Studies of Molecular Outflows Hsin-Lun Kuo Department of Physics,NTU Supervisor:Hsien Shang 2002 Summer Students Presentation, ASIAA
Aug 27,2002Summer Students,ASIAA Outline Bipolar Molecular Outflows of YSOs A Simple Physical Model Based on “Star Formation And The Nature Of Bipolar Outflows ”, Shu et al., ApJ 370, March 1991 Try To Produce Different Shapes of The Lobes
Aug 27,2002Summer Students,ASIAA Bipolar Molecular Outflows of YSOs Deeply related to the processes of star formation and early stellar evolution Observable from UV to radio, best traced by CO emission Flow sizes: less than 0.1pc ~ several pc Terminal velocities: a few kms -1 ~ several hundred kms -1 Kinematical time-scale: 10 3 ~ 10 5 yr Outflowing mass: M ~ 10 2 M
Aug 27,2002Summer Students,ASIAA Properties of Outflows Intrinsic or external, large-scale collimation? “Classical” and “highly collimated” outflows in observations Collimation factor--axial ratio Hubble-like law Jet-like and EHV bullets Class I and Class 0 YSOs
Aug 27,2002Summer Students,ASIAA Shu’s “Snowplow” Model Radiating shocks form a swept-up shell of ambient molecular cloud material Swept-up and shocked- wind material mixed well Momentum-driven Intrinsically collimated by MHD mechanism
Aug 27,2002Summer Students,ASIAA Equations Density distribution of an isothermal sphere Momentum input per steradian
Aug 27,2002Summer Students,ASIAA Solutions For momentum conserved winds blowing into 1/r 2 density profiles Shell speed Shell position Bipolarity function
Aug 27,2002Summer Students,ASIAA Constraints Q(μ) : P(μ) : B(μ) : and Axial ratio of lobe
Aug 27,2002Summer Students,ASIAA My “Guess” on P(μ), Q(μ) Q( μ ) P( μ ) μ μ μ B( μ )
Aug 27,2002Summer Students,ASIAA Reproducing The Lobes Axial ratio 3:1 (with [f/2] 1/2= 0.4, av w =100 )
Aug 27,2002Summer Students,ASIAA Some Trials– 2:1 Q( μ ) P( μ ) μ μ
Aug 27,2002Summer Students,ASIAA Some Trials – 4:1 Q( μ ) P( μ ) μ μ
Aug 27,2002Summer Students,ASIAA Some Trials – 5:1 Q( μ ) P( μ ) μ μ
Aug 27,2002Summer Students,ASIAA Some Trials – 8:1 Q( μ ) P( μ ) μ μ
Aug 27,2002Summer Students,ASIAA Some Trials – 10:1 Q( μ ) P( μ ) μ μ
Aug 27,2002Summer Students,ASIAA Future Work Change a few constraints Make more realistic guesses on P,Q Considering f, a, v w, t Compare to observational results of simple outflows