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Radiation transport in spectral lines
Planet. Space Sci. 1973, Vol. 21, p. 1463. PergamonPress. Printed in Northern Ireland
BOOK REVIEW
R. GRANT ATHAY: Radiation Transport in Spectral Lines. Reidel. 1972. VIII -k- 263. Dfl. 41. There are very few books on radiative transfer in spectral lines and another one is certainly welcome. This book is naturally influenced by the many original papers that the author has written on the interpretation of spectral lines from the solar chromosphere. In the introduction there is a careful explanation that the so-called non-L.T.E, theories do not exclude L.T.E. theories, but simply have fewer restrictions and include L.T.E. as an extreme case--an explanation which it is, alas, still necessary to make. The general expression for the source function is developed in Chapter 2 together with a discussion of line transfer in terms of the diffusion of photons in frequency and also in terms of thermalization lengths. Chapter 3 is devoted to a discussion of the two level atom and of the many numerical solutions including the effect of temperature gradients, density gradients, relative velocities, frequency redistribution and various geometries. Chapters 4 and 5 discuss the multi-level atom and line profiles. These two chapters present the results of numerical work applied mainly to the solar chromosphere. As the author admits in his introduction, they suffer a little from the difficulties of summarizing work which is entirely numerical. There is no doubt though that this collection of material will be useful to the specialist. The chapter on line profiles discusses the way in which information about the solar atmosphere has been obtained from line profile and limb darkening measurements. Chapter 6 discusses the interpretation of spectra when only the total intensity of the line is known and not its shape. The effect of line blanketing on the temperature structure of the atmosphere and on the line spectrum is discussed in Chapter 7 together with the Cayrel mechanism which causes a temperature rise through departures from local thermodynamic equilibrium. The last chapter gives a brief survey of some of the numerical methods used in studying radiation transfer in spectral lines. The book is well produced with only a few misprints. The list of references given at the end of each chapter is fairly comprehensive and includes references up to 1971. Compared with the prices of some book publishers, this book is reasonably priced and should find its way into the private libraries of those interested in this field. A. G. HEARN
1463
BOOK REVIEW
R. GRANT ATHAY: Radiation Transport in Spectral Lines. Reidel. 1972. VIII -k- 263. Dfl. 41. There are very few books on radiative transfer in spectral lines and another one is certainly welcome. This book is naturally influenced by the many original papers that the author has written on the interpretation of spectral lines from the solar chromosphere. In the introduction there is a careful explanation that the so-called non-L.T.E, theories do not exclude L.T.E. theories, but simply have fewer restrictions and include L.T.E. as an extreme case--an explanation which it is, alas, still necessary to make. The general expression for the source function is developed in Chapter 2 together with a discussion of line transfer in terms of the diffusion of photons in frequency and also in terms of thermalization lengths. Chapter 3 is devoted to a discussion of the two level atom and of the many numerical solutions including the effect of temperature gradients, density gradients, relative velocities, frequency redistribution and various geometries. Chapters 4 and 5 discuss the multi-level atom and line profiles. These two chapters present the results of numerical work applied mainly to the solar chromosphere. As the author admits in his introduction, they suffer a little from the difficulties of summarizing work which is entirely numerical. There is no doubt though that this collection of material will be useful to the specialist. The chapter on line profiles discusses the way in which information about the solar atmosphere has been obtained from line profile and limb darkening measurements. Chapter 6 discusses the interpretation of spectra when only the total intensity of the line is known and not its shape. The effect of line blanketing on the temperature structure of the atmosphere and on the line spectrum is discussed in Chapter 7 together with the Cayrel mechanism which causes a temperature rise through departures from local thermodynamic equilibrium. The last chapter gives a brief survey of some of the numerical methods used in studying radiation transfer in spectral lines. The book is well produced with only a few misprints. The list of references given at the end of each chapter is fairly comprehensive and includes references up to 1971. Compared with the prices of some book publishers, this book is reasonably priced and should find its way into the private libraries of those interested in this field. A. G. HEARN
1463