講義資料 2 京都大学大学院 2011 年 10 月 3-5 日 特別講義「電波天文学」 福井康雄 名古屋大学大学院 1

Part I GMCs in the LMC 2

Magellanic Clouds  D=50 kpc (one of the nearest)  Different environment from the MW.  High gas-dust ratio  Low metallicity  Active star formation  Massive star formation  Young populous clusters The Large Magellanic Cloud The Small Magellanic Cloud 3

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5 ~ 5 Myr ~ 10 Myr ~ 7 Myr Only HII regions 88 clouds (51 %) Clusters and HII regions 39 clouds (23 %) Only clusters ~ 5 Myr O-Starless 44 clouds(32 %) 150 pc Type I Type II Type III 3 Types of GMCs in the LMC

6 NN159 CO 3-2/1-0 vs. Ha

30Dor No.1 N206 No.1 GMC225 No.1 X CO = 3×10 -6 ； solid ： R 3-2/1-0,clump ； broken ： R 12/13 ＞ 50K, cm -3 (warm, dense) ＞ 30K, 10 3 cm -3 (warm. diffuse) 15-40K, 10 3 cm -3 (cool, diffuse) 7

CO(J=1-0)CO(J=3-2) CO(J=4-3) ASTEMopra NANTEN2 Spitzer(8, 24  m) (Meixner et al.2006) +NANTEN2 CO (4-3) N159S N159W N159E N159 region in the LMC NANTEN2 CO J=4-3 observations Mizuno et al

9 Results ： N159W –Temperature (K) –Density ×10 3 (cm -3 ) 1  level

10 Results ： N159S –Temperature (K) –Density ×10 3 (cm -3 )

11 Star formation Contours ： 12CO(J=4-3) Image ： optical B, V, H , O III (ESO)

12 イメージ： HI コントア： 12 CO ( コントアレベル １２ K から 3.6K ごと )

13 “3-D” comparison of CO and HI in the LMC Fukui et al Previous studies: 2D projection and larger spatial averaging, 100pc ~1kpc, e.g., Schmidt law Present study: local property of star forming GMC and HI at ~50pc scales X-Y and Velocity: 3-D datacube of CO NANTEN and HI ATCA (Kim et al.2003) Resolution: 40pc x 1.7 km/s HI CO

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15 SMC LMC

16 CO HI GMC grows by collecting HI [10 6 Mo per 10 Myr] Mass flow rate; dM/dt~0.1 solar mass/yr dM/dt=4  R 2 n(HI) V R~70pc n(HI)~10 cm -3 V~7 km/s

M33 Correlation with HI Deul & van der Hulst (1987) 17

18 Molecular clouds and star formation Ionized region High excited region Cold molecular gas N159S ＊ No massive star formation ＊ cold N159W ＊ massive star formation ＊ Ionized gas ＋ ＊ pre star forming region N159E ＊ Massive star formation ＊ extended ionized gas

Part II Westerlund 2, case of super-star cluster M20, isolated high mass star Collision-induced star formation 19

Genzel et al Super star cluster in the MW Figer et al [pc] 0.6[pc] 1.2[pc] Genzel et al Figer et al Central Cluster Arches ClusterQuintuplet Cluster O stars are rare in the MW It is important to study nearby young and rich cluster but, only five super star clusters in the MW 20

Smith et al blue: [OIII] green: Hα red: [SII] Car GMC (Yonekura et al. 2005)

Pre-cluster cloud core; requirements Compact, dense, massive cores; mass 10^4Mo – 10^5Mo, radius 1pc These are rare in the solar vicinity, because a dense core of 10^3Mo quickly forms a cluster and is dissipated e.g.,  Carnae We need non-star forming dense gas [magnetic field, strong turbulence, etc.] Case 1: quick formation of cores by shocks at km/s and/or Case 2: slow formation (3km s-1) but with gas of low-star formation efficiency 22

Total mass of star: 4500 M sun (Rauw et al. 2007) Age ： 2-3 Myr (Piatti et al. 1998) O type star ： 12 (Rauw et al. 2007) Wolf-Rayet (WRs) star ： 2 (Rauw et al. 2007) Distance:2.8 kpc (Ascenso et al.2007) 4.3 ± 1.4 kpc (Furukawa et al.2009) 8.3 ± 1.6 kpc (Rauw et al. 2007) Spitzer IRAC 3.6, 4.5, 5.8, 8.0  m HESS J Westerlund 2(Wd2) HII region RCW 49 HII region associated with the cluster (Churchwell et al. 2004) YSOs: 300 (Whitney et al. 2004) 23

Cloud-cloud collision scenario A collision between two clouds trigger the star formation of the central O7.5 star (Torii et al. 2011) Same scenario as Westerlund 2 (Furukawa+09; Ohama+10) 30km/s 24

Distribution of line intensity ratio Ratio is high near the cluster image: integrated intensity, cont.:CO(2-1) Red cross ： Wd2 Ratio 12 CO2-1/ 12 CO1-0Ratio 12 CO2-1/ 13 CO

LVG Analysis Gray ： error range15% line ： 12 CO2-1/ 12 CO1-0 wiggle line: 12 CO2-1/ 13 CO2-1 High Temp. Low Temp. Estimation of temperature and density by using the LVG analysis including 13CO(J=2-1) 26

Temperature distribution of the molecular clouds Image: Temperature, cont.: 12 CO(2-1) red cross ： Wd2 Suggesting gas is heated by the raditation from the cluster. 4 km/s Cloud16 km/s Cloud 27

Temperature with distance from Wd2 高温 → 分子雲全体が HII 領域に付随してい る 星団周辺で高温 星団から離れるにつれ て 減少している。 Molecular clouds are associated with Wd2 and RCW 49 Ohama, Furukawa et al

The Trifid Nebula (M20, NGC6514) D= kpc (Lynds & Oneil 85; Cambr´esy+11) Open cluster – ~500 Mo HII region （ ~0.3Myrs, Cernicharo+98 ） Central O star （ HD ） 2 nd generation star formation （ e.g., Cernicharo+98; Rho+01; Lefloch+08 ） 29

The Trifid Nebula (M20, NGC6514) (Rho+08) D= kpc (Lynds & Oneil 85; Cambr´esy+11) Open cluster – ~500 Mo HII region （ ~0.3Myrs, Cernicharo+98 ） Central O star （ HD ） 2 nd generation star formation （ e.g., Cernicharo+98; Rho+01; Lefloch+08 ） 30

NANTEN2 12 CO J=2-1 (Torii et al. 2011) 31

CO(J=2-1) + Spitzer 8um (Rho+08) 32

Velocity distribution 33

CO2-1/CO1-0 ratio 34

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(Dobashi+01) M20 37