that there is a certain correlation with the reddening. This correlation is such that the reddening is always present when polarization is observed, though the converse is not true. The theory for cylinders is analogous to the Mie theory of scattering by spheres. The efficiency factor for extinction varies with the direction of the electric vector of the incident light. The extinction is greatest when the electric vector is parallel to the cylinder axis, and least when it `is perpendicular. The ratio of the greatest to the least efficiency factor can be considered to define the amount of polarization. In computing the efficiency factors of cylinders we sum over the coefficients of extinction which appear in the solution of the scalar wave equation. These coefficients are in turn calculated from certain phase angles. The phase angles had already been calculated previously' for some real refractive indices. Our problem was to calculate the efficiency factors for slightly absorbing cylinders. A representative refractive index for such particles is m = 1.50 - 0.10 ~, for which the imaginary part is small. The computations were greatly simplified by using the results for real refractive indices and calculating the changes of the phase angles with small changes in the index. A graphical method of solution was used. Curves are given for theoretical extinction of particles with the refractive index I .500. lOt for the electric vector parallel and perpendicular to the cylinder axis, respectively. These curves follow an approximate I/N law such as that observed for the reddening. These particles could therefore produce the observed reddening. Curves were also calculated by Mr. Grootendorst and the second author for m = 1.414-1.414 t, a value representative for metallic particles. Comparison of the ratios of the extinction produced by the two alternative directions of the incident electric vector with the maximum observed values, indicate that the margin is even smaller for partially absorbing particles than for pure dielectric cylinders. It had been hoped that the opposite would be true, since the particles are presumably not perfectly aligned and may not be as long as we have assumed, and therefore would not show the maximum polarization as predicted by theory. I.van de Hulst, Ap. J. 112 1, 1949. Harvard College Observatory, Cambridge, Mass., and Leiden Observatory, Leiden, Netherlands. Title: The Shell of Nova Aquilae 1918 Authors: van de Hulst, H. C. Bibcode: 1951pca..conf..116V Altcode: No abstract at ADS Title: Interstellar Polarization and Magneto-hydrodynamic Waves Authors: van de Hulst, H. C. Bibcode: 1951pca..conf...45V Altcode: No abstract at ADS Title: The amount of Polarization by Interstellar Grains. Authors: van de Hulst, H. C. Bibcode: 1950ApJ...112....1V Altcode: The extinction of light by long dielectric cylinders is computed for different directions of polarization. Cylinders with diameters of the order of the wave length give the correct dependence of interstellar polarization on wave length, whereas cylinders or ellipsoids small compared to the wave length do not. The computed amount of polarization is barely sufficient to explain the observations, even if the grains are strongly elongated and fully aligned. Title: The electron density of the solar corona Authors: van de Hulst, H. C. Bibcode: 1950BAN....11..135V Altcode: No abstract at ADS Title: On the polar rays of the corona (Errata: 11 VIII) Authors: van de Hulst, H. C. Bibcode: 1950BAN....11..150V Altcode: No abstract at ADS Title: The solid particles in interstellar space. Authors: van de Hulst, Hendrik Christoffel Bibcode: 1949spis.book.....V Altcode: 1949QB4.U8l11p2.... No abstract at ADS Title: Scattering in the Atmospheres of the Earth and Planets Authors: van de Hulst, H. C. Bibcode: 1949aep..conf...49V Altcode: Introduction

The extinction

Scattering by haze, fog, and dust

The blue daylight sky

Exploration of the high atmosphere by optical methods

Some calculations on scattering in the atmospheres of the planets Title: Brightness Variations of the Solar Corona Authors: van de Hulst, H. C. Bibcode: 1949Natur.163...24V Altcode: BAUMBACH1 derived in 1937 the electron densities in the solar corona from a compilation of many measurements of its surface brightness. His values for Ne have proved useful in many investigations of the physical state of the corona and the radio waves emitted by it. However, for two reasons, they are not entirely accurate. First, it has now become clear2 that only part of the surface brightness arises from electron scattering (K-component). In the outer corona the other part (F-component) is stronger. It has circular symmetry and may be ascribed to diffraction by interplanetary dust. Secondly, the brightness and shape of the corona change with the 11-year cycle of solar activity. These changes, which are partially masked by the superposition of the constant F-component, have been neglected in Baumbach's work. Title: Scattering in a Planetary Atmosphere. Authors: van de Hulst, H. C. Bibcode: 1948ApJ...107..220V Altcode: In this paper the problem of multiple scattering in a planetary atmosphere, both with and without a diffusely reflecting bottom surface, is discussed. We assume that the atmospheric scattering is isotropic, with an albedo a, and that the ground surface reflects the radiation according to Lambert's law, with an albedo b. Sections 11-TV are devoted to the standard problem, i.e., to the problem of a finite atmosphere without a ground surface. After the exact expressions for single and double scattering have been obtained in Section II by direct integration, we show in Section III that an indirect method gives the same result in a more elegant way. This method is based on the use of Chandrasekhar's equations by which the in- tensities of the reflected and transmitted radiation can be expressed in terms of two functions, X(s) and Y(s). A new feature in the present discussion is that physical meanings are assigned to these func- tions. With these meanings the general relations are newly derived; and the expressions for single and double scattering are obtained in a simple manner. Section IV completes these calculations by adding an approximate expression for the third-order scattering. A numerical example shows that in this way an accuracy of 0.1 per cent is reached for an atmosphere with r = 0.1. Section V discusses the planet problem, i.e., the problem of an atmosphere with a bottom surface. The solution of this problem is expressed in a general way in terms of the solution of the standard prob- 1cm. The exact solution for the case of an isotropically scattering atmosphere involves the functions X(s) and Y(s) and their moments. Formulae suitable for the case of a thin atmosphere are also given and illustrated by a numerical example. A comprehensive discussion of the nw1 Itemat ical funcliins occurring in these calculations is given in the appendix. They are of three types: The functions E~(x) are the ordinary exponential integrals. The functions F~(b, x) are definite integrals, of which the integrand is the product of an E-function and an exponential function. The functions Gnm(X) and G~m(X) are definite integrals, of which the integrand is the product of two E-functions. Only the last type of functions cannot be. expressed in terms of known functions. For their calculation a new elementary function, the exponential integral of the second order, is introduced. Numerical values of all functions needed are given in four tables Title: Evolution and Physics of Solid Particles Authors: van de Hulst, H. C. Bibcode: 1948HarMo...7...73V Altcode: 1948cent.symp...73V No abstract at ADS Title: Line Breadths and Voigt Profiles. Authors: van de Hulst, H. C.; Reesinck, J. J. M. Bibcode: 1947ApJ...106..121V Altcode: Voigt functions are useful approximations for the intensity distribution in spectral lines. A table of these functions is given, and its use in computations on instrumental distortion is explained. Some mathematical properties of the Voigt functions are mentioned Title: Zodiacal Light in the Solar Corona. Authors: van de Hulst, H. C. Bibcode: 1947ApJ...105..471V Altcode: The observations of Grotrian and Ohman show that the continuous light of the corona consists of two components: a component K, strongly polarized and showing no Fraunhofer lines, and a component F, unpolarized and having unbroadened Fraunhofer lines. The former component is believed to arise from electron scattering; the latter is the subject of this paper. An analysis of the photometric data on the corona and on the zodiacal light indicates that the F-com- ponent dominates in the outer corona and suggests strongly that this component is just the extension of the zodiacal light. Other suggested explanations seem to be insufficient. A theory of the scattering in interplanetary space is given. The scattering by a solid particle consists of diffraction and reflection; the first and the most important part has been neglected in earlier discus- sion. Curves of the surface brightness as a function of the elongation are obtained for particles of various sizes on the assumption of a constant space density. The assumption that there are no particles within 0.1 A.U. from the sun changes the results only slightly. Theory and observations are then combined to give the distribution function of the radii, a. It has the form n(a) = 3.5 X 1O~°a~6 Title: Gas and smoke in interstellar space Authors: Oort, J. H.; van de Hulst, H. C. Bibcode: 1946BAN....10..187O Altcode: No abstract at ADS Title: Instrumental distortion of weak spectral lines Authors: van de Hulst, H. C. Bibcode: 1946BAN....10...79V Altcode: No abstract at ADS Title: The solid particles in interstellar space Authors: van de Hulst, H. C. Bibcode: 1946RAOU...11....2V Altcode: No abstract at ADS Title: Optics of spherical particles Authors: van de Hulst, H. C. Bibcode: 1946PhDT.........3V Altcode: 1946QB4.U8l11p1....; 1946RAOU...11....1V No abstract at ADS Title: Generalization of some methods for solving an integral equation of the first kind Authors: van de Hulst, H. C. Bibcode: 1946BAN....10...75V Altcode: No abstract at ADS Title: Radiogolven uit het wereldruim: II. Herkomst der radiogolven Title: Radiogolven uit het wereldruim: II. Herkomst der radiogolven Title: Radio waves from space. Authors: van de Hulst, H. C. Bibcode: 1945NTvN...11..210V Altcode: Radio waves, received from any celestial object -- they being the far infra red portion of its spectrum -- deserve attention. The 21.2 cm line due to transitions between hyperfine structure components of the hydrogen ground level, might be observaabe if the lifetime of the upper level does not exceed 4.10^8 year, which, however is improbable. [partial summary] Title: The atmospheric oxygen bands Authors: van de Hulst, H. C. Bibcode: 1945AnAp....8...12V Altcode: No abstract at ADS Title: Theory of absorption lines in the atmosphere of the Earth Authors: van de Hulst, H. C. Bibcode: 1945AnAp....8....1V Altcode: No abstract at ADS Title: The determination of the true profile of a spectral line Authors: van de Hulst, H. C. Bibcode: 1941BAN.....9..225V Altcode: No abstract at ADS