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, 04-03-03

SETTING A BACKGROUND: A schematic view of an AGB star

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

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

A view of EFOSC2 in polarimetry mode

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

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

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

SETTING A BACKGROUND: A schematic view of an AGB star

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

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

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: 1.0x1014 cm (~3R*) - Turbulent velocity: 0.5 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 

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

Outlook Observations: - Small sample: Interferometric maps - Large sample: Multi-line spectra Sources in the M range 10-6- 10-5 M/yr  Models: - CO : Photodissociation models Turbulent velocity - SiO : Dust modelling Cooling in the inner envelope Accelaration Envelope size