Very Low-Mass Stars and Brown Dwarfs (Cambridge Contemporary Astrophysics)

VERY LOW-MASS STARS AND BROWN DWARFS......Page 1
Half-title......Page 2
Cambridge Contemporary Astrophysics......Page 4
Title Page......Page 6
Copyright Page......Page 7
Contents......Page 8
Preface......Page 10
Acknowledgements......Page 11
Part I: Searches in Clusters, Stellar Associations and the Field......Page 12
2. HIPPARCOS distances......Page 14
3. Metallicity effects......Page 15
4. Illustrations of the problem......Page 16
4.1. The (M v, β) plane......Page 17
4.2. The Geneva photometry......Page 18
4.4. Kron and Cousins VI photometry......Page 20
4.5. Conclusion of this section......Page 22
5. Parameter determination......Page 23
6. Age determination......Page 24
References......Page 26
1. Introduction......Page 28
2. Astrometric errors as a function of magnitude......Page 29
3. Surveys for very low mass stars in nearby open clusters......Page 30
3.1. SuperCOSMOS......Page 31
4.1. Results......Page 34
4.2. Discussion......Page 36
References......Page 37
2. Science goals......Page 40
3. Current ground-based parallaxes......Page 41
4.1. Hubble Space Telescope......Page 42
5. Scientific results......Page 43
5.2. The Pleiades......Page 44
6. Prospects for ground-based parallaxes......Page 45
7.1. The Space Interferometry Mission (SIM)......Page 46
References......Page 47
2.1. Photometry......Page 49
3.1. Photometry......Page 50
3.2. Spectra......Page 51
4.1. The Initial Mass Function......Page 53
4.2. Brown dwarfs......Page 54
References......Page 56
1. Introduction......Page 57
2.1. Pioneering surveys......Page 58
2.2. Recent work: the substellar mass domain......Page 60
2.3. The low mass stellar and substellar mass function......Page 63
3.2. Younger clusters......Page 65
References......Page 66
2. The surveys......Page 70
4. Spatial distribution......Page 71
5. The luminosity and mass functions......Page 74
6. Conclusions......Page 76
References......Page 77
2.1. Imaging......Page 79
2.2. Spectroscopy......Page 82
2.3. H–R Diagram......Page 83
3. Conclusions......Page 84
References......Page 85
2. Mass functions......Page 86
3. Estimating the number of brown dwarfs......Page 88
4. Faint LFs in globular clusters......Page 89
5. Extending the mass–luminosity relation empirically......Page 91
6. Microlensing......Page 93
References......Page 94
1. Introduction......Page 95
2.2. The present sample......Page 96
3. Follow-up spectroscopy......Page 97
4.1.1. Error sources......Page 99
4.1.2. Malmquist-like biases......Page 102
4.1.3. Multiplicity bias......Page 105
4.2. DENIS Luminosity function......Page 106
5. Conclusions......Page 107
References......Page 108
1. Introduction......Page 110
2. Selection criteria......Page 111
3. The L dwarfs......Page 112
4. Flare activity in a 2MASS object......Page 115
References......Page 116
Part II: Spectroscopic Properties, Fundamental Parameters and Modelling......Page 118
2. Magnetic activity......Page 120
2.1. Activity effects on bandstrengths, colors and magnitudes......Page 121
2.2. Age and activity......Page 123
3. Luminosity functions and mass segregation......Page 126
References......Page 129
1.1. Substellar terminology......Page 130
2. Star-forming regions: ρ Oph and Orion......Page 131
3. Young open clusters: α Per and the Pleiades......Page 133
5. Evolution of VLM stars and BDs......Page 135
5.1. Activity......Page 136
5.3. Gravity sensitive spectral indicators......Page 137
5.4. Lithium dating of young open clusters......Page 138
References......Page 140
1. Introduction......Page 144
2. Observations and spectral analysis......Page 145
3. The model atmospheres......Page 146
4. Alkali resonance lines......Page 147
4.1. Neutral cesium......Page 149
5. Conclusions......Page 151
References......Page 153
1. Very low mass star models and the T eff scale......Page 155
2. Modelling the infrared colors of brown dwarfs......Page 157
3. Evolved brown dwarfs......Page 162
4. Conclusions......Page 163
References......Page 164
1. Introduction......Page 167
2. Thermodynamics of grain formation in stellar photosphere......Page 168
3.2.1. Case A : dust - free case......Page 169
3.2.2. Case B : dusty case......Page 170
4.1.1. Optical spectra......Page 171
4.1.2. Infrared spectra......Page 172
4.1.3. GD 165B - the proto-type of the case B......Page 173
4.1.4. Gliese 229B - the proto-type of the case C......Page 174
4.2. Infrared colors......Page 175
5. Concluding remarks......Page 177
References......Page 178
1. Introduction......Page 180
3. Atomic and molecular features......Page 181
4. The need for an additional opacity and its effects on the alkalis......Page 182
References......Page 184
1. Introduction......Page 186
2. The magnitude-colour diagram......Page 187
3. The mass-luminosity relation......Page 188
4. The calibration of effective temperatures and bolometric corrections......Page 190
5. Average calibrations......Page 191
6. Eclipsing binaries......Page 192
References......Page 195
1. Improvement of the theory......Page 197
2. Comparison with observations......Page 198
3. Remaining uncertainties and next challenges......Page 199
References......Page 200
Part III: Convection, Rotation and Activity......Page 202
1. Modeling convection: MLT and FST models......Page 204
2. Tests of the FST model......Page 205
3. Convection in low mass stars......Page 207
4. The FST model and Pre Main Sequence Evolution......Page 208
5. Mixing timescales......Page 210
6. The Lithium test in brown dwarfs......Page 211
References......Page 213
1. Introduction......Page 215
2. Theory of differential rotation......Page 216
3. The alpha-puzzle......Page 217
4. Models and their internal flows......Page 220
5. The M star dynamo model......Page 222
6. Conclusions......Page 224
References......Page 225
1. Introduction: why would we want to resolve stellar surfaces?......Page 226
2.2. General principles of Doppler imaging......Page 227
3.1. General observational constrains......Page 230
3.2. Systematic differences from spectral line to spectral line......Page 232
3.3. A closer look to two stellar examples: YY Geminorum and LQ Hydrae......Page 233
4. Could Doppler imaging be used to image the transit of an extra-solar planet?......Page 234
References......Page 238
2.1. The comparison of XLDFs: results......Page 240
2.2. The comparison of XLDFs: a possible explanation......Page 243
3. Coronal activity below the fully convective boundary mass......Page 244
4. Very low mass stars and Brown Dwarfs......Page 247
5. Conclusions......Page 249
References......Page 250
1. Introduction......Page 252
2. Stellar observations......Page 254
3. Pleiades dM stars......Page 256
References......Page 258
1. Introduction......Page 259
2.2. EV Lac PSPC spectra......Page 260
3.1. The SAX X–ray Light-Curves......Page 261
3.2.1. The SAX spectra of AD Leo......Page 262
4. Loop modeling......Page 263
References......Page 266
2. The Advanced X–Ray Astrophysics Facility (AXAF)......Page 267
3. The X-Ray Multi Mirror Mission (XMM)......Page 269
4. Stellar spectroscopy with AXAF and XMM......Page 270
5. Prospects for very-low mass stars and cluster stars......Page 274
6. Conclusions......Page 275
References......Page 276
Author Index......Page 278