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Origins of Stars and their Planetary Systems June 10–15 , 2012 Hamilton,
Ontario
Simulating Protostellar Evolution
and Radiative Feedback
in Stars and Clusters
Mikhail Klassen (1) , Ralph Pudritz (1,2) , Thomas Peters (3)
(1)
Dept. of Physics & Astronomy, McMaster University (2) Origins Institute, McMaster University
(3)
Institut für Theoretische Physik, Universität Zürich

Massive stars are the “movers and shakers” of
the interstellar medium. Their powerful
feedback processes include:
Radiation
Jets and outflows
Stellar winds
HII regions
Supernovae
These phenomena heat gas, inject turbulence,
skew stellar populations, raise galactic
metallicity, and destroy molecular clouds.
HST image of compact star forming region Sh 2-­‐106.
Credit: NASA & ESA

Massive stars are the “movers and shakers” of
the interstellar medium. Their powerful
feedback processes include:
Radiation
Jets and outflows
Stellar winds
HII regions
Supernovae
These phenomena heat gas, inject turbulence,
skew stellar populations, raise galactic
metallicity, and destroy molecular clouds.
HST image of compact star forming region Sh 2-­‐106.
Credit: NASA & ESA

How do clusters of massive protostars shape the dynamics of molecular clouds?
How do massive protostars evolve in a turbulent, possibly magnetized
environment?
How does protostellar evolution affect radiative feedback?

Simulating star formation on an adaptive Eulerian mesh
FLASH 2.5

Simulating star formation on an adaptive Eulerian mesh
SINK PARTICLE
Mass
Accretion Rate
PROTOSTELLAR MODEL
Stellar Radius
Luminosity
Deuterium Mass
Evolutionary Stage
Polytropic Index

Protostellar Model based on Offner et al. (2009), solid; compared to
Hosokawa & Omukai (2009) calculations, dashed.
Figures 1 and 2 from Klassen et al. (2012a)

Toy Model: Accretion onto a Single Protostar
Toy model because…
• Gravity turned off
• Spherical symmetry
• Isothermal, homogeneous
initial conditions
Interesting because…
• Connected to protostellar
evolution model
• First calculation of HII
region variability due to
variable ionizing source
Low
Mass Density
[ g cm -3 ]
High

Figure 1 from Klassen et al. (2012b, in prep)

HII Region Confined to Protostellar Outflow
Figure 3 from Tan & McKee (2003), IAU Symposium 221, Star Formation at High Angular Resolution

Radiative Feedback in the Cluster Environment
Setup
• 1000 M SUN clump
• r -­‐3/2 density profile
• Axisymmetric, with
rotation
• One of two protostellar
models:
• Peters et al. (2010a)
• Offner et al. (2009)

Note similarity to title slide / HST Image

Mass-­‐Radius Relation for a Cluster of Protostars
Figure 8 from Klassen et al. (2012a)

Turbulence and MHD
Setup
• 1000 M SUN clump
• r -­‐3/2 density profile
• Turbulence
(Burger’s spectrum, Mach 5 RMS)
• Uniform B-­‐field with
M/Φ ~ 3.5
Designed to explore
• Impact of HII region feedback in
turbulent, magnetized clusters
• Lifetimes of MC clumps
1 pc
• Interplay of MHD and radiative
feedback

Column Density (g/cm 2 )

Conclusions
• Numerical simulations are illuminating the cluster picture of massive star
formation
• Feedback effects are coupled and must be studied individually and in concert
with each other
• Single stars may show variability in their HII regions during their pre-­‐main-­sequence
evolution
• Clusters are dominated by their most massive stars, with choice of prestellar
model having little impact on overall dynamics
• MHD and turbulence may play crucial roles in enhancing radiative feedback
Future Work
• We are combining realistic initial conditions with turbulence, MHD, ionizing
radiation and prestellar modeling to address:
disruption of molecular clouds, cloud lifetimes, cluster population dynamics

Thank You
Ralph Pudritz
Thomas Peters
Philipp Girichidis
Daniel Seifried
Elizabeth Tasker
Stella Offner
Mark Krumholz
Takashi Hosokawa
Dennis Duffin

Extra Slides

Figure 2 from Klassen et al. (2012b, in prep)
HII Region Collapsing and Reforming

Mass-­‐Luminosity Relation for an Example Protostar
Figure 9 from Klassen et al. (2012a)

Figure 4 from Klassen et al. (2012a)
Mean Ionization and Temperature