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Structures of accretion and outflow on small scales in high-mass protostars CIRIACO GODDI
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Talk Objective I.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 (10 3-4 L ) and O-type (10 4-5 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 & masers ii.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
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I.I. Outflow Morphologies -H 2 O masers (VLBA): V 3D 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 H 2 O collimated bipolar flow Driver: an intermediate-mass protostar or B-type YSO (probably pre-ZAMS) AFGL5142 (L~5×10 3 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~7×10 4 L , D=7.7 kpc) Moscadelli, Goddi, ea 07
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6.7 GHz CH 3 OH masers (EVN) Contours radio continuum (VLA) 0.05” (90 AU) H2OH2O located in the foreground of the (optically-thick) radio continuum red-shifted V l.o.s. Equatorial Plane Outflow axis II. Spherical Infall 6.7 GHz CH 3 OH masers in an intermediate-mass protostar Goddi, Moscadelli, & Sanna 2011 AFGL5142 (L~5×10 3 L , D=1.8 kpc)
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II. Spherical Infall 0.05” (90 AU) V LSR (km/s) -8 5 6.7 GHz CH 3 OH masers in an intermediate-mass protostar Motions over 6 yrs located in the foreground of the (optically-thick) radio continuum red-shifted V l.o.s. Outflow axis Two distinct groups: 1)Masers towards the cont peak have large PMs towards the protostar 2)Masers in the eq. plane have small PMs and move mainly along the l.o.s. Equatorial Plane Goddi, Moscadelli, & Sanna 2011 OPEN Q: Can we measure direct accretion onto a single O type YSO? 6.7 GHz CH 3 OH masers (EVN) Contours radio continuum (VLA) H2OH2O AFGL5142 (L~5×10 3 L , D=1.8 kpc)
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NGC 7538 Star Forming Region (L~10 5 L , D=2.7 kpc) III. Rotating Disk(s) around an O-type YSO Moscadelli & Goddi, 2014, arxiv IRS1a (O-type YSO): M~25M , R disk ~700 AU, dominates most of L bol (L~10 5 L ), Keplerian IRS1b (B-type YSO): M * +M disk ~16 M , R disk ~500 AU, thick/massive disk (no Keplerian) 6.7 GHz CH 3 OH 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
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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
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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 H 2 O & CH 3 OH masers Over 100 sources already observed and their parallaxes measured: V 3D of H 2 O masers in outflows A very large sample of massive YSOs studied with maser VLBI from the BeSSeL VLBA Survey Reid ea 09, 14 Brunthaler ea 11 L bol from HI-GAL: mass/evolutionary stage of YSOs Combine 3-D velocity fields of H 2 O masers from VLBI with new sensitive maps of thermal ionized gas, continuum (JVLA) and RLs (ALMA)
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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 μ Jy: 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, CH 3 OH 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)
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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
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ALMA optically thin (more reliable V lsr ) less pressure broadened (kinematics) F l /F c 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 (CH 3 CN, CH 3 OH, etc.) Molecular Outflows (CO, 13 CO and C 18 O, 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?
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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 μ Jy with 1h on-source II. Hydrogen Radio Recombination Lines Over 80 RRLs in bands 3-5: H159 α to H78 α : 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 CH 3 OH: 6669, 12179 MHz (Band 5) H 2 O: 22235, NH 3 : 23694, 23723, 23870 MHz (high)
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Measurements of 3D velocity fields of CH 3 OH 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 jet 200 AU CH 3 OH H2OH2O 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 CH 3 OH masers CH 3 OH disk H 2 O Outflow
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Measurements of 3D velocity fields of CH 3 OH 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 CH 3 OH 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
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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
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