next up previous
Next: Atomic Models Up: Realistic Models For Expanding Previous: Introduction

The Concept of Radiation Driven Winds

Figure 3: Schematic sketch of the basic equations of stationary radiation-driven wind theory (see text).

\begin{figure}
\centerline {\hbox{
\psfig{file=06-concept.ps,width=14.cm}}}\end{figure}

The concept of our expanding-atmosphere model calculations is based on the homogeneous, stationary, and spherically symmetric radiation-driven wind theory initially outlined by Lucy & Solomon (1970) and Castor, Abbott & Klein (1975). This concept turned out to be adequate for the analyses of hot-star spectra (see Fig. 2) and in spite of its restrictive character we are confident that in general it correctly describes the time-average mean of the spectral features. Fig. 3 gives an overview of the physics to be treated, and in the following we will briefly discuss the characteristic features of the system and describe our model approach. (A comprehensive discussion of most points is found in Pauldrach et al. 1994a.)

The principal features are:

As our present treatment of O-star atmospheric models is of course not free from approximations - in common with all other approaches to the theory (e.g., Schaerer & de Koter 1997; Hillier & Miller 1997) - we will emphasize the crucial points which either have important consequences or which still imply some uncertainties for our model calculations in more detail.

Table 1: Summary of Atomic Data. Columns 2 and 3 give the number of levels in packed and unpacked form; in columns 4 and 5 the number of lines used in the rate equations and for the line-force & blocking calculations are given, respectively.

         

Ion

Number of

Number of

Total non-LTE

Total

 

packed levels

levels

lines

lines

         

CIII

50

90

520

4407

CIV

27

48

103

229

         

NIII

40

80

356

16458

NIV

50

90

520

4201

NV

27

47

104

229

         

OIII

50

118

582

25511

OIV

44

90

435

17933

OV

50

88

524

4336

         

NeIII

38

78

319

857

NeIV

50

113

577

4470

NeV

50

110

534

2664

         

SiIII

50

88

480

4044

SiIV

25

45

90

245

SiVI

50

122

596

3889

         

SIII

14

28

32

190

SIV

13

23

22

70

SV

14

26

17

82

SVI

18

32

59

142

         

ArIII

13

26

21

1912

ArIV

11

23

22

398

ArV

40

96

328

3007

ArVI

42

93

400

1335

         

FeIII

50

122

246

199484

FeIV

45

126

253

14346

FeV

50

122

442

10831

FeVI

50

104

452

11533

         

NiIII

40

112

281

131508

NiIV

50

148

528

11979

NiV

41

95

70

9207

NiVI

45

128

253

10821

         



Subsections


next up previous
Next: Atomic Models Up: Realistic Models For Expanding Previous: Introduction

1999-10-16