The Red MSX Source Survey. Massive Star Formation in the Milky Way. Stuart Lumsden University of Leeds

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1 The Red MSX Source Survey Massive Star Formation in the Milky Way Stuart Lumsden University of Leeds RMS Team: Melvin Hoare, Rene Oudmaijer, Heather Cooper, Ben Davies (Leeds) Joe Mottram (Exeter) James Urquhart (ATNF) Toby Moore (Liverpool JMU) Michael Burton (UNSW)

2 Massive Young Stellar Objects Luminous (>104 L ), embedded IR source. Compact, ionised wind (emission lines have v~100 km/s) radio weak. Often present: Molecular outflow/ Maser emission Well characterised MYSOs number in the tens Not found systematically, most nearby, GL2591 may not be representative Gemini JHK

3 Evolutionary Outline IRDCs? Hot Core MYSO UCHII SED: Ext. maps Sub-mm/FIR Mid-IR Mid/Near-IR Masers: Ice chemistry CH3OH H 2O OH Radio: No radio Weak Radio Strong Radio

4 Why are MYSOs Important? Final mass of star may be set in this phase (evidence for ongoing accretion) Outflow/momentum transfer to natal cloud may peak/terminate at this time Allows us to test models of massive star formation (eg collapse + disk accretion versus competitive accretion) before all the significant evidence is destroyed by the emergent OB star(s)

5 The Red MSX Source (RMS) Survey MSX survey: 8, 12, 14 and 21µ m, 18 resolution, b <5o Colour-select massive from the MSX PSC and 2MASS Delivers ~2000 candidates: Massive YSOs + UCHII regions + PN + C stars + OH/IR stars

6 Multi-wavelength Ground-based Follow-up Campaign Radio continuum (2arcsec resn, 5GHz, ATCA & VLA): ~500 detected UCHII regions (Urquhart et al. 2007, 2009) powered by O7+ stars Mid-IR (Glimpse, ground-based, Mottram et al 2007) give morphology (MYSO ~ point source) Contours: 6 cm Greyscale: 8 µ m

7 Multi-wavelength Ground-based Follow-up Campaign Kinematic Distances: CO at Mopra, JCMT, Onsala, PMO & GRS (Urquhart et al. 2007, 2008) ambiguity within solar circle solved using HII method after sources (MYSOs + HIIs) grouped into complexes (not complete) 13 Near IR spectra gives final class + source properties

8 Luminosities SED fitting (Robitaille et al 2007) Far-IR fluxes (MIPSGAL and Hi-GAL corrected for non-linearities) MIPSGAL 70µ m (15 areacross) combined with the distances to yield the luminosities (Mottram, PhD thesis 2008)

9 Final RMS Aims Testing SF Models Luminosity Function for massive YSOs => Massive star formation rate IMF Accretion rate history Envelope dispersal history Clustering and triggering High spatial/spectral resolution studies as function of luminosity, age and location.

10 Testing Star Formation Models Hosokawa & Omukai (2008): B0- have puffed up atmospheres, cooler, less UV McKee & Tan (2003): Accretion rate history with time

11 Testing Star Formation Models Simulated Star Formation: Star Formation follows gas distribution Galaxy Assume SF rate 3M yr-1 Davies et al 2009 Accretion rate history from McKee & Tan (2003) When on MS, compute radio emission (HII region) Let it evolve for 1 Myr Then select using RMS criteria (distance, IR, L, radio flux)

12 Testing Star Formation Models Early results: galactic distribution and numbers well reproduced already (Davies et al. 2009) Distribution with Galactocentric radius Davies et al 2009

13 Testing Star Formation Models And Galactic longitude and latitude

14 Luminosity Distribution Luminosity distribution also correct shape but observed data shows that objects not clearly defined as just HII or YSO helps fill the gap where there are no massive YSOs Observed data of ~50% of sample with firm distances As is luminosity distribution (Davies et al 2009)

15 HII/YSO example UCHII region MYSO (CO bandhead emission) in HII region star has Teff~36000K

16 Summary RMS survey has delivered ~500 MYSOs and a similar number of compact HII regions across the galaxy. Allows systematic global studies of trends for the first time MYSOs mostly appear as lower luminosity than UCHII regions, but some evidence for rare, young O8+ MYSOs as well.

17 Source Identification Sample definition complete. Mottram, PhD thesis 2008 From distances: sample is Galaxy wide.

18 Galactic Distribution Large scale clustering of MYSOs, UCHIIs and CO cores to establish group membership (GRS & SCUBA2) Spatial correlation analysis to test global star formation models

19 Emission Line Properties Carr (1990) observations of TTauri stars * Ishii et al (2001) observation of HAeBes X RMS, Clarke PhD thesis 2007