The$Luminosity$Func0ons$and$Timescales$of$ · PDF fileMYSOs$vs$HC/UCHIIs$ October19,2010 $...
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The Luminosity Func0ons and Timescales of Massive YSOs and UltraCompact HII regions Joe MoCram, University of Exeter, UK October 19, 2010 1 The Origin of Stellar Masses Red MSX Source (RMS) Survey Team U. of Leeds, UK: Melvin Hoare, Rene Oudmaijer, Stuart Lumsden, Cormac Purcell, Hugh Wheelwright, Heather Cooper Rochester Ins0tute of Technology, USA: Ben Davies ATNF, Australia: James Urquhart Liverpool JMU, UK: Toby Moore 10 ◦ 20 ◦ 30 ◦ l −1 ◦ +0 ◦ +1 ◦ b 40 ◦ 50 ◦ 60 ◦ −1 ◦ +0 ◦ +1 ◦ b
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The Luminosity Func0ons and Timescales of Massive YSOs and Ultra-‐Compact HII regions
Joe MoCram, University of Exeter, UK
October 19, 2010 1 The Origin of Stellar Masses
Red MSX Source (RMS) Survey Team U. of Leeds, UK: Melvin Hoare, Rene Oudmaijer, Stuart Lumsden, Cormac Purcell, Hugh Wheelwright, Heather Cooper Rochester Ins0tute of Technology, USA: Ben Davies ATNF, Australia: James Urquhart Liverpool JMU, UK: Toby Moore
10◦20◦30◦
l
−1◦
+0◦
+1◦
b
40◦50◦60◦−1◦
+0◦
+1◦
b
Massive Young Stellar Objects
October 19, 2010 The Origin of Stellar Masses 2
GL2591, Gemini JHK
• Luminous (L>104 Lꙩ) embedded mid-‐IR bright sources
• No HII region but some0mes ionised ‘wind’ (emission lines have v~100 km/s)
• Also frequently: – Supersonic molecular ouelow
– Maser emission
The Red MSX Source Survey
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• Colour-‐selected ~2000 candidates using MSX and 2MASS (Lumsden et al., 2002)
• |b| ≤ 5°, 10° ≤ l ≤ 350°
• Massive YSOs + UCHII regions + PN + C stars + OH/IR stars
Follow-‐up of Sample
• ~1” resolu0on radio con0nuum (Urquhart et al. 2007, 2009) => HII regions & PN
• ~1” resolu0on mid-‐IR (MoCram et al 2007) => dust morphology (MYSOs vs HII regions)
• 13CO & HI (Urquhart et al. 2007, 2008, 2010) => distances
• Spitzer MIPSGAL and IRAS IGA => Far-‐IR Flux => SEDs, Luminosi0es (MoCram et al 2010a, b)
• NIR spectroscopy (Cooper et al in prep) => final class and characterisa0on
• Data available at hCp://www.ast.leeds.ac.uk/RMS/
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The Luminosity Distribu0ons
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MSX completeness
180 90 0 -90 -180Gal l
2
4
6
8
10
50%
Com
plet
enes
s le
vel (
Jy) |b| < 1
1 < |b| < 33 < |b| < 5
|b| < 11 < |b| < 33 < |b| < 5
• Need Volume observed as a func0on of L
• Take a cylinder centred on galac0c centre and divide into cells • Exclude |l|<10°, |b|>5° • Calculate F21 for cell and include if ≥ completeness
Obtaining the Luminosity Func0on
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Weigh0ng Func0on
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– 1 –
weight(z) = exp�−|z|zd
�
zd = 41.9± 0.2pc
– 1 –
weight(r) = exp�−(r−r0)2
r2d
�− exp
�−(r−r0)2
r2h
�
rd = 6.55± 0.03kpc
rh = 1.73± 0.03kpc
r0 = 2.56± 0.02kpc
Volume of the Galaxy observed
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100% 50% 10%
The Luminosity Func0ons
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+ YSO + UCHII
100% 50%
Timescales
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+ YSO + UCHII
tKH tMS
MYSOs vs HC/UCHIIs
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Hosokawa, Yorke & Omukai, 2010
• Radio-‐quiet MYSOs with 104L ≤ L ≤ 105 L exit
• why no HII region? • Confined/quenched HII region (e.g. Walmsley 2005, Keto2003,
Tan & McKee 2003) ?
• Are they really in a main-‐sequence configura0on? Not for MYSOs
Summary
• The RMS survey has a sample of MYSOs and UCHII regions
• We have obtained the Luminosity func0on and 0mescales for these phases of massive star evolu0on for the first 0me
• No MYSO phase for L > 105 L -‐ go strait to HC/UCHII region
• For 104 L – 105 L, results consistent with swollen cooler MYSOs due to high accre0on
• Data available at hCp://www.ast.leeds.ac.uk/RMS/
October 19, 2010 The Origin of Stellar Masses 12
