Flare Stars - 1st Edition - ISBN: 9780080230351, 9781483148854

Flare Stars

1st Edition

International Series in Natural Philosophy

Authors: G. A. Gurzadyan
Editors: Yervant Terzian
eBook ISBN: 9781483148854
Imprint: Pergamon
Published Date: 1st January 1980
Page Count: 358
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Flare Stars covers the significant progress in photoelectric, photographic, and spectral observations of flare stars. Flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes believed to be due to extremely intense flares.

This book is composed of 16 chapters and begins with an overview of flare stars and the hypothesis of infrared photon transformation. The succeeding chapters deal with the inverse Compton Effect, X-ray radiation and the theory of the transition radiation and its importance to the T Tauri type stars and peculiar objects. These topics are followed by analysis of the photometric and colorimetric flare data based on the fast-electron hypothesis. Other chapters consider the theory of the chromophore of flare stars and the general laws for the behavior of flare stars in stellar association and for T Tauri type stars. The remaining chapters explore the observational data that have shed light on the problems of radio emission and flare dynamics. These chapters also describe the great cosmogonic importance of stellar flares, particularly for understanding the nature and the true character of energy sources within the stars.

This book will be of great value to astronomers and researchers.

Table of Contents

Preface to the English Edition

Editor's Preface

From the Preface by the Author to the Russian Edition

From the Preface of the Russian Edition

Chapter 1. General Information about Flare Stars

1. Discovery of the Flare Phenomenon in Stars

2. Flare Stars in the Neighborhood of the Sun

3. Flare Stars in Stellar Associations

4. The Morphological Composition of Flare Stars

5. Definition of a Flare

6. The Lightcurve. Two Types of Flares

7. The Parameters of the Lightcurve

8. The Rate of Development of the Flare

9. The Flare as an Accidental Phenomenon

10. Energy Distribution in the Spectra of Flare Stars

11. Flare Frequency

12. The Amplitude of the Flares

13. The Distribution Function of the Amplitudes of Flares

Chapter 2. The Hypothesis of Transformation of Infrared Photons

1. The Nonthermal Nature of the Continuous Emission

2. Main Properties of Flares in Unstable Stars

3. The Hypothesis of Transformation of Infrared Photons

Chapter 3. The Inverse Compton Effect

1. Collision of a Photon with a Thermal Electron

2. Collision of a Photon with a Relativistic Electron. The Inverse Compton Effect

3. The Effective Cross-Section for a Collision of a Photon with a Relativistic Electron

4. The Double Inverse Compton Effect

5. Polarization of the Radiation

6. Fast Electrons

Chapter 4. Transfer of Radiation through a Medium of Fast Electrons

1. The Statement of the Problem

2. The Equation of Radiation Transfer

3. Application to Stellar Photospheres

4. The Case of an Exponential Law for the Energy Distribution of the Electrons

5. Fast Electrons with a Gaussian Distribution

6. The Shell of Fast Electrons Around the Star

7. Application to Double Stars

8. Stellar Atmospheres Consisting of a Mixture of Thermal and Fast Electrons

9. The Deviation of the Stellar Radiation from Planck's Law

Chapter 5. The Continuous Spectrum of a Flare

1. The Theoretical Dpectrum of a Star during a Flare

2. Theoretical Spectra of Stars of Different Classes during Flares

3. The Spectrum of the Pure Flare

4. Continuous Spectra

5. Results of Multi-Channel Photometry

6. Flare Spectra for the Case of Gaussian Distribution of Fast Electrons

Chapter 6. Brightness of Flares

1. Theoretical Flare Amplitudes

2. Comparison with the Observations

3. Stars of UV Cet Type

4. The Average Strength of the Flares

5. Results of Three-Color Observations of Flares

6. Internal Agreement of Flare Amplitudes

7. Theoretical Amplitudes of the Fluctuations in Brightness for Thermal Processes

8. The Dependence of Flare Amplitude on Stellar Spectral Class

9. Interpretation of a Flare of H II 1306

10. Unusual Flare of the Star Hero 177

11. A Flare of a Star of Class K

12. A Flare of a Star of Class A

13. An Ultraviolet Flare of W UMa

14. The Probable Value of the Energy of the Fast Electrons

15. Energy Losses by Fast Electrons and by the Star during the Flare

16. The Negative Infrared Flare

17. Results of Observation of Stellar Flares at Infrared Wavelengths

18. The Frequency of Negative Infrared Flares

19. Flare Amplitudes in the Extreme Ultraviolet

20. The Effect of the Luminosity Decrease of the Star before the Flare

21. Short-Lived Flares

22. Radiative Energy Losses through the Flares

23. The Energy of a Flare

Chapter 7. Color Indices of Flares

1. Theoretical Color Indices

2. Theoretical Dependence of U - B on B - V

3. The Dependence of U - B on B - V in the Case of a Hot Gas

4. Comparison with Observations

5. Drift of Star in Color Diagram during Flare

6. Dependence of Color on Flare Amplitude

7. Color Indices Due Only to the Flare

8. Color Indices of the "Pure" Flare and the Fast Electron Hypothesis

9. Color "Portraits" of Flare Stars

10. Infrared "diagnostics" of flare stars

Chapter 8. Bremsstrahlung from Fast Electrons

1. The Problem

2. Intensity of Non-Thermal Bremsstrahlung

3. Radiation Spectrum

4. Color Indices

5. Flare Amplitude

6. Application to Hot Stars

Chapter 9. Excitation of Emission Lines. Chromospheres of Flare Stars

1. The Two Components of the Light of the Flare

2. The Intensity of the Ionizing Radiation

3. Excitation of the Emission Lines

4. Duration of Emission Lines (Observations)

5. Electron Temperature in the Chromosphere of Flare Stars

6. Electron Density in the Chromospheres of Flare Stars

7. Duration of Radiation of Emission Lines (Theory)

8. What Maintains the Emission Lines of the "Quiet" Star?

9. Degree of Ionization

10. The Balmer Decrement of the Emission Lines

11. Analysis of Profiles of Emission Lines

12. Dependence of Intensity of Emission Lines on Flare Amplitude

13. Haro's Two Types of Flare Stars

14. Effect of Dilution of Radiation

15. Effect of Spectral Class

16. On the Nature of Slow Flares

17. The Forbidden Lines

18. Possibility of Observing the Forbidden Line 4363 (OIII)

19. Excitation of Helium Emission Lines

20. Lyman-Alpha Emission in Flare Stars

21. The Emission Line 2800 Mg II in the Spectra of Flare Stars

22. Macrostructure of the Spectrum of Flare Stars in the Ultraviolet

Chapter 10. T Tauri Type Stars

1. Flare of T Tau Type Stars

2. Main Properties of T Tau Type Stars

3. The Permanent Flare of T Tauri Stars

4. T Tau Type Stars in the Color Diagram

5. The Stars T Tau and RW Aur Stars

6. Particularly Active Stars of T Tau Type

7. The Variations of U - B and B - V with Time

8. The Evolution of Stars of T Tauri Type

9. Brightness Fluctuations

10. Energy Losses by T Tauri Type Stars

11. Emission Lines

12. Emission Lines in Weak Flares

13. FUOR's

Chapter 11. Flares Stars in Stellar Associations

1. First Surveys

2. The Flare Stars in Orion

3. Flare Stars in the Pleiades

4. The Aggregate in Cygnus (NGC 7000)

5. Flare Stars in Other Aggregates

6. Flare Stars of the Galactice Background

7. The Spatial Concentration of Flare Stars

8. The Apparent Distribution of Flare Srars

9. Flare Stars in the Color-Color Diagram

10. A Method for Determining the Age of an Aggregate

11. The Relation Between Flare Stars and Stars with Emission Lines

12. The Spatial Distribution of Flare Stars in Aggregates

13. The Probable Number of Flare Stars in Aggregates

14. Do All Stars in an Aggregate Show Flares?

15. On the Periodicity of Flares

16. The Dependence of the Strength of the Optical Flare on the Star's Luminosity

17. The Average Strength of the Flare

18. Heating and Expansion of the Intrastellar Matter in Aggregates

Chapter 12. Transition Radiation and Peculiar Objects

1. The Problem

2. The Theory of the Transition Radiation

3. Properties of the Transition Radiation

4. The Effect of the "Formation Zone"

5. The Radiative Power of the Medium

6. Color Indices for the Transition Radiation

7. Transition Radiation in T Tau Type Stars

8. X-ray Radiation in T Tau Stars

9. Excitation of the Chromosphere of T Tau Type Stars

10. The Effect of Accumulation of Fast Electrons

11. Herbig-Haro Objects

12. The Ionization Equilibrium of the Herbig-Haro Objects

13. Thw FUOR Phenomenon

14. The Radiation of T Tau Type Stars in the Ultraviolet

Chapter 13. Radio Emission from Flare Stars

1. Discovery of Radio Emission from Flare Stars

2. Simultaneous Radio and Optical Observations of Flare Stars

3. Short-Lived Radio-Flares

4. The Dependence of the Radio Emission on the Amplitude of the Optical Flare

5. Main Properties of the Radio Emission of Flare Stars

6. The Nature of the Radio Emission of Flare Stars

7. The Contribution of Flare Stars to the Radio Emission of the Galaxy

8. Radio Emission of Flare Stars in Associations

Chapter 14. X-ray Emission from Flare Stars

1. The Theoretical Spectrum of the X-ray Emission

2. The Lightcurve of X-ray Flares

3. Expected Fluxes of X-ray Radiation

4. Results of Observations of Flare Stars in X-rays

5. On the X-ray Background of the Galaxy

6. The Possibility of Detecting Interstellar Helium

7. Flare Stars as Contributors of Primary Cosmic Rays?

Chapter 15. Flare Dynamics

1. Interpretation of Flare Lightcurves

2. The Problem. The Effects of Energy Losses of Fast Electrons

3. The Effect of "Evaporation" of the Fast Electrons

4. The Decrease of Brightness after Flare Maximum

5. On the Effective Strength of the Flare

6. On the Classification of the Forms of Flare Lightcurves

7. The Possibility of Distinguishing Thermal and Nonthermal Radiation

8. Heating of the Photosphere

Chapter 16. Fast Electrons

1. The Fast-Electron Hypothesis

2. The Problem of the Origin of the Fast Electrons

3. Beta Decay

4. The Anomalous Abundance of Lithium in the Atmosphere of T Tau Stars

5. Chromospheric Activity - Convection

6. Stellar and Solar Flares

7. The Role of Magnetic Fields

8. The Cosmogonical Significance of Stellar Flares


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About the Author

G. A. Gurzadyan

About the Editor

Yervant Terzian

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