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2. SHELL MODELThe dusty envelope is assumed to be an oblate spheroid with a power-law densitydistributiona21 -«/2n(7') o:(rX+ry+rzb2J , (1)Jwhere a and b are the semiaxes of the shell (so that the isodenses are ellipses).The dust-free innermost spherical region around the star is adopted to be due toevaporation of the grains. The outer radius of the shell has little effect on the resultsand is chosen large enough to be not in conflict with the observed far-IR flux.The dust grain model is a MRN-like one: a mixture of silicate and graphite sphericalgrains having a power-law size distribution n(a) = no a with the minimum andmaximum radii a ni,,, and amax-We believe that the photometric and polarimetric variability of the objects iscaused by the dense dust clumps orbiting the stars and screening them from theobservers (Grinin, 1988). It is assumed that the clumps do not affect spectral energydistribution (SED) and other characteristics of the objects significantly.For modelling of the observational data listed in Sect. 1, we use a 2D Monte-Carlocode (Fischer, 1995). To derive the dust temperature distribution for the Monte-Carlosimulations, spherical shells of the same volume are considered with a 1D radiationtransfer code (Men'shchikov & Henning, 1996).3. RESULTS AND DISCUSSIONAt first, we have considered the SED's in the IR and the stellar tracks in the CMD'sand restricted the set of the models fitting both types of the data. Such a proceduregives the reliable estimates of the optical thickness of the shells Tsh (Krivova, 1996).The obtained values of Tsh are presented in Table 1.The observed polarization of the stars with the shells presumably involves threecomponents: the interstellar polarization PIS , the polarization caused by opticaldichroism of the shell PCs, and the polarization due to light scattering in the nonsphericalshell Psh (see e. g. Berdiugin et al., 1990). For the "variable circumstellarextinction" model accepted, the polarization at given wavelength should vary withbrightness variations as follows:P(Om) = P IS + PshIshshJo , 10-0.4Am + PCs 1 C —. Jo . 10-0.4Am )where Om is the stellar brightness decrease, Ish is the flux of the scattered radiation,and lo = I* exp( — rsh) + Ish is the total flux of the object (star+envelope) at themaximum brightness level.The ratio Ish/Io can be estimated as the maximum brightness fall is limited bythe scattered light(Om)max < —2.5 log to . (3)(2)38
Table 1 Observational characteristics of the stars and derived parameters of the modelsStar BF Ori UX Ori WW Vul CQ TauM, mag -9.5 -9.6 -10.2 -9.5(0 m)max 3.0 2.7 2.4 1.8Pb, % (m) 0.2 (9.82) 0.7 (9.86) 0.6 (10.25) 2.7 (9.48)Pf , % (m) 5.1 (12.15) 7.2 (12.12) 5.9 (12.26) 6.7 (11.25)Pis, % 0.5 0.5 0.7 1.5Tsh 0.2 0.3 0.3 0.7Ishllo
Page 1 and 2: NASA Conference Publication 3343Fro
Page 3 and 4: PREFACEOn June 24 through 26, 1996,
Page 5 and 6: TABLE OF CONTENTSPreface...........
Page 7 and 8: The role of hydrogen in small amorp
Page 9: P PIC AND SIMILAR DISK-LIKE OBJECTS
Page 12 and 13: y linear deconvolution of the SSA i
Page 14 and 15: `planetesimals'. Those ones are spa
Page 16 and 17: o Variations of the size of the blo
Page 18 and 19: Table 1 Best-fitting model paramete
Page 20 and 21: 10-10SAO 179815 (HD 98800)10-1110-1
Page 22 and 23: 2. 0 Pic-like SYSTEMSOne of the gre
Page 24 and 25: Backman, D. E., and Paresce, F. 199
Page 27 and 28: PARTIALLY CRYSTALLINE SILICATE DUST
Page 29 and 30: 12D 100546 vs Forsterite (dashed) a
Page 31 and 32: HIGH RESOLUTION SPECTROSCOPY OF VEG
Page 33 and 34: accretion hypothesis, King (1994) i
Page 35 and 36: TRANSIENT ACCRETION EVENTS IN HERBI
Page 37 and 38: e ionized by the stellar radiation
Page 39: STAR FORMATION31
Page 42 and 43: 1980 1985 1990 19959.09.5®rIL10.01
Page 44 and 45: 4. DISCUSSION AND CONCLUSIONSWe hav
Page 48 and 49: — "Fluffiness" of dust particles.
Page 50 and 51: 2. OBSERVATIONSThe observations wer
Page 52 and 53: 1050.015^ ^o.,a •,o a0s0au0—5
Page 54 and 55: IMAGING POLARIZED DUST EMISSION IN
Page 56 and 57: Figure 3. The total intensity (left
Page 58 and 59: 0fvac = 0.3(dot), 0.5(dash), 0.7(li
Page 60 and 61: lo`lo'00axto-,00a10 -20lo-''10' to
Page 63 and 64: EXTERNALLY INDUCED EVAPORATION OF Y
Page 65 and 66: 0-6—7—8—9v -10OD0Dispersal Ra
Page 67: CIRCUMSTELLAR DUST59
Page 70 and 71: Table 1 SiC features and the Temper
Page 72 and 73: have very similar absorption featur
Page 74 and 75: mSE1 .-SE3 -SE4U NA iLtSE5 --SE6 SE
Page 76 and 77: 3. CARBON STARSSloan, Little-Mareni
Page 78 and 79: eferences therein). The arc dischar
Page 80 and 81: the time scale of their evolution:
Page 82 and 83: easily amended for any chemical spe
Page 84 and 85: 25002000a^a^H150010001 2 3 4r/Rstar
Page 86 and 87: 2. METHODThe stellar wind model is
Page 88 and 89: 0 0.04(a)3007EU200(b)0.03Ec 0.02^s0
Page 90 and 91: 0 CETIX = 8-9 µm ,(off dust featur
Page 92 and 93: Examining a number of grain types,
Page 95 and 96: REVISED DEPLETIONS AND NEW CONSTRAI
Page 97 and 98:
- 1 -Table 1.__Revised stellar and
Page 99:
ReferencesAannestad, P. 1995, ApJ,
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3.02.52.0CL1.51.00.50.03 4 5 61 /X
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ReferencesAnderson, C.M. et al. 199
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2.1. ExtinctionInfrared photometry
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THE EXTINCTION PROPERTIES OFHEAVILY
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3. ANALYSISUsing a Quantimet Q520 i
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HAC: BAND GAP, PHOTOLUMINESCENCE, A
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3.2. The 3.4 micron Absorption Band
Page 117 and 118:
THE ROLE OF HYDROGEN IN SMALL AMORP
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R 100an'c30w 0 Wa.AE-50A 1C.q-t0.5x
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OBSERVATIONS OF TWO NON-STANDARD GR
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where VSGs break off larger grains
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IRAS COLORS OF THE PLEIADESSEAN J.
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4. IDENTIFICATION OF DENSE (MOLECUL
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PAH EMISSION IN THE ORION BARJESSE
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0.80.60.40.20.8N 0.60.4DN 0.2^ E b:
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LABORATORY EXPERIMENTS ON THE REACT
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500Cto 8+ + 0 ®> CgH8+ + CO400AvrA
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433v02110 30 60 90 120 150 180 210F
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PROCESSING OF ICY MANTLES IN PROTOS
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tions of mixtures each provide exce
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THE ICE AND SILICATE SPECTRAL FEATU
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2.5Model C (a= 1µm)—f=0.2-'1 - -
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EVIDENCE FOR THE EVOLUTION OF GRAIN
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(a) Ih2FIRS,_I(h}p 56^LOo . o FIR4'
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THE ABUNDANCES OF CHARGED PARTICLES
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2.3. Grain Charge TransferIn order
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THE PROTOSOLAR NEBULA147
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CATALYSIS BY DUST GRAINS IN THE SOL
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Figure 1 shows the steps involved i
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(e.g., surface-catalyzed) ones. Thi
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RESTRUCTURING OF DUST AGGREGATES IN
Page 165 and 166:
3. AN EXAMPLE CALCULATIONWe have in
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EFFECT OF DUST COAGULATION DYNAMICS
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NUMERICAL SIMULATIONS FOR SUM KERNE
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SELF-CONSISTENT SIMULATION OF THE B
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and a diffusivity Di = Tfi kT/mi. D
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DUST COAGULATION IN PROTOPLANETARYA
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Coogulction tit?- )e• zn /5139,5
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SIZE SEGREGATION AND NUMBER DENSITY
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10`1100.01 cm . . . . .0.1 cm . . .
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FROM CHONDRULES TO PLANETESIMALS:SO
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Figure 2. Regions of high particle
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VORTICES AND PLANETESIMALSP. BARGE
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c0UdWU)0 10 -1ULUiCROSSING * ` yAjr
Page 191 and 192:
THE ROLE OF VORTICES IN THE FORMATI
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(a)(b)(c)606060Y40 ,^ Y40 OOY402020
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THE GLOBAL PERSPECTIVE ON THE EVOLU
Page 197 and 198:
103102 ..........................10
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TOWARD AN ASTROPHYSICAL THEORY OFCH
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and the subsolar temperatureTsub..I
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PLANETESIMAL FORMATION IN THE OUTER
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3. SUBLIMATION, CONDENSATION, AND G
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PLANETESIMALS AND COMETS199
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THE MASS OF LARGE IMPACTORSM. G. PA
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99 3JupiterNeptuneA0 20 — 0.00 0.
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TIDAL BREAKUP OF ASTEROIDS BY THE E
Page 215 and 216:
Figure 2. Time sequence showing the
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ON THE DYNAMICS OF THE ZODIACAL DUS
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de Log U®ro 1 — E2dt aysw Ecos z
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DUST AND SPUTTERED PARTICLE STREAMS
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A"P -0.1s^nntU 8 -- -3.2- - 3.6-- 3
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PRELIMINARY RESULTS OF OBSERVATIONS
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4. ULYSSES COMET WATCH NETWORKIn 19
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POROSITY AND PERMEABILITY OF CHONDR
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from the dessi cation of such a "we
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5. POROSITY MEASUREMENTS OF BULK CH
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RAMAN SPECTRUM OF QUENCHEDCARBONACE
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Raman shift (Acm -1)1000 1300 1600
Page 239 and 240:
AUTHOR INDEXAdamson, A.J. 101,131 G
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SUBJECT INDEXabundances, cosmic 89a
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plasma 216,218polarization 38, 39,
Page 245 and 246:
OBJECT INDEXAB Aur 20R Cas 15O Ceti
Page 247 and 248:
ADDRESSES OF PARTICIPANTS239
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Nancy AgeorgesEmma BakesESONASA Ame
Page 251 and 252:
Max BernsteinJurgen BlumNASA Ames R
Page 253 and 254:
Connie ChangSimon ClemettHarvard Un
Page 255 and 256:
Jamie ElsilaMarina FomenkovaKalamaz
Page 257 and 258:
Mayo GreenbergUniv. of LeidenHuygen
Page 259 and 260:
Dan JudnickJohn F. Kerridge5702 Cal
Page 261 and 262:
John KulanderOliver LayP.O. Box 704
Page 263 and 264:
Vito MennellaDaffel MoonObservatori
Page 265 and 266:
Pendleton YvonneSun Hong RhieNASA A
Page 267 and 268:
Anneila SargentRussell ShipmanCalif
Page 269 and 270:
Prof. Stanislav SvirschevskyHead of
Page 271 and 272:
Christoffel WaelkensFrancis P. Wilk
Page 273:
REPORT DOCUMENTION PAGEForm Approve
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