Searching for disks around high-mass (proto)stars with ALMA
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Transcript of Searching for disks around high-mass (proto)stars with ALMA
Searching for disksaround high-mass (proto)stars
with ALMAR. 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
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
TargetsG35.20-0.74N 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
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
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
CH3CN
CH3OH vt=1CH3OH
CH3CN
CH3OHCH3OH vt=1
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
IRAC 4.5 µm Hi-RES image
Filament or edge-on sheet?
Mass of “filament” ~80 MO
≥ 5 cores along “filament”
0.05 pc
IRAC 4.5 µm Hi-RES image
≥ 4 cores along filament
Prominent core (~4 MO) at center of bipolar nebula
0.05 pc
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
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
Intensity and velocity maps in different molecules
Velocity gradient roughly perpendicular to bipolar nebula
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
G35.20-0.74N core B• Position-velocity plots along velocity gradient• White pattern: Keplerian rotation about 18 MO
G35.03+0.35 main core• Position-velocity plots along velocity gradient• White pattern: Keplerian rotation about about 6 MO
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
G35.20-0.74N: Core B
Sánchez-Monge et al. (subm. to A&A)
Core A compactCore B resolved
Mgas(A) = 4.4 MO
Mgas(B) = 2.8 MO
Tgas ~ 100 K
A
B
1000 au
Image: CH3CN K=2Contours.: continuum
CH3CN CH3CN, CH3OH, HC3N
Kepleriandisk
500 au 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
• 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
• Line emission skewed to NE flared disk?
• Mstar = 18 MO Lstar ≥ Lbol = 3 104 LO binary system needed precessing outflow?
SW
NE
Luminosity of binary system with Mp+Ms=18 MO
Lbol(G35.20)
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
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
Core B lies at center of bipolar structure A
B
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
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
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