Diagnostics of the Earliest Stages of Massive Star ... - CRyA, UNAM

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Diagnostics of the Earliest Stages of Massive Star ... - CRyA, UNAM

Indicators of the Earliest Stagesof Massive Star FormationMichael BurtonMaria Cunningham, Tracey Hill, Paul Jones,Nadia Lo, Steve Longmore, Cormac Purcell,Andrew Walsh

Team Dust, Mt Etna, May 2005Maria CunninghamPaul JonesMichael BurtonSteve LongmoreNadia LoCormac PurcellTracey HillAndrew Walsh

Outline• Millimetre astronomy in Australia• Four inter-related studies–Dust and SEDs: Tracey Hill–Chemistry and Hot Cores: Cormac Purcell–NH 3 and HCHIIs: Steve Longmore–Molecular Mapping in G333:• Cold, cold cores: Nadia Lo


Australia Telescope Compact Array• Millimetre-capable– 3 mm (85-105 GHz)• 5 x 22m antennas– 7mm (30-50 GHz)• 6 x 22m antennas– 12 mm (18-26 GHz)• 6 x 22m antennas• 4 GHz bandwidth coming– The CABB…..5

The Mopra Radio TelescopeOTF Mapping with 22m dishMMICs using HEMT devicesUNSW-MOPS 8 GHz DFB

Wideband Mode: Simultaneous coverage of 8.3 GHz, = 0.25 MHzBand 1Band 2Band 3Band 42.2 GHz / 8192 chans1 Window138 MHz / 4096 chansZoom Mode: Up to 16 windows (4 in each Band), = 0.03 MHzExample: Broadband velocity resolution 0.84 km/s at 90 GHz, 8192 channelsZoom Mode velocity resolution 0.11 km/s at 90 GHz, 4096 channels

Andrew Walsh

Andrew Walsh

Andrew Walsh

Burton, Jones et al.

ParkesAre isolated Our original methanol question: masersAre there signposts methanol of masersmassive associated star formation? withIRAS “HII regions”?ATCAWalsh et al. 1997, MNRAS, 291, 261Walsh et al. 1998, MNRAS, 301, 640Yes!But how early does the signpost switch on?

Searching for anevolutionarysequence to MSF…..Lee, Walsh, Burton &Ashley2001, MNRAS, 324, 1102Purcell, PhD, 2006

Millimetre continuum dust mapsSEST/SIMBAMillimetre Dust Cores• mm-only• + methanol masers• + maser + UCHII• + UCHIIF = B (T dust)M gas R dusttogasd 2Hill et al, 2005, MNRAS, 363, 405

Categories of MM-emitting Cores?Log Mass 2 3 4mm-onlymm +masermm +maser +radiomm +radio0.5 1.0 1.5 Radius (pc)• MM-only cores less massive, on average• Cores without UCHII regions smaller, onaverageHill et al, 2005, MNRAS, 363, 405

Butwith* * *Hill et al, 2006,MNRAS, 368, 1223improvedSEDs…F = [ B(T hot ) R hot2+ B(T cold ) M cold ] / d 2TemperatureMassmm-onlymm +masermm +maser +radiomm +radioLuminosity

Bayesian Inference for mostprobable parameters from SEDs

Cumulative Distributions ofSource Categoriesmm-onlylessmassiveHill, Pinte, Minier,Burton &CunninghamSED modelling ofSouthern candidatemassive protostars2009, MNRAS, inpress.

Mass – Luminosity Distributionmm-only vs. meth maser vs. maser+radio vs. radioX mm-onlyM L 0.62/3rds sources• Methanol masers coresrepresentative of entiresample• Millimetre-only cores onaverage are less massive– If M lower then L higher• MM-only cores:– Less-evolved MSF or– Intermediate Mass SF or– Failed cores??• Further diagnostics of themm-only cores required

Methanol Maser selectedHot Molecular Core SurveyCormac PurcellPhD, 2006‘Isolated’ MasersUCHII region and MasersSEST/SIMBA 1.2mm contoursMSX 8 m image of the Galactic plane

CH 3 CN 92 GHzCH 3 OH 96 GHzHCO + HNC 13 COH 13 CO + HCN N 2 H +Cormac PurcellPhD Thesis 2006

Line Detection RatesMolecule:Detections: Rate:Sensitivity (mK):58 / 83CH 3 CNN 2 H + 82 / 83HCN 82 / 83HCO + 82 / 83HNC 82 / 8370%99%99%99%99%~25 mK~60 mK~60 mK~60 mK~ 60 mKCH 3 OH 78 / 83 94% ~35 mKH 13 CO + 80 / 83 98% ~35 mK

CH 3 CN: Detections & LuminositiesPurcell et al, 2006, MNRAS, 367, 553Found in ‘isolated’ masers internal heating sourcesMore common and brightertowards masers with UCHII regionsLuminosity to powerUCHII region, even thoughIR source often absent?!“Infrared dark clouds”often have methanol masersProvides a chemical clock?

Methanol-Masers &Hot Molecular Cores:Chemistry andCH 3 CN & CH 3 OHPurcell et al, 2009, MNRAS, in press.Methanol and methyl cyanideemission are enhancedwhen both a UCHII region and amethanol maserare present

HMC Line Widths and MassesN(CH 3 CN)4.5 km/sCH 3 CN4.5 km/s13CO4.5 km/sHCN3.0 km/sN 2 H +M dustM core related to M dust

HMC Gas Mass vs. Luminosityc.f. Cesaroni 2005SingleStarIMFM core > M stars+

Some conclusions re HMCs• L hot core M gas0.7– lower-mass clumps over-luminous– higher-mass clumps under-luminous– M gas > M stars : Heavy cores• Radio-loud HMCs are:– more massive and more luminous than radio-quiet• result of short timescale for most-massive objects to create UCHIIs?• and/or radio-quiet cores have HCHIIs?• Thus radio-loud cores are older– CH 3 CN and CH 3 OH are brighter/more abundant• M hot core related to M cold dust core

Ammonia Cores andHyper (?) Compact HII RegionsNH 324 GHzMethanolMaser(2,2) (1,1)Asymmetries(4,4)Longmoreet al, 2007,MNRAS,379, 535.

NH 3 : Linewidth vs. Temperature(4,4)LinewidthX NH 3 only NH 3 + Methanol MaserLongmore et al, in prep.(1,1)

Methanol Masers:Ammonia Cores & 24 GHz continuum• Cores with methanol masers are generally:– Warm– Larger linewidths (2-3 km/s)– 24GHz HII emission• Cores without methanol masers are generally:– Cold (< 40K)– Narrow linewidths (1-2 km/s; still turbulent)– No 24 GHz continuum– NH 3 (1,1) hyperfine asymmetries• unresolved narrow clumps, V

Extended Evolutionary Scenario for MSFImage Credit: Cormac PurcellNH 3 (1,1) profileasymmetriesNH 3 onlyNH 3 + methanol maserNH 3 + methanol maser + 24GHzNH 3 + 24GHz8 + 24GHz

Multi-molecular line mapping in G333: INadia LoPhD 2009andLo et al,MNRASsubmitted

Multi-molecular line mapping in G333: IINadia LoPhD 2009andLo et al,MNRASsubmitted

Principal Component Analysis

SiOCold Core at veryearly stage of MSF2 pcCS N 2 H + CH 3 OH HC 3 NHNC HCO + SO SiO1.2mm CO1.2mm+8m• Dense Core– M~2000 M , n~2x10 5 cm -3• Extremely Cold– Not detected for < 70m– T dust ~18K, N NH3 ~13K• Localised SiO emission– Broad line (9 km/s vs. 5 km/s)• Methanol & Water masers• Outflow from a deeplyembedded, massiveprotostellar object

Musings• Are mm-only cores different–Evolutionary state?–Mass of most massive member?–Failed core?• Multiplicity within mm-cores–NH 3 , Methanol masers & HCHIIs–Chemical composition & evolutionary state• Enhanced SiO in the coldest cores?

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