Cloud-Cloud Collisions: a promising mechanism to trigger formation of high mass stars Hidetoshi SANO Nagoya University

Collaborators: Y. Fukui, K. Torii, A. Ohama, K. Hasegawa, Y. Hattori, H. Yamamoto, K. Tachihara, A. Mizuno, T. Onishi, A. Kawamura, N. Mizuno, A. Kuwahara, A. Mizuno and NANTEN2 consortium O stars and formation mechanism

Wolfire & Cassinelli (1986) n Stars having more than 20 M n Staller wind, strong UV, SNe, etc.. However, it is not known how the O stars are formed? n Observational issues - few, distant from us etc.. n Theoretical issues - large mass accretion rate etc. −4 −3 ~ 10 –10 M/yr −6 [~10 M/yr for low-mass stars]

We need some triggering mechanisms

Mopra Workshop 2015, December 10–11, 2015, University of New South Wales Numerical simulations of Cloud-Cloud Collisions

Step 1

Step 2

Step 3

Habe & Ohta 92 Anathpindika+12 Mopra Workshop 2015, December 10–11, 2015, University of New South Wales Numerical simulations of Cloud-Cloud Collisions

Inoue & Fukui 13, ApJL courtesy by Inoue-san Mopra Workshop 2015, December 10–11, 2015, University of New South Wales Observational Evidence of Cloud-Cloud Collisions n Super star clusters Westerlund 2, NGC 3603, RCW 38, DBS[2003]179, Trumpler 14 etc. (Furukawa+09; Ohama+10; Fukui+14; Fukui+15) n Star burst regions NGC 6334 & NGC 6357 (Fukui 15), W43 (Fukui+16) n HII regions M 20 (Torii+11), M43 / M42 (Fukui+16) Spitzer bubbles (Torii+15; + in prep.) Vela Molecular Ridge (HS+ in prep.), Gum 31 (Higuchi+ in prep.) n Ultra compact HII regions RCW 116 (Ohama+ in prep.) , Southern UCHII regions n Wolf-rayet nebula using Mopra NGC 2359 (HS+ in prep.) observed by NANTEN2 (2015)

Mopra Workshop 2015, December 10–11, 2015, University of New South Wales Super star clusters (SSCs)

©NASA/ESA/STScI ©NASA/ESA/STScI ©ESA ©NASA/JPL/Caltech ©NASA/ESA/STScI Westerlund 2 NGC 3603 RCW 38 [DBS2003]179 Trumpler 14

Age Stellar Mass Size Molecular 4 Cluster Name n SSCs are rich clusters of 10 [Myr] [Log M] [pc] clouds members incl. 20-30 O stars Westerlund 2 2.0 4.0 0.8 Yes NGC 3603 2.0 4.1 0.7 Yes n 5 SSCs are associated with ISM RCW 38 <1.0 -- 0.8 Yes n Ages are on average 2 Myrs [DBS2003]179 3.5 3.8 0.5 Yes Trumpler 14 2.0 4.0 0.5 Yes Arches 2.0 4.3 0.4 No Westerlund 1 3.5 4.5 1.0 No Quintuplet 4.0 4.0 2.0 No Mopra Workshop 2015, December 10–11, 2015, University of New South Wales SSCWesterlund 2

n (l, b) = (284°.27, -0 °.33) n O-Star x 12, WR-star x 2

n Total mass of the stars 4,500 M (Rauw+07) n Age 2−3 Myr (Piatti+98) n Distribution of dust influenced by stars (Churchwell+98) n Star formation in progress n YSO ~300 (Whitney+04)

We found two giant molecular clouds (GMCs) associated with Westerlund 2 (Furukawa+09; Ohama+10)

Mopra Workshop 2015, December 10–11, 2015, University of New South Wales SSCWesterlund 2 (Furukawa+09; Ohama+10)

Furukawa+09 n Two GMCs (red/blue) are complementary distributed toward Westerlund2. n The velocity separation of the two clouds is 15–25 km s−1, can not be bound with the gravity. Mopra Workshop 2015, December 10–11, 2015, University of New South Wales SSCWesterlund 2 (Furukawa+09; Ohama+10)

Ohama+10

n Both the two GMCs are heated by the strong UV radiation from the SSC à Both the two GMCs are physically associated with the SSC, although they have a large velocity separation.

Mopra Workshop 2015, December 10–11, 2015, University of New South Wales SSC RCW 38

n High mass star-forming region n Bright HII region (Rodgers, Campbell & Whiteoak 60)

n Position: (l, b) = (268°, -1°) n Age: < 1 Myr (young cluster) n Distance: 1.7 kpc (Rodgers 60) n Number of stars: 103−4 (O ~30) (Wolk+06; Winston+11)

n Two bright mid-IR sources IRS 1 and IRS 2 (Frogel & Persson 74; Smith+99; IRS1 DeRose+09) IRS 2

A close-up of the central 2.5’ (1.2 pc) of RCW 38 (Wolk et al. 2006; credite ESO). In this VLT image, Z band data are printed as blue, H band data are green and K band are red. Mopra Workshop 2015, December 10–11, 2015, University of New South Wales SSC RCW 38 (Fukui+15, arXiv:1504.05391)

(a) (b) (c)

Fukui+15 (a-b) Mopra 13CO J = 1-0 intensity maps (c) p-v diagram of 12CO J = 3-2 / 1-0 ratio using the Mopra & ASTE telescopes n The ring-like and filamentary clouds are located toward the SSC. n Both the two clouds show a high-intensity ratio > 0.6 à Evidence for physical association with the SSC. Mopra Workshop 2015, December 10–11, 2015, University of New South Wales SSCTrumpler 14

n SSC in the Carina nebula (e.g., Hur+12) n Position: (l, b) = (287.4°, -0.6°) n Age: 2-3 Myr (Hur+12) n Distance: 2.3 kpc (Smith+06) n Number of stars in the Carina nebula - O stars: > 65 - Wolf-Rayet stars: 3 - intermediate mass stars: ~100 - low-mass pre-MS: ~10,000 - η Carina (Smith+06; Corcoran+04)

Most recently, we found two molecular clouds associated with the SSC by using NANTEN2 CO datasets.

HST image toward the super star cluster Trumpler 14. Mopra Workshop 2015, December 10–11, 2015, University of New South Wales SSCTrumpler 14

Trumpler 14

n Two clouds (red/blue) are complementary distributed toward Trumpler 14 à We observed the two clouds using the NANTEN2 CO J = 2-1 lines Mopra Workshop 2015, December 10–11, 2015, University of New South Wales SSCTrumpler 14 NANTEN2 2015

Images: CO 2-1/1-0 Contours: CO 2-1

n Both the red and blue clouds show a high-intensity ratio > 1.0 à Evidence for physical association with the SSC and Carina nebula Mopra Workshop 2015, December 10–11, 2015, University of New South Wales Spitzer Bubbles

False color images of the Spizer bubbles (Green: 8 μm, Red: 24 μm). n Churchwell+06 identified ~600 ring-like structures using the Spitzer 8 μm. The work was followed by an expanded catalog of 5106 bubbles (Simpson+12).

High-mass star n The pressure-driven expanding HII region is usually discussed to Ionized/hot gas explain the formation of the Spitzer bubbles (e.g., Deharveng+10) Expanding motion

à But, almost bubbles have no CO/ Collected neutral gas HI gas having an expanding motion. and cold dust

Mopra Workshop 2015, December 10–11, 2015, University of New South Wales Spitzer Bubbles as the site of Cloud-Cloud Collision

False color images of the Spizer bubbles (Green: 8 μm, Red: 24 μm). Superposed contours show the CO clouds (red & blue shifted cloud) taken by NANTEN2. n We observed ~60 Spitzer (Torii bubbles et in al. CO 2015lines using + α NANTEN2) Almost bubbles have two clouds (Vsep.~10-30 km/s) àCloud-Cloud Collision

0 I ccompressedompressed II HHIIII rregionegion III HHIIII rregionegion IV llargearge cloudcloud llayerayer ssmallmall ccloudloud

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CCompactompact HHIIII regionregion SSpitzerpitzer bbubbleubble SSpitzerpitzer bbubbleubble Cloud-Cloud Collision Model Spitzer Bubbles WWRR starstar Mopra Workshop 2015, December 10–11, 2015, University of New South Wales • Habe & Ohta (1992)による数値計算が基礎 • 大小２つの分子雲の理想的な正面衝突 • 観測より、衝突速度~10–30km/s • 分子雲(小)が分子雲(大)の内部に空洞と圧縮層→O型星を形成 • SpitzerバブルRCW120がStage IIIで理解可能(Torii et al. 2015) • ちょっと考えてみると…分子雲のサイズ、密度、速度、衝突角度、 軸のオフセットで様々な観測的特徴・形成される星の規模・形態 に多様なバリエーションがありそう

1 Spitzer Bubbles: RCW 120

n Galactic HII region (Rodgers+60) n Cataloged as S7 (Churchwell+06)

n Position: (l, b) = (348.3°, 0.5°) n Age: < 5 Myr (e.g.,Martins+10) n Distance: 1.3 kpc n Single O8-star (~20 M) n An HII region inside the ring

n The triggered star formation accumulated by the pressure- driven H II region (e.g., Zavagno+07; Deharveng+09)

We observed CO J = 1-0, 2-1, 3-2 using the NANTEN2, ASTE, and Mopra telescopes False color images of the RCW120 (Green: 8 μm, Red: 24 μm). Star symbol shows position of the O star. Mopra Workshop 2015, December 10–11, 2015, University of New South Wales The Astrophysical Journal, 806:7 (21pp), 2015 June 10 Torii et al.

The Astrophysical Journal, 806:7 (21pp), 2015 June 10 Torii et al.

The Astrophysical Spitzer Journal, 806:7 Bubbles:(21pp), 2015 June 10 RCW 120 (Torii+15) Torii et al.

NANTEN2 12CO(J = 1-0) Δθ ~180’’ ⬇ For large scale

The Astrophysical Journal, 806:7 (21pp), 2015 June 10 Torii et al.

Mopra 12CO(J = 1-0) Δθ ~45’’ Figure 3. Position–velocity maps for a very large area of RCW 120. Contours show the averaged ⬇ intensity of the NANTEN2 12CO data, and the color image shows that of the SGPS H I 21 cm data (McClure-Griffiths et al. 2005). The Forblack solid small line and scale dashed lines indicate the position of the O star and the approximate extent of the 8 μm ring, respectively. The red arrow and blue arrows indicate the directions of the bridging features seen in CO and H I, respectively. cloud, suggesting a physical interaction between the two clouds and RCW 120. In addition, H I has other several high velocity features throughout the blue cloud as shown by the blue arrows with the dashed lines in Figure 3. These H I features are not seen at the negative velocity range, and provides another Torii+15support for the physical connection between the red cloud and the blue cloud even outside RCW 120. The typical atomic column density of the high velocity H I features is 4 1020 Mopra Workshop 2015, December 10–11,12 2015, University of New South Wales ∼ × Figure 2. Large-scale CO J = 1–0 distributions toward RCW 120 are cm−2 by assuming optically thin 21 cm emission, and is presented12 with13 the NANTEN2 data18 set. The red cloud and the blue cloud are 20 −2 Figureshown 4. CO, in (a) andCO,(b) and, respectively. C O J The= 1 observed–0 distributions area in the toward Mopra RCW∼8 120× 10 withcm theby Mopra considering data set. the The opacity red correction cloud is shown of the in (a)–(c), while the blue cloud in (d)–(f). observations is hereFigure shown 3.12Position by white–13velocity lines. ( mapsc)18A forcomparison a very large of the area red of cloud RCW 120. Contours21 cm emission discussed in Fukui et al. (2014a, 2015a). At a −1 For both of the clouds, CO, CO, C O J 1–120 emission are presented in the left, center, and right panels, respectively. The unit of color bars is K km s . The show the averaged intensity of the NANTEN2= CO data, and the color image (image) and the blue cloud (white contours) is shown in a close-up view, in distance of RCW 120, the total atomic mass of the H I features −1 large cross indicatesshows the that O of star, the SGPS and H theI 21−1 YSOs cm data ( andMcClure-Grif dust condensationsfiths et al. 2005). The are plotted in the same manner as Figure 1. The gray contours in (a) are plotted at 90 K km s which the bridging feature at −23 to −20 km s shown in Figure 3 is plotted in is estimated to be 100 M for the optically thin case, and to be and indicatethe thick blackthe region contours.black solid that The line YSOs is and used anddashed dust to lines condensations estimate indicate the the are position plotted molecular of in the O mass star and of the the ring structure∼ ⊙(see Section 3.5). same manner asapproximate Figure 1, extent where of the the region 8 μm that ring, was respectively. used for theThe YSO red arrow and∼200 blueM⊙ by adopting the opacity correction by Fukui et al. identifications isarrows shown indicate by black the dashed directions lines. of the bridging features seen in CO and(2014a H I, , 2015a). respectively. cloud, suggesting a physical interaction between the two clouds 3.2. Detailedand RCW Molecular 120. In addition, Distributions H I has other several with high Mopra4 velocity CO distributions in the blueshifted velocity range obtained features throughout the blue cloud as shown by the blue arrows with Mopra are shown in Figures 4 d – f . The blue cloud is Detailed CO distributions toward RCW 120 using the Mopra ( ) ( ) with the dashed lines in Figure 3. These H I features are not detected in C18O with a more than 3 σ level, while the data sets are shownseen at atthe 0.2 negative pc spatial velocity resolution. range, and provides Figure another4 shows −1 12 the integratedsupport intensity for the distributionsphysical connection of between the 12 theCO, red cloud13CO, and and −33 km s cloud is seen only in CO at the southern part of 18 the blue cloud even outside RCW 120. The typical atomic the 8 μm ring. It is notable that the blue cloud has a molecular 20 C O emissioncolumn in density the of redshifted the high velocity and H I features blueshifted is ∼4× 10 velocity Figure 2. Large-scale 12CO J = 1–0 distributions toward RCW 120 are cm−2 by assuming optically thin 21 cm emission, and is protrusion just next to the western tip of the 8 μm ring, and it presented with the NANTEN2 data set. The red cloud and theranges. blue cloud In are Figures 4(a)–(c), the red cloud clearly shows a ring- 20 cm−2 by considering the opacity correction of the shown in (a) and (b), respectively. The observed arealike in the structure Mopra ∼ in8× all 10 of the three CO lines, where the molecular looks elongated inside the 8 μm ring through the opening at the observations is here shown by white lines. (c) A comparison of the red cloud 21 cm emission discussed in Fukui et al. (2014a, 2015a). At a −1 north. Typical N(H2) of the −33 km s cloud and the blue (image12) and the13 blue cloud (white18 contours) is shown in a close-upring view, consists in distance of small of RCW 120,clumps the total with atomic mass sizes of the of H I 0.3features–0.5 pc. Figurewhich 4. theCO, bridgingCO, feature and at − C23 toO−20J km= s1−1–shown0 distributions in Figure 3 is plotted toward in RCW18 120 with the Mopra data set. The red cloud is shown in (a)–(c), while the blue cloud in (d)–(f). 12 21 21 12 13 18 is estimated to be 100 M for the optically thin case, and to be cloud are estimated−1 with CO to be 4 10 and 8 10 For boththe thick of the black clouds, contours. TheCO, YSOs andCO, dust C condensationsO J 1Detection– are0 plotted emission in the are of presented C O suggests in the∼ left, the center,⊙ existence and right of panels, the denserespectively. gas The in unit of color bars is K km s . The ∼ × ∼ × = 200 M by adopting the opacity correction by Fukui et al. −2 same manner as Figure 1, where the region that was used for the YSO ∼ ⊙ cm , respectively, signi−1 ficantly smaller than that of the ring large crossidentifications indicates is shown the by O black star, dashed and lines. the YSOs andthe dust molecular condensations(2014a ring, are, 2015a plotted and). the in the dense same molecular manner as Figure ring1. corresponds The gray contours in (a) are plotted at 90 K km s and indicate the region that is used to estimate thewell molecular with the mass dust of the distribution ring structure(Zavagno(see Section et al.3.5)2007. ; Deharveng component of the red cloud. et al. 2009). Typical H2 column density N(H2) of the ring In Figure 5 comparisons between CO and other wavelengths 4 22 −2 12 – 13 component is estimated to be ∼3× 10 cm with the CO are presented. Figures 5(a) (c) show the CO integrated 3.2. Detailed Molecular Distributionsintegrated with Mopra intensities by assumingCO distributions an X-factor inof the 2 × blueshifted1020 velocityintensity range distributions obtained of the red cloud (black contours and −1 −1 −2 with Mopra are shown in Figures 4 d colors– f . The) superimposed blue cloud is on (a) the Spitzer 8 μm, (b) the Detailed CO distributions toward RCW(K 120 km s using) thecm Mopra(Strong et al. 1988), where the X-factor is ( ) ( ) 1812 SuperCOSMOS Hα (Parker et al. 2005), and (c) the SUMSS data sets are shown at 0.2 pc spatial resolution.an empirical Figure conversion4 shows factordetected from in the C OCO with integrated a more than 3 σ level, while the −1 12 843 MHz radio continuum (Bock et al. 1999) grayscale the integrated intensity distributions ofintensity the 12CO, to N13(CO,H2). and On the other−33 km hand, s cloudN(H2) istoward seen only the inO CO at the southern part of 22 −2 images. In the SUMSS image in Figure 5(c), the thick C18O emission in the redshifted andstar blueshifted located inside velocity the ring isthe estimated 8 μm ring. to be It1.4 is notable× 10 cm that the. blue cloud has a molecular contours are plotted at the 5σ level. As seen in Figure 5(a), the ranges. In Figures 4(a)–(c), the red cloudThis clearly estimate shows can a ring-be comparedprotrusion with the just visual next extinction to the westernAv tip of the 8 μm ring, and it derived as 4.65 mag toward thelooks same elongated direction inside(Avedisova the 8 μm & ring through8 μm the ring opening apparently at the traces the inner rim of the red cloud, like structure in all of the three CO lines, where the molecular −1 Kondratenko 1984), whichnorth. corresponds Typical toN( theH2) totalof the ISM−33 km ssupportingcloud and physical the blue association between the red cloud and ring consists of small clumps with sizes of 0.3–0.5 pc. 21 −2 18 12 RCW21 120. No apparent21 molecular counterpart is seen toward Detection of C O suggests the existencecolumn of the density dense gasN(H inI+H2) cloudof 9 are× estimated10 cm with, almostCO to be ∼4× 10 and ∼8× 10 −2 fi the molecular ring, and the dense molecularcomparable ring corresponds to the above columncm , respectively, densities, by signi usingficantly the smallerthe than western that tip of ofthe the ring 8 μm ring, which is also con rmed with 21 −2 −1 well with the dust distribution (Zavagnorelations et al. 2007N(;H DeharvengI+H2)=5.8×−component 10EB ( of V the) cm redmag cloud. and the Herschel 250 μm emission in Figure 1. In the supplemental Av 3.1EB ( V ) (Bohlin etIn al. Figure1978).5 Itcomparisons is thus suggested between COvelocity and other channel wavelengths maps in Figure 15, a possible counterpart for et al. 2009). Typical H2 column density=N(H2) of− the ring 12 −1 that22 the−2 exciting O12 star is on theare far presented. side of the Figures red cloud5(a along)–(c) showthe the western13CO tip integrated is seen in CO at around −10 km s , although component is estimated to be ∼3× 10 cm with the CO 13 18 integrated intensities by assuming anthe X-factor line of of sight 2 ×(LOS1020). intensity distributions of the red cloudit is(black weak contours in CO and and not detected in C O. Distribution of (K km s−1)−1 cm−2 (Strong et al. 1988), where the X-factor is colors) superimposed on (a) the Spitzer 8 μm, (b) the an empirical conversion factor from the 12CO integrated SuperCOSMOS Hα (Parker et al. 20055 ), and (c) the SUMSS intensity to N(H2). On the other hand, N(H2) toward the O 843 MHz radio continuum (Bock et al. 1999) grayscale 22 −2 star located inside the ring is estimated to be 1.4× 10 cm . images. In the SUMSS image in Figure 5(c), the thick This estimate can be compared with the visual extinction Av contours are plotted at the 5σ level. As seen in Figure 5(a), the derived as 4.65 mag toward the same direction (Avedisova & 8 μm ring apparently traces the inner rim of the red cloud, Kondratenko 1984), which corresponds to the total ISM supporting physical association between the red cloud and 21 −2 column density N(H I+H2) of 9 × 10 cm , almost RCW 120. No apparent molecular counterpart is seen toward comparable to the above column densities, by using the the western tip of the 8 μm ring, which is also confirmed with 21 −2 −1 relations N(H I+H2)=5.8×− 10EB ( V) cm mag and the Herschel 250 μm emission in Figure 1. In the supplemental Av = 3.1EB (− V ) (Bohlin et al. 1978). It is thus suggested velocity channel maps in Figure 15, a possible counterpart for that the exciting O star is on the far side of the red cloud along the western tip is seen in 12CO at around −10 km s−1, although the line of sight (LOS). it is weak in 13CO and not detected in C18O. Distribution of

5 The Astrophysical Spitzer Journal, 806:7Bubbles:(21pp), 2015 June RCW 10 120 (Torii+15) Torii et al.

Torii+15

Maps of 12CO J = 3-2 / 1-0 intensity ratio using the Mopra & ASTE telescopes n Both the two clouds show a high-intensity ratio > 1.0 à Evidence for physical association with the Spitzer bubble RCW 120 n No evidence for the expanding motion in the velocity space!!! Mopra Workshop 2015, December 10–11, 2015, University of New South Wales

12 Figure 6. R3–2/1–0 maps of the red cloud (a) and the blue cloud (b) are shown in the color image with the CO J = 1–0 contours. The exciting stars, YSOs, and dust condensations are plotted in the same manner as in Figure 1. The names of the condensations given by Deharveng et al. (2009) are shown in (b). Regions A–F depicted with dashed circles are the regions that are used for the LVG analysis in Figure 7. (c), (d) The regions with high R3–2/1–0 ⩾ 0.8 are shown in contours. The background is a composite image of the Herschel/SPIRE 250 μm (red) and the Spitzer/IRAC 8 μm (green). In (d), the outer boundary of the blue cloud is shown in yellow dashed contours. whose western rim is traced by the 8 μm and 250 μm emission, LVG analysis (e.g., Goldreich & Kwan 1974) to estimate the suggesting that the cloud is illuminated by the O star. The kinetic temperature Tk and number density n(H2) of the western tip of the 8 μm ring in contrast shows relatively low molecular gas, using the intensity ratios 13CO J = 1–0/12CO R3–2/1–0 compared with the other part of the 8 μm ring. On the J = 1–0 (hereafter R13 12) as well as R321−−0. It should be other hand, R3–2/1–0 in the blue cloud is high at its southern noted that the assumption of the uniform velocity gradient is part. The highest R3–2/1–0 is seen at an extension of the eastern not always valid in the molecular gas associated with H II tip of the 8 μm ring, while the western tip also shows high regions, but radiative transfer calculations considering a R3–2/1–0. As seen in Figure 6(d), these high R3–2/1–0 regions microturbulent cloud interacting with an H II region show no show excellent coincidence with the 250 μm emission, significant difference from the LVG analysis (e.g., Leung & particularly for the very tip of the western side of the 8 μm Liszt 1976; White 1977). We therefore adopt the LVG ring. Another high R3–2/1–0 is distributed toward condensation approximation in the present study. 5 a at the south-eastern rim of the blue cloud, suggesting Six target regions (regions A–F) used in the present analysis possible association between the blue cloud and the condensa- are shown in Figures 6(a) and (b). Since 12CO is strongly tion, although the red cloud also shows high R3–2/1–0 toward the affected by self-absorption toward the dense part of the ring, same direction as shown in Figure 6(a). particularly around condensations 1–3, these regions are not In order to investigate the origin of the highly excited gas in adopted. In the red cloud regions A and B are distributed both the red cloud and the blue cloud, we here perform the toward condensations 4 and 5c in the dense ring, respectively,

7 Spitzer Bubbles: RCW 120 (Torii+15)

n RCW 120 is able to form by Cloud-Cloud Collision between the large cloud and the small cloud half of which is dissociated by strong UV radiation from the O star.

n Collision velocity ~30 km/s n Time scale of O-star formation < 0.8 Myr −5 à dM/dt > 2 × 10 M/yr −4 (Torii et al. 2015 (up to 10+ α )M/yr )

0 I ccompressedompressed II HHIIII rregionegion III HHIIII rregionegion IV llargearge cloudcloud llayerayer ssmallmall ccloudloud

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CCompactompact HHIIII rregionegion SSpitzerpitzer bbubbleubble SSpitzerpitzer bbubbleubble Cloud-Cloud Collision Model RCW 120 WWRR starstar Mopra Workshop 2015, December 10–11, 2015, University of New South Wales • Habe & Ohta (1992)による数値計算が基礎 • 大小２つの分子雲の理想的な正面衝突 • 観測より、衝突速度~10–30km/s • 分子雲(小)が分子雲(大)の内部に空洞と圧縮層→O型星を形成 • SpitzerバブルRCW120がStage IIIで理解可能(Torii et al. 2015) • ちょっと考えてみると…分子雲のサイズ、密度、速度、衝突角度、 軸のオフセットで様々な観測的特徴・形成される星の規模・形態 に多様なバリエーションがありそう

1 HII Regions: Vela Molecular Ridge (VMR) & Gum 31

Vela Molecular Ridge (BLAST Vela deep field)

n We observed ~ 10 HII reigns in the Vela molecular ridge (VMR) and Gum 31 using the NANTEN2 CO 2-1 line in this season. Gum 31 (NGC 3324)

Mopra Workshop 2015, December 10–11, 2015, University of New South Wales HII Regions: VMR (HS+) & Gum 31 (Higuchi+)

Images and contours show red and blue shifted clouds having V separation of 5-20 km/s n All HII regions have two molecular clouds having different velocity. n We are observing CO 3-2 using ASTE (PI: HS) à We need Mopra CO 1-0!! Mopra Workshop 2015, December 10–11, 2015, University of New South Wales Ultra compact HII Regions (Ohama+) n UCHII regions are also abele to understand as cloud-cloud collision

RCW 116 (green: 8 μm, red: 24 μm)

(Torii et al. 2015 + α)

0 I ccompressedompressed II HHIIII rregionegion III HHIIII rregionegion IV llargearge cloudcloud llayerayer ssmallmall ccloudloud

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CCompactompact HHIIII rregionegion SSpitzerpitzer bbubbleubble SSpitzerpitzer bbubbleubble Cloud-Cloud Collision Model UCHII Region WWRR starstar Mopra Workshop 2015, December 10–11, 2015, University of New South Wales • Habe & Ohta (1992)による数値計算が基礎 • 大小２つの分子雲の理想的な正面衝突 • 観測より、衝突速度~10–30km/s • 分子雲(小)が分子雲(大)の内部に空洞と圧縮層→O型星を形成 • SpitzerバブルRCW120がStage IIIで理解可能(Torii et al. 2015) • ちょっと考えてみると…分子雲のサイズ、密度、速度、衝突角度、 軸のオフセットで様々な観測的特徴・形成される星の規模・形態 に多様なバリエーションがありそう

1

Workshop 2015, December 10–11, 2015, University of New South Wales Wales South New of University 2015, 10–11, December 2015, Workshop Mopra

Green: 52-57 km/s , Red: 35-39 km/s Blue: 65-68 km/s , 1 1

J CO 45-m Nobeyama Contours: =1-0 (HS+ in prep.)

に多様なバリエーションがありそう 12

軸のオフセットで様々な観測的特徴・形成される星の規模・形態

、 密度 、 分子雲のサイズ ちょっと考えてみると 、 衝突角度 、 速度

• …

で理解可能 が バブル

• (Torii et al. 2015) 2015) al. et (Torii III Stage RCW120 Spitzer

の内部に空洞と圧縮層 大 が分子雲 小 分子雲 型星を形成

• O → ) ( ) (

衝突速度 、 観測より

• ~10–30km/s ~10–30km/s

大小２つの分子雲の理想的な正面衝突

•

による数値計算が基礎

& & Habe • (1992) Ohta

Contours: HI (Cappa+99)

(Torii et al. 2015 + α)

r a t s star R W WR

WR Nebula

Spitzer bubble z t i p S Spitzer e l b b u b r e

Spitzer bubble e z t i p S Spitzer e l b b u b r

Compact HII region HII a p m o C Compact n o i g e r I I H t 0 I ccompressedompressed II HHIIII regionregion III HHIIII rregionegion IV c llargearge ccloudloud llayerayer

ssmallmall ccloudloud

r a t s star O O

O starstar

d u o l c cloud l l a m s small

(WR nebula) (WR

c cloud e g r a l large d u o l r e y a l layer

n o i g e r region I I H HII

n o i g e region r I I H HII

NGC 2359 NGC

0 IV I II

III d e s s e r p m o compressed CCompactompact HHIIII regionregion SSpitzerpitzer bbubbleubble SSpitzerpitzer bubblebubble c

WWRR starstar

Wolf- nebula NGC 2359 NGC nebula rayet (HS+)

(Torii et al. 2015 + + 2015 al. et (Torii ) α

• Habe & Ohta (1992)による数値計算が基礎 • 大小２つの分子雲の理想的な正面衝突 • 観測より、衝突速度~10–30km/s • 分子雲(小)が分子雲(大)の内部に空洞と圧縮層→O型星を形成 • SpitzerバブルRCW120がStage IIIで理解可能(Torii et al. 2015) • ちょっと考えてみると…分子雲のサイズ、密度、速度、衝突角度、 軸のオフセットで様々な観測的特徴・形成される星の規模・形態 に多様なバリエーションがありそう

1 Wolf-rayet nebula NGC 2359 (HS+)

Contours: Nobeyama 45-m 12CO J=1-0 (HS+ in prep.) Red: 35-39 km/s, Green: 52-57 km/s, Blue: 65-68 km/s Mopra Workshop 2015, December 10–11, 2015, University of New South Wales Observational Evidence of Cloud-Cloud Collisions n Super star clusters Westerlund 2, NGC 3603, RCW 38, DBS[2003]179, Trumpler 14 etc. (Furukawa+09; Ohama+10; Fukui+14; Fukui+15) n Star burst regions NGC 6334 & NGC 6357 (Fukui 15), W43 (Fukui+16) n HII regions M 20 (Torii+11) Only 38 sources have been observed Spitzer bubbles (Torii+15; + in prep.) Vela Molecular Ridge (HS+ in prep.), Gum 31 (Higuchi+ in prep.) n Ultra compact HII regions Only 8 sources have been observed RCW 116 (Ohama+ in prep.) , Southern UCHII regions n Wolf-rayet nebula We should be observed many NGC 2359 (HS+ in prep.) sources (red) by using Mopra!

Mopra Workshop 2015, December 10–11, 2015, University of New South Wales