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Breaking Barriers in Massive Star Formation with Stellar Interferometry

Breaking Barriers in Massive Star Formation with Stellar Interferometry. Willem-Jan de Wit (ESO) Rene Oudmaijer (Leeds) Melvin Hoare (Leeds) Hugh Wheelwright (Leeds). What are the dominant structures emitting in N-band?. Spherical models:. N-band. ISO-SWS. MIDI at the VLTI.

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Breaking Barriers in Massive Star Formation with Stellar Interferometry

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  1. Breaking Barriers in Massive Star Formation with Stellar Interferometry Willem-Jan de Wit (ESO) Rene Oudmaijer (Leeds) Melvin Hoare (Leeds) Hugh Wheelwright (Leeds)

  2. What are the dominant structures emitting in N-band? Spherical models: N-band ISO-SWS

  3. MIDI at the VLTI • Mid-IR beam combiner (N-band) • Combining 2 VLTI beams (UTs or ATs) • Spectrally dispersed fringes (30 & 230) • Baselines 10 to 200 meters (10 mas) • Visibilities 13 micron 8 micron Haguenaur et al. (2008): VLTI architecture Leinert et al. (2004): MIDI instrument

  4. The case of W33A: jets and outflows Davies et al. 2010 • L = 105Lo • Dkin = 3.8 kpc • Weak, compact radio emission (Rengarajan & Ho 1995) • Broad single peaked HI emission (Bunn et al. 1995) • Fast bipolar jet (Br g) (Davies et al. 2010) milli-arcsecond K-band (UKIDSS), VLTI baselines: milli-arcsecond JCMT/HARP 12CO(3-2):

  5. The case of W33A: jets and outflows • L = 105Lo • Dkin = 3.8 kpc • Weak, compact radio emission (Rengarajan & Ho 1995) • Broad single peaked HI emission (Bunn et al. 1995) • Fast bipolar jet (Br g) (Davies et al. 2010) Laser-guide star assisted NIFS at Gemini North (Davies et al. 2010) K-band (UKIDSS), VLTI baselines: JCMT/HARP 12CO(3-2): 4 AU

  6. The case of W33A: jets and outflows Davies et al. 2010 • L = 105Lo • Dkin = 3.8 kpc • Weak, compact radio emission (Rengarajan & Ho 1995) • Broad single peaked HI emission (Bunn et al. 1995) • Fast bipolar jet (Br g) (Davies et al. 2010) milli-arcsecond K-band (UKIDSS), VLTI baselines: milli-arcsecond JCMT/HARP 12CO(3-2):

  7. W33A MIDI observables • 4 baselines • Near perpendicular PAs • Baselines stretching between 40 and 60 meters Visibility spectrum FLUX spectrum 7 8 9 10 11 12 13 (micron) (micron)

  8. W33A MIDI observables • 4 baselines • Near-perpendicular PAs • Baselines stretching between 40 and 60 meters • Equivalent Gaussian FWHM sizes between 95 and 115AU Visibility spectrum FLUX spectrum 95AU No flux 7 8 9 10 11 12 13 (micron) (micron)

  9. W33A model fit • Axi-symmetric dust radiative transfer code (Whitney et al. 2002) • TSC Envelope, outflow cavity, and disk Near-IR: Observed Model H-band 350 micron: Model K-band Van der Tak et al. (2000) H - K

  10. W33A model fit (cont.) MIDI Visibilities: • Dust model parameters: • No disk, only envelope (cavities) • Minfall = 7 10-4 Mo/yr • Rsub = 25 AU (nominal) • Av = 230 • Teff= 35000 K • R* = 8.5 Ro • M* = 25 Mo • 2*q = 20o (opening angle) de Wit et al. 2010 Monochromatic images on the sky: 7.5 8.5 9.5 10.5 11.5 12.5 2200AU

  11. W33A and disk emission • Disk limits from N-band interferometry: • Dust disk : M < 0.01Mo • Accretion disk : Macc < 10-3Mo/yr Davies et al. 2010

  12. Disk signature in AFGL 2136 ? • L= 7e4 Lsol • D= 2.0 Kpc • Polarization disk (Murakawa et al. 2008) • Arcmin bipolar CO outflow (Kastner et al. 1995) • Compact, 70AU radio emission (Menten & Van der Tak 2004) UKIDSS K-band K-band polarization (Murakawa et al. 2008) outflow 1 arcminute

  13. Disk signature in AFGL 2136 ? • Same procedure as W33A (2.5D axisymmetric dust radiative transfer) • Fit envelope emission (SED, 24.5 mu and N-band short spacing) • Necessity of compact emitting source at <8.5 micron for MIDI visibilities

  14. Disk signature in AFGL 2136 ? • Same procedure as W33A (2.5D axisymmetric dust radiative transfer) • Fit envelope emission (SED, 24.5 mu and N-band short spacing) • Necessity of compact emitting source at <8.5 micron for MIDI visibilities • Either accretion disk or supergiant star to fit N-band dispersed visibilities Monnier et al. (2009)

  15. Disk signature in AFGL 2136 ? • Same procedure as W33A (2.5D axisymmetric dust radiative transfer) • Fit envelope emission (SED, 24.5 mu and N-band short spacing) • Necessity of compact emitting source at <8.5 micron for MIDI visibilities • Either accretion disk or supergiant star to fit N-band dispersed visibilities

  16. Disk signature in AFGL 2136 ? • Same procedure as W33A (2.5D axisymmetric dust radiative transfer) • Fit envelope emission (SED, 24.5 mu and N-band short spacing) • Short spacing + SED : 120 AU dust radius • Necessity of compact emitting source at <8.5 micron for MIDI visibilities • Either accretion disk or supergiant star to fit N-band dispersed visibilities • Macc : 3 10-3 Mo/yr 8 micron 1.5”

  17. Conclusions • N-band interferometry is able to provide important new insights in the formation of high-mass stars. • In W33A: N-band emission at 100 AU scale is dominated by warm dust in the interface between outflow cavity and envelope • Contribution by accretion disk is similar or less than TSC envelope infall rate • AFGL 2136: evidence for compact emission: supergiant star or accretion disk

  18. Near future with VLTI PIONIER : 4 beam combiner H & K bands, R=40 Commissioning & early science November 2010 (JP Berger et al. 2010) MATISSE: 4 beam combiner L, M, N bands (R=30, 1500) 2014 (Wolff et al.)

  19. MIDI observations of IRAS 13481 2.2 micron • Image cuts 0.1% and 10% of maximum • Visibilities: over-resolved component 40% flux 20AU 8.0 micron

  20. IRS9A (Vehoff et al. 2010) AFGL 2136 IRS1 (de wit et al. In prep) W33A (de Wit et al 2010)

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