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Searching for disks around high-mass (proto)stars with ALMA

Searching for disks around high-mass (proto)stars with ALMA. R. Cesaroni, H. Zinnecker, M.T. Beltr án, S. Etoka, D. Galli, C. Hummel, N. Kumar, L. Moscadelli, T. Preibisch, T. Ratzka, Á. Sánchez-Monge, T. Stanke, F. Van der Tak, S. Vig, C.M. Walmsley, K.-S. Wang.

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Searching for disks around high-mass (proto)stars with ALMA

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  1. Searching for disksaround high-mass (proto)stars with ALMA R. Cesaroni, H. Zinnecker, M.T. Beltrán, S. Etoka, D. Galli, C. Hummel, N. Kumar, L. Moscadelli, T. Preibisch, T. Ratzka, Á. Sánchez-Monge, T. Stanke, F. Van der Tak, S. Vig, C.M. Walmsley, K.-S. Wang Cycle 0 proposal after meeting at ESO in 2011

  2. Immediate Goal (Cycle 0) • Increase the number of bona-fide circumstellar (Keplerian?) disks around B-type (proto)stars • Demonstrate that B-type stars form through disk accretion • Assess disk structure and rotation curve Mstar Long-term Goal (Cycle 2…) • Search for circumstellar rotating disks around O-type (proto)stars

  3. Targets G35.20-0.74N and G35.03+0.35: • Closeby: 2.2 kpc and 3.4 kpc • Luminosities (~104 LO)  B-type • Free-free emission (VLA)  thermal jets/HII regions • Bipolar nebulosities, green “fuzzies”, broad SiO wings  bipolar outflows/jets  disks??? • Prominent CH3CN emission (single dish)  hot molecular cores

  4. Observations • Band 7: 350 GHz • Most extended Cycle 0 array configuration • Resolutions: 0.4 arcsec and 0.4 km/s • Primary beam: 18 arcsec • Maximum structure: 2 arcsec • Correlator setup: CH3CN(19-18), CH3OH(7-6), SiO(8-7), C34S(7-6), C17O(3-2), H13CO+(3-2), and many others

  5. Results • Rich spectra with many hot-core tracers (CH3CN) • “Filaments” across hour-glass nebulosities • Molecular cores with velocity gradients roughly perpendicular to bipolar nebulosities • PV patterns typical of (sub)Keplerian rotation • Problems: • “extended” tracers (C34S, C17O, H13CO+) resolved out by ALMA • SiO line partly blended and difficult to interpret

  6. CH3OH CH3OH vt=1 CH3CN

  7. CH3OH CH3OH vt=1 CH3CN

  8. Results • Rich spectra with many hot-core tracers (CH3CN) • “Filaments” across hour-glass nebulosities • Molecular cores with velocity gradients roughly perpendicular to bipolar nebulosities • PV patterns typical of (sub)Keplerian rotation • Problems: • “extended” tracers (C34S, C17O, H13CO+) resolved out by ALMA • SiO line partly blended and difficult to interpret

  9. IRAC 4.5 µm Hi-RES image Filament or edge-on sheet? Mass of “filament” ~80 MO ≥ 5 cores along “filament” 0.05 pc

  10. IRAC 4.5 µm Hi-RES image ≥ 4 cores along filament Prominent core (~4 MO) at center of bipolar nebula 0.05 pc

  11. Results • Rich spectra with many hot-core tracers (CH3CN) • “Filaments” across hour-glass nebulosities • Molecular cores with velocity gradients roughly perpendicular to bipolar nebulosities • PV patterns typical of (sub)Keplerian rotation • Problems: • “extended” tracers (C34S, C17O, H13CO+) resolved out by ALMA • SiO line partly blended and difficult to interpret

  12. CH3CN line and 3.6 cm continuum (Gibb et al. 2003) overlayed on CH3CN velocity map Velocity gradients roughly perpendicular to bipolar nebula 1000 au

  13. Intensity and velocity maps in different molecules Velocity gradient roughly perpendicular to bipolar nebula

  14. Results • Rich spectra with many hot-core tracers (CH3CN) • “Filaments” across hour-glass nebulosities • Molecular cores with velocity gradients roughly perpendicular to bipolar nebulosities • PV patterns typical of (sub)Keplerian rotation • Problems: • “extended” tracers (C34S, C17O, H13CO+) resolved out by ALMA • SiO line partly blended and difficult to interpret

  15. G35.20-0.74N core B • Position-velocity plots along velocity gradient • White pattern: Keplerian rotation about 18 MO

  16. G35.03+0.35 main core • Position-velocity plots along velocity gradient • White pattern: Keplerian rotation about about 6 MO

  17. Results • Rich spectra with many hot-core tracers (CH3CN) • “Filaments” across hour-glass nebulosities • Molecular cores with velocity gradients roughly perpendicular to bipolar nebulosities • PV patterns typical of (sub)Keplerian rotation • Problems: • “extended” tracers (C34S, C17O, H13CO+) resolved out by ALMA • SiO line partly blended and difficult to interpret

  18. G35.20-0.74N: Core BSánchez-Monge et al. (subm. to A&A)

  19. Core A compact Core B resolved Mgas(A) = 4.4 MO Mgas(B) = 2.8 MO Tgas ~ 100 K 1000 au A B Image: CH3CN K=2 Contours.: continuum

  20. Dots:peaks from 2D Gaussian fit to CH3CN K=2 line emission in each channel (i.e. velocity) Curves:50% contour levels of CH3CN K=2 emission in each channel 500 au Keplerian disk CH3CN CH3CN, CH3OH, HC3N

  21. Best fit to velocity pattern with Keplerian disk: • Mstar = 18 MO • angle disk-l.o.s. = 19° • disk P.A. = 157° • star position very close to continuum peak • systemic velocity: VLSR(star) = 30.0 km/s • Peaks distribution Rdisk = 2500 au • 350 GHz continuum Mdisk = 3 MO< Mstar consistent with Keplerian rotation

  22. NE • Line emission skewed to NE  flared disk? • Mstar = 18 MO Lstar≥ Lbol = 3 104 LO  binary system needed  precessing outflow? SW

  23. Luminosity of binary system with Mp+Ms=18 MO Lbol(G35.20)

  24. Conclusions • Hot, dense cores detected at geometrical center of bipolar nebulae • Velocity gradients in cores, roughly perpendicular to axes of bipolar nebulae • PV plots suggestive of (sub)Keplerian rotation • Possible circumbinary Keplerian disk detected in G35.20-0.74N

  25. Future ALMA projects? G35.20 & G35.03: • Unresolved cores with <0.4” resol. • SiO jets at 3mm (less blending) 1”-2” resol.  direction of jets close to cores • “filaments” in C17O, CS, etc. with >2” beam  velocity field of gas  filaments or rotating edge-on sheets? Disks around O-type stars: • E.g. 13CH3CN in HMCs with <0.1” resolution

  26. Core B lies at center of bipolar structure A B

  27. CH3CN line and 3.6 cm continuum (free-free) emission maps over IRAC 4.5 micron image Both A and B contain free-free sources B lies at center of possible N-S thermal jet A B

  28. CH3CN line map over IRAC 4.5 µm image enhanced with HIRES Stars are free-free continuum sources Core at center of bipolar structure is prominent in CH3CN and associated with free-free source

  29. 50% level contours of CH3CN emission in different velocity channels. The solid circles are the peaks of the emission in different channels, obtained with 2-D Gaussian fits. Colours correspond to velocities. Extreme red- and blue-shifted peaks converge towards same position, as expected for (sub)Keplerian rotation

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