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