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1)Disks and high-mass star formation: existence and implications 2)The case of G31.41+0.31: characteristics 3)Velocity field in G31.41: rotation or expansion?

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Presentation on theme: "1)Disks and high-mass star formation: existence and implications 2)The case of G31.41+0.31: characteristics 3)Velocity field in G31.41: rotation or expansion?"— Presentation transcript:

1 1)Disks and high-mass star formation: existence and implications 2)The case of G : characteristics 3)Velocity field in G31.41: rotation or expansion?  toroid vs outflow 4)Possible solution: measurement of 3D velocity field Kinematics of high-mass star formation: The case of G Riccardo Cesaroni with: M. Beltran, Q. Zhang, C. Codella, J.M. Girart, P. Hofner, etc…

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 observational bias Evidence for rotating toroids (M >> M star )  could be envelopes of circumstellar disks? Hot molecular core G 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 G : 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 UC HII HMC

5 G : 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 SMA spectrum of CH 3 CN, etc… First detection of glycolaldehyde outside Galactic center (Beltran et al. 2009)

7 G : 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 low energy optically thin high energy continuum SMA (Zhang et al. in prep.)

9 NH 3 (4,4) main line NH 3 (4,4) satellite VLA A-array (Cesaroni et al. subm.)

10 G : 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: M dyn = 175 M O < M HMC = 490 M O from mm cont.  dynamically unstable –Outflow: dM/dt = 0.04 M O yr -1 and dP/dt = 0.23 M O 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.) NH 3 (4,4) main line NH 3 (4,4) satellite

13 G : 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: M dyn = 175 M O < M HMC = 490 M O from mm cont.  dynamically unstable –Outflow: dM/dt = 0.04 M O yr -1 and dP/dt = 0.23 M O km s -1 yr -1 very large (but still acceptable)

14 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 Toroid VS Outflow

15 Flux V LSR (km/s) Inverse P Cyg profiles (Girart et al. 2009)  infall H 2 CO( ) CN(2-1)

16 VLA A-array (Cesaroni et al. subm.) NH 3 (4,4) main line NH 3 (4,4) satellite rotating & infalling ring

17 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 Toroid VS Outflow

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19 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 Toroid VS Outflow

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

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

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

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

24 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 Toroid VS Outflow

25 Hour-glass shaped magnetic field (Girart et al. 2009) high-masslow-mass G NGC 1333 IRAS4A G NGC1333 IRAS4A disk B

26 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

27 outflow… toroid…

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29 Beltran et al. (2005); Hofner et al. (in prep.) NH 3 red-shiftedNH 3 blue-shiftedNH 3 bulk CH 3 CN(12-11)

30 IRAS Cesaroni et al. Hofner et al. Moscadelli et al. Keplerian rotation: M * =7 M O Moscadelli et al. (2005)

31 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 observational bias

32 Assumptions: HPBW = R disk /4 FWHM line = V rot (R disk ) M disk  M star same in all disks T B > 20 K obs. freq. = 230 GHz 5 hours ON-source spec. res. = 0.2 km/s S/N = 20 edge-on i = 35°

33 Assumptions: HPBW = R disk /4 FWHM line = V rot (R disk ) M disk  M star same in all disks T B > 20 K obs. freq. = 230 GHz 5 hours ON-source spec. res. = 0.2 km/s S/N = 20 no stars edge-on i = 35°

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

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36 NH 3 (4,4) Red-shifted self-absorption (Cesaroni et al. subm.) NH 3 (4,4)

37 rotating & infalling ring


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