1. THE CIRCUMSTELLAR MEDIUM OF AGB STARS:
A study of scattered stellar light and
molecular radio line emission
PART I : A study of episodic mass loss:
The detached shells of some AGB stars
seen in scattered stellar light
PART II : Modelling of radio line emission
from circumstellar molecules in a sample of
M-type AGB-variables
Thesis Presentation
Stockholm,

2. SETTING A BACKGROUND:
A schematic view of an AGB star

3. Observations of Scattered Stellar Light
* Spectroscopy
R Scl KI line
Gustafsson et.al.,1997
F77 filter
Paper I
* Direct imaging
* Imaging polarimetry
Stokes U
Paper II

4. Direct Imaging Observations Image reduction - Telescopes: ESO 3.6m NOT
- Cameras:
EFOSC1
EFOSC2
ALFOSC
- Coronographic mask
- Filters: F59, F77
- Lyot stop
Image reduction
- Templates stars
- Data Calibration

5. A view of EFOSC2 in polarimetry mode

6. The Targets CO maps: - Carbon stars with detached gas shells:
R Scl, U Ant, TT Cyg, S Sct, U Cam
AGB stars with detached dust shells:
U Hya, R Hya, X Tra, VX Sgr
CO line profiles:
CO maps:
CO 10

7. Achievements * Feasibility of this type of observations
* The circumstellar medium of R Scl
* The circumstellar medium of U Ant

8. Outlook
- New data:
U Ant
S Sct
- New observations with VLT, HST

9. SETTING A BACKGROUND:
A schematic view of an AGB star

10. Circumstellar Molecules
- In all type of Circumstellar Envelopes H2
- In Oxigen-rich Circumstellar Envelopes CO
SiO OH
H2O
- In Carbon-rich Circumstellar Envelopes CO
HCN

11. The Sample & Detection Rate
28 detected in SiO
8 detected in SiO
12 detected in CO
Original sample:
1442 SRVs
Subsample:
SRVs
IRVs
91 objects
33 objects
S60 ≥ 5 Jy
S60 ≥ 2 Jy
IRAS [12] - [25] > 1.2
47 detected in CO
22 detected in CO
Miras
12 detected in SiO
12 objects

12. The Model Goal: CO Mass loss rates SiO Gas expansion velocities
Abundances
Code: Montecarlo code by F. Schöier
Standard CSE envelope:
- Density law: r -2 (constant M and vexp)
- CSE inner radius: x1014 cm (~3R*)
- Turbulent velocity: km/s
Radiation field: A central blackbody
CMB radiation at 2.7K
Cooling processes: Adiabatic expansion
Line cooling (CO,H2O,H2 )
Heating processes: Dust drift through gas
Photoelectric heating
h-parameter 

13. Achievements Mass loss rates 12 -8.5 -5.5 Gas expansion velocities 20
IRVs
SRVs 12
-8.5
-5.5
Gas expansion velocities
IRVs
SRVs 20 25
SiO abundances
10-4
10-8
10-7

14. Outlook Observations: - Small sample: Interferometric maps
- Large sample:
Multi-line spectra
Sources in the M range M/yr 
Models:
- CO :
Photodissociation models
Turbulent velocity
- SiO :
Dust modelling
Cooling in the inner envelope
Accelaration
Envelope size