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

NRAO Socorro 05/2009 Outline Introduction: DR21 VLA Observations of Massive Protostars: Jets Photoevaporating Disks Accretion Shocks IR and X-Ray Counterparts

NRAO Socorro 05/2009 Cygnus at 5 GHz Downes & Rinehart ft single dish telescope at Fort Davis, TX 5GHz, FWHM: 10.8' Many discrete sources: thermal spectra

NRAO Socorro 05/2009 Cygnus at 5 GHz Downes & Rinehart ft single dish telescope at Fort Davis, TX 5GHz, FWHM: 10.8' Many discrete sources: thermal spectra DR21

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

NRAO Socorro 05/2009 Ultracompact HII Regions Harris 1973 Cambridge 5 km Interferometer 5 GHz, FWHM: 3" Component D: Cometary UCHII Region EM= 8.2x10 7 pc cm -6, n e =6.5x10 4 cm -3 Central star: B0

NRAO Socorro 05/2009 Surveys for Massive Protostars Selection Criteria: FIR color L > 10 3 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, 2000 Sridharan et al. 2002, Beuther et al. 2002

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

NRAO Socorro 05/2009 Radio Continuum Emission Models Dust emission Ionized accretion flows Photoevaporating disks Accretion shocks H, H 2 – e - free-free Spherical or Equatorial Winds Shocks in flows Jets   

NRAO Socorro 05/2009 Deeply Embedded Sources Molecular Clumps: Size = 1 pc N H = cm -2 Hot Molecular Cores: Size = 0.1 pc N H  cm -2 Predicted Extinction: A V > 1000  cm observations ! Cesaroni et al. 2005

NRAO Socorro 05/2009 IRAS Distance: 1.7 kpc Luminosity: 1.3  10 4 L  HMC: T  200 K n H 2  7  10 8 cm -3 Bipolar Molecular Flow: 2 N-S in CO + 30  NW-SE in HCO + Velocity gradient  Flow  Disk ? Cesaroni et al GHz CH 3 OH Masers

NRAO Socorro 05/2009 IRAS Hofner et al VLA A-configuration X-band Where is the massive protostar ? a) In between N1 and N2 b) Near peak of N1 c) Somewhere else

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 Hofner et al. 2007

NRAO Socorro 05/2009 IRAS Ionization equilibrium: N1 and N2 not photo-ionized by protostar  shock ionization  episodic H 2 O masers: 100 km/sec proper motion  rotation of molecular jet predicted by magneto- centrifugal jet theory Pudritz et al  Hofner et al N1

NRAO Socorro 05/2009 G Outflow characteristics: L ~ 20L , M > 15 M  T dyn ~ 4 x 10 3 yr CH 3 OH (44.1 GHz )‏ Distance: 7.9 kpc L IRAS : 2.6 x 10 5 L  (06 ZAMS) NH 3 (4,4) Size: 2" – 0.08 pc n(H 2 )  10 7 cm -3 T= 200 K (CH 3 CN) Cesaroni et al., in prep.Araya et al. 2008

NRAO Socorro 05/2009 DR21(OH) MM1: L= 1.7 x 10 4 L , B0.5V ZAMS, M ~ 350 M ,T ~ 60 K MM2: Early B ZAMS, M ~ 570 M , T ~ 30 K Davis et al Araya et al. 2009

NRAO Socorro 05/2009 Photoevaporating Accretion Disks Hollenbach et al. 1994, Yorke et al. 1996, Lizano et al. 1996, Lugo et al. 2004, Originally developed for UCHII/HCHII regions Diffuse Ionization  Static ionized atmosphere within gravitational radius r g Photoevaporative flow for r > r g

NRAO Socorro 05/2009 Orion Source I Reid et al Orion KL Source I d=414 pc VLA: SiO J=1-0, v=0, 1, 2 7mm continuum FWHM: 30 mas Ionized accretion disk (+ Jet ?) H2OH2O

NRAO Socorro 05/2009 Other Candidates Gibb et al CO Flow S140-IRS1 VLA 7mm S106-IR MERLIN 1.3cm

NRAO Socorro 05/2009 Accretion Shocks Neufeld et al. 1994, 1996 Supersonic Infall: v s = 5 – 100 km/sec Pre-Shock Densities: n H = – cm -3  Ionized pre/post-shock layer  cm/mm free-free emission

NRAO Socorro 05/2009 Accretion Shocks Neufeld et al. 1994, 1996  High optical depths  High brightness temperatures

NRAO Socorro 05/2009 Accretion Shocks Neufeld et al. 1994, 1996 Assumptions: Cassen & Moosman 1981 Infall Solution Accretion Rate: 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)

NRAO Socorro 05/2009 IR Counterparts Precise Positions of massive protostars: adaptive optics, w/ laser guide star: similar resolution Unclear why detectable at NIR: massive dust condensations predict A V > 1000 IRAS18566: SPITZER/IRAC VLA-7mm/2MASS-K Araya et al Anderson et al. in prep.

NRAO Socorro 05/2009 X-Ray Counterparts IRAS20126: CHANDRA VLA –A conf. Anderson et al., in prep. 0.5 – 8 keV 3.6 cm

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