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ALMA Regional Centre Allegro
Ionized and Molecular Gas Dynamics in High Mass Star
Forming Regions
Pamela Klaassenwith:
Roberto Galvan-Madrid (ESO)Thomas Peters (U Zurich)
Steve Longmore (ESO)Matthias Maercker (ESO/AlfA)
Outline
• High Mass Star Formation
• what’s different for us
• Gas Dynamics
• and the ionization boundary
• Rotation
• Infall
• Outflow
Star Formation
• Over-density in a cloud begins to contract
• Accretion through disk
• Powerful outflow
• release of angular momentum
• envelope is eaten awayBill Saxton, NRAO
Dynamically
Higher Masses• Is it just scaled up?
• Does radiation pressure cause problems?
• What happens above 8 M⦿?
• When does an HII region form?
• How does accretion continue?
RadiationPressure
accretion?Looking at the gas
dynamics can help us understand what’s going on
Ionization Boundary
• Once the protostars begin ionizing their surroundings...
• Dynamics become more complicated
• but the gas is still moving
• and we can track thatScience/AAAS
Ionized Gas• Can use radio recombination
lines to probe the ionized gas dynamics:
• Shifts in line peak
• must account for pressure broadening
• Comparison with models
Spectral resolution & sensitivity have hampered
progress in the past
Gas Dynamics• Now we can begin to probe the dynamics
on both sides of the ionization boundary!
• with various molecular species
• and RRLs for ionized gas
Frequencies of Hnα lines
ALMAJVLA
And we can do this on size scales where we can
resolve the flows
Ionized Rotation
W51e2
Keto & Klaassen 2008, Klaassen et al. 2009
Velocity gradients in the ionized and molecular gas are
consistent with each other
SO2
H53α5100 AU
�v
�r= 175± 22km/s/pc
�v
�r⇠ 200km/s/pc
Rotation seems to be consistent regardless of ionization
Ionized Infall
Infall can continue through the ionization boundary
Keto & Wood 2006, Klaassen et al. 2011
G10.6-0.4
Velocity
Offs
et
Min = 2⇥ 10�4M�/yrMin = 10⇥ 10�4M�/yr
Ionized Outflow
• Has this been seen?
• Can we find a molecular counterpart?
Yes!
The case of K3-50A
Previous Observations
• 14.7 GHz Continuum
• H76α outflow?
DePree et al. 1994
Redshifted
Blueshifted
New Observations
• CARMA C config
• 90 GHz continuum
• H41α
• HCO+ (J=1-0)
• 1.8’’ spatial res.
• 1.7 km/s spectral res.
• VLA B config
• 23 GHz continuum
• 0.2” spatial res.
• ~55 channels averaged to obtain continuum
K3-50A is at a distance of 8.7 kpc
Klaassen et al. 2012b, submitted
HCO+
HCO+ emission superimposed on 15 GHz continuum
HCO+ velocities on 23 & 90 GHz continuum
Klaassen et al. 2012, submitted
HCO+
HCO+ First moment map
0.2 pc
Klaassen et al. 2012, submitted
HCO+
• HCO+ extends over a pc
• Bulk motions indicate large scale:
• rotation
• infall
• Does it look like outflow?
• it’s perpendicular to the ionized outflow
On the whole, no, it doesn’t look like outflow
Klaassen et al. 2012, submitted
HCO+
• We suggest most of the HCO+ is rotating/infalling
Mgas ⇠ 2200M�
Size ⇠ 1.1pc
This is not what we were expecting(but what we got was way cooler!)
There’s just too much stuff for an
outflowpgas ⇠ 7000M� km s�1
Klaassen et al. 2012, submitted
HCO+
• There seem to be high velocity spikes in the HCO+ emission at the edges of the HII region
But remember the ionized gas?
Klaassen et al. 2012, submitted
Entrained Outflow?
•
HC
O+ velocity scale slightly com
pressed compared to H
41α
Is the ionized gas hitting the ionization boundary, and continuing outward, taking the molecular gas with it?
�v
�r= 145± 13km/s/pc
�v
�r= 142± 23km/s/pc
Klaassen et al. 2012, submitted
Gas VelocitiesMomenta of the ionized and molecular gas components
mvion = 90 M km/s mvmolec = 30 M km/s
Klaassen et al. 2012, submitted
Circles indicate MIR sources from Okamoto et al. (2003)
K3-50a Dynamics
MolecularMolecular
Ionised
Ionised
Molecular
Molecular
HCO+
H76α,H41αKlaassen et al. 2012, submitted
Conclusions
• Ionized and molecular gas components appear to be undergoing the same dynamics in and around HII regions
• Rotation: W51e2
• Infall: G10.6-0.4
• Outflow: K3-50A
• this gives us an extra constraint on the processes in the later stages of high mass star formation