School of something FACULTY OF OTHER School of Physics & Astronomy FACULTY OF MATHEMATICS & PHYSICAL SCIENCES AMI and Massive Star Formation Melvin Hoare

Evolutionary outline – High-mass Object: Molecular Core  MYSO  UCHII  Hot Star SED: Sub-mm  Mid-IR  Near-IR  Visual Radio: Undetected  Weak  Strong

Radio Survey for UCHII regions The Co-Ordinated Radio ‘N’ Infrared Survey for High-mass star formation or CORNISH survey High spatial resolution VLA survey of the Galactic Plane 5 GHz, 1.5  resolution (B configuration) Covers northern Spitzer GLIMPSE survey 10 o <l<65 o, |b|<1 o

Over-resolution of CORNISH HIIs

Over-resolution/snapshot VLA B config 15 GHz snapshot Integrated flux 2.6 Jy VLA D config 15 GHz observation Integrated flux 3.9 Jy

Ionizing Star(s) Spectral Type Correct optically thin, integrated radio flux is crucial to determine the ionizing flux and hence spectral type of the ionizing star(s)

Massive Young Stellar Objects Luminous (>10 4 L  ) embedded IR point source no UCHII region - star swollen due to ongoing accretion? bipolar molecular outflow (~10 km s -1 ) ionised wind (~100 km s -1 ) GL 2591

MYSOs display weak radio emission A few have been resolved to show jets Proper motions show velocities ~500 km s -1 Ionized Jets Cep A2 (Patel et al. 2005)

Others show evidence of radiation driven disc wind Disc winds S140 IRS 1 (Hoare 2006) Drew, Proga & Stone (1998)

Wind Spectra Gibb & Hoare (2007)

Radio vs IR luminosity Clear distinction between UCHIIs and MYSOs at luminous end MYSOs also distinguished from OB star winds – MS OB stars not detected yet  Jets  Evolved OB stars Hoare & Franco (2007)

Red MSX Source Survey sample of about 500 MYSOs from mid-IR survey and ground-based follow-up e-Merlin Legacy programme to detect and map the winds/jets for sub-sample of 75 of these ongoing near-IR spectroscopy programmes to study H I emission line profiles which constrain outflow velocity study the ionized feedback as a function of stellar mass (luminosity) and age (embeddedness)

Detection of winds by AMI Non-detection by VLA 5 GHz <0.75 mJy Detection by AMI 16 GHz 1.8 mJy

Summary AMI can play a useful role following-up 100s of: CORNISH UCHII regions for spectral typing ionizing star(s) RMS MYSOs for (pre-) detecting wind/jet emission, although really need resolution of EVLA to be sure of detection and e-Merlin to actually resolve the emission