Book contents
- Frontmatter
- Contents
- Preface to the first edition
- Preface to the second edition
- Preface to the third edition
- 1 Background
- 2 Fourier transforms
- 3 Spectroscopic tools
- 4 Light detectors
- 5 Radiation terms and definitions
- 6 The black body and its radiation
- 7 Radiative and convective energy transport
- 8 The continuous absorption coefficient
- 9 The model photosphere
- 10 The measurement of stellar continua
- 11 The line absorption coefficient
- 12 The measurement of spectral lines
- 13 The behavior of spectral lines
- 14 The measurement of stellar radii and temperatures
- 15 The measurement of photospheric pressure
- 16 Chemical analysis
- 17 Velocity fields in stellar photospheres
- 18 Stellar rotation
- Appendix A A table of useful constants
- Appendix B Physical parameters of stars
- Appendix C A fast Fourier transform Fortran program
- Appendix D Atomic data
- Appendix E The strongest lines in the solar spectrum
- Appendix F Computation of random errors
- Index
- References
18 - Stellar rotation
Published online by Cambridge University Press: 05 March 2015
- Frontmatter
- Contents
- Preface to the first edition
- Preface to the second edition
- Preface to the third edition
- 1 Background
- 2 Fourier transforms
- 3 Spectroscopic tools
- 4 Light detectors
- 5 Radiation terms and definitions
- 6 The black body and its radiation
- 7 Radiative and convective energy transport
- 8 The continuous absorption coefficient
- 9 The model photosphere
- 10 The measurement of stellar continua
- 11 The line absorption coefficient
- 12 The measurement of spectral lines
- 13 The behavior of spectral lines
- 14 The measurement of stellar radii and temperatures
- 15 The measurement of photospheric pressure
- 16 Chemical analysis
- 17 Velocity fields in stellar photospheres
- 18 Stellar rotation
- Appendix A A table of useful constants
- Appendix B Physical parameters of stars
- Appendix C A fast Fourier transform Fortran program
- Appendix D Atomic data
- Appendix E The strongest lines in the solar spectrum
- Appendix F Computation of random errors
- Index
- References
Summary
In this chapter, we concern ourselves primarily with the spectroscopic effects of stellar rotation, including the line broadening caused by rotation, techniques for extracting the rotation rate from the broadening, and some of the results. Many of the analysis tools are the same as those discussed in Chapter 17.
Stellar rotation is the driving force for diverse phenomena in stellar atmospheres such as circulation currents, mass loss, and magnetic field generation and its offshoots: starspots, flares, chromospheres and coronae, and activity cycles. The existence of stellar rotation comes as no surprise. Since we believe stars form out of interstellar clouds, and clouds collide with one another and are subject to other torques such as those induced by galactic rotation, we would predict rather large stellar rotation on the basis of the conservation of angular momentum. Moment of inertia scales roughly as the square of the linear dimension. With 44 million solar radii per parsec, cloud rotation should be magnified by something like 15 orders in coming to stellar dimensions. Some stars rotate near the “break-up” velocity, where the gravitational acceleration is comparable to the centripetal force at the equator, but even these rates are small compared to what is expected. Apparently dissipation of angular momentum is an integral part of star formation.
- Type
- Chapter
- Information
- The Observation and Analysis of Stellar Photospheres , pp. 458 - 504Publisher: Cambridge University PressPrint publication year: 2005
References
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