Structures of accretion and outflow on small scales in high-mass protostars

CIRIACO GODDI

Talk ObjectiveI. Multi-epoch VLBI observations of molecular masers enable

to measure the molecular gas 3D velocity field on scales~1-10 AU and at radii <100-1000 AU from YSOs at a few kpc distances

i. Outflows: B-type (103-4 L) and O-type (104-5 L) YSOs

ii. Infall onto an intermediate-mass YSO

iii. Rotating disk around an O-type YSO

II. Observational program of a statistically significant sample

of high-mass star forming regions:

i. The BeSSeL project: mapping the MW with the VLBA & masersii. Complementary JVLA survey to image thermal emission from

ionized and molecular gas iii. Future prospects and synergies: VLBA/EVN, JVLA, ALMA, SKA1-

Mid, and SKA1-Mid+EVN

I. I. Outflow Morphologies- H2O masers (VLBA): V3D of molecular gas- radio cont. (VLA): structure of ionized gas

OPEN Q: Are collimated ejections found more probably associated with less luminous (early-B type) than more luminous (O type) young stars? Trend with mass? Age? Or both?

500 AU

Type I: a shock-excited radio jet and an H2O collimated bipolar flow

Driver: an intermediate-mass protostar or B-type YSO (probably pre-ZAMS)

AFGL5142(L~5×103 L, D=1.8 kpc)

Goddi ea 11

Type II: a stellar wind driving a wide-angle expansion of a hyper-compact HII region

Driver: a massive (~20 M) O-type YSO (probably in ZAMS)

G24.78+0.08 (L~7×104 L, D=7.7 kpc)

Moscadelli, Goddi, ea 07

6.7 GHz CH3OH masers (EVN)Contours radio continuum (VLA)

0.05” (90 AU)

H2O

located in the foreground of the (optically-thick) radio continuum red-shifted Vl.o.s.

Equatorial Plane

Out

flow a

xis

II. Spherical Infall 6.7 GHz CH3OH masers in an intermediate-mass protostar

Goddi, Moscadelli, & Sanna 2011

AFGL5142(L~5×103 L, D=1.8 kpc)

II. Spherical Infall

0.05” (90 AU)

VLS

R (k

m/s

)

-8

-1

5

6.7 GHz CH3OH masers in an intermediate-mass protostar

Motions over 6 yrs

located in the foreground of the (optically-thick) radio continuum red-shifted Vl.o.s.

Out

flow a

xis

Two distinct groups:1) Masers towards the cont peak have large PMs towards the protostar2) Masers in the eq. plane have small PMs and move mainly along the

l.o.s.

Equatorial Plane

Goddi, Moscadelli, & Sanna 2011OPEN Q: Can we measure direct accretion onto a single O type YSO?

6.7 GHz CH3OH masers (EVN)Contours radio continuum (VLA)

H2O

AFGL5142(L~5×103 L, D=1.8 kpc)

NGC 7538 Star Forming Region(L~105 L, D=2.7 kpc)

III. Rotating Disk(s) around an O-type YSO

Moscadelli & Goddi, 2014, arxiv

IRS1a (O-type YSO): M~25M , Rdisk~700 AU, dominates most of Lbol (L~105 L),

Keplerian IRS1b (B-type YSO): M*+Mdisk~16 M , Rdisk~500 AU, thick/massive disk (no Keplerian)

6.7 GHz CH3OH masers (EVN)

OPEN Q: Do Keplerian disks normally exist around massive O-type YSOs?

Fit to positions, l.o.s. velocities, accelerations, and proper motions of maser spots

Edge-on Disk Model

What’s Next?

I. Extend the VLBI program of molecular masers to a statistically significant sample

II. Complement VLBI-maser measurements with imaging surveys of radio continuum, thermal molecular lines and possibly radio recombination lines

I. Extend the VLBI program of molecular masers to a statistically significant sample

II. complement it with radio continuum imaging, RLs and thermal molecular line observations (ALMA, JVLA, SKA)

Trigonometric parallaxes and proper motions of 400 massive star forming regions in the MW via VLBI of H2O & CH3OH masers

Over 100 sources already observed and their parallaxes measured: V3D of H2O masers in outflows

A very large sample of massive YSOs studied with maser VLBI from the BeSSeL VLBA Survey

Reid ea 09, 14Brunthaler ea 11

JVLA

Goal: Nature and morphology of ionized gas on scales 100s-1000s AU Spectral index: jet or HC-HII? Intensity structure:

Elongated (jet) vs. Spherical (wind/HCHII)

II. JVLA imaging Survey of the BeSSeL sample (Outflows)I. Radio Continuum imaging

EVLA AB-Array: θ=0. 09” (22 GHz), 0. 33” (6 GHz) Continuum emission in 3 bands: C, Ku, K Deep, rms~10 μJy: Sensitive down to B2-type YSOs up to 9 kpc 2 spw at 6.7 GHz and at 22.2 GHz for self-cal and astrometry with VLBI

maps 41 sources observed in 2012-2014 (Analysis completed for 14)

II. Molecular Outflows SiO 1-0, CH3OH Class I, etc. D-Array, θ=1.5”, Q-band 30h pilot approved with high priority

Goal: morphology & kinematics of molecular outflows on scales 1000-10000 AU

III. Hydrogen Radio Recombination Lines (RRLs) too faint in high-mass YSOs w/o a developed HII region: stacking? (see

next)

I. Structure and dynamics of molecular and ionized gas with ALMA

II. Radio continuum, RLs, and masers with SKA1-Mid and SKA1-Mid phased with the EVN

Future prospects and synergies

ALMA

optically thin (more reliable Vlsr) less pressure broadened (kinematics) Fl/Fc higher than the cm: easier to

detect!

Future prospects and synergies I: ALMA

Structure and dynamics of molecular and ionized gas

I) Structure and dynamics of

molecular gas molecular portion of the accretion

in infalling envelopes and disks

(CH3CN, CH3OH, etc.)

Molecular Outflows

(CO, 13CO and C18O, SiO, SO, etc.)

Only ALMA can resolve the kinematics of ionized gas inside HC HII regions

II) Dynamics of Ionized Gas: mm RLs

Open Q:

- Are HC-HII regions all expanding?

- Is there an ionized accretion flow in early stages of HC-HII?

I. radio continuum imaging Needs bands 3-5 (1.7-13.8 GHz) Needs subarcsecond resolution sensitive to larger scales (no need of multiple configurations as for the

JVLA) rms~a few μJy with 1h on-sourceII. Hydrogen Radio

Recombination Lines Over 80 RRLs in bands 3-5:

H159α to H78α: stacking?

Future prospects and synergies II: SKA1-Mid

Structure and dynamics of ionized gas

III. Masers (Wouter’s talk)

OH: 1612, 1665, 1667, 1720, 4751, 4766, 6031,

6035, 13441 MHz

CH3OH: 6669, 12179 MHz (Band 5)

H2O: 22235, NH3: 23694, 23723, 23870 MHz

(high)

Measurements of 3D velocity fields of CH3OH masers with VLBI provides a unique tool to unveil gas accreting inside 100 AU from massive YSOs

Single direct measurement of accretion of molecular gas onto an intermediate YSO and the best accretion disk candidate in an O-type YSO so far

Limited to 7-8 YSOs studied with the EVN overal several years Maser VLBI images limited by dynamic range and sensitivity

IRAS 20126 (1.8 kpc) (Moscadelli et al.

2011)disk+jet

disk

jet200 AU

CH3OH

H2O

Where is the red part of the disk?

Need more sensitive long baselines to detect the weakest masers to sample “missing” portions of circumstellar disks and construct a rotation curve

Future prospects and synergies III: SKA1-Mid + EVN

Accretion with CH3OH masers

CH3OH disk H 2

O Outflo

w

Measurements of 3D velocity fields of CH3OH masers with VLBI provides a unique tool to unveil gas accreting inside 100 AU from massive YSOs

Future prospects and synergies III: SKA1-Mid + EVN

Accretion with CH3OH masers

Phasing SKA1-mid with the EVN Very sensitive N-S baseline (similar to EVN-Ar) Easier to look at the Galactic Center A factor of ~3 gain in sensitivity wrt present EVN Weakest masers in disks around massive YSOs and in low-mass YSOs Essential for astrometry: phase-reference with sources of tens of mJy maybe

feasible

THANK YOU!

Goals of our observational program of massive SFRs

1) Outflow structure as a function of protostellar mass and age

2) Establish mass accretion in a massive YSO once a HC HII region has formed

3) Synergy between the VLBA, EVN, JVLA, SKA, and ALMA

Summary