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Kinematics of high-mass star formation: The case of G31.41+0.31

Kinematics of high-mass star formation: The case of G31.41+0.31. Riccardo Cesaroni with: M. Beltran, Q. Zhang, C. Codella, J.M. Girart, P. Hofner, etc…. Disks and high-mass star formation: existence and implications The case of G31.41+0.31 : characteristics

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Kinematics of high-mass star formation: The case of G31.41+0.31

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  1. Kinematics of high-mass star formation: The case of G31.41+0.31 Riccardo Cesaroni with: M. Beltran, Q. Zhang, C. Codella, J.M. Girart, P. Hofner, etc… • Disks and high-mass star formation: existence and implications • The case of G31.41+0.31: characteristics • Velocity field in G31.41: rotation or expansion?  toroidvsoutflow • Possible solution: measurement of 3D velocity field

  2. Disks in high-mass (proto)stars • So far only disks in B-type (proto)stars • No detection of disks in early O-type (proto)stars  implications on high-mass star formation models • Absence of evidence: may be observationalbias • Evidence for rotating toroids (M >> Mstar)  could be envelopes of circumstellar disks? • Hot molecular core G31.41+0.31 excellent toroid candidate (Beltran et al. 2005), but Araya et al. (2008) propose bipolar outflow interpretation important to establish true nature of G31.41

  3. G31.41+0.31: characteristics • HMC with nearby UC HII region inside pc-scale clump • HMC detected in lots of molecular lines: first detection of glycolaldheide outside Galactic center (Beltran et al. 2009) • High-excitation lines and mm continuum peak at geometrical center  temperature increasing outside-in  embedded heating star(s) inside HMC

  4. Clump UCHII HMC

  5. G31.41+0.31: characteristics • HMC with nearby UC HII region inside pc-scale clump • HMC detected in lots of molecular lines: first detection of glycolaldheide outside Galactic center (Beltran et al. 2009) • High-excitation lines and mm continuum peak at geometrical center  temperature increasing outside-in  embedded heating star(s) inside HMC

  6. First detection of glycolaldehyde outside Galactic center (Beltran et al. 2009) SMA spectrum of CH3CN, etc…

  7. G31.41+0.31: characteristics • HMC with nearby UC HII region inside pc-scale clump • HMC detected in lots of molecular lines: first detection of glycolaldheide outside Galactic center (Beltran et al. 2009) • High-excitation lines and mm continuum peak at geometrical center temperature increasing outside-in  embedded heating star(s) inside HMC

  8. SMA (Zhang et al. in prep.) low energy high energy optically thin continuum

  9. VLA A-array (Cesaroni et al. subm.) NH3(4,4) main line NH3(4,4) satellite

  10. G31.41+0.31: the velocity field • Clear NE-SW velocity gradient seen in HMC (Beltran et al. 2004, 2005) • Same velocity gradient in all molecular lines • Possible interpretations: rotation or expansion  toroid or outflow? • Toroid: Mdyn = 175 MO < MHMC = 490 MO from mm cont.  dynamically unstable • Outflow: dM/dt = 0.04 MO yr-1 and dP/dt = 0.23 MO km s-1 yr-1 very large (but still acceptable)

  11. SMA (Zhang et al. in prep.)

  12. VLA A-array (Cesaroni et al. subm.) NH3(4,4) main line NH3(4,4) satellite

  13. G31.41+0.31: the velocity field • Clear NE-SW velocity gradient seen in HMC (Beltran et al. 2004, 2005) • Same velocity gradient in all molecular lines • Possible interpretations: rotation or expansion toroid (Beltran et al.) or outflow (Araya et al.)? • Toroid: Mdyn = 175 MO < MHMC = 490 MO from mm cont.  dynamically unstable • Outflow: dM/dt = 0.04 MO yr-1 and dP/dt = 0.23 MO km s-1 yr-1 very large (but still acceptable)

  14. Toroid VS Outflow • Red-shifted (self) absorption infall  toroid • Two unresolved continuum sources oriented parallel to velocity gradient and with power-law spectra  • Loose binary system  toroid • Bipolar jet  outflow • Mid-IR emission brighter towards red-shifted gas  HMC heated by nearby O star  toroid • Hour-glass shaped magnetic field perpendicular to velocity gradient  toroid

  15. Flux VLSR (km/s) Inverse P Cyg profiles (Girart et al. 2009)  infall H2CO(312-211) CN(2-1)

  16. rotating & infalling ring VLA A-array (Cesaroni et al. subm.) NH3(4,4) main line NH3(4,4) satellite

  17. Toroid VS Outflow • Red-shifted (self) absorption infall  toroid • Two unresolved continuum sources oriented parallel to velocity gradient and with power-law spectra • Loose binary system  toroid • Bipolar jet outflow • Mid-IR emission brighter towards red-shifted gas  HMC heated by nearby O star  toroid • Hour-glass shaped magnetic field perpendicular to velocity gradient  toroid

  18. Toroid VS Outflow • Red-shifted (self) absorption infall  toroid • Two unresolved continuum sources oriented parallel to velocity gradient and with power-law spectra • Loose binary system  toroid • Bipolar jet outflow • Mid-IR emission brighter towards red-shifted gas  HMC heated by nearby O star toroid • Hour-glass shaped magnetic field perpendicular to velocity gradient  toroid

  19. Outflow? mid-IR should brighter towards blue lobe… 20 µm

  20. Toroid? mid-IR should brighter along axis… 20 µm

  21. But… toroid could be heated from outside by nearby O star

  22. GG Tau – CO & 1.3mm cont. analogy with low-mass case…

  23. Toroid VS Outflow • Red-shifted (self) absorption infall  toroid • Two unresolved continuum sources oriented parallel to velocity gradient and with power-law spectra • Loose binary system  toroid • Bipolar jet outflow • Mid-IR emission brighter towards red-shifted gas  HMC heated by nearby O star toroid • Hour-glass shaped magnetic fieldperpendicular to velocity gradient  toroid

  24. B disk G31.41+0.31 NGC 1333 IRAS4A Hour-glass shaped magnetic field (Girart et al. 2009) high-mass low-mass NGC1333 IRAS4A G31.41+0.31

  25. Conclusion • Observational evidence seems to favour rotating + infalling toroid, but controversy is still open… • Only 3D velocity field will discriminate  maser spot proper motions VLBI measurements undergoing

  26. toroid… outflow…

  27. CH3CN(12-11) NH3 red-shifted NH3 bulk NH3 blue-shifted Beltran et al. (2005); Hofner et al. (in prep.)

  28. IRAS 20126+4104 Cesaroni et al. Hofner et al. Moscadelli et al. Keplerian rotation: M*=7 MO Moscadelli et al. (2005)

  29. Disks in high-mass (proto)stars • So far only disks in B-type (proto)stars • No detection of disks in O-type (proto)stars  implications on high-mass star formation models • Absence of evidence: could be observationalbias

  30. Assumptions: HPBW = Rdisk/4 FWHMline = Vrot(Rdisk) Mdisk Mstar same <Ncol> in all disks TB > 20 K obs. freq. = 230 GHz 5 hours ON-source spec. res. = 0.2 km/s S/N = 20 edge-on i = 35°

  31. Assumptions: HPBW = Rdisk/4 FWHMline = Vrot(Rdisk) Mdisk Mstar same <Ncol> in all disks TB > 20 K obs. freq. = 230 GHz 5 hours ON-source spec. res. = 0.2 km/s S/N = 20 edge-on i = 35° no stars

  32. Disks in O stars might exist, but not detectable at O-star distances • Evidence for rotating toroids (M >> Mstar)  could be envelopes of circumstellar disks? • Hot molecular core G31.41+0.31 excellent toroid candidate, but Araya et al. (2008) propose bipolar outflow interpretation important to establish true nature of G31.41

  33. Red-shifted self-absorption (Cesaroni et al. subm.) NH3(4,4) NH3(4,4)

  34. rotating & infalling ring

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