Evolution of highmass YSOs Pathfinder Sample Riccardo Cesaroni

Evolution of high-mass YSOs: Pathfinder Sample Riccardo Cesaroni, Maite Beltràn, Roberta Paladini Main steps: 1. Choose templates of high-mass YSOs in different evolutionary phases 2. Establish characteristics of each phase 3. Select sources in each phase from Hi. Gal survey 4. Optimize characterization using Hi. Gal info

Adopt “classical” evolutionary sequence (maybe questionable/incomplete, but reasonable starting point to be improved later) IR-dark cloud Work in progress: HMC (+ HC HII) 1. Identify ~10 templates per phase UC HII 2. Obtain images and SEDs from NIR to (sub)mm extended HII 3. Establish possible differences among phases

Choice of templates • IRDCs relatively easy (Chambers et al. 2009, Beltràn et al. 2006, Pillai et al. 2006, 2007): compact submm cores without GLIMPSE source then check no MIPSGAL source and no maser • HMCs & UCHIIs more difficult: only few HMCs known (e. g. Kurtz et al. 2000) many UCHIIs (e. g. Wood & Churchwell 1989, Kurtz et al. 1994), but… many problems • Extended HIIs easy (lots of optical/radio and recombination lines catalogs: Sharpless 1959, Rodgers 1960, Paladini et al. 2003, Caswell & Haynes 1980, etc. ): optical counterpart, size > 1 arcminute, electron density ne ~ 10 - 102 cm-3

Problems with HMCs & UCHIIs: • Contamination: many UCHIIs w/o HMCs but almost no HMC w/o UCHII reject HMCs with embedded “large” UCHIIs • Authenticity: some UCHIIs might be peaks (w/o star!) of (resolved out) extended emission Kurtz et al. (1999), Kim & Koo (2001) show that only very few UCHII suffer by this problem • Extended emission: might affect UCHII properties UCHII should dominate within 20”

• Multiplicity: confusion due to >1 UCHIIs inside HPBW (~20”) reject complex UCHIIs and clusters of UCHIIs; accept only “simple” morphologies • Distance: implications on multiplicity, morphology, etc… choose more or less same distance (< 9 kpc, but with some exception) Additional selection criterion for Hi. Gal: |l|<60° & |b|<1° For tables of selected sources see Hi. Gal WIKI page

Examples of IRDCs

Examples of HMCs NOTE: all images and SEDs obtained after smoothing to 20” resolution (MSX, MIPSGAL 70µm)

Examples of UCHIIs NOTE: all images and SEDs obtained after smoothing to 20” resolution (MSX, MIPSGAL 70µm)

Comparison between SEDs of all HMCs and UCHIIs HMCs UCHIIs

Findings for HMCs & UCHIIs • Large majority saturated in MIPSGAL (some also in GLIMPSE 8 µm) • IRAS fluxes likely overestimate by ~10 • SEDs and morphologies are basically the same for HMCs and UCHIIs: – SED = cold mm component + hot IR component – Morphology = IR peak coincident with submm core both HMCs and UCHIIs analogous to IR-P sources of Molinari et al. (2008) perhaps different luminosities i. e. 100 µm fluxes? Only Hi. Gal will tell us need for intermediate phase (MM-P sources) between IRDCs and HMCs ?

Examples of EHIIs

M 16 : 16. 95 + 0. 79 40 - 250 m (Mc. Breen, Fazio, Jaffe 1982)

GUM 38 d: 309. 28 - 00. 40 ( Karr, Manoj, Ohashi 2009 ) H IRAC 8 m 1420 MHz MIPS 24 m

RCW 79: 308. 6+0. 6 (Zavagno et al. 2006) H Red: IRAC 8 m Blue: H IRAC 8 m