nrao socorro 05/2009 radio continuum studies of massive protostars peter hofner new mexico tech...

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NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

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Page 1: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Radio Continuum Studiesof Massive Protostars

Peter Hofner

New Mexico Tech & NRAO

Page 2: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Collaborators

E. Araya NRAO/UNM

S. Kurtz, L. Rodriguez CRyA-UNAM

M. Goss, D. Shepherd NRAO

H. Linz MPIA

R. Cesaroni Arcetri Observatory

C. Anderson NMT

Page 3: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Outline

• Introduction: DR21

• VLA Observations of Massive Protostars: Jets Photoevaporating Disks Accretion Shocks

• IR and X-Ray Counterparts

Page 4: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Cygnus at 5 GHz

Downes & Rinehart 1966

85 ft single dish telescope at Fort Davis, TX

5GHz, FWHM: 10.8'

Many discrete sources: thermal spectra

Page 5: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Cygnus at 5 GHz

Downes & Rinehart 1966

85 ft single dish telescope at Fort Davis, TX

5GHz, FWHM: 10.8'

Many discrete sources: thermal spectra

DR21

Page 6: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Compact HII Region

Ryle & Downes 1967: Cambridge 1 mile Interferometer:First Aperture Synthesis, 1.4 GHz, FWHM: 30"

DR21: the first compact HII region

Page 7: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Ultracompact HII Regions

Harris 1973Cambridge 5 km Interferometer5 GHz, FWHM: 3"

Component D: Cometary UCHII RegionEM= 8.2x107 pc cm-6, ne=6.5x104 cm-3

Central star: B0

Page 8: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Surveys for Massive Protostars

Selection Criteria: FIR color L > 103 L

dense, hot molecular gas ‘absence’ of radio continuum

> 200 candidates 90 % detection rate of outflows (CO) evolutionary stage of candidates ?

Pankonin et al. 2001, Araya et al. 2005, Palla et al. 1991, Molinari et al. 1998, 2000Sridharan et al. 2002, Beuther et al. 2002

Page 9: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Radio Continuum Emission

• Signposts for positions of massive protostars

• Emission mechanisms: How does the intensity of radio continuum relate to overall luminosity ? Evolutionary state

• Multiplicity/Cluster vs Accretion Disks

Page 10: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Radio Continuum Emission Models

• Dust emission• Ionized accretion flows• Photoevaporating disks• Accretion shocks• H, H2 – e- free-free • Spherical or Equatorial Winds• Shocks in flows• Jets

Page 11: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Deeply Embedded Sources

Molecular Clumps: Size = 1 pc NH = 1023 cm-2

Hot Molecular Cores: Size = 0.1 pc NH 1025 cm-2

Predicted Extinction:AV > 1000

cm observations ! Cesaroni et al. 2005

Page 12: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

IRAS 20126+4104

Distance: 1.7 kpc

Luminosity: 1.3 104 L

HMC: T 200 K nH2

7 108 cm-3

Bipolar Molecular Flow: 2 N-S in CO

30 NW-SE in HCO++

Velocity gradient Flow Disk ?

Cesaroni et al. 1999

+

++++

+ 44 GHz CH3OH Masers

Page 13: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

IRAS 20126+4104

Hofner et al. 2007

VLA A-configuration X-band

Where is the massive protostar ?

a) In between N1 and N2

b) Near peak of N1

c) Somewhere else

Page 14: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Thermal dust at 3 & 1.3 mm extended dust disk 2.5 M

(1500 AU)

Ionized gas with density gradient at 3.6, 1.3 & 0.7 cm (< 50 AU) associated with outflow

Limit on Disk Mass: < 0.8 M

(< 50 AU)

IRAS 20126+4104

Hofner et al. 2007

Page 15: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

IRAS 20126+4104

Ionization equilibrium: N1 and N2 not photo-ionized by protostar shock ionization episodic

H2O masers: 100 km/sec proper motion rotation of molecular jet predicted by magneto- centrifugal jet theory Pudritz et al. 2005

Hofner et al. 2007

N1

Page 16: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

G31.41+0.31

Outflow characteristics:

L ~ 20L, M > 15 M

Tdyn ~ 4 x 103 yr

CH3OH (44.1 GHz)

Distance: 7.9 kpc LIRAS: 2.6 x 105 L (06 ZAMS) NH3(4,4) Size: 2" – 0.08 pc n(H2) 107 cm-3

T= 200 K (CH3CN)

Cesaroni et al. , in prep. Araya et al. 2008

Page 17: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

DR21(OH)

MM1: L= 1.7 x 104 L, B0.5V ZAMS, M ~ 350 M,T ~ 60 K

MM2: Early B ZAMS, M ~ 570 M, T ~ 30 K

Davis et al. 2007 Araya et al. 2009

Page 18: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Photoevaporating Accretion DisksHollenbach et al. 1994, Yorke et al. 1996, Lizano et al. 1996, Lugo et al. 2004,

Originally developedfor UCHII/HCHII regions

Diffuse Ionization Static ionized atmospherewithin gravitational radius rg

Photoevaporative flowfor r > rg

Page 19: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Orion Source I Reid et al. 2007

Orion KL Source Id=414 pc

VLA: SiO J=1-0, v=0, 1, 2 7mm continuum FWHM: 30 mas

Ionized accretion disk (+ Jet ?)

H2O

Page 20: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Other Candidates Gibb et al. 2007

CO FlowCO Flow

S140-IRS1 VLA 7mm S106-IR MERLIN 1.3cm

Page 21: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Accretion Shocks Neufeld et al. 1994, 1996

Supersonic Infall: vs = 5 – 100 km/secPre-Shock Densities: nH = 107.5 – 1012 cm-3

Ionized pre/post-shock layer cm/mm free-free emission

Page 22: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Accretion Shocks Neufeld et al. 1994, 1996

High optical depths High brightness temperatures

Page 23: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

Accretion Shocks Neufeld et al. 1994, 1996

Assumptions: Cassen & Moosman 1981 Infall Solution Accretion Rate: 10-4 M/year Accretion Radius: 10 AU Central Mass: 10 M

Predicted fluxes: 1.2 Jy (X) dist. = 5 kpc (4 mas) 31 Jy (Q)

7.5 Jy (X) dist. = 2 kpc (10 mas) 200 Jy (Q)

Page 24: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

IR Counterparts

Precise Positions of massive protostars: adaptive optics, w/ laser guide star: similar resolutionUnclear why detectable at NIR: massive dust condensations predict AV > 1000

IRAS18566: SPITZER/IRAC VLA-7mm/2MASS-K

Araya et al. 2007 Anderson et al. in prep.

Page 25: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

X-Ray Counterparts

IRAS20126: CHANDRA VLA –A conf.

Anderson et al. , in prep.

0.5 – 8 keV 3.6 cm

Page 26: NRAO Socorro 05/2009 Radio Continuum Studies of Massive Protostars Peter Hofner New Mexico Tech & NRAO

NRAO Socorro 05/2009

EVLA

• Jy sensitivity across a wide range of wavelengths

• Observe entire sample of massive protostars • Map brightness distribution, SED

• Relative duration of different physical scenarios

• Correlate with other age indicators: Evolution

• However: want matching resolution: e-MERLIN