A Submillimeter A Submillimeter studystudy

ofofthe Magellanic the Magellanic

CloudsCloudsTetsuhiro MinamidaniTetsuhiro Minamidani

(Nagoya University)(Nagoya University)&&

NANTEN teamNANTEN teamASTE teamASTE team

Mopra – ATNF teamMopra – ATNF team

Large Magellanic CloudLarge Magellanic Cloud Nearest galaxy Nearest galaxy (( ～～ 50kpc)50kpc)

We can resolve individual GMCs.We can resolve individual GMCs. Face-onFace-on

less contamination along the line of sightless contamination along the line of sight Different environmentDifferent environment from that of Our Galaxy from that of Our Galaxy

Low metallicity (e.g., Dufour 1984), Low metallicity (e.g., Dufour 1984), High gas to dust ratio (Koornneef 1982),High gas to dust ratio (Koornneef 1982), High FUV fieldHigh FUV field

Active star formationActive star formation 30 Doradus ~ 39 O3 stars (Massey & Hunter 1999)30 Doradus ~ 39 O3 stars (Massey & Hunter 1999)

Current formation of Current formation of young massive star clusteryoung massive star clusterss (populous clusters)(populous clusters) ~ 10~ 1044 stars (e.g., Hodge 1961) stars (e.g., Hodge 1961)

Purpose of this workPurpose of this work Proto cluster condensationProto cluster condensation

Compact (<1pc), dense (10Compact (<1pc), dense (1044/cc) and warm /cc) and warm (50K)(50K)

Derive density, temperature and kinematicsDerive density, temperature and kinematics

⇒ ⇒ high resolution CO(J=3-2)high resolution CO(J=3-2) Envelope of molecular cloudsEnvelope of molecular clouds

In low metallicity, intense UV environmentIn low metallicity, intense UV environment CO → C → CCO → C → C+ + (PDR)(PDR)

⇒ ⇒ high resolution [CI] observationhigh resolution [CI] observation

OutlineOutline

Results of CO(1-0) observationsResults of CO(1-0) observations

(NANTEN, (NANTEN, SEST)SEST)

ASTE CO(3-2) observationsASTE CO(3-2) observations ASTE [CI] observationsASTE [CI] observations SummarySummary

Molecular clouds in the Molecular clouds in the LMCLMC NANTEN 4m radio telescope

12CO(1-0) : 115GHz

259 CO clouds (Mvir > 104 Msun)

Total molecular mass ~ 7×107 Msun

Total Total

~ 27,000 points~ 27,000 points

Contours;Contours;

from 1.2Kkm/sfrom 1.2Kkm/s

intervals 2.4Kkm/sintervals 2.4Kkm/s

Reveal large scale distribution of GMCs in Reveal large scale distribution of GMCs in LMCLMC Complete sample of GMCsComplete sample of GMCs

Need Need higher resolution observationshigher resolution observations to to find individual find individual proto clusterproto cluster condensationscondensations

Observations with SESTObservations with SESTDiameter: 15mLine ： 12CO(J=1-0)Frequency: 115GHz

Beam size: 44”(115GHz) ⇒10pc@50kpc

Tsys: 450K(115GHz)

Vel. res.: 0.2 km/s (115GHz)

Observation: Aug., 2001 Feb., 2002

(@La Silla, Chile)

CO(3-2) Observations CO(3-2) Observations with ASTEwith ASTE

Diameter ： 10mLine ： 12CO(J=3-2)Frequency ： 345GHz

Beam size ： 22”(345GHz) ⇒5pc@50kpcObserving grid: 30”, 20”, 15”, 10”Tsys ： 300K (DSB)Intg. Time ： 30 – 240 sec.Vel. res. ： 0.44km/s (wide-band mode)

Observation : Oct. 2004

(@Pampa la Bola, Chile)

Proto cluster Proto cluster condensation ?condensation ?

Cluster (Hunter et al. 2003)Cluster (Hunter et al. 2003) size D = 1pcsize D = 1pc MM**

tottot = 3×10 = 3×1022MMsunsun

Star formation efficiency = 10%Star formation efficiency = 10%↓↓

MMgasgastottot = 3×10 = 3×1033MMsunsun

dv = sqrt(Mdv = sqrt(Mgasgastottot/(190×D/2)) = 5.62 km/s/(190×D/2)) = 5.62 km/s

MM ～～ 101055MMsunsun, R, R ～～ 10pc, dv10pc, dv ～～ 7km/s (observ7km/s (observed)ed)

From ASTE CO(3-2) obs.From ASTE CO(3-2) obs.

Clump size Clump size ～ ～ 10pc, 10pc, Clump mass Clump mass ～ ～ 101055MMsunsun

Substructure -> proto cluster condensationSubstructure -> proto cluster condensation II3-23-2/I/I1-01-0 - Hα flux correlation - Hα flux correlation From LVG analysisFrom LVG analysis

Tkin > 120K, n(HTkin > 120K, n(H22) ) ～ ～ 101044/cc (30Dor)/cc (30Dor) Tkin > 70K, n(HTkin > 70K, n(H22) ) ～ ～ 101044/cc (N159W)/cc (N159W) Clumps near the HII regions/clusters are heatedClumps near the HII regions/clusters are heated

[CI] line[CI] line Different environmentDifferent environment from that of Our Galaxy from that of Our Galaxy

Low metallicity (e.g. Dufour 1984)Low metallicity (e.g. Dufour 1984) High gas to dust ratio (Koornneef 1982)High gas to dust ratio (Koornneef 1982) High FUV fieldHigh FUV field

↓↓ ＣＯ　→　Ｃ　→　ＣＣＯ　→　Ｃ　→　Ｃ ++

[CII] : strongly depend to FUV field[CII] : strongly depend to FUV field（（ Stacy et al. 1991, Mochizuki et Stacy et al. 1991, Mochizuki et

al. 1994al. 1994 ）） [CI]/CO : no significant dependence to FUV field[CI]/CO : no significant dependence to FUV field

（（ Bolatto et al. 2000Bolatto et al. 2000 ））

Johansson et al. 1998

30Dor -N159 region

SEST CO(1-0)

Bolatto et al. 2000

white: CII (55”)black: CO (33”)color : CI (250”)

ASTE telescopeASTE telescope Sept., 2003Sept., 2003 [CI] ([CI] (33PP11--33PP00) 492.160651GHz) 492.160651GHz Beam size 15” Beam size 15”

3.6pc @ LMC(50kpc)3.6pc @ LMC(50kpc) 4.3pc @ SMC(60kpc)4.3pc @ SMC(60kpc)

Observing gridObserving grid 30”, 20”, 15”, 7.5”30”, 20”, 15”, 7.5”

Velocity res. Velocity res. ～ ～ 0.31km/s0.31km/s TsysTsys ～～ 800 - K 800 - K （（ DSBDSB ）） Intg. Time Intg. Time ～～ 10min./on-positi10min./on-positi

onon Tr.m.s. Tr.m.s. ～ ～ 0.5K0.5K

[CI] [CI] observationsobservations

From ASTE [CI] obs.From ASTE [CI] obs. [CI][CI]

Similar/weaker than the Galactic GMCsSimilar/weaker than the Galactic GMCs 55 ～～ 15km/s line width (larger than the Galactic 15km/s line width (larger than the Galactic

GMCs)GMCs) N(C) : 0.8-3×10N(C) : 0.8-3×101717cmcm-2-2 （（ smaller than Orionsmaller than Orion ））

N(C)/N(N(C)/N(1313CO)CO) No significant difference among 30Dor, N159W, No significant difference among 30Dor, N159W,

N159SN159S Similar/larger than OrionSimilar/larger than Orion

SummarySummary

CO(3-2) observationsCO(3-2) observations Clump size is Clump size is ～ ～ 10pc, 10pc, Clump mass is Clump mass is ～ ～ 101055MMsun sun

⇒⇒larger than cluster’s size and larger than cluster’s size and massmass

⇒⇒substructuresubstructure

⇒⇒higher resolution observationshigher resolution observations

⇒⇒compare to Spitzer datacompare to Spitzer data

R(3-2)/(1-0) - HR(3-2)/(1-0) - Hαα flux correlation flux correlation From LVG analysisFrom LVG analysis

Tkin > 120K, n(HTkin > 120K, n(H22) = 10) = 104±0.54±0.5/cc (30Dor)/cc (30Dor) Tkin > 70K, n(HTkin > 70K, n(H22) ) ～ ～ 101044/cc (N159W)/cc (N159W)

⇒⇒HII regions -> dust -> molecular gasHII regions -> dust -> molecular gas⇒⇒compare to dust temperaturecompare to dust temperature

CO(3-2)/(1-0) sensitive to temperatureCO(3-2)/(1-0) sensitive to temperature Determine density independentlyDetermine density independently

⇒⇒1313COCO

[CI] Observations[CI] Observations [CI][CI]

Weaker than the Galactic GMCsWeaker than the Galactic GMCs 55 ～～ 15km/s line width (larger than the Galactic 15km/s line width (larger than the Galactic

GMCs)GMCs) N(C)/N(N(C)/N(1313CO)CO)

N(C) : 0.8-3×10N(C) : 0.8-3×101717cmcm-2-2 （（ smaller than Orionsmaller than Orion ）） No significant difference among 30Dor, N159W, No significant difference among 30Dor, N159W,

N159SN159S Similar/larger than OrionSimilar/larger than Orion

⇒ ⇒ SMCSMC

⇒ ⇒ Detailed comparison LMC, SMC, OrionDetailed comparison LMC, SMC, Orion