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

Structures of accretion and outflow on small scales in high-mass protostars. CIRIACO GODDI. Talk Objective.

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

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  1. Structures of accretion and outflow on small scales in high-mass protostars CIRIACO GODDI

  2. Talk Objective • 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 • Outflows: B-type (103-4L)and O-type (104-5L) YSOs • Infallonto an intermediate-mass YSO • Rotating disk around an O-type YSO • Observational program of a statistically significant sample of high-mass star forming regions: • The BeSSeL project: mapping the MW with the VLBA & masers • Complementary JVLA survey to image thermal emission from ionized and molecular gas • Future prospects and synergies: VLBA/EVN, JVLA, ALMA, SKA1-Mid, and SKA1-Mid+EVN

  3. I. Outflow Morphologies • H2O masers (VLBA): V3D of molecular gas • radio cont. (VLA): structure of ionized gas AFGL5142 (L~5×103L, D=1.8 kpc) Type I: a shock-excited radio jet and an H2O collimated bipolar flow Driver: an intermediate-mass protostaror B-type YSO (probably pre-ZAMS) 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~7×104L, D=7.7 kpc) 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 Moscadelli, Goddi, ea 07

  4. II. Spherical Infall 6.7 GHz CH3OH masers in an intermediate-mass protostar AFGL5142 (L~5×103L, D=1.8 kpc) 6.7 GHz CH3OH masers (EVN) Contours radio continuum (VLA) H2O • located in the • foreground of the • (optically-thick) • radio continuum • red-shifted Vl.o.s. Equatorial Plane Outflow axis 0.05” (90 AU) Goddi, Moscadelli, & Sanna 2011

  5. II. Spherical Infall 6.7 GHz CH3OH masers in an intermediate-mass protostar AFGL5142 (L~5×103L, D=1.8 kpc) -8 6.7 GHz CH3OH masers (EVN) Contours radio continuum (VLA) VLSR (km/s) Motions over 6 yrs H2O -1 • located in the • foreground of the • (optically-thick) • radio continuum • red-shifted Vl.o.s. Equatorial Plane Outflow axis 0.05” (90 AU) Two distinct groups: Masers towards the cont peak have large PMs towards the protostar Masers in the eq. plane have small PMs and move mainly along the l.o.s. 5 Goddi, Moscadelli, & Sanna 2011 OPEN Q: Can we measure direct accretion onto a single O typeYSO?

  6. III. Rotating Disk(s) around an O-type YSO 6.7 GHz CH3OH masers (EVN) NGC 7538 Star Forming Region (L~105L, D=2.7 kpc) Edge-on Disk Model Moscadelli & Goddi, 2014, arxiv Fit to positions, l.o.s. velocities, accelerations, and proper motions of maser spots • IRS1a (O-type YSO): M~25M, Rdisk~700 AU, dominates most of Lbol(L~105L), Keplerian • IRS1b (B-type YSO): M*+Mdisk~16 M, Rdisk~500 AU, thick/massive disk (no Keplerian) OPEN Q: Do Keplerian disks normally exist around massive O-type YSOs?

  7. What’s Next? Extend the VLBI program of molecular masers to a statistically significant sample Complement VLBI-maser measurements with imaging surveys of radio continuum, thermal molecular lines and possibly radio recombination lines

  8. Extend the VLBI program of molecular masers to a statistically significant sample A very large sample of massive YSOsstudied with maser VLBI from the BeSSeL VLBA Survey Reid ea 09, 14 Brunthalerea 11 • Trigonometricparallaxes and propermotions of 400 massive star formingregions in the MW via VLBI of H2O & CH3OH masers • Over 100 sourcesalreadyobservedand theirparallaxesmeasured: V3D of H2O masers in outflows Combine 3-D velocity fields of H2O masers from VLBI with new sensitive maps of thermalionized gas, continuum (JVLA) and RLs (ALMA) complement it with radio continuum imaging, RLs and thermal molecular line observations (ALMA, JVLA, SKA) • Lbolfrom HI-GAL: mass/evolutionary stage of YSOs

  9. JVLA II. JVLA imaging Survey of the BeSSeLsample (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) • 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. Molecular Outflows • SiO1-0, 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)

  10. Future prospects and synergies Structure and dynamics of molecular and ionized gas with ALMA Radio continuum, RLs, and masers with SKA1-Mid and SKA1-Mid phased with the EVN

  11. Future prospects and synergies I: ALMA Structure and dynamics of molecular and ionized gas ALMA • I) Structure and dynamics of molecular gas • molecular portion of the accretion in infalling envelopesand disks • (CH3CN, CH3OH, etc.) • Molecular Outflows • (CO, 13CO and C18O, SiO, SO, etc.) II) Dynamics of Ionized Gas: mm RLs • optically thin(more reliable Vlsr) • less pressure broadened (kinematics) • Fl/Fc higher than the cm: easier to detect! Only ALMA can resolve the kinematics of ionized gas inside HC HII regions • Open Q: • Are HC-HII regions all expanding? • Is there an ionized accretion flow in early stages of HC-HII?

  12. Future prospects and synergies II: SKA1-Mid Structure and dynamics of ionized gas • 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-source II. Hydrogen Radio Recombination Lines Over 80 RRLs in bands 3-5: H159α to H78α: stacking? 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)

  13. IRAS 20126 (1.8 kpc) (Moscadelliet al. 2011) disk+jet disk H2O CH3OH jet 200 AU Future prospects and synergies III: SKA1-Mid + EVN Accretion with CH3OH masers Measurements of 3D velocityfieldsof CH3OH masers with VLBI provides a unique tool to unveil gas accreting inside 100 AU from massive YSOs Where is the red part of the disk? H2O Outflow CH3OH disk • 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 Need more sensitive long baselines to detect the weakest masers to sample “missing” portions of circumstellardisks and construct a rotation curve

  14. Future prospects and synergies III: SKA1-Mid + EVN Accretion with CH3OH masers Measurements of 3D velocityfieldsof CH3OH masers with VLBI provides a unique tool to unveil gas accreting inside 100 AU from massive YSOs • 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

  15. Summary Goals of our observational program of massive SFRs Outflow structure as a function of protostellar mass and age Establish mass accretion in a massive YSO once a HC HII region has formed Synergy between the VLBA, EVN, JVLA, SKA, and ALMA THANK YOU!

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