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