Star

1
Star Planet Formation

• Alyssa A. Goodman
• Harvard-Smithsonian Center for Astrophysics

2
Which Stars form Where, When, and How?
?
?
3
Mass Matters
4
Orion Constellation Movie
5
(No Transcript)
6
Which Stars form Where, When, and How?
?
Implications -evolution of galaxys gas stars
with time -variety/longevity of extrasolar
systems
7
Star-Forming Region in Perseus
60 light years
Image by E.E. Barnard, c. 1907
8
Brightness color measurements give information
on the mass distribution (IMF) of stars, and
the DISKS around those stars.
60 light years
9
How many stars of each mass form?
IMF Initial Mass Function of Stars
Number of Stars of each Mass
Stellar Mass
10
How does the IMF vary with environmental
conditions?
FLAMINGOS J,H,K Composite Muench et al. 2003
IC 348 Luhman et al. 2003 Taurus Briceño et
al. 2002
11
Key Questions

• How does the IMF vary with environment?
• How fast do clouds stars form?
• What creates variety in protoplanetary disks?

12
Science Technology
13
Simulations as Data Interpretation
Data Censes of Young Stars Radio spectral-line
maps of gas motions Thermal-continuum maps of
dust emission photos of dust extinction Dynamic
Range gt104 Simulations Including effects of
gravity, magnetic fields, chemistry, heating
cooling, stars forming, thermal pressurebut
not all at once (yet) Dynamic Range lt102
Simulated spectral-line map, based on work of
Padoan, Nordlund, Juvela, et al. Excerpt from
realization used in Padoan, Goodman Juvela 2003
14
Synthetic Star Forming Regions
Strong Magnetic Field
Weak Magnetic Field
b0.01
b1

• Driven Turbulence M? K no gravity
• Colors log density
• Computational volume 2563
• Dark blue lines B-field
• Red isosurface of passive contaminant after
  saturation

Stone, Gammie Ostriker 1999
15
Simulations Let Us Live Longer

• MHD turbulence (another simulation) gives initial
  conditions
• 50 Msun, 1 lyr, navg3 x 105 ptcls/cc
• forms 50 objects
• T10 K
• SPH, no magnetic fields or heating and cooling
• movie1.4 free-fall times

Bate, Bonnell Bromm 2002 c.f. Ostriker, Stone
Gammie 2001
16
Circumstellar Disks
17
Which Stars form Where, When, and How?
?
Implications -evolution of galaxys gas stars
with time -variety/longevity of extrasolar
systems
18
Key Questions

• How does the IMF vary with environment?
• How fast do clouds stars form?
• What creates variety in protoplanetary disks?