1 / 37

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

Analyzing disk presence in high-mass star formation, identifying characteristic features of G31.41+0.31, and exploring toroid vs outflow phenomena. Investigating evidence for rotating toroids and the implications on star formation models. Addressing observational bias and distinguishing the true nature of G31.41. Utilizing molecular line detections and spectral data to determine the velocity field. Investigating NE-SW velocity gradient, potential rotation, or expansion scenarios. Determining physical properties and stability of toroids and outflow mechanisms. Comparing potential outcomes like self-absorption, continuum sources, and magnetic field orientations. Investigating potential heating sources and mid-IR emissions. Evaluating evidence for infall, power-law spectra, and embedded stars within the G31.41 system.

carlyt
Download Presentation

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

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related