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Subject Index Absolute flux determinations AHS in Herbig-Haro objects 209 for Herbig-Haro objects 214 Angular dimensions Absolute radiation, measurements 9 of H20 sources 265 Absorption of OH sources 262,263 continuous 42 Anisotropy in masers 270,282 line 38,41 Anti-inversion 289 molecular 44 Ap phenomenon 129 Absorption coefficient 29,267 origin 132 depth dependence 27 Ap stars effecti ve 336 magnetic fields 107 for grains 242 magnetosphere 137 f. negative 257 major groups 109 f. Absorption profiles in masers 266 nuclear reactions 132 Abundance anomalies 102 separation of elements 132 Abundance gradients 102 supernova-binary hypothesis 134 Abundances surface spallation 134 definition 102 Ap-type anomalies 132 in CNO stars 119 H. detectability 117 of heavy elements 21 ff. hot boundary in Clog g, log Teff)­ in helium stars 81 plane 140 H. in Herbig-Haro objects 220 of population II B stars 129 metal 51 ATLAS, model atmosphere program 15 normal 104 Atmospheric parameters iri O-subdwarfs 83,84 of helium stars 72 in population II B stars 125 ff. A-type horizontal branch stars 149 ff. relative 103 solar 15,104 Backwarming effect 23 in weak-helium-line stars 112 f.,116 Balmer decrement in the spectrum in white dwarfs 177,182 ff. of Herbig-Haro objects 209 Accretion 139,189,192,306,315 Balmer discontinuity 34,36,37 Acoustic waves 302 in helium stars 68,73,76 Activity, stellar 305,309 in horizontal branch stars 153 358 subject Index Balmer lines 39,45,303,308 Carbon stars 57 in horizontal branch stars 153 Center to limb variation solar 13 in cosmic masers 270 Be stars 313 solar 8 Binaries 302,314 ff. Central intensities, solar 8 close 302,306,309,310 Central limit theorem 334 X-ray 315 Cepheids 52,53 Birthrate function of helium stars 96 Chandrasekhar limit 195 Birthrate of white dwarfs 189 Chemical composition Black holes 316 of horizontal branch stars 166 ff. Blanketing effect 38 Chemical pumping 287,288,293 in horizontal branch stars 154 Chromospheres, stellar 54,302 ff.,30' by hydrogen lines 151,177 311 in white dwarfs 177,199 Chromospheric Call K2 emission Blocking effect 175 core 231,232 of metal lines in horizontal Chromo spheric emission at branch stars 154,156 radio wavelengths 242,301 ff. Blue halo stars 122 ff. Chromospheric lines, stellar 305,308 Bolometric correction 49 Chromospheric temperature rise, solar Brightness temperature Circumstellar absorption lines 230 fj coronal 304 Circumstellar envelopes 229 ff.,311 of flares 305 density 233,250 of H20 sources 264 expansion velocity gradient 233,231 of OH sources 260 temperature 233 Brightness variations turbulent velocity 233 of HBV 475 314 Circumstellar HII region 313 of Herbig-Haro objects 207 Circumstellar material 189 Broadband photometry 179 Classification as a Herbig-Haro B-type stars, helium-rich 117 object 212 B-V 46 c1 - m1 diagram 150 solar 11 CNO anomalies 119 ff. CNO burning 121 Call CNO stars 118 ff.,142 K emission 53,54,303,307 element abundances 119 ff. K-line flux in Herbig-Haro variability 119 objects 219 CO emission 312,313 K4 absorption 231,232,239 Collisional excitation 218 lines in the spectrum of Herbig-Haro Collisional pumping 287,289,293 objects 209,220 Colors, color indices Carbon abundance in white dwarfs 183,185 extreme-ultraviolet of Carbon enrichment 194 weak-helium-line stars 111 Subject Index 359 of helium stars 68 C/O ratios in white dwarfs 180,183,185 of horizontal branch stars 153 ff. Corona Australis dark cloud 215 solar 11 ff. Coronas UBV 46 f. stellar 54,301 ff. Color magnitude diagram 52,53 of supergiants 304 Column densities in cosmic masers 278 Correlation length 328 Compact HI! regions 259 Cristallization in white dwarfs 188 Condensations in Herbig-Haro C-type anomaly 118,121 objects 207,209,215 Cumulants 331 typical diameter of 207 Curve of growth 54 Continuous absorption in cosmic masers 268,281 ff. Damping wings 21,39 Continuous opacity of the solar Debye-temperature 186 atmosphere 14 Densities, in cosmic masers 278 Continuous spectra of Herbig-Haro Density distribution around objects 212 ff. T Tauri 226 interpretation 216 ff. Deutsch's line strength-velocity Continuum correlation 234,237 energy distribution 34 Diffusion 129,130,132,135,142,182,184 solar 13,14 helium convection 136 ultraviolet 36 in helium stars 81,83 Continuum radiation in Herbig-Haro Doppler shifts in the spectra of objects 223 Herbig-Haro objects 212 Convection 51,53,55,139,302,303,307 Dust in horizontal branch stars 152 in cosmic masers 283 of nondegenerate layers 199 in Herbig-Haro objects 223 overshooting 55 Dust clouds, OH emission from 263 velocities 54 Dust shell in white dwarfs 177,317 circumstellar 241 ff.,302,311,312 Convective envelope of radius 243 ff. white dwarfs 192 Convective instability 51,55 EB_V' in Herbig-Haro objects 208,209 Convective mixing 192 Eigenfunctions 346 Convective stars, location in Electrons, fast, in Herbig-Haro Clog g, Teff)-diagram 51,52 objects 223 Cooling age of white dwarfs 199 Electron density near Herbig-Haro Cooling region in Herbig-Haro objects 207,217 ff. objects 225 Electron temperature in Herbig-Haro in supernova remnants 223 objects 207,217 ff.,222 Cooling sequence of Element abundances, see abundances white dwarfs 175,184 Emission, stimulated 257 360 Subject Index Emission features in helium stars 94 Faraday effect in cosmic masers 285 Emission line intensities of HH 1 Fast rotators 81,95 211 Field horizontal branch stars 149,159 Emission profiles in masers 266 Filling factor of Herbig-Haro Energy distribution objects 207,221 of stellar spectra 55 Fine analysis of helium stars 76 in the spectra of Herbig-Haro Flare stars 302,307 ff. objects 213,225 Flares, stellar 302,305,307,309 surface 21 Flux density 304 Energy level diagram Fokker-Planck equation 342,353 of H20 molecule 292 Forbidden lines in Herbig-Haro of OH molecule 259 objects 208 ff.,217 Energy output, total, of Herbig-Haro [Fe] 209,214 objects 214 [NeIll] 210 Envelope composition of [0] 209,210,223 white dwarfs 191,193 [SIl] 208 ff. Envelopes Fraunhofer lines, solar 14 circumstellar 229 ff.,311 F-type supergiants 249 hydrogen-rich 188 of M giants and supergiants, Galaxy, mass budget 194 densities 238 Generalized transfer equation 344 Evolutionary stage of Herbig-Haro formal solution 348 objects 224 ff. numerical integration 349 Evolutionary tracks of Globular clusters 149,163,164,196, helium stars 86 229,252 Evolution H-R diagram 21 of helium stars 84 Grain temperature 243 of T Tauri stars 225 Gravitational redshift 193 Excitation Gravitational separation 135,182,184, collisional 218 192 of Herbig-Haro objects 222 (g, Teff)-classification of Expanding envelopes 263 helium stars 89 Expansion velocity model 237,240 (g, Teff)-diagram of helium stars Extended horizontal-branch 84,85 hypothesis 123 Extinction H- 14,27,29,32,34,36 atmo~pheric 2,3 Harman-Seaton sequence 190,197 in Herbig-Haro objects 208,209 Hayashi limit 86 line 5 HCN emission from carbon stars 313 Extreme-ultraviolet fluxes of Helium abundance weak-helium-line stars 116 in CNO stars 119 f. Subject Index 361 in horizontal branch stars 168 H20 sources 263 ff.,288,293 in population II B stars 122 ff. observational data 264 in weak-helium-line stars 110 ff. Horizontal branch 185,187 in white dwarfs 179 Horizontal branch stars 123 ff.,130, HeI discontinuity in helium stars 68,73 141,149 ff.,229,252 Helium burning 121 H-R diagram, of globular clusters 21 Helium enrichment 90 HII regions 259 Helium problem 129 surrounding cool stars 303,311 ff. Helium-rich atmospheres 185 Hydrogen abundance in helium Helium stars 57 ff. stars 72,87 abundances in 65,72,81,87 Hydrogen deficiency in helium Balmer and HeI discontinuities 68,73 stars 57 distribution on the sphere 62 Hydrogen deficient atmospheres 179 emission feature at H 94 a Hydrogen lines 13,39,45 evolution 84,86 Hyperfine splitting in OH molecule 258 extreme subclass 58,59,76,91 galactic distribution 63 (g, Teff)-classification and Induced emission 257,276 masses 89 Infrared emission 311,312 (g, Teff)-diagram 84,85 Infrared excess 311 ff. intermediate subclass 57,58,59,78,91 in Mira variables 261 spectra 66,68 ff. silicate 231,241 ff.,250 statistics of 63 Infrared HeI-triplet 305 variability 93 Infrared lines in OH sources 280,282, velocities 62,64 283 Helium zero age main sequence 87 Infrared sources 259 Helmholtz-Kelvin time 252 related to Herbig-Haro Herbig-Haro objects 205 ff. objects 214 ff.,224 central star 222 Inhomogeneities in Herbig-Haro observations 206 ff. objects 218,221 theory of 216 Initial mass function 197 H/He ratio Instability strip 52,53 in helium stars 65 Integrating sphere 5 in white dwarfs 181 Intensity, expectation value 330 High-altitude experiments 1,2,4 Interferometry, VLB 260,264 results of 7 Interlocking states 291 High-luminosity population II Intermediate helium stars 95 stars 123 ff.,127 Interstelllar absorption H20 emission 246,257,260,261,309, in the spectrum of Herbig-Haro 312,313 objects 208 H20 molecule 292 Interstellar material 198,311 362 Subject Index Interstellar medium, mass balance of 254 Macroturbulence 325,340,342 Interstellar scattering 296 Magnetic accretion 135 ff.,142 Ionization,of Herbig-Haro objects time s,\a1e 139 206,207,220,222 ££.,226 Magnetic fields in M giant envelopes 236 in Ap stars 107 by protons, in Herbig-Haro obiects 224 in cosmic masers 285 Irregular variables 312 in weak-helium-line stars 112,116 IR stars 261,262,265 in white dwarfs 181 Magnetosphere of Ap stars 137 f.
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  • ASTR 4008 / 8008, Semester 2, 2020

    ASTR 4008 / 8008, Semester 2, 2020

    Class 18: Protostellar evolution ASTR 4008 / 8008, Semester 2, 2020 Mark Krumholz Outline • Models and methods • Timescale hierarchy • Evolution equations • Boundary conditions • The role of deuterium • Qualitative results: major evolutionary phases • Evolution of protostars on the HR diagram • The birthline • The Hayashi and Heyney tracks Timescale hierarchy Similarities and differences to main sequence stars • Protostellar evolution governed by three basic timescales: • Mechanical equilibration: tmech ~ (R / cs) ~ (R3 / GM)1/2 ~ few hours • Energy equilibration (Kelvin-Helmholtz): tKH = GM2 / RL ~ 1 Myr • Accretion: tacc = M / (dM / dt) ~ 0.1 Myr −5 −1 • Numerical values for M = M⊙, R = 3 R⊙, L = 10 L⊙, dM / dt = 10 M⊙ yr • Implication: protostars are always in mechanical equilibrium, but are not generally in energy equilibrium while they are forming • By contrast, main sequence stars in energy equilibrium because tKH ≪ lifetime • This hierarchy applies to low-mass stars; somewhat different for high mass Equations of stellar structure For protostars • Equations describing mass conservation, hydrostatic balance, and energy transport are exactly the same as for main sequence stars: <latexit sha1_base64="zQBTVeYWRUq5mFjggJdG88FmPGo=">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</latexit>