The Observation And Analysis Of Stellar Photospheres

by David F. Gray

• ISBN13: 9780521851862
• ISBN10: 0521851866
• Edition: 3rd
• Format: Hardcover
• Copyright: 2005-11-28
• Publisher: Cambridge University Press

Summary

The Observation and Analysis of Stellar Photospheres describes the equipment, observational techniques, and analysis used in the investigation of stellar photospheres. This third edition builds on the success of the previous editions, improving the presentation, and revising topics and results to keep up to date with the latest research. The first half of the book develops the tools of analysis and the second half demonstrates how they can be applied. Topics covered include radiation transfer, models of stellar photospheres, spectroscopic equipment, observing stellar spectra, and techniques for measuring stellar characteristics. Useful real star data can be found throughout the text and in the appendices, and there are extensive references to the primary literature. This comprehensive textbook is suitable for advanced undergraduates and graduate students of stellar physics. Each chapter contains exercises to test understanding and a wealth of useful reference material is included.

Table of Contents

Preface to the first edition	xiii
Preface to the second edition	xv
Preface to the third edition	xvi
Background	1	(25)
What is a stellar atmosphere?	1	(2)
Spectral types	3	(4)
Magnitudes and color indices	7	(3)
The Hertzsprung-Russell diagram	10	(1)
The gas laws	10	(2)
The velocity distributions	12	(1)
Atomic excitation and ionization in thermodynamic equilibrium	13	(5)
Stellar catalogues, tables, and atlases	18	(8)
References	20	(2)
Questions and exercises	22	(4)
Fourier transforms	26	(26)
The definition	26	(3)
Some common transforms	29	(5)
Data sampling and data windows	34	(2)
Convolutions	36	(1)
Convolution with a δ-function	37	(1)
Convolutions of Gaussians and dispersion profiles	38	(1)
Resolution: our blurred data	39	(1)
Sampling and aliasing	40	(2)
Useful theorems	42	(1)
Numerical calculation of transforms	43	(2)
Noise transfer between domains	45	(2)
Time-series analysis	47	(5)
References	50	(1)
Questions and exercises	50	(2)
Spectroscopic tools	52	(37)
Spectrographs: some general relations	52	(2)
Diffraction gratings	54	(7)
The blazed reflection grating	61	(4)
Wavelength of the true blaze	65	(2)
Shadowing	67	(2)
Grating ghosts	69	(3)
Dispersion, slit magnification, and spectral resolution	72	(3)
Echelle spectrographs	75	(3)
Multi-object spectroscopy	78	(1)
Spectra from interferometers	78	(5)
Aspects of telescopes	83	(6)
References	85	(2)
Questions and exercises	87	(2)
Light detectors	89	(18)
Quantum efficiency and spectral response	90	(1)
Linearity	90	(2)
Silicon-diode arrays	92	(3)
Background and cosmic rays	95	(1)
Noise in the measurements	96	(1)
Choosing a detector to maximize s/n	97	(2)
Dynamic range and well capacity	99	(1)
Measuring the noise of a detector	100	(1)
Spatial resolution	101	(3)
Photomultiplier tubes	104	(1)
The photographic plate	105	(2)
References	106	(1)
Questions and exercises	106	(1)
Radiation terms and definitions	107	(11)
Specific intensity	107	(2)
Flux	109	(2)
The K integral and radiation pressure	111	(2)
The absorption coefficient and optical depth	113	(1)
The emission coefficient and the source function	113	(1)
Pure isotropic scattering	114	(1)
Pure absorption	115	(1)
The Einstein coefficients	115	(3)
Questions and exercises	117	(1)
The black body and its radiation	118	(9)
Observed relations	119	(2)
Planck's radiation law	121	(2)
Numerical values of black-body radiation	123	(1)
The black body as a radiation standard	124	(3)
References	125	(1)
Questions and exercises	125	(2)
Radiative and convective energy transport	127	(20)
The transfer equation and its formal solution	127	(2)
The transfer equation for different geometries	129	(4)
The flux integral	133	(1)
The mean intensity and K integrals	134	(1)
Exponential integrals	134	(2)
Radiative equilibrium	136	(3)
The grey case	139	(2)
Convective transport	141	(2)
Conditions for convective flow	143	(1)
The mixing-length formulation	144	(3)
References	145	(1)
Questions and exercises	146	(1)
The continuous absorption coefficient	147	(23)
The origins of continuous absorption	147	(1)
The stimulated emission factor	148	(1)
Neutral hydrogen	149	(5)
The negative hydrogen ion	154	(3)
Other hydrogen continuous absorbers	157	(1)
Absorption by helium	158	(2)
Electron scattering	160	(3)
Other sources of continuous absorption	163	(2)
Line opacity	165	(1)
The total absorption coefficient	166	(4)
References	167	(2)
Questions and exercises	169	(1)
The model photosphere	170	(34)
The equation of hydrostatic equilibrium	171	(3)
The temperature distribution in the solar photosphere	174	(4)
Temperature distributions in other stars	178	(3)
The Pg--Pe--T relation	181	(4)
Completion of the model	185	(1)
The geometrical depth	185	(1)
Computation of the spectrum	186	(3)
Properties of models: pressure relations	189	(4)
The effects of chemical composition	193	(3)
Changes with effective temperature	196	(1)
Tabulations of model photospheres	197	(1)
Reflection	198	(6)
References	200	(2)
Questions and exercises	202	(2)
The measurement of stellar continua	204	(27)
Ultra-low-resolution spectrographs	205	(1)
Observations using standard stars	206	(1)
Absolute calibration of standard stars	207	(6)
Photometric standard stars	213	(1)
Observations of stellar continua	213	(2)
Continua from photospheric models	215	(3)
Line absorption	218	(1)
Comparison of model to stellar continua	219	(4)
Luminosity and bolometric flux	223	(8)
References	227	(2)
Questions and exercises	229	(2)
The line absorption coefficient	231	(34)
The natural atomic absorption	232	(4)
Damping constants for natural broadening	236	(2)
Pressure broadening	238	(2)
The impact approximation	240	(2)
Theoretical evaluation of the collisional damping constant	242	(2)
Numerical values for collisions with charged perturbers	244	(1)
Numerical values for collisions with neutral perturbers	245	(2)
Hydrogen line broadening	247	(6)
Thermal broadening	253	(1)
Microturbulence	254	(1)
Combining absorption coefficients	255	(4)
Hyperfine and isotopic splitting	259	(1)
The mass absorption coefficient for lines	260	(1)
Comments	261	(4)
References	262	(2)
Questions and exercises	264	(1)
The measurement of spectral lines	265	(39)
The coude grating spectrograph	266	(4)
The Bowen image slicer	270	(1)
Fiber-optics slicers	270	(1)
The Richardson image slicer	270	(3)
Diffraction gratings for precise spectral-line work	273	(1)
Spectrograph cameras	273	(1)
The instrumental profile	274	(3)
The restoration process	277	(1)
Noise and its complications	278	(2)
Fourier noise filters	280	(3)
The discrete Fourier transform	283	(1)
δ-function spectra	284	(2)
Measurement of the instrumental profile	286	(1)
Scattered light	287	(1)
Measurement of scattered light	288	(2)
Corrections for scattered light	290	(1)
Continuum normalization	291	(1)
Determination of the dispersion and the wavelength scale	292	(1)
Line measurements with low resolution	293	(2)
Measurement of line broadening and shape	295	(2)
Measurement of asymmetry	297	(2)
Measurement of line position	299	(5)
References	300	(2)
Questions and exercises	302	(2)
The behavior of spectral lines	304	(34)
The line transfer equation	304	(1)
The line source function	305	(3)
The level populations	308	(1)
Other formalisms for Sv	309	(1)
Computation of a line profile in LTE	310	(3)
Contribution functions and the depth of formation of spectral lines	313	(1)
The behavior of line strength	314	(1)
The temperature dependence	315	(5)
The pressure dependence	320	(6)
The abundance dependence	326	(4)
Comment	330	(8)
References	335	(1)
Questions and exercises	336	(2)
The measurement of stellar radii and temperatures	338	(27)
Interferometers	339	(1)
Lunar occultations	340	(2)
Eclipsing binaries	342	(1)
Radii from bolometric flux	343	(1)
Photometric radii: a simpler method	344	(2)
The surface-brightness method	346	(2)
Inferred radii: the radius calibration	348	(2)
Measured effective temperatures	350	(1)
Stellar temperatures from model photospheres	351	(1)
Inferred temperatures: the temperature calibration	352	(2)
``Generalized'' temperatures	354	(1)
The Paschen continuum	354	(1)
Color indices: synthetic colors	355	(1)
The Balmer jump	356	(1)
Hydrogen lines	356	(1)
Metal lines as temperature indicators	357	(8)
References	360	(3)
Questions and exercises	363	(2)
The measurement of photospheric pressure	365	(19)
The continuum as a pressure indicator	366	(1)
The hydrogen lines	367	(2)
Other strong lines	369	(2)
The weak lines	371	(1)
The gravity--temperature diagram	372	(2)
Empirical indicators of gravity	374	(2)
The helium abundance	376	(1)
Binaries for calibration	377	(1)
Inferred surface gravity	377	(7)
References	380	(2)
Questions and exercises	382	(2)
Chemical analysis	384	(39)
What can be determined	385	(1)
Direct computational analysis	386	(1)
Curves of growth for analytical models: an historical note	387	(1)
Scaling relations	387	(4)
Temperature effects	391	(1)
Surface gravity effects	391	(2)
Saturation: the flat part of the curve of growth	393	(3)
A reference curve of growth	396	(1)
Derivation of abundances	397	(2)
Differential analysis	399	(1)
The synthesis method	400	(2)
Abundance indices	402	(1)
The solar chemical composition	403	(3)
Stellar abundances: summaries	406	(1)
Galactic variations	407	(2)
Evolutionary changes: lithium	409	(3)
Evolutionary changes: carbon	412	(1)
Chemically peculiar stars	413	(2)
Comments	415	(8)
References	415	(6)
Questions and exercises	421	(2)
Velocity fields in stellar photospheres	423	(35)
Examples of velocity broadening	424	(2)
Solar velocity fields	426	(2)
Modeling the motions	428	(1)
From velocity to spectrum	429	(1)
Microturbulence in line computations	430	(1)
Macroturbulence in line computations	431	(1)
(Fictitious) isotropic macroturbulence	432	(1)
Radial--tangential anisotropic macroturbulence	433	(1)
Including rotation	434	(3)
Disk integration mechanics	437	(2)
Fourier analysis for turbulence	439	(3)
Some results from line broadening	442	(1)
Line asymmetries	443	(4)
The stellar case: cool stars	447	(2)
The stellar case: hot stars	449	(1)
The granulation boundary	450	(1)
Modeling line bisectors	451	(7)
References	454	(2)
Questions and exercises	456	(2)
Stellar rotation	458	(47)
The Doppler-shift distribution	460	(1)
The rotation profile	461	(6)
Profile fitting for v sin i	467	(3)
Profile width as a measure of v sin i	470	(1)
Fourier analysis for large v sin i	471	(4)
Transform width as a measure of v sin i	475	(1)
Fourier analysis for moderate to small rotation	475	(2)
Additional aspects of spectroscopic rotation analysis	477	(5)
Statistical corrections for axial projection	482	(1)
Rotational modulation	483	(2)
Rotation of dwarfs	485	(3)
Rotation of evolved stars	488	(2)
Rotation and magnetic activity	490	(2)
Rapid rotators	492	(3)
Rotation of binary stars	495	(1)
Rotational mapping	496	(9)
References	499	(5)
Questions and exercises	504	(1)
Appendix A. A table of useful constants	505	(1)
Appendix B. Physical parameters of stars	506	(3)
Appendix C. A fast Fourier transform Fortran program	509	(2)
Appendix D. Atomic data	511	(10)
Appendix E. The strongest lines in the solar spectrum	521	(1)
Appendix F. Computation of random errors	522	(3)
Index	525