star formation in a dynamic interstellar medium workshop hosted by the yale university astronomy...
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Star Formation in a Dynamic Interstellar Medium
Workshop hosted by the Yale University
Astronomy Department
May 20, 2002
Simulation is a preview of work by Bate, Bonnell &
Bromm…stay tuned
The PlanTime Speaker Topic
09:40 Alyssa Goodman (CfA/Yale) Introduction
10:00 Phil Myers (CfA) What are the properties of the observed environment for star formation?
10:40 Coffee Break
11:00 Richard Larson What are the real observational constraints on the IMF?
11:40 Paolo Padoan (Caltech/JPL) What have we learned from numerical simulations of the star-forming ISM, on >1 pc scales?
12:20 Lunch
1:50 Bruce Elmegreen (IBM) On what scale is an IMF determined, and how might the answer to this question change? (Opinion #1)
2:30 Ian Bonnell (U. St. Andrews) On what scale is an IMF determined, and how might the answer to this question change? (Opinion #2; simulation figure above from Bate, Bonnell & Bromm)
3:10 Coffee Break
3:30 Richard Larson (Yale) Thoughts, and an open fourm, on the day's presentations
4:00 Meeting Adjourns, but those interested stay on to chat
Questions Raised by a Dynamic View of Star Formation
Scale Names Static Dynamic
100-1 pc Giant MolecularClouds, Cloud
Complexes
Formation ofGMCs in SpiralDensity Wave
• Ho w importan t ar e supernov ae a nd oth er b igoutflo ws increati ng b igmolecula r cloud ?s
• Doe s turbulenc e nee d drivin g on thes e scales?
10-0.1 pc Dark Clouds,Cl oudCores
(Jeans-like)Instabiliti es within
clouds le ad tostructures
• Assuming turbulenc e determine s the "clump IMF", wi th ashallowe r sl opet han th e stella r IM F at th is scale, w hatisthe ri ghtclu mp IM ? F (log-normal?)
• Ho w muc h of a rol e d o outflows pla y on th is scal : e r -eshapin g m ass distributio , n drivin g turbulence?
1-0.01 pc Dense Cores,Coher entCores,
Kernels
Gravitationalcollap se of J eans-m ass fragments
• D o inwar d motion s an d "coherent" cores rea lly resul t fromcollidi ngstreams?
• I s th (e stella ) r IM F se t b y th e turbulenc e a t these scales?i. . e Do es the"cl ump IMF" of self-gravitati ng blob =s stellarIMF?
• Ho w muc h dointeraction s amongs t forming densit y peaksand/ oryo ungstar s ma ?tter
0.1 pc-200 AU
Kernel , s Pse -udodisks, Disks,
Star +sProtoplanetary
Disks
Disk instabilitiesfragmen t d isks into
multipl e pieces,depending on
or dero f instability
• W hata re th e interacti on among stblobs, star s an d d isks i n aformi ngclust ?er
• W hata re th e blob ?s
• Ho w lon g dostructur es las ?t
• A re man y planet s discar ?ded
PV Ceph: Episodic ejections
from precessing or
wobbling moving source
Implied source motion ~7 km/s (3 mas/year)
assuming jet velocity ~100 km/s
Goodman & Arce 2002
Insights from a “Plasmon” Model4x1018
3
2
1
0
y knot positions (cm)
-4x1017
-2 0
x knot posns. w.r.t. star "now" (cm)
500x1015
400
300
200
100
0
Distance along x-direction (cm)
15x103
1050
Elapsed Time since Burst (Years)
70
60
50
40
30
20
10
0
Knot Offset/Star Offset (Percent)
Knot
Star
Star-KnotDifference
Star-KnotDifference
(%)
Initial jet 250 km s-1; star motion 10 km s-1